Leaf-cutting ants (Hymenoptera: Formicidae) are one of the main pests found in the Americas and they cause global economic losses worth several billions of dollars. While pesticides have been the most widely used control method, new management alternatives in a context of agroecological transition are now being considered. This study focuses on the leaf-cutting ants species found in the pan-Amazon region. As part of efforts to improve management of these pests, this multi-criteria analysis of control strategies covers a total of 691 experiments collected from 153 studies, and the control were evaluated as a function of their management efficacy, environmental and human health impacts, and their ease of application. Chemical control methods were effective but posed a danger to human health and the environment, whereas mechanical methods and integrated management were more sustainable but not always very effective. Some of the biocontrol methods were evaluated as effective and safe for the environment and human health, including the use of entomopathogenic fungi Beauveria bassiana (Bals.-Criv) Vuill. (Hypocreales: Cordycipitaceae) and Metarhizium anisopliae (Metschn.) Sorokïn (Hypocreales: Clavicipitaceae) in the form of bait or sprayed in the nest, or the application of plant mulch in the nest using Tithonia diversifolia (Hemsley) A. Gray (Asterales: Asteraceae) or Canavalia ensiformis L. DC. (Fabales: Fabaceae). Because of variations in the efficacy data between laboratory and field tests, we are in favor of evaluating these control methods during field studies with different leaf-cutting ant species and under different environmental conditions. These methods should adopt experimental arrangements that are appropriate for local socioeconomic conditions adapted for farmers.

Graphical Abstract

Buzz-pollinated plants require visitation from vibration producing bee species to elicit full pollen release. Several important food crops are buzz-pollinated including tomato, eggplant, kiwi, and blueberry. Although more than half of all bee species can buzz pollinate, the most commonly deployed supplemental pollinator, Apis mellifera L. (Hymenoptera: Apidae; honey bees), cannot produce vibrations to remove pollen. Here, we provide a list of buzz-pollinated food crops and discuss the extent to which they rely on pollination by vibration-producing bees. We then use the most commonly cultivated of these crops, the tomato, Solanum lycopersicum L. (Solanales: Solanaceae), as a case study to investigate the effect of different pollination treatments on aspects of fruit quality. Following a systematic review of the literature, we statistically analyzed 71 experiments from 24 studies across different geopolitical regions and conducted a meta-analysis on a subset of 21 of these experiments. Our results show that both supplemental pollination by buzz-pollinating bees and open pollination by assemblages of bees, which include buzz pollinators, significantly increase tomato fruit weight compared to a no-pollination control. In contrast, auxin treatment, artificial mechanical vibrations, or supplemental pollination by non-buzz-pollinating bees (including Apis spp.), do not significantly increase fruit weight. Finally, we compare strategies for providing bee pollination in tomato cultivation around the globe and highlight how using buzz-pollinating bees might improve tomato yield, particularly in some geographic regions. We conclude that employing native, wild buzz pollinators can deliver important economic benefits with reduced environmental risks and increased advantages for both developed and emerging economies.

Tropilaelaps mite (Mesostigmata: Laelapidae) is an ectoparasite of bees present, to date, only on the Asian continent. In the context of the threat of Tropilaelaps's introduction into new regions, accurate, rapid, and sensitive detection of the Tropilaelaps spp. is essential. In the present study, we developed a novel molecular method for bee mite's identification, which consists of a new real-time PCR method. A high-resolution melting analysis (HRM) was then performed on the amplified products to differentiate the species. PCR amplification was applied on the cytochrome c oxidase subunit I gene (580 bp). Short fragments from the most variable regions of this gene were identified in silico to amplify and discriminate among the four Tropilaelaps species. Four reference plasmids were synthesized to characterize species by well-distinguished melting curves. The method was then validated in terms of its specificity and sensitivity using a panel of 12 specimens. The results showed that an HRM method can be applied for the intended objective: for rapid and simultaneous identification of Tropilaelaps species. To our knowledge, this study reports the first direct HRM assay developed for the genome of a bee mite, specific for Tropilaelaps species. This COI barcode-HRM technique could be a promising tool for mite species identification.

Interrupting the spring incubation of Megachile rotundata (F.) with a period of low-temperature storage for synchronizing the bees' emergence with crop bloom is an essential part of M. rotundata management. Previously, we demonstrated that bees exposed to thermoperiods (TPs) during low-temperature storage have higher survival rates than bees exposed to constant temperatures. But changing the temperature in the large mass of bees commonly found in most commercial settings would place considerable stress on the chambers' refrigeration system. Reducing the difference between a TP's cryophase and thermophase would decrease the stress on the refrigeration system. Therefore, we investigated a range of TPs with cryophases (12 h) of 6, 12, or 15°C and thermophases (12 h) of 15 or 18°C and compared the survival rates of these bees against bees exposed to constant temperatures of 12, 15, or 18°C. For eye-pigmented pupae, the TP 6–18°C and the control fluctuating thermal regime (FTR; 6°C with a daily 1-h pulse at 20°C) had the highest survival rates for the 2 yr tested. For the constant-temperature storage protocols, constant 15 and 18°C were either equivalent or lower survival than the control FTR. For emergence-ready adults, the 6–18°C TP had the highest survival rates. The constant 15°C and the control FTR had equivalent survival rates. Under the current constraints imposed by a commercial chamber's refrigeration system, interrupting M. rotundata spring incubation by exposing the developing bees to constant temperatures of 15–18°C is currently the best option for commercial operations.

Hive design and apicultural processes have not been fundamentally changed since the design and commercialization of the Langstroth moveable frame hive in 1854. Colonies of Apis mellifera Linnaeus (Hymentoptera: Apidae) (the honey bee) maintain a brood nest temperature within the narrow range of 34.5–35.5°C, critical for brood development. Apis mellifera invest considerable energy to maintain hive homeostasis through behavioral modification of the hive environment. Human honey-harvesting processes and removal of the honey-filled comb (a source of thermal mass) have a detrimental impact on hive temperature that requires an increased investment of energy to rectify. This additional energy demand on the bees is a form of stress to the colony and diverts workers away from other essential tasks to that of environmental management. We investigated the thermal energy loss resulting from the removal and extraction of honey, the rate of thermal loss of an Australian standard Langstroth 10 frame hive, and the effect of honey and wax as a thermal mass in unoccupied bee hive. The results demonstrate that considerable energy expenditure would be required to rectify the hive thermal environment after honey harvesting or honeycomb frame addition. Honey provides thermal mass in the beehive, acting as a thermal buffer to external temperature change, which may mediate part of the thermal losses from the simplistic design of the Langstroth hive. Identification of these impacts in current apicultural practice and hive design allows for the improvement in the design of beehives and associated practices. These improvements may reduce stress to the bee colony, increasing colony efficiency for pollination and nectar foraging.

In nature, a plant can be infected by multiple viruses simultaneously. However, the effects of coinfection on plant–vector interactions are less well studied. Two begomoviruses of the family Geminiviridae, Tomato yellow leaf curl virus (TYLCV) and Tomato yellow leaf curl China virus (TYLCCNV), occur sympatrically in China. Each of them is reported to increase the performance of whitefly vector via manipulation of plant traits. In this study, we examined the effects of coinfection by the two viruses TYLCV and TYLCCNV on plant–whitefly interactions, compared to that infected by a single virus. We found that plants infected by two viruses showed aggravated symptoms but the performance and preference of whiteflies were not altered significantly compared to singly-infected plants. Coinfection suppressed the transcription of genes involved in jasmonic acid (JA) signaling pathway in plants, but showed no significant difference to single-virus infected plants. These findings suggest that although TYLCV and TYLCCNV may synergistically induce plant symptoms, they did not manipulate synergistically plant-mediated responses to the insect vector.

Many growers on mushroom farms producing white and brown varieties of Agaricus bisporus have noticed a potential association between sciarid fly (Lycoriella ingenua) pest populations and green mold (Trichoderma aggressivum) disease expression, and suspect that in addition to other preventative measures, controlling flies may be important to controlling green mold spread. In this study, we examined the association between L. ingenua populations and green mold disease incidence in commercial mushroom farms. In addition, we studied how relevant variables related to farming practices and farm characteristics may affect fly and disease incidence. Our data show that L. ingenua and green mold incidence are associated and that preventative measures such as sanitation and new technologies to reduce human-substrate contact are correlated with reduced green mold incidence. In addition, data indicated farm characteristics such as the proximity to neighboring farms as well as an organic mushroom growing regime are associated with fly incidence.

