For ectotherms such as insects, their low- and/or high-temperature tolerance is one of the most important traits not only for their physiological as well as ecological and evolutional processes. Here, we review the temperature tolerance of insects in relation to their development and suggest a novel method of specifying low and high threshold temperatures. To date, the upper and lower critical thermal threshold for development as T_min and T_max, respectively, which are derived from nonlinear empirical models, has been extensively used. These indicators, which originated from the artificial empirical models, however, may not be reliable. Consequently, the Sharpe–Schoolfield–Ikemoto (SSI) model which is a nonlinear theoretical model based on thermodynamics, was implemented as an alternative tool to express tolerance temperatures. In the model equation constructed with subunits, when the reversed denominator (P₂ function) is maximum (nearly 100% in general), it denotes the probability of an enzyme being in the almost fully-active state of the intrinsic optimum temperature (T_Φ). The profile of the P₂ function shows a peak at the T_Φ temperature and the two temperatures of T_L50 and T_H50 which indicate the 50% active and 50% inactive state (P₂ = 50%), respectively, are given as parameters in the P₂ function of the SSI model. Even so, it is possible to select any values within the range of 0<P₂<100% to determine the lower and upper threshold. Namely, the two temperatures associated with a specified P₂ value could be determined also within the range of real-medium temperature in which ectotherms is living in nature.

Spalangia endius Walker is a parasitoid wasp that is commercially available as a biological control agent for filth fly pests in livestock-rearing operations. Imidacloprid is often used to control these flies. The present study examined the sublethal effect of field-realistic concentrations of imidacloprid on mating behavior, offspring sex ratios, and male preference for virgin females. After exposure to imidacloprid, S. endius females that survived were less likely to mate than control females, which will result in male-biased sex ratios because only mated females can produce daughters. Males did not avoid exposed females, but exposed females were almost always unreceptive. Males that survived exposure to imidacloprid exhibited reduced mating competitiveness against unexposed males. However, if an exposed male mated, his mate's sex ratio and ability to control flies was unaffected. Exposed males were also still able to discriminate against mated, and thus usually unreceptive, females. Together with previous studies, these results suggest that not only does imidacloprid reduce the ability of S. endius females to survive and parasitize hosts, but when an exposed female does survive and parasitize hosts, she is likely to produce just sons, because of her lack of receptivity. More-male-biased populations of S. endius will decrease their efficacy for fly control. Thus, the use of imidacloprid along with this parasitoid may be financially inefficient for pest management.

The European gypsy moth, Lymantria dispar L., is an invasive insect in North America that feeds on over 300 species of trees and shrubs and occasionally causes extensive defoliation. One regulatory practice within quarantine zones to slow the spread of this insect recommends that wood products (e.g., logs, pulpwood) originating from quarantine areas are staged within 100 foot-radius buffer zones devoid of host vegetation before transport outside the quarantine boundary. Currently, there are little data underpinning the distance used. We conducted field experiments in Wisconsin to assess buffer zone efficacy in reducing risk of larval gypsy moth encroachment on wood staging areas. We released late-instar gypsy moth larvae in groups around the perimeter of a 100-ft radius zone and tracked their movements for 10-h periods using harmonic radar and tested whether host vegetation staged around the perimeter or food availability before release altered movement patterns. Three larvae moved over 300 ft in 10 h, but 93% of larvae moved <100 ft total. The presence of host vegetation reduced the likelihood of larvae entering the buffer zone by 70%. Food availability before release did not affect movement. Using these field data, we parameterized a Monte Carlo simulation model to evaluate risk of larvae crossing zones of different sizes. For zones >100 ft in radius, <4% of larvae reached the center. This percentage decreased as zone size increased. Implications of these results for the regulatory practices of the gypsy moth quarantine are discussed.

In this study, we assess how chrysopids (generalist predators widely used as biological control agents) use olive, almond, oak, and pine trees for oviposition. We sampled clutches of chrysopids from tree canopies in August 2016 and 2017. Additionally, we checked the stage (alive, predated, emerged, or parasitized) and the site (upper side, edge, or underside of leaves) and mode (single and cluster clutches) for oviposition in every clutch. The clutches collected alive in August 2016 were raised in the laboratory and identified to species level. No differences in clutch abundance were observed amongst tree species, years and locations, suggesting that chrysopids are geographically well spread and that all of the tree species are equally suitable to support clutches of active chrysopids in this period. Additionally, chrysopids preferred to lay their clutches on the edge and upper side of the leaves and the single clutches were the most frequent. We collected clutches of 9 chrysopid species (Neuroptera: Chrysopidae) belonging to four genera, from which Pseudomallada prasinus (Burmeister, 1839), Cunctochrysa baetica (Hölzel, 1972), and Chrysoperla mutata (McLachlan, 1898) were the most abundant.The almond trees shelter the highest chrysopid species richness. We found C. mutata as the only Chrysoperla Steinmann, 1964 species laying on the olive trees and Chrysoperla lucasina (Lacroix, 1912) and Chrysoperla pallida Henry et al., 2002 on the almond trees. Although every tree species is able to shelter a similar abundance of eggs of chrysopids, conserving different trees ensures the existence of a diverse assemblage of chrysopids that might respond to periodical perturbations and moves to olive groves in the case of a pest outbreak.

