Bed bugs are an important group of medical and urban insect pests. They are obligate blood-feeders. Their bites may cause skin irritation and allergic reactions and, under some circumstances, may lead to mental and other health issues. Despite numerous discoveries on the biology of these obnoxious pests and progress in control strategies over the last two decades, bed bugs continue to preferentially plague those from low socioeconomic communities because the poor generally could not afford effective control options. As a result, such infestations in poorer communities serve as a reservoir for wider society. This Special Collection of the Perspective on Biology and Management of Bed Bugs presents nine original research papers on bed bug detection, insecticide performance and resistance, nonchemical treatment, fungal biopesticides, and pest management procurement and contracts. We hope that these investigative findings will spur research on safer, more affordable, and effective control options in the future.

Numerous bed bug research papers have been published in the past 20 yr as a result of bed bug (Cimex spp.) (Hemiptera: Cimicidae) resurgence in the world.Yet, few of them focused on the management of the tropical bed bug, C. hemipterus (F.). Here, we describe a case of tropical bed bug infestation in two dormitory buildings and effectiveness of a tropical bed bug treatment program. The study site consisted of 125 dormitories in two buildings. An initial building-wide monitoring with ClimbUp interceptors revealed 25 infestations. The spatial distribution of bed bug infested rooms showed a significant aggregated distribution pattern with same infestation status for neighboring units sharing walls. All infested rooms were monitored every 2 wk and treated using a combination of steam and diatomaceous earth (DE) dust application if bed bugs were still found. For the 25 initially identified infested rooms, after 14 wk treatment, 44% of them no longer had bed bugs, and the mean number of bed bugs captured per room decreased by 94.1%. A combination of steam and DE dust treatment is an effective strategy for suppressing tropical bed bug infestations in dormitory environment.

The common bed bug, Cimex lectularius L., is a difficult urban pest to control. A simulated field study was conducted to compare the efficacy of steam application and an insecticide mixture spray (0.05% acetamiprid and 0.06% bifenthrin mixture) against C. lectularius. Three types of furniture (desk chair, upholstered armchair, and wooden table) were treated in the laboratory. The efficacy of the treatments was evaluated by visual inspection and placement of interceptor traps under the legs of the furniture. One hundred mixed stages of an insecticide-resistant population of C. lectularius were released onto each furniture item. After a 10-day acclimation period, each furniture item received steam treatment, insecticide spray, or no treatment. The second application of treatment was conducted 14 d later. Bed bug counts from interceptors and visual inspections were recorded at 13 d and 28 d after the initial treatment. At 28 d, the mean (± SE) live bed bug count in the steam, spray, and control group was 1 ± 0, 2 ± 1, and 83 ± 10, respectively. Both treatment methods were highly effective in controlling bed bugs on furniture. The mean bed bug count from interceptors in the steam, spray, and control groups were 0.3 ± 0.2, 11 ± 7, and 47 ± 9, respectively. There was no significant difference in the efficacy between steam and spray treatments based on either visual inspection or bed bug counts from interceptors. However, based on interceptor counts, the steam treatment caused faster bed bug population reduction than insecticide sprays.

Modern bed bugs are resistant to multiple insecticide classes, particularly the pyrethroids. The efficacy of pyrethroid-impregnated mattress liners marketed for bed bug management has been variable. This study evaluated the efficacy of a permethrin-impregnated mattress liner, ActiveGuard, against 24 bed bug strains, consisting of both Cimex hemipterus (F.) and Cimex lectularius L. A ‘mat assay’, employing an allethrinimpregnated mat, was used to establish the pyrethroid resistance profile of all strains. Three experiments were conducted to evaluate the effect of ActiveGuard exposure on bed bug knockdown: 1) exposing the bed bugs continuously on the liner for up to 24 d, 2) holding the bed bugs on the liner for either 4 or 6 h, and 3) placing a noninsecticide treated fabric above the liner with the bed bugs held continuously on top. Our results indicated that all modern strains (collected within the last 15 years during the current resurgence) were pyrethroid-resistant, although the magnitude of resistance was highly variable between strains. In the continuous exposure study, an incomplete knockdown was recorded for most modern bed bug strains, with some having no knockdown even up to 7 d of constant exposure. In the 4 or 6 h exposure study, the level of knockdown was reduced even further, and very few bed bugs were knocked down in the double fabric study. The results of this study indicate that pyrethroid-impregnated mattress liners are not likely to be effective in the management of most modern bed bug infestations involving either C. hemipterus or C. lectularius.