One environmentally friendly method used to manage Bactrocera dorsalis (Hendel), a key agricultural pest of substantial economic importance, is the sterile insect technique (SIT). Nevertheless, several deficiencies related to this strategy impair the success of the SIT, including the inferior performance of released sterile males compared with wild males, which could be partly solved by the utilization of gut symbionts as probiotic dietary components. In this study, a culture-dependent method was used to isolate and characterize gut-associated bacterial species in adult B. dorsalis genetic sexing strain (GSS) males. In addition, three bacterial isolates from the Enterobacteriaceae family, namely, Enterobacter sp., Morganella morganii, and Moellerella wisconsensis, were used as supplements in larval and adult diets to assess their effects on the life-history traits of irradiated males. Consistent with many previous studies, Enterobacter spp. was shown to be beneficial, with some quality control indices, such as adult size, pupal weight, survival rate under stress and nutritionally rich conditions, and mating competitiveness, being significantly increased, while slight nonsignificant increases in emergence rate and flight ability were observed. Conversely, the M. morganii and M. wisconsensis strains both had negative effects on irradiated male fitness and mating competitiveness. Our results, in combination with those of earlier studies, can contribute to improving the effectiveness of SIT application by enhancing the different aspects of augmentative rearing and biological traits of pests under laboratory rearing conditions.

An effective stockpiling method for egg masses of the invasive brown marmorated stink bug (Halyomorpha halys [Stål]; Hemiptera: Pentatomidae) would be useful for rearing and field studies of its egg parasitoid Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae). The current method of stockpiling H. halys egg masses at subzero temperatures has lethal and sublethal fitness consequences for T. japonicus. Our goal was to test the efficacy of refrigeration as an alternative method for stockpiling H. halys eggs. We show that parasitoid emergence from egg masses refrigerated at 8°C for up to two months before parasitism is higher than from frozen egg masses. In addition, 8°C cold storage usually had minimal or no sublethal fitness effects on emerging T. japonicus. Only after two months of host egg refrigeration did the emergence of T. japonicus begin to decrease significantly (by ∼10% relative to untreated viable egg masses), whereas egg masses previously frozen at –80°C had a ∼59% reduction in parasitoid emergence after 14 d of storage. Refrigerated egg masses that were subsequently exposed to a range of field-realistic average temperatures were still suitable for T. japonicus parasitism after 7 d. Our results demonstrate that refrigeration at 8°C, while resulting in complete mortality of H. halys embryos after 10 d, are more suitable for T. japonicus parasitism than those stored at –80°C. The quantity and quality of H. halys eggs that can be stockpiled with this method could facilitate T. japonicus laboratory colony maintenance, field monitoring, and releases.

The bug Orius similis Zheng is a native generalist predator of insect pests in southern China. The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is a notorious defoliator that is now an economically important insect pest throughout China. To investigate the ability of O. similis to control FAW, we evaluated the predatory capacity, behavior, and functional response of O. similis with respect to FAW and their olfactory response. Both females and males successfully preyed on FAW eggs and first-instar larvae but not on second-instar or older larvae. Adult O. similis only attacked and killed one egg or one larva at a time before sucking the prey, and similar predatory behavior was also observed with regard to FAW egg masses. Both female and male O. similis exhibited type II functional response when preying on FAW eggs and first-instar larvae. Maximum estimated prey consumed per day was 23.7 eggs and 26.2 larvae for adult females and 22.5 eggs and 19.6 larvae for adult males. Moreover, in a Y-tube olfactometer experiment, both female and male O. similis exhibited a significant preference for maize (Zea mays L.) seedlings damaged by FAW over clean air, healthy seedlings, FAW feces, and FAW, suggesting that seedlings damaged by FAW may releases specific volatiles attracting the predator. Collectively, the results of the study suggest that O. similis is a promising candidate for the biological control of FAW eggs and first-instar larvae, particularly given its attraction to FAW-damaged leaves, which may enable it to locate the target prey rapidly.

This study evaluated parasitism and predation on sentinel egg masses of three stink bug species, the spined soldier bug, Podisus maculiventris (Say), the brown stink bug, Euschistus servus (Say), and the invasive brown marmorated stink bug (BMSB), Halyomorpha halys (Stål), in ornamental landscapes composed of either native or exotic plants. This study also compared the species composition of parasitoids attacking two native stink bug species (P. maculiventris and E. servus) with those attacking the invasive BMSB on the same tree species in the same habitat. Overall, egg parasitism and predation were much higher on the two native stink bug species compared with BMSB, with an average parasitism rate of 20.6% for E. servus, 12.7% for P. maculiventris, and only 4.2% for H. halys and an average predation rate of 8.2% for E. servus,17.7% for P. maculiventris, and 2.3% for H. halys. Egg predation was also significantly higher on P. maculiventris than on E. servus eggs. Eight parasitoid species attacked sentinel stink bug eggs in the ornamental landscaped plots. Trissolcus euschisti (Ashmead) (Hymenoptera: Scelionidae) was the predominant parasitoid for all three stink bug species. There were no significant differences in parasitism and predation rates on any of the stink bug species between native and exotic plots. Therefore, there is no evidence that ornamental landscapes composed of native plants increased parasitism or predation rates of sentinel egg masses of two native stink bug species or the invasive BMSB, compared with those composed entirely of exotic plants.

Recent studies have revealed multiple roles of insect-associated microbes such as lignin degradation, entomopathogen inhibition, and antibiotic production. These functions improve insect host fitness, and provide a novel source of discovering beneficial microbes for industrial and agricultural production. Previously published research found that in the symbiosis formed by the dipteran pest Delia antiqua (Meigen) (Diptera: Anthomyiidae) and its associated bacteria, the bacteria showed effective inhibition of one fungal entomopathogen, Beauveria bassiana. The antifungal activity of those associated bacteria indicates their potential to be used as biocontrol agents for fungal phytopathogens. In this study, we first isolated and identified bacteria associated with D. antiqua using a culture-dependent method. Second, we tested the antifungal activity of these bacteria against four phytopathogens including Fusarium moniliforme, Botryosphaeria dothidea, and two Fusarium oxysporum strains using the dual-culture method. In total, 74 species belonging to 30 genera, 23 families, eight classes, and four phyla were isolated and identified. Among those bacteria, Ochrobactrum anthropi, Morganella morganii, Arthrobacter sp. 3, and Acinetobacter guillouiae showed significant volatile inhibition activity against F. moniliforme, B. dothidea, and both F. oxysporum, respectively. Moreover, bacteria including Rhodococcus equi, Leucobacter aridicollis, Paenibacillus sp. 3, and Lampropedia sp. showed significant contact inhibition activity against F. moniliforme, B. dothidea, and both F. oxysporum. Our work provides a new source for discovering biocontrol agents against phytopathogens.

Two egg parasitoids from Pakistan, Gryon sp. nr. gonikopalense Sharma (Hymenoptera: Scelionidae) and Trissolcus hyalinipennis Rajmohana & Narendran (Hymenoptera: Scelionidae), are currently being investigated as potential classical biocontrol agents for Bagrada hilaris Burmeister. The former is the most promising because of its ability to attack B. hilaris eggs in soil, but the latter was recently discovered in California. This study detailed the patch use and oviposition behavior of both species and assessed their relative foraging efficiency. We also investigated possible competitive interactions by assessing 1) the occurrence of intra- and interspecific host discrimination, 2) mutual interference between females (extrinsic competition), 3) the outcome of multiparasitism (intrinsic competition), and 4) the effect of competition on host suppression. Our results showed that T. hyalinipennis females tended to probe repeatedly in the same hosts leading to longer host patch time and lower foraging efficiency. Both species avoided conspecific superparasitism, but not multiparasitism. When the two species foraged simultaneously, G. sp. nr. gonikopalense seemed to be slightly superior in extrinsic competition, while neither species seemed to have an advantage in intrinsic competition. Also, neither species could develop as a facultative hyperparasitoid, but they inflicted non-reproductive mortality on eggs containing 4-d-old larvae of their competitor. Lastly, host mortality inflicted by G. sp. nr. gonikopalense and T. hyalinipennis when acting together appeared to be additive. These results suggest that the presence of T. hyalinipennis in California is unlikely to reduce G. sp. nr. gonikopalense efficiency, but will instead improve the biological control of B. hilaris.

Barometric pressure is an important factor influencing several insect traits. Most studies have been conducted on the behavior of insects in relation to rapid and slight changes in pressure magnitudes or short-term pressure trends, but there is little information on the effect of long-term and large pressure variations on insect traits. Here, we assessed the effects of static low barometric pressure on the tethered flight, lifespan and reproductive performance of Mythimna separata (Walker), a long-distance migratory insect, using an apparatus simulating low barometric pressure at altitudes of 500 m above sea level. We found that both the flight distance and flight duration of M. separata moths were significantly longer under low barometric pressure conditions. Exposure to low barometric pressure conditions for 24 and 48 h significantly shortened the lifespan of female moths but had no influence on male moths. The ovaries of female moths developed earlier, and the preoviposition and oviposition periods were significantly shortened under low atmospheric pressure. Moreover, low atmospheric pressure reduced the respiration rate of female moths. However, there was an increase in the respiration rate of female moths after being returned to standard barometric pressure conditions. Our results show that the behavior and physiological traits of insects are affected by the low-pressure environment during migration. The low barometric pressure conditions at high altitudes is one of important factors accelerating reproductive behavior of M. separata after migration.