The invasive pest Diaphorina citri Kuwayama was first detected in Arizona in 2009. Since late 2013, the parasitoid Tamarixia radiata (Waterson), the main biocontrol agent of D. citri, has been released as part of a biological control program on citrus grown in urban areas of two western Arizona counties in the lower Colorado desert environment. Here we report a 3-yr survey aimed at evaluation of T. radiata releases on D. citri populations and assess the impact of the climate conditions on the phenology of D. citri and on the establishment success of T. radiata. We also monitored the phenology of D. citri as part of this assessment on different citrus host species. We show that the high summer temperatures in the Arizona desert halt the development of D. citri for about 3 mo every year which appears to have limited the establishment and impact of T. radiata. At survey sites distant from release areas the parasitism rates over the season ranged from 0 to 75% and on average peaked around 50% in 2016 but it was low or absent in 2015 and 2017, respectively. We discuss the consequences of this phenology of D. citri in the desert areas for the prospects of long-term establishment of T. radiata and the management of this key citrus pest.

No-choice tests can help select weed biological control agents with a high degree of host specificity but may exclude potentially effective agents that can develop on nontarget plants under laboratory conditions. The actual amount of damage to nontarget plants often goes unstudied, even though agents may exploit nontarget plants without inflicting significant harm. Furthermore, tests typically assess whether prospective agents can complete one generation on nontarget plants, and rarely examine whether agents are likely to persist on the nontarget plants over the long term. Pre-release assessments that occur over multiple generations of the agent could help determine whether prospective agents pose a threat to nontarget plants under field conditions.This study focused on the psyllid Arytinnis hakani Loginova (Hemiptera: Psyllidae), which is under consideration in California for release against the invasive shrub French broom, Genista monspessulana (L.) LAS Johnson. We examined the host suitability of seven nontarget Lupinus spp. (Fabales: Fabaceae) for the psyllid using no-choice tests, and assessed psyllid impacts on Lupinus arboreus Sims, which consistently supported psyllid oviposition and development. The psyllid oviposited on all of the tested Lupinus spp., and completed two generations on five of the Lupinus spp., although numbers of psyllids were highest on French broom. In an additional experiment, A. hakani did not affect growth or survival of L. arboreus, but reduced growth and dramatically reduced survival of French broom. Taken together, these results indicate that Lupinus spp. are suboptimal hosts for the psyllid and are unlikely to be significantly impacted by its feeding.

The summer phenology and survivorship of the stem-mining weevil, Mecinus janthiniformisToševski and Caldara, a biocontrol agent of Dalmatian toadflax, Linaria dalmatica (L.) Miller, was studied in 2015–2016 as it developed within host plant stems at a low elevation, open rangeland site in northern Utah. Hatching from eggs in spring and early summer, weevils occurred as larvae within stems in June. Earliest maturing adults occurred in mid-July, and the majority of individuals had completed pupal development by early August. Survivorship within stems was high, with two-thirds or more of individuals surviving from egg hatch to adulthood as assessed in mid-September. Mortality rates within stems were highest during larval development, with parasitism accounting for the majority of deaths. At least three parasitoid species (Chalcidoidea: Pteromalidae and Eupelmidae), including both endoparasitoids and ectoparasitoids, were found attacking weevils within stems. Although most surviving weevils remained as adults within stems to overwinter, some adults were found to have chewed exit holes, and in some cases had exited from stems, beginning in July; the fate of these prematurely exiting adults is unknown. Low summer mortality rates within stems should promote weevil establishment under the hot, dry conditions of northern Utah, but parasitism and premature exiting of adults from host stems merit further investigation concerning their potential to reduce biocontrol efficacy. The results presented here for M. janthiniformis phenology within host stems will contribute to the development of standardized, summer monitoring for this biocontrol agent by stem dissection.

Carotenoids are fundamental precursors for hormones and antioxidants, and insects must acquire carotenoids from their diet. Previous research has shown that insects can selectively absorb dietary carotenoids, often modifying them qualitatively or quantitatively, and quantities may be proportional to those found in the diet. Trichoplusia ni Hübner is a generalist herbivore with host plants varying greatly in carotenoid profiles and concentrations. Larvae sequester carotenoids in their hemolymph, and carotenoid sequestration contributes to their cryptic green coloration. Our objectives were to compare the types of carotenoids found in T. ni and their host plants to determine whether qualitative changes occurred, and compare the amounts of sequestered carotenoids in T. ni reared upon different host plants to determine whether quantitative variation influences sequestration. To fulfill these objectives, larvae were fed romaine lettuce (Lactuca sativa L. [Asterales: Asteraceae] var. longifolia) or kale (Brassica oleracea L. [Brassicales: Brassicaceae] var. sabellica) for a period of 5 d, and sequestered carotenoids from the entire insect were resolved with thin-layer chromatography and measured with spectrophotometer. All carotenoids resolved from plants were also resolved from larvae, and although the carotenoids of plants differed quantitatively, the sequestered carotenoids did not differ between host plants. Regardless of host plant species, T. ni sequestered carotenoids at concentrations up to 20 times higher than the concentrations found in the plants. Future research may be able to explicitly identify enzyme systems involved in the transport and modification of carotenoids in T. ni and other animals.