The residual performance of two pyrethroid-neonicotinoid mixture formulations: Temprid SC (10.5% beta-cyfluthrin and 21% imidacloprid) and Tandem (3.5% lambda-cyhalothrin and 11.6% thiamethoxam) on two substrates (glass and filter paper) against eight pyrethroid-resistant strains (BM-MY, BP-MY, CH-MY, GL-MY, KL-MY, SAJ-MY, TT-MY, and QLD-AU) of the tropical bed bug, Cimex hemipterus (F.) (Hemiptera: Cimicidae) collected from Malaysia, and Australia were evaluated. The aging effect of treatment residues on glass was also investigated. A susceptible C. lectularius L. strain (Monheim) was used for comparison. Temprid SC showed varying levels of performance against all C. hemipterus strains: TT-MY (PR₅₀ = 6.5-fold, high performance), BM-MY, GL-MY, SAJ-MY, and QLD-AU (12.8–21.6-fold, moderate performance), BP-MY, and KL-MY (48.2–49-fold, poor performance), CH-MY (128.2-fold, very poor performance). On the other hand, Tandem displayed high performance against all C. hemipterus strains (1.8–8.3-fold). Tandem caused faster mortality than Temprid SC for all strains. Temprid SC and Tandem residues killed C. hemipterus significantly faster on glass than filter paper. Compared with fresh residues, the efficacy of Temprid SC residues significantly declined after one week of aging, while the effectiveness of Tandem residues declined after two weeks of aging. Further investigations using the topical assay method with a diagnostic dose of imidacloprid found two strains (CH-MY and GL-MY) resistant to imidacloprid. The six other strains (BM-MY, BP-MY, KL-MY, SAJ-MY, TT-MY, and QLD-AU) were susceptible.

The use of the entomopathogenic fungus Beauveria bassiana (Bals. – Criv.) Vuill. (Hypocreales: Cordycipitaceae) has been recently incorporated in the management of bed bugs, Cimex lectularius L. (Hemiptera: Cimicidae). Bed bugs produce a set of aldehydes that are known to affect the growth of some fungi. Considering that bed bugs or their exuviae release these aldehydes, it was suspected that the bed bugs' aggregation sites would contain an increased level of the bed bug aldehydes. The current study examined if elevated levels of the bed bug aldehydes in the microhabitats would impact the efficacy of B. bassiana. Following a brief exposure to the residues of commercial products containing B. bassiana, the treated bed bugs were kept in a vial with or without a natural or artificial blend of bed bug aldehydes (i.e., exuviae or synthetic compounds). For a B. bassiana product that is not currently registered for bed bugs control, the presence of aldehydes significantly reduced 15-d mortality (61–62%) compared to the no aldehydes control (97.7%). However, when tested with a B. bassiana formulation designed for bed bug control, the aldehydes only caused delayed mortality for the treated bed bugs. When tested in culture, the growth rate of B. bassiana on a medium was significantly reduced when the bed bug aldehydes were provided in the headspace. Implications on practical bed bug management using fungal biopesticides are discussed.

Little is known about the economics of small-scale beekeeping, due in part because many of these beekeepers are motivated by personal enjoyment and not profit. These beekeepers, however, represent more than 90% of US beekeeping population, so economic analysis of this majority group is warranted. Understanding how management practices impact colony profitability in small apiaries can inform beekeeper management decisions. Best management practices (BMPs) can increase colony productivity and survival, but often require additional labor and materials compared to less intensive beekeeping practices. Here, we investigate the impact of BMPs on the profitability of small-scale beekeeping. We found that BMPs required higher costs in labor and materials, but that they also produced higher revenue from honey and nucleus colony production. As a result, after three years, BMP apiaries were 8 times more profitable than less intensively managed apiaries. The increased profitability in BMP apiaries is largely attributed to improved colony health and survival due to more active Varroa management and reduced Varroa and viral loads. These results can inform small scale beekeeper budgeting and management, and also support extension efforts to increase BMP adoption.

Several resistance traits have been proposed to select honey bees (Apis mellifera L.) that can survive in the presence of parasitic mite Varroa destructor (Anderson and Trueman) and enable a more sustainable apiculture. The interest for uncapping-recapping has recently increased following its identification in several naturally surviving honey bee populations, yet the utility of this trait for human-mediated selection is poorly known. Here, we evaluated the repeatability of recapping and its correlations with mite infestation levels, and assessed the expression of the trait in the often neglected drone brood. We also calculated correlations between recapping, mite infertility, and mite fecundity, expressed either at the level of individual brood cells or of the whole colony. Recapping measured in worker brood showed moderate repeatability (ranging between 0.30 and 0.46). Depending on sample, recapping slightly correlated negatively with colony infestation values. Recapping was also measured in drone brood, with values often comparable to recapping in worker brood, but no significant correlations were obtained between castes. At cell level, recapped cells in drone brood (but not in workers) were significantly less infested than nonrecapped cells, whereas in workers (but not in drones), recapped cells hosted mites with significantly lower fecundity. At colony level, with a few exceptions, recapping did not significantly correlate with mite infertility and fecundity, caste, sample, or number of infested cells considered. These results indicate limited possibilities of impeding mite reproduction and possibly mite infestation of honey bee colonies by recapping, which would need to be confirmed on larger, different populations.