The melon thrips (Thrips palmi) is a serious insect pest of vegetables and ornamental plants. To control and monitor this thrips, blue traps are widely used. We previously reported that irradiation of cucumber plants with red light-emitting diodes (660 nm) causes T. palmi to avoid the plants. Here, we evaluated the responses of T. palmi adults to a cucumber plant in an experimental arena with either a transparent sticky trap or a blue sticky trap, without or with illumination by a red LED panel. When T. palmi were introduced into the arena, the number of thrips attracted to the plant was lowest in treatments using the red light and blue trap. On the other hand, when T. palmi were inoculated on plants first, most thrips stayed put on the plants. Placing both red LEDs and blue sticky traps in greenhouses before the thrips invade the greenhouse from the outside might effectively control T. palmi.

With significant surge of international trade in recent decades, increasingly more arthropod species have become established outside their natural range of distribution, causing enormous damage in their novel habitats. However, whether a species can colonize its new environment depends on its ability to overcome various barriers which may result in establishment failure, such as inbreeding depression and difficulty to find mates. Here, we used a haplodiploid pest, Tetranychus ludeni Zacher (Acari: Tetranychidae), which is native to Europe but now cosmopolitan, to investigate whether its reproductive strategies have facilitated its invasion success, providing knowledge to develop programs for prediction and management of biological invasions. We show that inbreeding had no negative influence on female reproductive outputs and longevity over 11 successive generations, allowing mother-son and brother-sister mating to occur at the invasion front without adverse consequences in fitness. Virgin females produced maximum number of sons in their early life to ensure subsequent mother-son mating but later saved resources to prolong longevity for potential future mating. Females maximized their resource allocation to egg production immediately after mating to secure production of maximum number of both daughters and sons as early as possible. Furthermore, mated females with mating delay increased proportion of daughters in offspring produced to compensate the loss of production of daughters during their virgin life. We suggest that the lack of inbreeding depression in successive generations and the ability to adjust resource allocations depending whether and when mating occurs may be the key features that have facilitated its invasion success.

To understand the effect of fluctuating temperature on the population characteristics of Tetranychus pacificus, we determined their life tables under constant temperatures between 10 and 35°C and fluctuating temperatures (12 h per day at each of 5°C above and 5°C below the corresponding constant temperature). Tetranychus pacificus eggs did not hatch when held at a constant temperature of 10°C, whereas 77.6% of the T. pacificus eggs reached an adult life stage at fluctuating temperature 10°C ± 5°C. Female preadult development was faster under fluctuating temperatures 12.5, 15, and 20°C than under constant temperatures, whereas it was not significantly different at temperatures ≥ 22.5°C. The lower developmental thresholds (T₀) for female preadult development were 10.24 and 5.73°C for the constant and fluctuating temperatures, respectively, while the thermal summations (K) were 215.10 and 265.64 degree days, respectively. The net reproductive rates (R₀) at constant temperatures 15 and 35°C were significantly higher than those at the corresponding fluctuating temperatures. However, for 20, 25, and 30°C, the R₀ values were not significantly different between constant and fluctuating temperatures. The intrinsic rate of increase (r) and finite rate of increase (λ) at fluctuating temperatures 10, 20, and 30°C were higher compared to the corresponding constant temperature. However, the values of r and λ at constant 25 and 35°C were higher than those at fluctuating temperature. The differential responses of life history between constant and fluctuating temperatures help to understand the population dynamics of T. pacificus under natural conditions.

Monitoring is critical to control efforts for Drosophila suzukii Matsumura, an invasive polyphagous fly that has the potential to cause significant losses in commercial soft fruit and berry production worldwide. We used an iterative process to identify trap colors, trap designs, and volatile mixtures to improve monitoring efforts in commercial blueberry, raspberry, and blackberry crops. Our results suggest that the selection of trap color and design and attractant lures should be customized to the crop in which they are deployed. In raspberries grown in high tunnel systems, DrosaLure paired with Drosal traps painted green and purple were highly specific to D. suzukii although actual capture counts were low. However, in field grown raspberries, BioLure and Multilure traps were most effective, but with significant nontarget bycatch. In blueberries, we had greatest success with a 5 µg:50 ng mixture of ethyl acetate–acetoin in a green/purple-colored jar-style trap with large (5 cm) mesh covered openings.

Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) is a delicacy in many African countries. It is commonly mass-harvested from the wild using light traps consisting of energy-intensive mercury bulbs which pollute the environment when poorly disposed. The catch is collected using open-ended drums which are inefficient in retaining the insects. The drums also collect nontarget insects including those that produce toxic chemicals (such as pederin) that cause severe burns to human skin. To prevent escape of trapped R. differens, trappers apply potentially hazardous substances like waste cooking oil on the walls of drums. Here, we modified the collection drum by fitting a funnel to retain R. differens; and partitioned it into three compartments with wire meshes of variable sizes to filter nontarget insects. Additionally, we replaced mercury bulbs with light-emitting diode (LED) bulbs which are energy-efficient. We evaluated the performance of the modified R. differens trap (modified drums and LED bulbs) compared to the current collection drums and mercury bulbs. The catch of R. differens in the modified drums was comparable to that of current drums. Nontarget insects were significantly filtered from the catch collected in modified drums compared to the current drums. Further, LED bulbs of 400 W trapped a comparable quantity of R. differens as 400 W mercury bulbs, but with less than half the consumption of electricity compared to the mercury bulbs. We concluded that modified R. differens light traps have better energy-use efficiency and ensure safety to collectors, processors, and consumers.

In many cases, pesticides' side effects on natural enemies have closely related to their exposure route. We assessed long-term lethal and sublethal effects of thiamethoxam (TMX) on the predatory bug, Orius albidipennis (Reuter), fed on Aphis gossypii Glover (Hemiptera: Aphididae), through three exposure routes. First-instar nymphs were treated with the maximum field recommended concentration (MFRC), ½ MFRC, and ¼ MFRC of TMX for 24 h. Based on the results, the soil-application treatment (bottom-up effect: plant-aphid-predator) led to the lowest survival reduction. In contrast, leaf-dip (residual contact) and aphid-dip (oral exposure route) treatments decreased the survival severely. While the soil-application treatment had no significant effect on adult longevity and egg production, all tested concentrations of TMX in the leaf-dip and aphid-dip treatments negatively affected both traits. The egg hatchability was not affected by the insecticide in all exposure routes. Among all treatments, ¼ MFRC of TMX in the residual contact and oral treatments shortened the egg incubation period compared to control, but others failed to affect it. Finally, based on the criteria provided by the International Organization for Biological and Integrated Control (IOBC) regarding toxicity classification, systemic (soil) application of TMX was harmless for this predator. However, it was moderately harmful and harmful (depending on concentration) to the predator through the residual contact and oral exposures, even at ¼ MFRC. Given our results, the soil-application of TMX is compatible with O. albidipennis, and it can improve conservation approaches of the predator in the integrated management of A. gossypii.

Onion maggot, Delia antiqua (Meigen), is a serious pest of onion Allium cepa L. in northern temperate regions. Over the last decade, D. antiqua has been managed principally using a pesticide seed treatment package containing the reduced-risk insecticide spinosad. While spinosad protects onion seedlings from D. antiqua, very little is known regarding how protection occurs. The main objectives of this study were to assess susceptibility of 1- and 2-wk-old larvae to spinosad through two different modes of exposure: ingestion and contact, and to evaluate larval feeding behavior in choice and no-choice tests with onion seedlings grown from treated and untreated seeds. Results showed that spinosad was more than twice as lethal to 1-wk than 2-wk-old larvae when it was ingested, but was equally toxic to both larval ages via contact exposure. In choice assays, larvae preferred feeding on untreated plants; however, without a choice, larvae fed and survived equally well on untreated and treated plants, suggesting that spinosad may have a deterrent effect. In a field study, levels of spinosad within young onion plants and in the soil around roots were monitored in addition to the cumulative number of onion seedlings killed by D. antiqua. Spinosad was detected in the soil and in both aboveground and belowground plant tissue, indicating that spinosad translocates into foliage, but declines in plant tissue and soil as plant mortality from D. antiqua feeding increases. Together, these results provide valuable insight into how spinosad protects onion seedlings and reveal key areas in need of further investigation.

Plant densities in Mid-South U.S. soybean, Glycine max (L.) Merr., fields can vary greatly due to a wide range of factors, although soybean yields are generally insensitive to variations in density. Currently, it is unknown if yield loss from insect-related defoliation varies across different soybean stand densities. Soybean was planted in Starkville and Stoneville, MS, in 2016 and 2017 at five seeding rates ranging from 123,500 to 420,070 seed/ ha in 74,130 seed/ha increments. Each seeding rate contained a nondefoliated plot and a plot that was defoliated 67% at the R1 growth stage. Defoliated plants had a greater leaf expansion rate from R1 to R3 than nondefoliated plants. Defoliation reduced yield where plant densities were <192,800 plants/ha, but greater densities were not affected. Reduced yield in defoliated plots when compared with nondefoliated plots at equivalent R3 leaf area index values indicated that some resources were used to replace the removed leaf area instead of seed production. These results suggest that fields with substandard plant densities might benefit from a reduced treatment threshold for defoliating pests.