Aggregation can be adaptive by providing protection from predators, facilitating thermoregulation, and expediting the location of food, shelter, and mates. German cockroaches Blattella germanica L. (Blattodea: Ectobiidae), are obligatory commensals in human-built structures, where they aggregate in crevices during the day. The source of the aggregation pheromone that drives this behavior and its chemical identity remain unclear. Cuticular hydrocarbons (CHCs) in feces have been proposed to serve as aggregation pheromone, but this function has not been investigated in relation to visual and tactile cues that mediate aggregation. Our objective was to delineate how CHCs in the feces and on the cockroach body operate in conditions that reflect the German cockroach's ecology—either applied to shelters, representing fecal deposition, or to previously extracted cockroaches, representing shelter co-habitation with other cockroaches. Cockroaches and feces-conditioned filter papers were extracted, CHCs were purified by flash chromatography, and two-choice behavior assays were performed with first instar nymphs. Our results confirmed that nymphs preferred to rest within feces-conditioned shelters. However, purified CHCs did not elicit more aggregation than solvent-treated control shelters. Nymphs significantly preferred to rest in shelters that contained a CHC-free dead female, but the addition of CHCs to the female did not enhance aggregation. Nymphs preferred to aggregate with the CHC-free female over CHC-treated shelters. Finally, a methanol extract of feces was highly effective at eliciting aggregation, contesting previous reports that fecal CHCs serve as aggregation pheromone. We assert that CHCs play a minor, if any, role in the aggregation behavior of German cockroaches.

Psyllids (Hemiptera: Psylloidea) are phloem-feeding insects that tend to be highly specific in their host plants. Some species are well-known agricultural pests, often as vectors of plant pathogens. Many pest psyllids colonize agricultural fields from non-crop reproductive hosts or from non-host transitory and winter shelter plants. Uncertainty about which non-crop species serve as sources of psyllids hinders efforts to predict which fields or orchards are at greater risk of being colonized by psyllids. High-throughput sequencing of trnL, trnF, and ITS was used to examine the dietary histories of three pest and two non-pest psyllid species encompassing a diversity of lifecycles: Cacopsylla pyricola (Förster) (Psyllidae), Bactericera cockerelli (Šulc) (Triozidae), Diaphorina citri Kuwayama (Liviidae), Aphalara loca Caldwell (Aphalaridae), and a Cacopsylla species complex associated with Salix (Malphighiales: Salicaceae). Results revealed an unexpectedly high level of feeding on non-host species by all five psyllid species. The identification of the dietary history of the psyllids allowed us to infer their landscape-scale movements prior to capture. Our study demonstrates a novel use for gut content analysis—to provide insight into landscape-scale movements of psyllids—thus providing a means to pinpoint the non-crop sources of pest psyllids colonizing agricultural crops. We observed previously unknown psyllid behaviors during our efforts to develop this method and discuss new research directions for the study of psyllid ecology.

Invasive species may interact with resident species and disrupt previously established interactions, with effects on the whole community. If introduced seeds are selectively consumed by native granivores, this could limit the establishment or spread of invasive plants (biotic resistance), and reduce the predation pressure upon native seeds. We determined if the presence of introduced plants affects the diet and the seed preferences of the ant Pogonomyrmex carbonarius (Mayr) in a Patagonian steppe. We expected a higher proportion of introduced seeds in the diet of nests located in areas with a high abundance of introduced species (roadsides) than in nests located in low invaded areas. Diet composition was obtained by collecting items retrieved by workers to colonies and compared between areas of contrasting abundance of introduced species. Field-based choice experiments were performed to evaluate whether exotic seeds were preferred to native ones under a paired comparisons design. Native seeds predominated in the diet. A low proportion of introduced species were included only in colonies close to the road. Ants preferred native seeds to introduced ones, and showed a marked preference for seeds of the native grass Pappostipa speciosa (Trin. & Rupr.) Romasch. (Poaceae), typical of the Patagonian steppe. The presence of introduced plants had little influence on interactions of P. carbonarius with seeds in the Patagonian steppe. Therefore, this ant species would not exert a control on the studied introduced plants, illustrating a case of low biotic resistance to invasion by these species.

Spatio-temporal dynamics of multi-species pest communities and the interactions between them influence the structure of pest complex that attack crops. In East and Southern Africa, cereal crops, especially maize, is attacked by a complex of lepidopteran stemborer species made up of Busseola fusca (Fuller) and Sesamia calamistis Hampson (Lepidoptera: Noctuidae), and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae). There is inadequate information on the extent of single- and multi-species infestations by this pest complex, their current spatio-temporal variations, and the primary abiotic factors that influence these. Furthermore, the recent invasion of the fall armyworm, Spodoptera frugiperda J.E. Smith, in sub-Saharan Africa will likely influence this stemborer community structure. Sampling was conducted in maize fields to record stemborer species and larval numbers from infested plants, in 28 localities found in six agro-ecological zones (AEZs) of Kenya and parts of Tanzania, as well as in one locality in the mid-altitudes where the three stemborer species occurred together. Both single- and multi-species stemborer communities characterized infestation of maize at field and plant levels, but varied in proportions between the AEZs. Infestation patterns and larval densities varied between seasons at mid-locality stemborer communities followed a clustered distribution pattern. Temperature was the most significant abiotic factor influencing the composition of stemborer communities at all spatial scales. Rainfall was significant only at the local scale. Results are discussed in relation to current stemborer community structures in maize fields and what the likely potential implications are, in the light of climate change and the recent establishment of the fall armyworm in Africa.