Landscapes can affect parasite epidemiology in wild and agricultural animals. Honey bees are threatened by loss of floral resources and by parasites, principally the mite Varroa destructor and the viruses it vectors. Existing mite control relies heavily on chemical treatments that can adversely affect bees. Alternative, pesticide-free control methods are needed to mitigate infestation with these ectoparasites. Many flowering plants provide nectar and pollen that confer resistance to parasites. Enrichment of landscapes with antiparasitic floral resources could therefore provide a sustainable means of parasite control in pollinators. Floral rewards of Asteraceae plants can reduce parasitic infection in diverse bee species, including honey and bumble bees. Here, we tested the effects of sunflower (Helianthus annuus) cropland and pollen supplementation on honey bee resistance to macro- and microparasites. Although sunflower had nonsignificant effects on microparasites, We found that increased sunflower pollen availability correlated with reduced Varroa mite infestation in landscapes and pollen-supplemented colonies. At the landscape level, each doubling of sunflower crop area was associated with a 28% reduction in mite infestation. In field trials, late-summer supplementation of colonies with sunflower pollen reduced mite infestation by 2.75-fold relative to artificial pollen. United States sunflower crop acreage has declined by 2% per year since 1980, however, suggesting reduced availability of this floral resource. Although further research is needed to determine whether the observed effects represent direct inhibition of mite fecundity or mite-limiting reductions in honey bee brood-rearing, our findings suggest the potential for sunflower plantings or pollen supplements to counteract a major driver of honey bee losses worldwide.

Huanglongbing (HLB), or citrus greening, is the most destructive disease of cultivated citrus worldwide. Candidatus Liberibacter asiaticus (CLas), the putative causal agent of HLB, is transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae). In Florida, D. citri was first reported in 1998, and CLas was confirmed in 2005. Management of HLB relies on the use of insecticides to reduce vector populations. In 2016, antibiotics were approved to manage CLas infection in citrus. Diaphorina citri is host to several bacterial endosymbionts and reducing endosymbiont abundance is known to cause a corresponding reduction in host fitness. We hypothesized that applications of oxytetracycline and streptomycin would reduce: CLas populations in young and mature citrus trees, CLas acquisition by D. citri, and D. citri abundance. Our results indicate that treatment of citrus with oxytetracycline and streptomycin reduced acquisition of CLas by D. citri adults and emerging F1 nymphs as compared with that observed in trees treated only with insecticides, but not with antibiotics. However, under field conditions, neither antibiotic treatment frequency tested affected CLas infection of young or mature trees as compared with insecticide treatment alone (negative control); whereas trees enveloped with mesh screening that excluded vectors did prevent bacterial infection (positive control). Populations of D. citri were not consistently affected by antibiotic treatment under field conditions, as compared with an insecticide only comparison. Collectively, our results suggest that while foliar application of oxytetracycline and streptomycin to citrus reduces acquisition of CLas bacteria by the vector, even high frequency applications of these formulations under field conditions do not prevent or reduce tree infection.

The functional responses of Oligota flavicornis (Boisduval & Lacordaire) (Coleoptera: Staphylinidae) preying on the eggs of Tetranychus urticae Koch (Acarina: Tetranychidae) were examined at seven constant temperature settings (12, 15, 18, 22, 25, 30, and 32°C) to elucidate the predator–prey interactions between them. Logistic regression showed that O. flavicornis exhibited type II functional responses to T. urticae eggs at different temperatures. The reciprocal of handling time declined exponentially with warming, and the search rate presented a single hump-shaped relationship with temperature. For the search rate, the lower temperature thresholds were 9.1°C (linear) and 8.7°C (Briere). The optimal temperature and upper temperature threshold were 29.1 and 37.8°C for Logan and 29.7 and 35.8°C for Briere, respectively. The predation threshold window of O. flavicornis reached 27.1°C with a range of 8.7–35.8°C. The predator could consume 244.7–388.4 T. urticae eggs in a day in the optimal temperature range (18–32°C). The voracious predatory behavior of O. flavicornis against T. urticae eggs over a broad temperature range indicates that the predator shows promise as a potential biological control agent and that temperature-dependent predation could be a basis for formulating strategies to control tetranychid mites.

Graphical Abstract

This study decribes a highly effective insecticidal isolate of Cordyceps javanica (Frieder. & Bally) (Hypocreales: Cordycipitaceae) named IJ-tg19, which was isolated from soil. Spray bioassays were performed with IJ-tg19 on Myzus persicae (Sulzer) (Hemiptera: Aphididae) adults, third-instar nymphs of Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae), and third-instar larvae of Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) to determine the pathogenicity of the isolate. The corrected mortality rates for all three pests were 100% when the conidia concentration was 1 × 10⁶ conidia/ml, the lowest concentration in this study, and the median survival times (MST) were 4, 4, and 3 d. The MST shortens with increasing conidia concentration. The effects of laboratory culture conditions on the sporulation and growth of the isolate were also studied. This isolate had the greatest conidia production and fastest growth rate on malt extract agar medium at 25°C. The amount of conidia produced had positive correlation to light duration, with the highest production at 24 hr light. The growth of mycelium can adapt to a moderately alkaline environment, but the optimum conidial production occurred at the pH of 7. Our finding and research will be useful in biocontrol programs that are considering using the new isolate of C. javanica against greenhouse pests.