Edible fruit plants of tropical forests are important for the subsistence of traditional communities. Understanding the most important pollinators related to fruit and seed production of these plants is a necessary step to protect their pollination service and assure the food security of these communities. However, there are many important knowledge gaps related to floral biology and pollination in megadiverse tropical rainforests, such as the Amazon Forest, due mainly to the high number of plant species. Our study aims to indicate the main pollinators of edible plants (mainly fruits) of the Amazon forest. For this, we adopted a threefold strategy: we built a list of edible plant species, determined the pollination syndrome of each species, and performed a review on the scientific literature searching for their pollinator/visitors. The list of plant species was determined from two specialized publications on Amazon fruit plants, totaling 188 species. The pollination syndrome was determined for 161 species. The syndromes most frequently found among the analyzed species were melittophily (bee pollination), which was found in 101 of the analyzed plant species (54%) and cantharophily (beetle pollination; 26 species; 14%). We also found 238 pollinator/visitor taxa quoted for 52 (28%) plant species in previous publications, with 124 taxa belonging to Apidae family (bees; 52%), mainly from Meliponini tribe (58 taxa; 47%). Knowledge about pollinators is an important step to help on preserving their ecosystem services and maintaining the productivity of fruit trees in the Amazon.

Graphical Abstract

The subfamily Plusiinae of the moth family Noctuidae is made up 400 species worldwide. Two species of the subfamily, the soybean looper, Chrysodeixis includens (Walker), and the cabbage looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), are important defoliating insect pests of various field crops and have been the subject of previous Plusiinae surveys in the Southern U.S. Soybean fields were sampled in the Mississippi Delta from 2010 to 2012 to determine the temporal occurrence of various Plusiinae species on soybean. As in previous surveys, C. includens was the most common Plusiinae species in soybean during the 3-yr survey, especially in late season collections (July–September). Rachiplusia ou (Guenée) (Lepidoptera: Noctuidae) was the predominant species observed in early season collections (May–early July). Populations of R. ou during the first sample dates during 2010 were much higher than those observed during the other years of the survey. Only three collected larvae successfully developed into T. ni adults, one each collected during May, June, and July. Although R. ou was not commonly reported in previous studies on soybean, it occurred in low numbers during June and July during the 3-yr study.The temporal occurrence and species composition followed a predictable pattern in all 3 yr of the study.

Swede midge (Contarinia nasturtii Kieffer) is an invasive, economic pest of canola (Brassica napus L.) that threatens production throughout Canada. Swede midge has up to four overlapping generations, placing canola at risk of multiple infestations in the field. The relationship between single and multiple swede midge infestations at different canola stages, and the resulting impacts on yield, are unknown. Laboratory experiments were conducted to evaluate the impact of single and multiple infestations of swede midge on four plant stages of canola: three-leaf, seven-leaf, primary bud, and secondary bud. Previously, the seven-leaf and primary bud stages were considered vulnerable to swede midge, but we determined that the secondary bud stage is also vulnerable. Evidence of compensation by canola in response to herbivory by swede midge was discovered. Compensation occurred mainly through increased production of tertiary racemes and pods and was maximized with exposure of 4.5–6.5 female midges per plant. Although compensation may increase potential yield, it also results in uneven crop maturation resulting in delayed harvest and yield loss. Consequently, to prevent delays in maturation and harvest, insecticides should be applied before these densities are reached.

Tarnished plant bug, Lygus lineolaris Palisot de Beauvois (Hemiptera: Miridae), has become a primary pest of cotton in the Midsouthern United States. Insect growth regulators such as novaluron are an important part of L. lineolaris management. While novaluron is lethal to nymphs, it does not kill adults, so it has been used when nymphs are the primary stage present. However, cotton yield protection was observed from an application of novaluron when adults were the predominant stage present. To explain this, a series of studies were conducted to examine sublethal impacts of novaluron to L. lineolaris adults. Novaluron ingestion by adults reduced hatch rate and sometimes reduced oviposition rate. Ingestion by either males or females reduced hatch rates, but the reduction was greater from female exposure. Contact exposure of adults with novaluron residues within 1 d of application reduced hatch rate by about 50%, but the impact on oviposition was inconsistent. A field study showed reduced hatch rate from contact exposure to mixed-age natural populations, but the overall net reproductive rate was not reduced. Surface exposure of eggs to novaluron did not reduce hatch rate. Overall, exposure of tarnished plant bug adults to novaluron, regardless of adult age or exposure route, reduced egg viability. However, the impact on oviposition rate and net reproductive rate varied with adult age and exposure route. This understanding of sublethal impacts of novaluron, in addition to lethal impacts on nymphs, should be considered when choosing application times to maximize effects on L. lineolaris populations.

Thresholds for Helicoverpa zea (Boddie) in cotton Gossypium hirsutum L. have been understudied since the widespread adoption of Bt cotton in the United States. Our study was possible due to the widespread presence of H. zea populations with Cry-toxin resistance. We initiated progressive spray timing experiments using three Bt cotton brands (Deltapine, Stoneville, and Phytogen) widely planted across the U.S. Cotton Belt expressing pyramided toxins in the Cry1A, Cry2, and Vip3Aa19 families. We timed foliar insecticide treatments based on week of bloom to manipulate H. zea populations in tandem with crop development during 2017 and 2018. We hypothesized that non-Bt cotton, cotton expressing Cry toxins alone, and cotton expressing Cry and Vip3Aa19 toxins would respond differently to H. zea feeding. We calculated economic injury levels to support the development of economic thresholds from significant responses. Pressure from H. zea was high during both years. Squares and bolls damaged by H. zea had the strongest negative yield associations, followed by larval number on squares. There were fewer yield associations with larval number on bolls and with number of H. zea eggs on the plant. Larval population levels were very low on varieties expressing Vip3Aa19. Yield response varied across experiments and varieties, suggesting that it is difficult to pinpoint precise economic injury levels. Nonetheless, our results generally suggest that current economic thresholds for H. zea in cotton are too high. Economic injury levels from comparisons between non-Bt varieties and those expressing only Cry toxins could inform future thresholds once H. zea evolves resistance to Vip3Aa19.

The sugarcane aphid, Melanaphis sacchari (Zehntner), emerged as a severe pest of sorghum, Sorghum bicolor (L.), in Texas and Louisiana in 2013 and currently threatens nearly all sorghum production in the United States. Proper management of populations is critical as sugarcane aphid has a high reproductive potential and can rapidly damage plants, resulting in extensive yield losses. The overall objective of this work was to investigate sugarcane aphid population dynamics, and subsequent sorghum injury and grain yield on commercially available grain sorghum varieties in Alabama. This research includes three-site years of data that show variation in plant injury, physiological maturity, and yields among varieties tested. Although performance of each variety was variable among locations, potentially due to abiotic factors, four varieties including DKS 37-07, 1G588, 1G855, and 83P17 exhibited characteristics consistent with resistance and corroborates reports of resistance from other states.

Spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), is the most severe defoliator of Pinaceae in Nearctic boreal forests. Three tools widely used to guide large-scale management decisions (year-to-year defoliation maps; density of overwintering second instars [L2]; number of males at pheromone traps) were integrated to derive pheromone-based thresholds corresponding to specific intergenerational transitions in larval densities (L2i → L2i₊₁), taking into account the novel finding that threshold estimates decline with distance to defoliated forest stands (DIST). Estimates of thresholds were highly variable between years, both numerically and in terms of interactive effects of L2i and DIST, which limit their heuristic value. In the context of early intervention strategy (L2i₊₁ > 6.5 individuals per branch), however, thresholds fluctuated within relatively narrow intervals across wide ranges of L2i and DIST, and values of 40–200 males per trap may thus be used as general guideline.

More than 60 non-native bark and ambrosia beetle species (Coleoptera: Curculionidae: Scolytinae) are established in North America and several have had severe negative impacts on ecosystems. Non-native scolytines can introduce fungi which may cause vascular wilts and compete with native fungi and lead to reductions in native species through host reduction. The Early Detection Rapid Response (EDRR) program was created by the USDA Forest Service in 2007 to detect non-native bark and ambrosia beetles and provide a baseline for tracking populations over time. This program has led to new collection records and increased communication among agencies to delimit non-native scolytine populations and perform appropriate management. Although insect responses to different lure types vary, it is unknown how different lures compare in attracting bark and ambrosia beetles. Our goal was to examine how lure combinations used in the EDRR program affect captures of bark and ambrosia beetle communities and to determine the most effective combination of lures for targeting non-native scolytines. The highest proportion of non-native scolytines was captured with ethanol, as was the greatest total number of species, and the most diverse beetle community. Traps with Ips (Coleoptera: Curculionidae) lures captured the highest proportion of native scolytines but the lowest total number of total species and was also the least diverse. Communities of scolytines differed significantly among lures, states, and years. While ethanol is an appropriate lure for generalist trapping and targeting a wide range of non-native bark and ambrosia beetles, more targeted lures are needed for monitoring certain species of non-natives.