Geographic variation in body size has fascinated biologists since the 19th century as it can provide insight into the evolution of the body size of various organisms. In this study, we investigated body size variation in eight carabid species/subspecies (Coleoptera: Carabidae) along elevational gradients in six Central European mountain ranges. First, we examined elevational variation in body size and whether female and male body sizes differed in their responses to elevation. Second, we examined intrapopulation variation in body size along an elevational gradient, and we compared the degrees of intrapopulation variation between males and females. The investigated species either followed a converse Bergmann's cline (Carabus auronitens auronitens Fabricius 1792; Carabus linnei Panzer 1810; Pterostichus melanarius (Illiger, 1798); Pterostichus pilosus (Host, 1789)) or their size was unaffected by elevation (Carabus auronitens escheri Palliardi, 1825; Carabus sylvestris sylvestris Panzer, 1796; Carabus sylvestris transsylvanicus Dejean, 1826; Pterostichus burmeisteri Heer, 1838). Females were the larger sex in all the investigated species, but the degree of sexual size dimorphism differed between species. In general, the degree of sexual size dimorphism showed no change with elevation. The degree of intrapopulation variation in body size slightly increased with elevation in C. sylvestris sylvestris and P. pilosus. Overall, the intrapopulation variation in body size significantly differed among the investigated carabid species. The existing literature on intrapopulation variation in the body size of insects is limited, but further investigation of this issue could provide a better understanding of the mechanisms that generate geographical clines.

Cellulose and lignin decomposition is crucial for efficient nutrient cycling, yet few studies have been performed regarding the effects of soil fauna on cellulose and lignin decomposition. This study was conducted to better understand the effects of soil fauna on lignin and cellulose decomposition in the Changbai Mountain. Litterbags of two different mesh sizes were used to examine cellulose and lignin decomposition of 11 species of plant litter in the four vegetation zones of the Changbai Mountain North Slope over a 24-mo period. Cellulose and lignin clearly declined over time for all 11 species of plant litter. Cellulose decomposition rate faster than the rate of lignin decomposition in the majority of plant species. Soil fauna could promote the decomposition of cellulose and lignin. The abundance and richness of soil fauna in coniferous broad-leaved mixed forests were greater than in coniferous forest, Betula ermanii Cham. (Fagales: Betulaceae) forest, and alpine tundra. Soil fauna had a greater effect on Abies nephrolepis Maxim. (Pinales: Pinaceae) cellulose and lignin, whereas contribution rates were relatively lower in the Fraxinus mandshurica Rupr. (Contortae: Oleaceae) and Acer mono Maxim. (Sapindales: Aceraceae) litterbags at the end of the experiment. Litter quality was negatively correlated with the soil faunal contribution to litter decomposition directly. Overall, the findings of this study have implications for the effects of soil fauna on cellulose and lignin decomposition in the alpine ecosystem, and also can provide experimental evidence that soil faunal contribution is affected by soil faunal communities and litter quality.

The Scolytinae is highly diversified in tropical forests, but richness and abundance patterns within most Ecuadorian forest habitat types are not yet characterized. In this study, we assessed patterns of variation in Scolytinae richness, abundance, and species composition in a primary and a secondary natural forest, and a commercial balsa plantation in Ecuador. We conducted a 1-yr survey of Scolytinae communities with baited traps and measured associated environmental variables. In total, 18,169 Scolytinae individuals were captured and comprised 85 species, 16 genera, and six tribes. In the natural forests, main indicator species were Xylosandrus morigerus, Xyleborus affinis, Xyleborus sp.02, and Corthylus sp.01, whereas all species of Hypothenemus were indicator species in the balsa plantation. The exotic Premnobius cavipennis (Ipini), Xylosandrus compactus, and Xylosandrus morigerus were indicator species for the natural forests. We provide evidence that commercial balsa plantations provide abundant favorable resources for native and exotic scolytines in Ecuador, and that scolytine communities in natural forest and in plantations are more likely to differ in their species composition than in their cumulated species richness. In all habitats, species composition, abundance, and species richness showed temporal patterns of variation that coincided with seasonal variations in climatic conditions, with highest records during the coldest and driest months in the primary forest and the balsa plantation. We provide new knowledge on the native Ecuadorian scolytine fauna and a foundation for the monitoring for potential scolytine pest species of natural and planted tropical forest ecosystems.

The date palm hopper, Ommatissus lybicus de Bergevin, is one of the most important pests of the date palm in the Middle East and North Africa.This insect uses its needle-like sucking mouthparts to feed on phloem, which is devoid of most essential amino acids and many vitamins. The absence of essential nutrient in its diet is suggested to be ameliorated by endosymbionts in O. lybicus. Arsenophonus is one of the main bacterial endosymbionts widely prevalent in O. lybicus. In this study, we used antibiotics to eliminate Arsenophonus from O. lybicus originating from three populations (Fin, Qale’e Qazi, and Roodan) and studied the effects on the fitness of the pest. Our results revealed that the removal of Arsenophonus increased the developmental time of the immature stages and reduced the values of different life-history parameters including nymphal survival rate and adult longevity in the host. Furthermore, elimination of Arsenophonus completely obliterated offspring production in all O. lybicus populations investigated. These results confirm the dependency of O. lybicus on Arsenophonus for fitness and give a new insight regarding the possibility of symbiotic control of O. lybicus.