Graphical Abstract

Entomopathogenic fungi (EPF) represent promising control agents against wireworms but success in field experiments is inconsistent. The physiological condition of the targeted insect is crucial for its ability to withstand fungal infection. In particular, nutritional status is among the most important determinants of the insects' immune defense. In this study, we investigated the effects of diet on the development of the wireworm Agriotes obscurus (L.) (Coleoptera: Elateridae) and its subsequent susceptibility to the fungal pathogen Metarhizium brunneum (Petch) (Hypocreales: Clavicipitaceae) in a pot experiment. After being reared on one of five plant diets for eight weeks, wireworms were exposed to an environment inoculated with the EPF and monitored for their susceptibility to fungal infection. We then performed a field experiment in which three plant diets (clover, radish, and a cover crop mix), selected according to the insects' performance in the laboratory experiment, were grown as a cover crop with EPF application. Plant diet influenced growth and development of larvae, but there were no strong differences in susceptibility toward fungal infection in the laboratory experiment. Damage levels in EPF-treated plots in the field varied depending on the cover crop. Damage was highest in plots planted with a mix of cover crop species, whereas damage was lowest in plots with clover or radish alone. This agrees with the laboratory results where insect performance was inferior when fed on clover or radish. Cover crop effects on wireworm damage in the subsequent cash crop may thus vary depending on the cover crop species selected.

Agasicles hygrophila Selman and Vogt (Coleoptera: Chrysomelidae) is a natural enemy of Alternanthera philoxeroides (Mart.) Griseb (Amaranthaceae: Alternanthera), a worldwide invasive weed. Elevated atmospheric CO₂ concentrations may have significant impacts plants, herbivorous insects, and natural enemies. To assess the concurrent effect of elevated CO₂ on the development time, fecundity, and population parameters of A. hygrophila, the age-stage, two-sex life table was used to understand the fitness and population parameters of individually-reared and group-reared A. hygrophila under elevated CO₂ concentration. In individually-reared population, the development time of preadults, adult pre-oviposition period, and total pre-oviposition period of A. hygrophila in the elevated CO₂ (eCO₂, 750 ppm) treatment were shorter than those in the ambient CO₂ (aCO₂, 420 ppm) treatment. In group-reared population, the developmental time of preadults, female adult longevity, female proportion, adult pre-oviposition period, and total pre-oviposition period of A. hygrophila in eCO₂ were longer than those in aCO₂. Additionally, in both individually-reared and group-reared population, fecundity and oviposition days of A. hygrophila in eCO₂ were higher than those in aCO₂, and a higher intrinsic rate of increase, finite rate of increase, and the net reproductive rate of A. hygrophila were observed at eCO₂. Moreover, shorter preadult development time, adult pre-oviposition period, total pre-oviposition period, male adult longevity, and higher fecundity were found in group-reared cohort at both aCO₂ and eCO₂. The results indicates that elevated CO₂ has effects on the growth and reproduction of A. hygrophila, and the population growth rate of group-reared was faster and produced more offspring.

The beet webworm, Loxostege sticticalis (Linnaeus) (Lepidoptera: Crambidae), is a destructive pest inhabiting the northern temperate zone. In Xinjiang, China, this species has only occasionally infested certain areas, but has been causing severe damage since 2005. Early studies showed that most of the outbreak populations in northern Xinjiang are immigrant populations. However, the specific source area is still unknown. In this study, we determined the source area of the immigrant population of L. sticticalis in northern Xinjiang from 2010 to 2013 using daily monitoring data of L. sticticalis adults; we explained the causation of why an overwintering area of L. sticticalis could build up in Central Asia. Results showed that the direct source area of L. sticticalis in northern Xinjiang was eastern Kazakhstan, and the initial source area could be traced further to Altai Krai, Russia. Both regions were located at the foothills of the westernmost portion of Altai Mountains. The thermal conditions in these regions could not support L. sticticalis development for two generations before 1990. Hence, a few cocoons could be formed in the autumn. Influenced by global warming, L. sticticalis in these regions could complete two whole generations most years after 2001. The increased generation number, combined with sufficient precipitation, and mountainous terrain in the westernmost portion of Altai Mountains have created an overwintering area for L. sticticalis.