Conservation biological control could be an alternative to insecticides for the management of the aphid Myzus persicae (Sulzer). To develop sustainable strategies for M. persicae control in peach orchards in the Mediterranean, a 2-yr field experiment was conducted to identify the key predators of the aphid; to determine whether the proximity of insectary plants boost natural enemies of M. persicae in comparison to the resident vegetation; and whether selected insectary plants enhance natural enemy populations in the margins of peach orchards. Aphidoletes aphidimyza Rondani (Diptera: Cecidomyiidae) and Episyrphus balteatus De Geer (Diptera: Syrphidae) were the most abundant predators found among sentinel aphid colonies, accounting for 57% and 26%, respectively. Samplings during 2015 yielded twice as many hoverflies in M. persicae sentinel plants close to the insectary plants as those close to the resident vegetation. The abundance of other natural enemies in sentinel plants, depending on their proximity to the insectary plants, was not significantly different in either of the 2 yr. Hoverflies hovered more often over the insectary plants than over the resident vegetation and landed significantly more often on Lobularia maritima (L.) Desv., Moricandia arvensis (L.) DC., and Sinapis alba L. (Brassicales: Brassicaceae) than on Achillea millefollium L. (Asterales: Compositae). Parasitoids were significantly more abundant in L. maritima and A. millefollium. The vicinity of selected insectary plants to peach orchards could improve the presence of hoverflies, which might benefit the biological control of M. persicae.

Frankliniella flower thrips are pests of numerous fruit and vegetable crops as they feed and reproduce in the flowers and fruits. The invasive Frankliniella occidentalis (Pergande) from the Southwestern United States, an economic pest in Florida since 2005, and the native Frankliniella bispinosa Morgan are both found in Florida strawberries. The objective of this research was to characterize injury to strawberry fruit from these species. Densities of 0, 2, 4, 8, 16, or 32 adult females of each species were caged on a strawberry plant with one flower. The cages were removed after 2, 5, or 10 d, and the number of surviving adults and the number of larvae determined. Injury was quantified on the mature fruit 21 d after thrips were introduced onto the experimental plant. Initial densities as low as two adult F. occidentalis females per flower decreased fruit set and increased cat-facing on the fruits that developed. There were no significant effects on fruit set and cat-facing by any initial density of F. bispinosa. Feeding by thrips on the small, green fruit affected the size and shape of the mature fruit: the diameters were decreased as a linear function of increased feeding by F. bispinosa, and the weights were decreased as a linear function of increased feeding by F. occidentalis. Overall, results showed that F. occidentalis was more damaging to strawberry than F. bispinosa. The differences in pest status between these common flower thrips species in Florida presents challenges to management programs.

The monoculture situation of truffle cultivation is favoring the appearance of pests that would not be economically important in naturally balanced forest ecosystems. The most prominent of them is the European truffle beetle Leiodes cinnamomeus (Panzer) (Coleoptera: Leiodidae), for which there are no effective control methods capable of reducing its populations. The potential of the mass trapping technique against this beetle, based on adapted pitfall traps and the semiochemical methyl disulfide as an attractant, is explored in the present work. Two trap densities (40 and 80 traps/ha) were tested in 2-yr field trials carried out in the region of Teruel (Spain) with black truffle cultivation tradition. Kairomone dispensers were placed in the field immediately before adult outbreak and remained active there throughout the season. The efficacy of each treatment was measured according to the reduction in beetle populations and the damaged truffles in the center of the treated areas. The results showed that both trapping densities reduced adult populations (mean 57% catch reduction), but 80 traps/ha were needed to significantly lower damage parameters (>40% reduction), percentage of attacked truffles and number of galleries/g truffle. The cost effectiveness of these treatments and possible improvements are discussed.

The Japanese beetle, Popillia japonica Newman, is an invasive insect to the United States that feeds on turfgrass roots as a larva and the foliage, flowers, and fruit of many major ornamental and agricultural crops, such as apple, as an adult. Despite its generalist feeding behavior, P. japonica shows preferences for certain plant species and cultivars. Classical biological control for P. japonica, including release of Istocheta aldrichi (Mensil), has been pursued in Minnesota. This study was conducted to assess the effects of apple cultivar on season-long abundance of adult P. japonica and their defoliation; and to assess effects of apple cultivar and P. japonica abundance and sex on parasitism of P. japonica by I. aldrichi. Sampling occurred during the summers of 2017 and 2018 on Zestar! and Honeycrisp cultivars in four different apple orchards. Abundance and defoliation of P. japonica was higher on Honeycrisp than Zestar!. Parasitism of P. japonica by I. aldrichi was higher for females than for males. In 2018, the relationship between parasitism of P. japonica and host density varied by cultivar. These findings may help growers determine which apple cultivars should be prioritized for scouting and management efforts and may provide an estimate of potential biological control by I. aldrichi in agricultural areas in the Midwest.

Twospotted spider mite, Tetranychus urticae Koch (Trombidiformes: Tetranychidae), is an important, worldwide pest of watermelon, Citrullus lanatus L. (Thunb.) Matsum. & Nakai (Cucurbitales: Cucurbitaceae). Feeding results in chlorotic spots and leaf necrosis, which can substantially reduce yields. In watermelon, T. urticae is managed solely with acaricides. Issues with acaricide resistance and pesticide label restrictions on number of applications per season require research-based recommendations on products with effective, long-lasting residues. To improve recommendations for T. urticae management in watermelon and to measure possible effects on non-target beneficial mites, we conducted acaricide efficacy trials in two locations in South Carolina, United States. The adulticidal products abamectin, bifenazate, fenpyroximate, and tolfenpyrad and the ovicidal products spiromesifen and etoxazole were tested. We also conducted two bioassays to better determine duration of acaricide residues. In the field trials, all acaricides except tolfenpyrad reduced T. urticae abundance, but all acaricides also reduced abundance of the most common predatory mite, Neoseiulus fallacis (Garman) (Mesostigmata: Phytoseiidae). In the bioassays, abamectin and bifenazate residues caused high adult T. urticae mortality at up to 21 d after treatment, performing better than fenpyroximate and tolfenpyrad. Etoxazole and spiromesifen were longer lasting, with <1 offspring per treated female in the etoxazole treatment at 28 d after treatment. Based on efficacy, abamectin or bifenazate should be rotated with etoxazole for fast knockdown of active stages while reducing reproduction, respectively. However, development and registration of more selective acaricides in watermelon is needed to preserve biological control of T. urticae by predatory mites.

The European grapevine moth, Lobesia botrana (Denis et Schiffermuller), is a serious invasive pest that causes significant losses to the flowers and fruits of grapes in most of the world. This multivoltine pest passes the winter as the third-generation diapausing pupa. The current study was designed to compare nondiapausing (first and second generations) and diapausing pupae (third generation) and to investigate the relationship among cold tolerance, the supercooling point (SCP), and diapause development of the third-generation diapausing pupae. The lethal temperatures (LTs) for the three generations were determined using 24-h exposure at subzero temperatures. The mean SCP of the pupae was estimated at approx. –22.6°C, the lowest level of which (–23.7°C) was recorded in the well-developed diapausing pupae in February. The highest level of cold tolerance was also recorded in February. There were no significant differences among the temperatures required to kill 30, 50, and 90% of the pupae. The temperatures significantly decreased from October onward and reached the lowest levels in February during which the lowest SCP and the highest cold tolerance were observed in the diapausing pupae. No significant differences were found in the cryoprotectant levels, among the diapausing and nondiapausing pupae, and the diapause development. The highest activity of cAMP-dependent protein kinase (AMPK) was recorded in the late diapause in February. The findings suggested a relationship among SCP depression, cold tolerance enhancement, and diapause development. A bimodal cold-tolerance strategy (freeze-intolerant and freeze-tolerant) was found to be a feature of the pupae.