Turfgrasses are ubiquitous in urban landscapes and can provide numerous ecosystem services. However, most warm season turfgrasses are produced, planted, and maintained as cultivar monocultures, which may predispose them to herbivore attack and reduce the services lawns provide. Though rarely done, host plant resistance can be used as a strategy to reduce herbivory and preserve beneficial services. Increasing turfgrass cultivar diversity may provide similar or greater benefits through associational resistance, whereas conserving desirable maintenance and aesthetic traits. However, no studies have examined this in warm season turfgrasses. To address this, we evaluated host plant resistance to fall armyworm (Spodoptera frugiperda [J.E. Smith] [Lepidoptera: Noctuidae]) in commercially available cultivars of St. Augustinegrass (Stenotaphrum secundatum [(Walt.) Kuntz] [Lepidoptera: Noctuidae]) and then investigated if the resistance or susceptibility of St. secundatum cultivars carried over in mixed cultivar plantings. Through a no-choice experiment and a limited-choice experiment, we detected no host plant resistance in monocultures of St. secundatum cultivars. However, we did find that as cultivar diversity increased, female Sp. frugiperda larval weight and herbivory decreased. Additionally, choice tests indicated that larvae prefer less diverse stands of St. secundatum cultivars. Interestingly, our results suggest that in the absence of host plant resistance, warm season turfgrass cultivar diversity may reduce herbivore pest fitness and damage. These results demonstrate that warm season turfgrass cultivar diversity may be a viable integrated pest management tool that warrants further investigation.

Fumigants are often the primary material used to manage plant disease agents, soil-borne arthropods, and weeds in California agriculture, particularly in the absence of crop rotation. However, some fumigants have come under increased regulatory scrutiny and are therefore no longer available for use. We tested two biologically based preplant crop-protection fumigant alternatives for their effectiveness in reducing populations of Delia radicum (L.), a soil-borne insect pest of cole crops. Laboratory and field tests compared pest survival in untreated control soil with survival under anaerobic soil disinfestation (ASD), which is induced by incorporating a carbon source (rice bran or grape pomace) and subsequently saturating the soil with water. We also measured and compared the effects of standard grower practices (fumigation), ASD and biofumigation (mustard seed meal incorporated before planting), and untreated control soils on fly abundance, pupal survival, and root damage in Brussels sprout fields. In both laboratory and field studies, D. radicum pupal survivorship was reduced in ASD-treated soils relative to control soils. Pupal survivorship of Musca domestica (L.) (Diptera: Muscidae), which was used as a proxy for D. radicum in some field experiments, was also reduced in ASD- and biofumigation-treated soils, when compared with untreated control soils. These results indicate that fumigant alternatives may provide useful insect pest management opportunities for compatible cropping systems.

Physiological limits of non-native species to environmental factors are critical for their establishment and spread in the adventive range. The crapemyrtle bark scale, Acanthococcus lagerstroemiae (Kuwana), is a major pest of crapemyrtles. Despite concerns on its rapid spread, there is a lack of information on potential distribution range of this scale in the United States. To understand this scale's distribution potential, its thermal tolerance was evaluated using higher and lower thermal limits. Exposure time leading to 50 and 90% mortality (Lt₅₀ and Lt₉₀) at extreme low or high temperatures were measured under controlled conditions. A model was then built to fit temperature data of cold fronts from 2001 to 2016 and to calculate potential mortalities along latitudes. Isothermal lines delineated at 90% mortality were defined as the northern limits. Modeling results suggested that A. lagerstroemiae nymphs collected in summer could tolerate heat; however, they were more susceptible to cold temperatures. Laboratory assays suggested that cold tolerance of A. lagerstroemiae nymphs varied from summer to winter. For example, SCP of nymphs collected in summer was higher than those collected in fall (−21 vs. −27°C), and the exposure time leading to Lt₉₀ at 0°C was also different, which were 8 versus 50 h comparing nymphs collected in summer versus fall. Our prediction suggested that A. lagerstroemiae is likely to be limited by cold temperatures along the 43° N latitude. Based on these results, integrated management strategies can be developed for A. lagerstroemiae within the predicted range.

Currently the area with the inundative release of Cotesia flavipes (Cameron) in the country is approximately 3.5 million hectares per year in regions of tropical and subtropical climate, but there are questions about its efficiency since they are not considered the thermal requirements of the strains used. The objective of the study was to evaluate the biology in different thermal conditions of five C. flavipes strains, from different places of origin. Insects from Paraná (Strain PR), Minas Gerais (Strain MG), Alagoas (Strain AL) and two strains from São Paulo state (SPI and SPII strains) were submitted to different constant temperatures (10, 15, 18, 20, 22, 25, 30, and 32°C), relative air humidity of 70 ± 10% and 12-h photophase. The duration the egg-adult of C. flavipes was inversely proportional to the temperature in the thermal range of 18 to 30°C. No development occurred at temperatures of 10, 15, and 32°C. The highest survival of the biological cycle (egg-adult) (above 70%) occurred in the thermal range of 25 to 28°C. Also, temperatures from 28 to 30°C characterize significantly more females than males (sex ratio > 0.70). Based on the development of the biological cycle, the threshold temperature (Tt) was similar among the C. flavipes strains (ranging from 9.6 to 11.1°C), providing the thermal constants of 229.4 to 273.9 degree-days. The biological control of Diatraea saccharalis (Fabricius 1794) (Lepidoptera: Crambidae) may be more efficient to use C. flavipes strains more adapted to the thermal conditions of each region.