The Asian corn borer, Ostrinia furnacalis (Guenée), is a notorious pest of maize that migrates seasonally in Asia. Two migration peaks were found on Beihuang island in the Bohai Strait of China by observing the number of migrants. However, the origins and host plants of the migrants in the two migration periods remain unclear. Here, stable hydrogen (δ²H) and carbon (δ¹³C) isotope levels were measured to infer the origin and host plants of the O. furnacalis captured on Beihuang island in 2017–2019. δ²H in wings of spring-summer O. furnacalis captured from May to June ranged from –99 to –56‰, while that of autumn migrants from August to September ranged from –127 to –81‰. Based on the linear relationship between δ²H in the wing of migrants (δ²H_w) and δ²H in precipitation (δ²H_p), the spring-summer O. furnacalis likely originated from the summer maize area in the Huang-Huai-Hai Plain in China. In contrast, the autumn migrants came from the northern spring maize area in Liaoning, Jilin and Inner Mongolia. Based on δ¹³C, the spring-summer migrants fed on both C₃ plants such as wheat (47.76%) and C₄ weeds or belonged to the over winter individuals in maize field (52.24%), while the autumn migrants mainly fed on maize (C₄, 91.21%). The results point to a northward migration in spring-summer and southward migration in autumn of O. furnacalis. Our study gives an important knowledge for improving the forecasting and management level of this pest.

Border rows of grain sorghum were planted along two to four sides of an organic Granadero tomato crop in North Florida to reduce fruit injury caused by native and invasive stink bugs. During the 2-yr study, 14 species of stink bugs were encountered, six only in sorghum: Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae), Thyanta spp., Oebalus pugnax (Fabricius), Chinavia hilaris (Say), C. pensylvanica (Gmelin), and Mormidea pama (Rolston). There were four species only in tomato: Euschistus obscurus (Palisot de Beauvois), E. tristigmus (Say), E. ictericus (L.), and Arvelius albopunctatus (De Geer). The three most abundant pests in tomato were collected in both crops: Nezara viridula (L.), Euschistus servus (Say), and E. quadrator Rolston, along with Proxys punctulatus (Palisot de Beauvois). Nezara viridula and P. guildinii were the most abundant stink bugs on sorghum. The border rows of sorghum did not reduce the total number of stink bug adults or nymphs in the tomato crop, although many more stink bug adults were captured in sorghum than tomato when the sorghum panicles were in the milk to soft dough stage. Generally, 30% of the females in the sorghum and tomato crops were mated and contained more than 15 eggs, indicating they could generate a considerable number of nymphs. Tomato fruit from the plot with sorghum border rows had significantly more punctures than fruit from the plot without sorghum. The stink bugs frequently probed and blemished tomato fruit in all stages of ripeness but fruit covered with probing sites were nevertheless suitable for human consumption.

Overuse of pesticides can result in the development of resistance, secondary pest outbreaks, and pest resurgence due to a reduction in natural enemies. The present study compares the residual toxicity of lambda-cyhalothrin, a relatively nonselective insecticide, with abamectin, indoxacarb, and spinosad, compounds which have been reported to be less harmful to arthropod natural enemies. Two key cosmopolitan pests of crucifer crops, (Plutella xylostella) and (Myzus persicae), and two of their respective hymenopteran parasitoids, (Cotesia vestalis) and (Aphidius colemani) were used as representative pests and natural enemies. The pyrethroid lambda-cyhalothrin was found to be the most persistent toxicant against both pest and both parasitoid species tested, while the lactones abamectin and spinosad were the least persistent toxicants. A leaf wax stripping technique was used to compare the contact toxicity of insecticide residues against adult C. vestalis and A. colemani in the epicuticular wax layer. For each compound, removal of epicuticular wax reduced the 24 h residual toxicity (LC₅₀) of fresh deposits (day 0) by about an order of magnitude against C. vestalis. A second residual toxicity experiment showed that removal of epicuticular wax significantly reduced the residual toxicity of each compound against A. colemani at 0, 7, and 14 d after application, with little or no detectable residual activity for the oxadiazine indoxacarb or abamectin/spinosad respectively after 14 d. The present data supports the view that in addition to the intrinsic toxicity of insecticides to natural enemies, differences in their persistence as foliar residues should also be considered in IPM systems.

The corn earworm, Helicoverpa zea (Boddie), is a major pest of row crops in the Southern United States. Control of this insect is dependent on preventative insecticidal transgenic crops and synthetic insecticide applications when damaging populations are encountered in the field. Recently, the use of chemicals from the diamide class of insecticides, particularly chlorantraniliprole, has been used to control unacceptable populations. Due to the increased importance of this active ingredient for control of corn earworms, populations of this insect from the Mississippi Delta have been monitored for susceptibilities annually since 2016. Overall, 58 populations of H. zea were examined for their susceptibility to chlorantraniliprole through diet-incorporated bioassays from 2016 to 2021. Based on probit analysis, there was only a 4-fold difference between the highest and lowest LC₅₀ estimates for all populations tested. Through weights of 2nd and 3rd instar larvae, there appears to be a substantial fitness cost associated with surviving caterpillars that fed on various concentrations of chlorantraniliprole in bioassays, which is not captured through the yes or no response of typical survival analysis. Overall, there was not a detectable trend of reduced susceptibility to chlorantraniliprole over the course of the six-year study.