The ambrosia beetles Xylosandrus germanus (Blandford) and Xylosandrus crassiusculus (Motschulsky) bore into flood-stressed trees to establish colonies, but the influence of flooding duration on colonization is unknown. This relationship was examined by flooding trees for various time periods and evaluating colonization. In one experiment, X. germanus bored into 20 dogwood (Cornus florida L.) trees during a 3-d flood treatment. Ten trees dissected that season had no offspring present in tunnels; the remaining trees appeared healthy and bloomed the following spring. In another experiment, dogwood trees were flooded for 3 or 7 d and then dissected to assess colonization. The incidence of superficial (short unbranched) and healed (callus tissue in entrance) tunnels was greater in the 3-d trees, while the incidence of tunnels with X. germanus or offspring was greater in the 7-d trees. Four experiments (three in Ohio and one in Virginia) had flood treatments of 0 (nonflooded), 3, 5, 7, and 10 d. Numbers of tunnel entrances, tunnels with X. germanus, and incidence of tunnels with offspring or live foundresses tended to increase as flood duration increased on apple (Malus × domestica Borkh.), dogwood, and redbud (Cercis canadensis L.) in Ohio and redbud in Virginia. Nonflooded trees in Ohio had no boring activity, but ambrosia beetles bored into three nonflooded trees in Virginia. Indicators of unsuccessful colonization, such as superficial tunnels and healing, decreased as flood duration increased. These results suggest tree crops may recover from boring by ambrosia beetles following short-duration flood events, and not necessarily require culling.

To evaluate perimeter trap crops for management of harlequin bug, Murgantia histrionica (Hahn), we undertook greenhouse and field experiments with mustard greens as trap crop for a collard cash crop. We confirmed that harlequin bugs prefer to immigrate to and reside on mustard. Females, however, in greenhouse cage experiments, ‘commuted’ to collards to lay their eggs. In separate spring and fall field plantings, using replicated 12 m by 12 m collard plots in 1-ha fields, we tested mustard planted as an adjacent perimeter trap crop, or a perimeter trap crop separated by 2 unplanted rows (2.3 m), or with no trap crop. Adults accumulated on the spring mustard crop but overall numbers remained low, with all collards sustaining <1% leaves damaged. In the fall, the separation of 2.3 m reduced oviposition on collards fourfold, and feeding damage approximately 2.5-fold, compared to collards with an adjacent trap crop. Fall control plots with no border trap crop showed even lower foliar damage; likely result of preferential immigration of harlequin bugs to mustard at the field scale, resulting in fewer bugs near the control treatment plots. Thus, the spatial arrangement of the mustard trap crop, and its separation from the cash crop, influences pest abundance and damage. A separated mustard border can reduce bug movement including female commuting and egg-laying, thus better protecting the collard cash crop. Future research should address reduction in area of trap crops, deployment of semiochemicals, and possible changes in timing, to promote trap cropping that is practical for grower implementation.

This study investigated the efficacy of using Vikane gas fumigant (sulfuryl fluoride) at the 1.9× dosage rate for eliminating bed bugs (Cimex lectularius L.) in two challenging infestation situations: personal vehicles, and confined spaces densely packed with personal belongings.The vehicles used in this study were large minivans with seating that folded into the floor.The confined spaces were cargo trailers filled to 85% capacity with books, furniture, and other household items. Each van and trailer was equipped with ∼90 sentinel bed bugs consisting of three groups of 9–11 bed bug eggs, 10 nymphs, and 10 adults.The Vikane Fumiguide calculator was used to determine the target dosage (g-h/m³) to apply in each replicate (e.g., one van or trailer). Sulfuryl fluoride concentrations were measured throughout the fumigation process using a Spectros SF-ReportIR. Concentration readings were input into the Fumiguide to determine when the accumulated dosage (g-h/m³) was achieved, and when aeration should be initiated. After aeration was complete, the sentinel bed bugs were removed from the replicates and bed bug nymph and adult mortality was recorded. Bed bug eggs were monitored for 23 d to determine latent mortality. Fumigated bed bug mortality for each replication was 100% regardless of life stage. Latent mortality was observed in a single bed bug egg, but the first instar never fully eclosed. This study determined that fumigation with sulfuryl fluoride at the 1.9× dosage factor is an effective method for eliminating resistant bed bugs from vehicles and personal belongings in densely packed situations.

Yellowjackets are notable pests of humans due to their opportunistic foraging behaviors, painful stings, and potential for causing dangerous allergic reactions. Baited traps provide a useful supplement for controlling yellowjackets compared with nest treatments, which are often dangerous, time consuming, costly, and do little to prevent nuisance interactions between humans and foragers. This study compares three homemade yellowjacket traps and three commercially available traps in Lake County, California, to determine efficacy and cost benefit. Traps were set at five sites and randomly rotated between six plots per site and baits were changed every 2 wk per commercial manufacturer recommendations. Cost benefit was determined using material and bait cost, as well as bait change frequency and overall trap efficacy. Yellowjacket count data were analyzed using a hurdle model. Traps compared included the Rescue! Yellowjacket trap, the Rescue! Wasp, Hornet, and Yellowjacket trap, the Victor Yellowjacket trap, a homemade bottle trap, jar trap, and homemade jug trap. The total number of yellowjackets collected was 33,321. The trap that collected the highest number of yellowjackets was the Rescue! Yellowjacket trap (n = 19,257) and the trap that collected the fewest yellowjackets was the jar trap (n = 65). The Rescue! Yellowjacket trap was the most cost-effective, calculated at approximately $0.40/100 yellowjackets collected. The jar trap was the least cost-effective, calculated at approximately $31.10/100 yellowjackets collected. The Rescue! Yellowjacket trap was overall the most effective and cost-effective trap evaluated for Lake County, California.

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is a key pest of Brassicaceae worldwide. Populations have globally evolved resistance to various insecticides including chlorfenapyr, which was observed at high frequency in Brazil. We report the genetic characterization and fitness costs associated with chlorfenapyr resistance in a field-derived strain. The resistant strain (BZR-RR) and a susceptible strain (REC-SS) were used in both concentration–response bioassays and demography-based approach. Inheritance pattern of chlorfenapyr resistance was determined by conducting reciprocal crosses between susceptible and resistant strains, and by backcrossing. Next, life table analysis for the susceptible, heterozygotes, and resistant strains was performed to assess eventual fitness costs associated with chlorfenapyr resistance. Resistance of P. xylostella (BZR-RR) strain to chlorfenapyr was very high (RR₅₀ = 421.58-fold) and also autosomal (no differences between reciprocal crosses), monofactorial and incompletely dominant (F₁ pool DD = 0.26 ± 0.14). Dominance (h) was concentration dependent with 16 mg/l allowing at least 95% survival of the resistant heterozygotes. Recessive fitness cost was observed to be associated with resistance to chlorfenapyr. The relative fitness of heterozygotes (RS) and resistant homozygotes (BZR-RR) in comparison to the susceptible strain (REC-SS) was 0.91 and 0.23, respectively. Significant differences were found for many fitness components in the resistant homozygotes. Altogether, results suggest a rational use of chlorfenapyr in areas where susceptible populations still prevail, in parallel with the use of diagnostic concentrations (e. g., 20 mg chlorfenapyr/l), and rotation with different mode of actions, for which fitness costs of resistance are nonrecessive in P. xylostella.

We evaluated different monitoring protocols for phosphine resistance in adults of three populations of the cigarette beetle, Lasioderma serricorne (F.), termed LB, 2KT, and E1. The protocols evaluated were as follows: 1) the Food and Agriculture Organization (FAO) bioassay, i.e., the exposure at 30 ppm of phosphine for 20 h, 2) the dose response, based on the exposure at 50–1,000 ppm of phosphine for 3 d, 3) the Cooperation Center for Scientific Research Relative to Tobacco (CORESTA) bioassay, which is based on exposures of 4 d at 200 ppm, and, if there are surviving individuals, of 10 d at 700 ppm, and 4) Detia Degesch Phosphine Tolerance Test Kit (DDPTTK), based on the evaluation of the exposed insects for short intervals of exposure (in our case 90 min) at 3,000 ppm. From the populations tested, E1 indicated the highest survival in the FAO bioassay. Moreover, adults of this population were able to survive at 200 ppm, in the dose response, in contrast with the other populations. However, both 2KT and E1 gave similar results in DDPTTK, but only E1 had survivors after 7 d postexposure. Finally, only adults of E1 survived the CORESTA bioassay for 200 ppm and 4 d, but not for 700 ppm and 10 d. Our results show that, at least in the range of the populations tested here, there are some trends that are comparable among the different diagnostics for L. serricorne, which can be utilized further in designing a widely adopted standardized protocol.