Lymantria dispar L. and Lymantria monacha (L.) are Eurasian pests that have the potential for accidental introduction via trade into other world areas. Establishment of first instars of Lymantria depends on larvae surviving long enough to disperse and finding suitable hosts. The survival and development of newly hatched Lymantria larvae from nine geographic populations at seven temperatures (1–30°C) held without food, with summer foliage of a preferred or conifer host was determined. There was considerable variation both within and among the Lymantria populations in the survival of larvae at different temperatures when held with and without food. Without food survival declined from about a month at 5°C to a few days at 30°C, following a typical enzymatic kinetic rate function. At 1°C larval survival was less than at 5°C likely because the larvae were susceptible to freezing. Larvae from the one L. monacha population fed and gained weight on the summer foliage, particularly on the conifer, at 10–15°C but < 20% survived for 14 d at 20–30°C. The newly hatched L. dispar larvae from all eight populations fed (at 10–30°C) and developed (at 15–30°C) on the summer foliage of one or both of the hosts. This suggests that they may be able to find adequate food for establishment even if hatch is not synchronous with bud break in the invaded habitat. Survival on the conifer was highest for one Chinese and two European populations of L. dispar, suggesting the ability to utilize conifers is population and not subspecies specific.

In recent times, several studies have been undertaken on the artificial mass-rearing of insects in which clinical antibacterial antibiotics, including gemifloxacin, which is a DNA gyrase and topoisomerases inhibitor, are amended into the diet to control microbial contamination and preserve diet. The findings of these studies have suggested the possibility that these antibiotics influence the biological traits of insects in relation to their oxidative effects. This study investigated the effects of gemifloxacin on Drosophila melanogaster (Meigen) survival rates, development times, and male–female adult longevity. And we also determined the effects of gemifloxacin on lipid peroxidation product, malondialdehyde, protein carbonyl levels, and glutathione S-transferase activity of fruit fly eggs. First instars were fed on artificial diets containing 150, 300, 600, and 900 mg/liter concentrations of gemifloxacin until adult emergence. Our results indicate that sublethal effects of gemifloxacin are likely to significantly impair adult fitness and life-history parameters in D. melanogaster, probably because of its oxidative effects.

As agricultural practices intensify, species once common in agricultural landscapes are declining in abundance. One such species is the monarch butterfly (Danaus plexippus L.), whose eastern North American population has decreased approximately 80% during the past 20 yr. One hypothesis explaining the monarch's decline is reduced breeding habitat via loss of common milkweed (Asclepias syriaca L.) from agricultural landscapes in the north central United States due to the adoption of herbicide-tolerant row crops. Current efforts to enhance monarch breeding habitat primarily involve restoring milkweed in perennial grasslands. However, prior surveys found fewer monarch eggs on common milkweed in grassland versus crop habitats, indicating potential preference for oviposition in row crop habitats, or alternatively, greater egg loss to predation in grasslands. We tested these alternative mechanisms by measuring oviposition and egg predation on potted A. syriaca host plants. Our study revealed that habitat context influences both monarch oviposition preference and egg predation rates and that these patterns vary by year. We found higher monarch egg predation rates during the first 24 h after exposure and that much of the predation occurs at night. Overall, we documented up to 90% egg mortality over 72 h in perennial grasslands, while predation rates in corn were lower (10–30% mortality) and more consistent between years. These findings demonstrate that weekly monarch egg surveys are too infrequent to distinguish oviposition habitat preferences from losses due to egg predation and suggest that monarch restoration efforts need to provide both attractive and safe habitats for monarch reproduction.

Bumble bee pollinators can be exposed to pathogens when foraging on flowers previously visited by infected individuals. Infectious cells may be deposited in floral nectar, providing a site for pathogens to interact with nectar secondary compounds prior to infecting bees. Some nectar secondary compounds can reduce pathogen counts in infected bumble bees, but we know less about how exposure to these compounds directly affects pathogens prior to being ingested by their host. We exposed the trypanosomatid gut pathogen, Crithidia bombi (Lipa & Triggiani 1988) (Trypanosomatida: Trypanosomatidae), to six different compounds found in nectar (aucubin, catalpol, nicotine, thymol, anabasine, and citric acid) for 1-h prior to ingestion by Bombus impatiens (Cresson 1863) (Hymenoptera: Apidae) workers that were then reared for 1 wk on a control diet. All of these compounds except citric acid reduce pathogen levels when consumed in hosts after infection, and citric acid is a common preservative found in citrus fruits and some honeys. We found that both citric acid and aucubin reduced Crithidia cell counts compared with controls. However, catalpol, nicotine, thymol, and anabasine did not have significant effects on Crithidia levels. These results suggest that Crithidia exposure in some floral nectars may reduce cell viability, resulting in a lower risk to visiting pollinators, but this effect may not be widespread across all flowering species.