Hemlock woolly adelgid (HWA), Adelges tsugae Annand, threatens hemlock forests throughout eastern North America. Management efforts focus on early detection of HWA to ensure rapid management responses to control and stop the spread of this pest. This study's goal was to identify an affordable, efficient trap to aid with airborne environmental DNA (eDNA) sampling approaches as an early monitoring tool for HWA. We initially compared HWA detection success between a standard sticky trap, commonly used for HWA monitoring, and trap designs potentially compatible with eDNA protocols (i.e., passive trap, funnel trap, and motorized trap). Passive, funnel, and motorized traps' estimated capture success probabilities compared to sticky traps were 0.87, 0.8, and 0.4, respectively. A secondary evaluation of a modified version of the motorized trap further assessed trap performance and determined the number of traps needed in a set area to efficiently detect HWA. By modifying the original motorized trap design, its estimated capture success probability increased to 0.67 compared to a sticky trap. Overall, the cumulative capture success over the 16-week sampling period for the motorized trap was 94% and 99% for the sticky trap. The number of traps did impact capture success, and trap elevation and distance to infested hemlocks influenced the number of adelgids captured per trap. As eDNA-based monitoring approaches continue to become incorporated into invasive species surveying, further refinement with these types of traps can be useful as an additional tool in the manager's toolbox.

In China, Hyphantria cunea (Drury) is an invasive phytophagous pest; it attacks nearly all species of defoliated trees. To develop integrated pest management programs (IPM) for H. cunea, we need to ensure the availability of insects by mass-rearing them on artificial diets under laboratory conditions. This study compared the growth characteristics, nutritional indices, growth indices, and digestive enzyme activity of insects reared on Pterocarya stenoptera C.DC (Fagales: Juglandaceae), the Chinese wingnut, and an artificial diet. We also investigated the correlation between diet components and growth indices using principal components analysis and Pearson correlation analysis. We found that mass-rearing of H. cunea on an artificial diet was feasible. It led to a shorter developmental period, with heavier larvae and pupae than natural diets. The principal components analysis indicated that the growth indices and α-Amylase were significantly positively associated with PC1, which explained 82.45% of the total data variability. Pearson correlation analysis showed a significant correlation between digestion, absorption parameters, and growth. Developing a mass-rearing program to produce H. cunea on an artificial diet will be valuable for improving IPM strategies. Understanding the mechanism of the responses of phytophagous insect populations to anthropogenic diet regulation can provide new ideas and methods for pest control.

We assessed bioactivity of ethanolic extracts from 35 species of Jatropha L. against an ornamental plant pest, the azalea lace bug, Stephanitis pyrioides (Scott). Jatropha extracts were prepared by air-drying stem, root, or whole plant material, grinding the tissue into a fine powder, adding 70% ethanol, and then vacuum filtering the contents. Emulsions included the extract diluted to the desired concentration in de-ionized water and 10% dimethyl sulfoxide (DMSO). Treatments involved pipetting 20 µl of emulsion onto three adult lace bugs in each well of a 96-well microtiter plate. Treated wells served as replicates for each of six extract concentrations and were arranged according to a RCBD. Extracts of Jatropha clavuligera Müll. Arg. and J. ribifolia (Pohl) Ballion from 0.06 to 0.50% were the most acutely bioactive with bug mortality exceeding that of the positive control – azadirachtin, a terpenoid and chief active ingredient in neem oil. At 1.00%, extracts of J. clavuligera, J. ribifolia and azadirachtin killed 100% of bugs within 3 hr. Jatropha clavuligera induced the lowest LC₅₀ and ranked first in insecticidal potency based on ≥98% of bugs dying within 3 hr. Extracts of J. curcas L., J. gossypiifolia L., J. excisa Griseb, and azadirachtin were equally bioactive; although after 3 hr, the three Jatropha species killed bugs faster. When compared with DMSO, all extract emulsions were bioactive against adult bugs. Thus, active ingredients in a new biopesticide could be sourced from the stem, root, or whole plant extracts of at least five Jatropha species.

Spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is a key pest of many berry and fruit crops worldwide. The primary method of controlling this pest is the application of insecticides. Attract- and-kill is a management tactic that may reduce the number of insecticide applications needed to manage D. suzukii. ACTTRA SWD OR1 and ACTTRA SWD TD, developed by ISCA Technologies Inc., combine D. suzukii attractants with a gel matrix. Growers add an insecticide as a killing agent. The only USDA National Organic Program approved organic insecticide that has been shown to be effective as a killing agent is spinosad. This study aimed to determine the efficacy of other USDA National Organic Program approved organic insecticides, including Grandevo 30 WDG (Chromobacterium subtsugae strain PRAA4-1 30%), MBI-203 SC2 (C. subtsugae strain PRAA4-1 98%), Venerate XC (Burkholderia spp. Strain A396 94.45%), MBI-306 SC1 (B. rinojensis Strain A396 94.45%), Azera (azadirachtin 1.2% + pyrethrins 1.4%), and PyGanic (pyrethrins 1.4%), when used as the killing agent with the two ACTTRA SWD products. Lab and cage bioassays were conducted. Entrust (spinosad 22.5%) and PyGanic were the only compounds that showed some efficacy when used with ACTTRA SWD OR1 and ACTTRA SWD TD.

Cuticular hydrocarbon (CHC) mixtures from workers of five distinct CHC phenotypes of Reticulitermes Holmgren 1913 from two locations in northern California were examined from monthly collections taken over a 3-yr period. The objectives of this study were (1) to identify and quantify variations of the CHCs of multiple colonies of each of these phenotypes (= species or subspecies) to demonstrate consistency, (2) to assess the potential of CHC mixtures to separate or identify colonies within each phenotype, and (3) to detect any temporal changes in each of the hydrocarbons in the CHC mixtures. Nonmetric multidimensional scaling of all CHC mixtures of all samples collected at both locations separated the samples into five clearly visible, different groups of CHC phenotypes (taxa or species) of Reticulitermes. The degree of variability of the CHC mixtures among colonies of each phenotype was such that nonmetric multidimensional scaling did not separate or identify colonies. Strong seasonal fluctuations were evident in some of the CHCs of all five phenotypes and were significantly consistent with a sine curve. Maximum proportions of seasonal CHCs within a phenotype occurred in all seasons of the year but occurred mostly in the winter and summer. In general, the CHCs displaying maximum values in the winter were short-chained (C23–C27) methyl-branched alkanes, whereas the CHCs displaying maximum values in the summer were long-chained (C35–C43) methyl-branched alkanes, which likely influences water retention. These consistent chemical fingerprints are probably responsible for inter-phenotype recognition patterns and are thus useful for chemical taxonomy.

Spodoptera litura is one of the most destructive lepidopteran insects of cabbages and cauliflowers in the world. Cry1 and Vip3 toxins from Bacillus thuringiensis have been reported to show toxicity in multiple lepidopteran insects. Binding of toxic molecules to specific receptors on the midgut epithelial cells is known to be a key step in the action mode of Bt toxins. Aminopeptidase N (APN) -like proteins have been reported to be binding sites of multiple Cry toxins in the midgut of Cry susceptible insects. In the present study, we identified six midgut APNs by analysis of the genome and midgut transcriptome of S. litura. CRISPR/Cas9 mediated gene-knockout system was utilized to mutate the GPI-anchor signal peptide at the C terminus of SlAPN1. SlAPN1 was verified to be removed from the midgut brush border membrane vesicles of a homozygous knockout strain of S. litura (SlAPN1-KO). Bioassay results indicated that susceptibility of the SlAPN1-KO strain to Cry1Aa, Cry1Ac, Cry1Ca, and Vip3Aa toxins was close to that of the wild-type strain of S. litura. RT–qPCR results showed that the transcriptional level of SlAPN2-6 was not up-regulated after knockout of the SlAPN1. Results in this study indicated that the SlAPN1 did not play a critical role in the pathway of toxicity of Cry1Aa, Cry1Ac, Cry1Ca, and Vip3Aa toxins in S. litura.

Controlling the number of ticks as carriers of infectious diseases is very important. The process is sometimes compromised by activating the protective mechanisms of the tick itself. Glutathione-S-transferases activity (GSTs) was the subject of our investigation of tick abundance after pyrethroid treatment. We determined GSTs activity in ticks collected from six locations in Belgrade before and after pyrethroid treatment and correlated it with the number of ticks in the locations. The results showed that tick abundance correlated with GSTs activity. On the other hand, treatment efficiency was location-dependent, being similar in each particular location in both April (spring) and October (autumn). Our results suggest that GSTs activity reflects the influence of both present local allelochemicals from different environmental seasonal vegetation and applied pyrethroid. We can conclude that by evaluating GSTs activity in ticks from particular locations as well as during the treatment with acaricides tick removal practice could be improved.