The plant bug Lygus pratensis Linnaeus (Hemiptera: Miridae) is an important insect pest of alfalfa in grassland farming in northern China. A field population of L. pratensis was selected in the laboratory for 14 consecutive generations with lambda-cyhalothrin to generate 42.555-fold resistance. Selection also induced low cross-resistance to imidacloprid and beta-cypermethrin, and medium cross-resistance to deltamethrin. Realized heritability (h2) of lambda-cyhalothrin resistance was 0.339. Susceptible baselines of L. pratensis were established for five insecticides using the glass-vial method, the values of which were 6.849, 3.423, 8.778, 3.559, and 117.553 ng/cm² for phoxim, methomyl, imidacloprid, lambda-cyhalothrin, and avermectin, respectively, along with the calculated LC₉₉ diagnostic doses. This resistance risk assessment study suggests that a high risk of lambda-cyhalothrin resistance exists in the field. In addition, a 5-year field investigation of resistance monitoring of L. pratensis was conducted in seven alfalfa regions in farming-pastoral ecotones in northern China. The resistance levels of most populations were very low for phoxim, methomyl, and avermectin, with an upward trend for lambda-cyhalothrin resistance in the DK (Dengkou County), TKT (Tuoketuo County), XL (Xilinhot), and LX (Linxi County) populations during 2015–2019, and medium resistance level to imidacloprid in the TKT population in five years we sampled. The study provided information on chemical control, lambda-cyhalothrin resistance development, baseline susceptibility, and the status of resistance to five commonly-used insecticides against L. pratensis.These results could be used to optimize pyrethroid insecticide use as part of a pest integrated resistance management strategy against this key insect pest of alfalfa.

Spodoptera frugiperda (J.E. Smith) is one of the key cross-crop pests in Brazilian agroecosystems. Field-evolved resistance of S. frugiperda to some conventional insecticides and Bt proteins has already been reported. Thus, the use of insecticides with new mode of action such as sodium channel blockers (indoxacarb and metaflumizone) could be an important tool in insecticide resistance management (IRM) programs. To implement a proactive IRM, we conducted baseline response and monitoring to indoxacarb and metaflumizone in 87 field populations of S. frugiperda collected from major maize-growing regions of Brazil from 2017 to 2020, estimated the frequency of resistance alleles to indoxacarb, and evaluated cross-resistance of indoxacarb and metaflumizone to some selected insecticides and Bt proteins. Low variation in susceptibility to indoxacarb (4.6-fold) and metaflumizone (2.6-fold) was detected in populations of S. frugiperda in 2017. The frequency of the resistance allele to indoxacarb was 0.0452 (0.0382–0.0527 CI 95%), by using F₂ screen method. The mean survival at diagnostic concentration, based on CL₉₉, varied from 0.2 to 12.2% for indoxacarb and from 0.0 to 12.7% for metaflumizone, confirming high susceptibility of S. frugiperda to these insecticides in Brazil. No cross-resistance was detected between sodium channel blocker insecticides and other insecticides (organophosphate, pyrethroid, benzoylurea, spinosyn, and diamide) and Bt proteins. These findings showed that sodium channel blocker insecticides are important candidates to be exploited in IRM strategies of S. frugiperda in Brazil.

The whitefly, Bemisia tabaci MEAM1 Gennadius causes serious losses to Florida vegetable and ornamental production. In 2019, a maximum dose bioassay was administered to 20 field populations of B. tabaci MEAM1 collected from various economic and weed hosts across south Florida to assess insecticide efficacy. The maximum dose bioassay tests the top labeled rate of the insecticide against B. tabaci adults on treated cotton leaves in a Petri dish over a 72-h period. A susceptible laboratory colony of B. tabaci MEAM1 and a colony of B. tabaci MED were also tested. Survival over 72 h was used to produce an area under the maximum dose curve, which was used to compare insecticide effects on different populations. Overall, imidacloprid demonstrated the poorest efficacy, dinotefuran and flupyradifurone were the most effective, and bifenthrin, cyantraniliprole, and thiamethoxam tended to group together, providing intermediate control. Across populations tested, survival in whitefly adults treated with dinotefuran was 50% lower than whiteflies treated with imidacloprid, about 33% lower than whiteflies treated with thiamethoxam, bifenthrin, and cyantraniliprole, and 10% lower than whiteflies treated with flupyradifurone. Efficacy of bifenthrin was less than imidacloprid on some populations, particularly from the Homestead area. Imidacloprid and thiamethoxam had no effect on mortality of the MED population when it was tested after 22 mo in culture without exposure to insecticides, although 7 mo later, these materials resulted in some mortality for the MED population.

The small hive beetle, Aethina tumida Murray (Coleoptera: Nitidulidae), is a serious threat to the honey bee industry, which relies on chemicals for the control of major honey bee pests. We developed a glass vial bioassay for resistance monitoring of adult A. tumida populations in honey bee colonies. We also determined concentrations that could be used to discriminate between susceptible and resistant strains. These include the pyrethroids cypermethrin (25.0 µg per vial) and fluvalinate (25.0 µg per vial) and the organophosphates malathion (10.0 µg per vial), chlorpyrifos (2.5 µg per vial), and coumaphos (25.0 µg per vial). Here, we report that resistance to fluvalinate and coumaphos was widespread in A. tumida populations in Florida in 2019. Aethina tumida populations were still susceptible to cypermethrin, malathion, and chlorpyrifos. The levels of resistance differed between pyrethroid and organophosphate insecticides. Over the last 10 yr, A. tumida populations have developed 43.7-fold resistance to coumaphos and 5.4-fold to fluvalinate. The levels of insecticide resistance were not similar within insecticides in the same class, which suggest that this type of resistance is manageable. Our results demonstrate the usefulness of glass vial bioassays to detect resistance in adult A. tumida and provide the foundation for a resistance management strategy. To the best of our knowledge, this is the first report of insecticide resistance in small hive beetle populations and suggests an urgent need for alternative control strategies for these serious pests of honey bee colonies.

Field development for optimizing the use patterns of spatial repellents are an ongoing research need. To investigate volatile pyrethroids in blends containing multiple active ingredients, metofluthrin was formulated into a vegetation spray for application to foliage and mosquito harborage. Metofluthrin was compared by itself and in combination with Sector (permethrin), Hyperion (sumithrin), Onslaught Fast Cap (s-fenvalerate, prallethrin), and against a benchmark for comparison, OneGuard (λ-cyhalothrin, prallethrin, pyriproxyfen). Field sites with established Aedes albopictus (Skuse) (Diptera: Culicidae) populations were allocated as control and treatment and surveilled with both adult traps and oviposition cups before and after treatment. Adult mosquito reductions were consistently higher over 4 wk in the combination treatments and were comparable to OneGuard. In contrast, efficacy provided by metofluthrin alone or the standalone existing product (Sector, Hyperion, Onslaught) by were consistently less effective than OneGuard and the comparative blends. Additionally, poorly melanized and collapsing eggs were identified from mosquito adults collected at treated field sites. A 20–50% significant decrease in nonviable mosquito eggs, a 50% or more reduction in total eggs and an 80% or more reduction in adult mosquitoes collected at the local field sites was demonstrated across all metofluthrin-containing treatments. Metofluthrin applications both supplemented the adulticidal control of the selected pyrethroid-containing products and provided significant reduction in egg laying frequency and viability during monitoring of areas adjacent to the treated vegetation. Metofluthrin, and possibly other volatile ingredients, appears to have complex interactions for mosquito control in the field and could be unique as a supporting ingredient to other insecticides.

Microbiome associated with insects play vital roles in host ecology and physiology. The small brown planthopper (SBPH), Laodelphax striatellus, is a polyphagous insect pest that caused enormous damage to a wide range of cereal crops. Previous studies have assessed the effects of environmental factors, such as antibiotics, insecticide, and geographical habitat on the bacterial composition of SBPH. However, the influence of host plants on the microbial community in SBPH still unclear. Here, we characterized and compared the microbial community in three SBPH populations feeding on rice, barley, and wheat, respectively, using high-throughput amplicon sequencing. Our observations revealed that the microbiome harbored by SBPH was abundant and diverse. Ten phyla comprising 141 genera of bacteria were annotated, and four fungal phyla consisting of 47 genera were assigned. The bacteria belonging to the phylum Proteobacteria were the most prevalent and the fungi with the highest abundance were from the order Hypocreales. Comparative analysis showed that host plants could significantly induce structural changes of SBPH microbiome. Significant differences in abundance were observed in two main bacterial orders (Rickettsiales and Rhodospirillales) and three fungal classes (Sordariomycetes, an unclassified class in Ascomycota and Eurotiomycetes) among three host-adapted SBPH populations. Our results could broaden our understanding of interactions among SBPH, its microbial associates and host plants, and also represented the basis of future SBPH biological management.

We used transcriptome analysis to research ovary development in Bactrocera dorsalis (Hendel). The ovary transcriptome of B. dorsalis yielded 66,463,710 clean reads that were assembled into 23,822 unigenes. After aligning to the Nr database in NCBI, 15,473 (64.95%) of the unigenes were matched to identified proteins. As determined by BLAST search, 11,043 (46.36%), 6,102 (25.61%), and 12,603 (52.90%) unigenes were each allocated to clusters via gene ontology, orthologous groups, and SwissProt, respectively. The Kyoto encyclopedia database of genes and genomes (KEGG) was further used to annotate these sequences, and 11,068 unigenes were mapped to 255 known pathways. Afterward, the genes that were possibly involved in oogenesis and ovary development were obtained from the transcriptome data and analyzed. Interestingly, seven ovary-specific genes were identified, including a Nanos gene that is involved in maintaining the primordial germ cells in many insects. Therefore, we further focused on the function of the BdNanos gene, and the gene was injected into B. dorsalis. As expected, the knocking down of Nanos gene expression led to significant inhibition of ovary development, suggesting an important role of this gene in the reproductive process of B. dorsalis. In summary, the present study provides an important reference for identifying the molecular mechanisms of oogenesis and ovary development in B. dorsalis. The BdNanos gene is crucial for ovary development in B. dorsalis and is therefore a potential new pest control target.