Pollination services provided by the honey bee, Apis mellifera (Hymenoptera: Apidae, Linnaeus, 1758) have broad economic impacts and are necessary for production of a diversity of important crops. Hives may be transported multiple times per year to provide pollination. To test how temperature may contribute to transportation stress, temperature sensors were placed in hives in different locations and orientations on the trailer during shipping. Colony size prior to shipping significantly contributed to loss of population immediately after shipping which contributed to colony failure with smaller colonies more likely to fail and fail faster. Colony size also affects thermoregulation and temperature stress. Internal hive temperature varies significantly based on location and orientation. While colonies near the front and rear of the trailer and those oriented toward the center aisle had significantly different average internal temperatures, colony size best predicts loss of thermoregulation. Additionally, we profiled gene expression at departure, on arrival, and after a recovery period to identify transcriptional responses to transportation. Functional and enrichment analysis identified increased methylation and decreased ribosomal and protein-folding activity. Pheromone and odorant-binding transcripts were up-regulated after transportation. After recovery, transcripts associated with defense response, immune activity, and heat shock decreased, while production of antibiotic peptides increased. We conclude that hives experience considerable temperature stress possibly caused by turbulent airflow in exposed locations. Transportation stress should be considered an important component of annual colony losses which can be mitigated with improved management strategies.

Analysis of pollen provisions in Xylocopa virginica (L.) nests in southern Rhode Island showed that this species produced pollen loaves from 21 different genera of plants in 2016, 19 in 2017, and 39 in 2018. Antirrhinium majus L. (garden snapdragon) pollen was the most common type collected in all three years (21.4%). Overall, windpollinated tree pollen comprised 22.1% of all pollen loaves. Blueberry pollen was a minor component of pollen loaves (0.1%), despite abundant blueberry plants nearby. Mean values of X. virginica nest measurements (tunnel length 15.4 ± 1.2 cm, width 15.0 ± 0.5 mm, and cell length 17.7 ± 0.3 mm) were similar to those reported in previous studies. Only 2 of the 216 trap nests deployed in 2017 were occupied by 11 X. virginica bees (9 females and 2 males). However, 17 nests contained 230 Osmia taurus Smith, 6 nests contained 73 O. cornifrons (Radoszkowski), and 1 nest contained 8 O. lignaria Say. Thirty-four nests (15.7%) were occupied by 151 grass-carrying wasps, Isodontia sp. and 6 vespid wasps occupied three nests (1.4%) in 2017. In 2018, 4 of 96 trap nests were occupied by carpenter bees. Understanding the nesting and foraging habits of X. virginica will help us to manage natural populations for pollination services.

Bumble bees are generalist pollinators that typically collect floral rewards from a wide array of flowering plant species. Among the greatest threats to wild bumble bee populations worldwide, many of which are declining, is a loss of floral resource abundance and diversity in the landscapes they inhabit. We examined how composition of pollen diet impacts early nesting success in laboratory-reared queens of the bumble bee Bombus impatiens. Specifically, we provided queens and their young nests with one of three pollen diets, each of which was dominated by a single pollen type, and explored how this diet treatment influenced the length of time until queens initiated nests, total counts of brood in the nest at the end of the experiment (8 wk later), and the size and weight of adult offspring produced. We found that the amount of later-stage brood (pupae and/or adults) produced by recently-initiated nests was strongly impacted by pollen diet. For example, on average 66% fewer later-stage brood were found in nests provided with the Cistus pollen Linnaeus (Cistaceae), relative to the predominantly Asteraceae pollen.This finding suggests that particular pollen diet compositions may delay larval growth, which delays colony development and may ultimately be detrimental for young nests. This study sheds light on how one of the leading stressors for bumble bees (nutritional stress) may negatively impact populations through its influence on brood production during the nest-founding stage of the colony cycle.

Eastern carpenter bees, Xylocopa virginica (L.) (Hymenoptera: Apidae), are among the most abundant native bee visitors to highbush blueberry, Vaccinium corymbosum L., flowers in the northeastern United States, and they sometimes display corolla-slitting behavior to rob nectar. We studied foraging behavior of X. virginica on 14 blueberry cultivars in an experimental planting in Rhode Island, and assessed factors related to slitting frequency, and the effects of slitting on fruit set and blueberry quality. Among 14 cultivars in bloom, an average of 35% (range 16–67%) of flowers were slit in 2017, and 39% (range 20–62%) in 2018. Factors that affected the proportion of corollas slit included cultivar, anther length, flower volume, and number of days in bloom at or above 15°C. Corolla slitting did not affect fruit set. Average weight and percent soluble solids of fruit resulting from slit and non-slit corollas did not differ significantly in two early- (‘Bluehaven’, ‘Earliblue’), two mid- (‘Collins’, ‘Bluecrop’), and two late-season (‘Herbert’, ‘Lateblue’) ripening cultivars in 2017. In 2018, average fruit weight and percent soluble solids resulting from slit and non-slit flowers did not differ significantly in most cultivars, but slit corollas resulted in berries with greater mass in two cultivars, ‘Bluehaven’ and ‘Collins’. ‘Collins’ fruit from non-slit corollas had a significantly higher percentage of soluble solids at maturity than fruit from slit corollas in 2018. Corolla slitting and nectar robbery by X. virginica did not have a significant negative effect on fruit quality under the described growing conditions and pollinator community.