Insecticides are a primary means for suppressing populations of insects that transmit plant pathogens. Application of insecticides for limiting the spread of insect-transmitted plant pathogens is often most effective when applied on an area-wide scale. The glassy-winged sharpshooter is a vector of the bacterial pathogen Xylella fastidiosa, which causes numerous plant diseases including Pierce's disease of grapevine. The glassy-winged sharpshooter has been the subject of an area-wide suppression program in California for nearly two decades. Overreliance on a limited number of active ingredients including the neonicotinoid imidacloprid has resulted in increased levels of resistance to commonly applied products. In California, glassy-winged sharpshooters move between citrus, an important overwintering host, and vineyards. Accordingly, imidacloprid is routinely applied via the irrigation system in vineyards and citrus orchards. For soil applied applications, it may take days to weeks for concentrations in plants to increase to lethal doses. Further, as the dose of imidacloprid required to kill sharpshooters increases due to resistance, so too does the period that sharpshooters are exposed to sub-lethal doses. Response of glassy-winged sharpshooter to cowpea plants treated with sub-lethal doses of imidacloprid was evaluated by conducting no-choice and choice tests. In no-choice feeding assays, glassy-winged sharpshooters caged on plants treated with sub-lethal doses of imidacloprid ceased feeding and produced little excreta. Further, sub-lethal exposure to a range of doses over a 4-d period did not affect viability over a 9-wk post-exposure holding period on untreated plants. In choice-tests, glassy-winged sharpshooters avoided treated plants and were observed predominately on untreated plants. Results suggest that application of imidacloprid to vineyards and citrus orchards may push glassy-winged sharpshooters out of treated habitats rather than kill them.

Livestock farming is currently reducing the use of synthetic insecticides because of the development of resistance in insect pests. Plant-based bioinsecticides are considered alternatives to synthetic pesticides. Therefore, the present study investigated the chemical composition and discriminating concentrations (DCs) of essential oils from Syzygium aromaticum (L.) Merr. and L. M. Perry (SA), Cinnamomum porrectum (Roxb.) Kosterm (CP), and Litsea cubeba (Loureiro) Persoon (LC) against laboratory-reared Musca domestica (larvae and adults) and field-derived Stomoxys indicus (adults) using larval dip and adult contact bioassays. All essential oils were analyzed using gas chromatography/mass spectroscopy. The most common components in the SA, CP, and LC oils were eugenol, safrole, and terpenoids, respectively. The results of a larval test indicated that CP was most effective against M. domestica with a DC of 6.134% v/v. In adult bioassays, CP was also the most toxic oil against M. domestica (DC = 30.644% v/v), whereas SA displayed the greatest toxicity against S. indicus (DC = 1.434% v/v). Moreover, in the larval bioassay results of oils tested at 1, 5, and 10% v/v in M. domestica, 1% and 5% v/v CP had the shortest median lethal times values of 68.88 and 19.44 min, respectively, whereas, at 10% v/v, SA displayed the shortest median lethal time (0.03 min), followed by CP (1.74 min) and LC (19.02 min). However, additional data are needed to further evaluate the semi-field and field effects of CP and SA on M. domestica and S. indicus under realistic operational conditions.

Hymenopteran parasitoids generally show a haplo-diploid sex determination system. Haploid males are produced from unfertilized eggs, whereas diploid females develop from fertilized eggs (arrhenotokous). In some cases, diploid females develop from unfertilized eggs (thelytokous). Diglyphus wani (Hymenoptera: Eulophidae) is a biological control agent for agromyzid leafminers and have arrhenotokous and thelytokous strains. However, the morphological characteristics of two strains of D. wani are so similar that it is difficult to accurately distinguish them based on morphology. Here, a rapid molecular identification method was developed based on the mitochondrial gene cytochrome c oxidase I (COI) and one-step multiplex PCR. Two primer combinations, PC1 (Ar-F1/Th-F1/WR2) and PC2 (Ar-F1/Th-F4/WR2), were designed and repeatedly screened to distinguish two strains simultaneously, of which two special forward primers Th-F1/Th-F4 were used for the thelytokous strain and one special forward primer Ar-F1 was used for the arrhenotokous strain. In addition, a common reverse primer, WR2, was used for both strains. The PC1 and PC2 PCR assays were effective in distinguishing the two strains at different developmental stages and field colonies. This method provides a reliable, highly sensitive, and cost-effective tool for the rapid identification of the two strains of D. wani.

Insect resistance to toxins derived from Bacillus thuringiensis (Bt) is a major issue in agriculture. Resistance to Bt has been linked to the loss of toxin binding sites within the insect, changes within the gut microbiota, and midgut tissue regeneration. Histopathological documentation of intoxication and resistance to Bt is lacking for rootworms in the genus Diabrotica (Coleoptera: Chrysomelidae), a major target of Bt corn. Here, we document the morphological response of both Bt-resistant and Bt-susceptible larval western corn rootworm, Diabrotica virgifera virgifera LeConte, to intoxication with eCry3.1Ab. Gut lumen structural differences are subtle between the two colonies when feeding on non-Bt corn. However, upon ingestion of Bt-corn roots, susceptible larvae develop symptoms indicative of gut disruption by Bt, whereas resistant larvae incur milder effects. Mild disruption of the peritrophic matrix and gut lumen is accompanied by stem cell proliferation that may lead to midgut tissue regeneration. These results help contextualize the multifaceted nature of Bt-resistance in western corn rootworm for the first time from a histopathological perspective.