Since 2013 Melanaphis sacchari (Zehnter) (Hemiptera: Aphididae), the sugarcane aphid, has been a threat to sorghum production in the United States. The development of resistant sorghum hybrids has been one of the main management strategies. However, plant resistance can be overcome over time and new resistance genes need to be identified and introduced into adapted sorghum hybrids to secure sorghum production. Sorghum plant introduction (PI) genotypes were screened for resistance to M. sacchari through laboratory, greenhouse, and field assays. In addition, the feeding parameters of M. saccahri were analyzed and detailed in seven sorghum genotypes through EPG assays. Results showed sorghum genotypes PI 524770, PI 564163, and PI 643515 expressed resistance to M. sacchari consistently in laboratory, greenhouse, and field tests. EPG analysis suggested sorghum genotypes PI 524770 and PI 564163 express antibiosis to M. sacchari while PI 643515 expresses both antibiosis and antixenosis. Increasing the number of sorghum hybrids resistant to M. sacchari is key to improving integrated pest management of M. sacchari. By utilizing host plant resistance, sorghum producers can decrease insecticide applications while enhancing biological control.

Complaints of severe damage by whiteflies in soybean fields containing genetically engineered (GE) varieties led us to investigate the role of transgenic soybean varieties expressing resistance to some insects (Cry1Ac Bt toxin) and to herbicide (glyphosate) on the population growth and feeding behavior of Bemisia tabaci (Gennadius) MEAM1 (Hemiptera: Aleyrodidae). In the laboratory, the whiteflies reared on the GE Bt soybeans had a net reproductive rate (R₀) 100% higher and intrinsic rate of population increase (rm) 15% higher than those reared on non-GE soybeans. The increased demographic performance was associated with a higher lifetime fecundity. In electrical penetration graphs, the whiteflies reared on the GE soybeans had fewer probes and spent 50% less time before reaching the phloem phase from the beginning of the first successful probe, indicating a higher risk of transmission of whitefly-borne viruses. Data from Neotropical fields showed a higher population density of B. tabaci on two soybean varieties expressing glyphosate resistance and Cry1Ac Bt toxin. These results indicate that some GE soybean varieties expressing insect and herbicide resistances can be more susceptible to whiteflies than non-GE ones or those only expressing herbicide resistance. Most likely, these differences are related to varietal features that increase host-plant susceptibility to whiteflies. Appropriate pest management may be needed to deal with whiteflies in soybean fields, especially in warm regions, and breeders may want to consider the issue when developing new soybean varieties.

Grain commodities in postharvest storage often deteriorate because of fungal and insect attacks. With the green consumption requirements of consumers, ecofriendly and safe pesticides are needed for grain storage. The current study investigated the efficacy of the plant volatile compound trans-2-hexenal against the storage insect pest Tribolium castaneum (Herbst) and three commonly occurring storage fungi, viz., Fusarium graminearum, Aspergillus flavus, and Aspergillus niger, to recommend its application as a botanical fumigant for grain commodities. trans-2Hexenal weakly repels T. castaneum but has favorable insecticidal activity against multiple developmental stages of T. castaneum, ranging in sensitivity as follows: eggs (LC₅₀ = 14.3 µl/l) > adults (31.6 µl/l) > young larvae (42.1 µl/l) > mature larvae (64.5 µl/l) > pupae (70.5 µl/l). Moreover, trans-2-hexenal caused a high malformation rate and high mortality in adults developed from fumigated pupae. In a 7-d grain, trans-2-hexenal at 0.8 µl/ml provided an appreciable efficacy (81.3%), and concentrations ≥ 0.1 µl/ml completely inhibited the offspring of T. castaneum. trans-2-Hexenal was nonphytotoxic to the seed germination and seedling growth of wheat seeds. Furthermore, trans-2-hexenal completely inhibited the growth of A. flavus, F. graminearum, and A. niger at 5, 10, and 10 µl/l, respectively. The favorable biological activity of trans-2-hexenal against T. castaneum and three frequently occurring mycotoxigenic storage fungi indicated the potential of trans-2-hexenal for simultaneously controlling pests and pathogens, which could reduce its application frequency in grains and decrease pesticide resistance risks.

Graphical Abstract

The house fly, Musca domestica L., is an international nuisance and vector of numerous pathogens that cause disease syndromes in humans and animals. In urban areas, fly exclusion is a major part of the pest management program at many commercial establishments. If flies elude the exclusion techniques, a system for fly management inside the building is the next line of defense. Permission was given to evaluate the fly management system consisting of 12 GT-180 and 6 MX-360 ultraviolet (UV) light traps inside of a large supermarket for 8 wk. GT-180 traps mounted 2 m high on walls captured significantly fewer flies than MX-360s, larger portable traps placed on the floor. Both glue boards in GT-180 traps captured similar fly numbers. In the MX-360 traps, mean fly numbers captured by the two vertically mounted glue boards combined were not significantly different from those captured by the single lower horizontal glue board. Changing from white to black glue boards significantly reduced fly numbers captured by both traps. Three of the six traps capturing the largest mean fly numbers were in the Bakery, followed by the Deli. A total of 3,626 house flies (453/week) was captured during the study. Changes in weekly fly populations inside the store were visibly obvious because fly numbers were so high. Difference in flies trapped because of trap location and height, and glue board color are further discussed.

Soybean, Glycine max (L.) Merr., is planted during 3.5–4 mo across the Mid-South United States. Currently, no information exists regarding the effects of planting date on soybean yield loss from early season defoliation. In 2015 and 2016, to evaluate the effects of planting date on yield loss from defoliation, soybean were planted in field plots 2 wk apart from early April to mid-June, for a total of six planting dates. Each planting date included a nondefoliated control and a 100% defoliation treatment where leaves were manually excised at the V4 growth stage. Mean yield loss from defoliation varied across planting dates, with mid-April plantings having the least amount yield reduction, 573 kg/ha, and early-June plantings having the greatest yield reduction, 904 kg/ha. Percent yield reduction from defoliation increased as planting was delayed, suggesting that defoliation thresholds might need adjustment based on planting date and yield potential. However, more research is needed at lower levels of defoliation to accurately delineate such thresholds.

From 2012 through 2020, a survey of wheat stem sawfly, Cephus cinctus Norton, was conducted in wheat (Triticum aestivum L.) fields in Eastern Colorado. In 2013, results showed sawfly infestations concentrated in the northern part of the state with only a few highly infested sites, with 38 of the 94 sampled sites having any infestation (five of which had >50% infestation levels). By 2020 sawfly had been found in all eastern counties sampled, and 72 of the 106 sites sampled were found to contain sawfly (11 of which had >50% infestation levels). The spread of this pest across the Colorado wheat-growing region will have lasting economic effects. The information gathered from this and future surveys will inform wheat variety development and aid in management decisions made by growers across the state.

Due to increasing usage of copper fungicides in citrus orchards shortly before the application of protein baits for fruit fly control and the risk of this combination causing fruit phytotoxicity, an investigation of attractants containing higher amounts of yeast autolysate rather than protein hydrolysate was conducted. A commercial yeast autolysate from Australia was less attractive than a South African product HymLure (with a mixture of autolysate and hydrolysate) to three Ceratitis species: Ceratitis capitata (Wiedemann), Ceratitis rosa s.s. Karsch, and Ceratitis cosyra (Walker). Other custom-formulated autolysates were also inferior to HymLure for these species. Consumption of autolysates during the first hour of feeding was similar to that of HymLure. The inferior attraction of these three species of fruit flies to autolysates, relative to one containing hydrolysate, did not warrant further investigation of autolysates for use in baits to control these quarantine pests.

The South American soybean pest, Rachiplusia nu (Guenée), is naturally infected by Autographa californica multiple nucleopolyhedrovirus (AcMNPV) and Rachiplusia nu nucleopolyhedrovirus (RanuNPV). We compared their pathogenicity to fourth-instar R. nu larvae, by evaluating time to death and virus spread throughout the tissues in single and mixed infections. Bioassays showed that generalist AcMNPV had a faster speed of kill than specific RanuNPV, while the mixed-virus treatment did not statistically differ from AcMNPV alone. Histopathology evidenced similar tissue tropism for both viruses, but co-inoculation resulted in mostly AcMNPV-infected cells. In sequential inoculations, however, the first virus administered predominated over the second one. Implications on baculovirus interactions and biocontrol potential are discussed.

Graphical Abstract