Worker size and geographical distribution of red imported fire ants (Solenopsis invicta Buren), black imported fire ants (Solenopsis richteri Forel), and their hybrid (S. invicta × S. richteri) (Hymenoptera: Formicidae) were evaluated from colonies sampled across Tennessee. The fire ant species and hybrid status were determined using cuticular hydrocarbon and venom alkaloid indices obtained from gas chromatography and mass spectrometry. Hybrids were the most common fire ant throughout Tennessee. With the exception of a few isolated S. invicta samples, only hybrids were found in east Tennessee, and hybrids predominated in middle Tennessee. In west Tennessee, mixed populations of S. richteri and hybrids were found. Hybrids were more common in west Tennessee than a survey performed a decade earlier. No statistical differences were detected in the average inter-colonial worker size of S. richteri and hybrids. Likewise, average worker size was not related to geographic location in Tennessee. The similarity in average worker size among hybrid colonies with a wide range of cuticular hydrocarbon and venom alkaloid values suggests introgression was not impacting ant size in colonies sampled throughout Tennessee.

The South Texas coastal plains are mostly dominated by mesquite-thorn scrub from the Mexican border to cattle ranches extending north from Willacy Co. A wildlife corridor on the plains, composed of natural habitat, supports hosts of many ixodid species. Occasional wind (not lunar) tides and infrequent storm surges inundate coastal plain areas with hypersaline water from the Lower Laguna Madre, creating large areas of saline soil. Laboratory and field experiments and observations were used to identify relationships between salinity and other abiotic and biotic factors that influence ixodid distribution. Exposure of lone star tick, Amblyomma americanum (L.), and Rhipicephalus microplus (Canestrini) eggs to hypersaline water is lethal. Although intermittent hypersaline flooding kills ixodid eggs, saline soil was not particularly toxic. When relative humidity is relatively low, desiccation causes high egg mortality on dry soil, regardless of salinity. Substantial year-round populations of mud flat fiddler crabs, Uca rapax (Smith) (Decopoda: Ocypodidae), occur on saline soil and eliminated ≈80% of A. americanum egg masses overnight. On saline and low-salinity soils predatory formicids, including the red imported fire ant, Solenopsis invicta (Buren), were indifferent to the eggs. Saline soils were dominated by the sea ox-eye daisy, Borrichia frutescens (L.) DC, and its color allowed production of a GIS-based map. At least 24.4% of the wildlife corridor supports heavy stands of B. frutescens which is indicative of high U. rapax populations. Ixodid populations were negligible on heavy B. frutescens stands because of associated salt water toxicity, desiccation, and predation by U. rapax on eggs.

Zebra chip disease (ZC) in potato (Solanum tuberosum L. [Polemoniales: Solanaceae]) can produce unmarketable tubers with striped necrotic patterns. ZC is associated with the bacterium “Candidatus Liberibacter solanacearum” (Lso), which is transmitted by the potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae). Potato psyllids are associated with numerous noncrop host plants, especially from the Solanaceae and Convolvulaceae; however, the contribution and importance of these hosts to ZC epidemiology in potato is poorly understood. To clarify seasonal phenologies on two such hosts, we sampled potato psyllids from bittersweet nightshade, Solanum dulcamara L. (Polemoniales: Solanaceae), and field bindweed, Convolvulus arvensis L. (Polemoniales: Convolvulaceae), over 2013–2017 and 2014–2016, respectively. Adult psyllids were sampled using yellow sticky traps, vacuum samples, and beat sheets. Each psyllid was tested for the presence of Lso by polymerase chain reaction. Psyllids often were abundant on bittersweet nightshade during May to November, with low numbers observed over each winter. Vacuum samples often captured more psyllids than other methods. Lso incidence was low except during 2016 when vacuum samples showed 23% incidence. Potato psyllids regularly overwinter on bittersweet nightshade in Idaho; however, differences in psyllid populations and Lso incidence from those found on potato suggest that this host plant may only partly contribute to infestations in potato. Observations of psyllids on field bindweed suggest only transient visits to this plant around potato harvest, with no evidence of overwintering and no Lso detected. Further work is needed to clarify how potato psyllid use of other noncrop hosts is related to their abundance in Idaho potato fields.

Many insects adopt seasonal, trans-latitudinal migration in response to altering climatic conditions, resource availability or reproductive requirements. Though the migration behavior of the cotton bollworm, Helicoverpa armigera (Hübner)(Lepidoptera: Noctuidae), has been well-studied, little is known about the extent of intra-specific variation between northward- and southward-migrating individuals. In this study, we captured H. armigera adults along the species' migration route during 2017–2018 to determine seasonal variability in their morphology, flight capability, and reproductive performance. Northward migrants have broader, longer bodies and are 1.33 times heavier than southward migrants, hinting at a comparatively higher allocation of resources in the abdomen. Accordingly, the former migrants engaged in longer flights, had greater reproductive capacity and a longer lifespan than southward ones. As northward migrants originate from favorable environmental conditions, their fitness is higher than that of the southward cohorts that develop on less favorable host plants and in perhaps more adverse climatic or ecological conditions. Northward H. armigera migrants thus possess an advantageous morphology that benefits habitat colonization and resource exploitation. Our work offers a novel perspective on the ecological and reproductive benefits of long-distance migration and can aid the development of population monitoring and forecasting methods for this globally important agricultural pest.