Environmental Entomology最新文献

Diapause regulates seasonal insect life cycles and may be highly variable within and among populations due to genetic and environmental variability. Both types of variation may influence how populations respond plastically or evolutionarily to changing climates. We assessed diapause variability in spruce beetle Dendroctonus rufipennis Kirby (Coleoptera: Curculionidae, Scolytinae), a major forest pest whose life cycle timing is regulated by both prepupal and adult diapauses. Using mating studies and ovary dissections, we tested for variability in adult diapause within and between collection sites in Colorado and Wyoming, USA. Ovary morphology suggested that most females from both sites enter diapause prior to egg formation (oogenesis) when reared at warm temperatures. Though previous studies suggested that adult diapause is obligate, we found that a small proportion of females from both populations terminated diapause without winter chilling in the lab. Moreover, we found that most female beetles sampled at the Colorado field site had mature ovaries relatively early in the fall, suggesting that transient exposure to low temperatures may potentiate pre-winter reproductive development. Adult diapause may act primarily as a block to prevent offspring production late in the season but not necessarily as an overwintering phenotype. Overall, our data do not suggest imminent life cycle shifts mediated by adult diapause, but if the observed variability is heritable, diapause regulation may evolve in response to changing environmental conditions.

Climate change is expected to lead to rising winter temperatures in temperate zones, coinciding with a decrease in winter snow cover. Insects adapted to winter conditions in the temperate zone might be exposed to changing winter conditions and higher temperature fluctuations, which can affect diapause and mortality. We studied the effects of climate change on Chrysolina polita, a temperate zone species overwintering as an adult in the shallow surface of the soil. We tested the effects of increased and fluctuating temperature on the mortality and body composition of the beetles in a laboratory environment, as well as the effects of snow cover removal on the mortality and body mass in field conditions. We found that in the laboratory study, a 2 °C increase in mean temperature increased mortality and resulted in increased lipid consumption, whereas temperature fluctuation caused desiccation of the beetles but did not affect mortality compared to the control condition. In the field study, the snow removal caused the mean soil temperature to decrease by 3 °C and fluctuate (ranging from -26.4 to 2.5 °C compared to a range of -1.7 to 0.5 °C in the control), yet these differences did not affect beetle mortality or body mass. We conclude that C. polita exhibits greater resistance to cold temperatures than to higher temperatures during diapause. Therefore, the rising temperatures associated with climate change can pose challenges for overwintering.

Imidacloprid is a widely used insecticide for controlling piercing-sucking pests. However, its impact on nontarget insects must not be ignored. In this study, we assessed the effects of sublethal dose of imidacloprid on Sclerodermus alternatusi (Hymenoptera: Bethylidae), which is an important predator of many pests. The data indicate that imidacloprid at LD10 (0.1468 ng active ingredient per insect) and LD30 (0.2376 ng active ingredient per insect) significantly reduced the longevity and fecundity of the F0 generation of S. alternatusi. However, the adult female longevity of the F1 generation of the LD10 dose group showed a significant increase, and the LD30 dose group showed a nonsignificant increase. The study found that as the imidacloprid dose increased, the intrinsic rate of increase (r) decreased, while the mean generation time (T) increased. The imidacloprid groups also showed a decrease in age-stage specific survival rate (Sxj) and age-specific survival rate (lx). However, the female age-specific survival rate (fx4) showed an increasing and then decreasing trend for all treatments. The study found that imidacloprid had an impact on the longevity of S. alternatusi in the F0 generation and extended the mean generation time (T) in the F1 generation. However, it had negative effects on population growth parameters. These findings can be used as a basis for developing integrated pest management strategies.

Insect pollinators are essential for natural ecosystems. Without pollination, native plants are less likely to be able to persist. As natural ecosystems have become more fragmented and degraded, interest in their restoration and preservation has increased. Understanding the roles that individual plant and pollinator species play in an ecosystem can assist with these tasks. One way to examine the ecological drivers for patterns of pollination is through module analysis. The Palouse Prairie is a fragmented native prairie that supports high plant and insect diversity and has experienced severe habitat loss. Bees were collected on native plants in prairie fragments in 2022 and 2023 to construct a plant-pollinator network. From this network, modules were computed and analyzed. This network contained 10 modules representing multiple different ecological patterns, including modules grouped by morphological, taxonomic, and phenological similarities. These modules also identified plant-pollinator pairs with specialized relationships. The network was then analyzed to identify plant and insect members that play structural roles in the network. Understanding the patterns of interactions represented in the modules and the network structure may allow for better conservation and restoration of this imperiled ecosystem.

To assess the effects of sublethal concentrations of 3 acaricides-Bifenazate, Etoxazole, and Azocyclotin-on the development and reproduction of Tetranychus urticae Koch (Acari: Tetranychidae) and Polyphagotarsonemus latus Banks. Our results indicated that the LC20 values of Bifenazate, Etoxazole, and Azocyclotin against T. urticae are 3.196, 25.249, and 32.387 mg/L, and against P. latus to be 18.058, 4.641, and 13.755 mg/L, respectively. Sublethal concentrations of these acaricides significantly impacted the development time, lifespan, and fecundity of both mite species. Among the acaricides, Azocyclotin significantly extended the immature developmental period of T. urticae and P. latus. All acaricides reduced the lifespan and fecundity of both species, with Etoxazole having the most substantial impact on the daily fecundity and reproductive of T. urticae. The intrinsic rates of natural increase (rm) for T. urticae exposed to Bifenazate, Etoxazole, and Azocyclotin were 0.17, -0.04, and 0.20, respectively. For P. latus, the rm values were 0.27, 0.23, and 0.25, respectively. These results suggest that under the exposure of sublethal acaricides, P. latus gained a competitive advantage in population competition. These findings underscore the importance of understanding the differential impacts of acaricides on various mite species to develop effective pest management strategies.

Stink bug species emerged as major insect pests of cotton in the mid-southern United States following the eradication of the boll weevil and the introduction of genetically modified Bt cotton for lepidopteran pests. Considering the limited number of chemical classes available for insect control, further insights into other chemistries are necessary to inform management strategies with the overall goal of establishing and maintaining the most cost efficient and efficacious control programs for stink bugs in Alabama. The insect growth regulator, novaluron, has shown control of tarnished plant bugs, but little research has been done on its effect in stink bugs. The objective of our study is to evaluate the effects of novaluron, in a laboratory setting, on adult fecundity, nymphal mortality, and yield and damage in the field. We hypothesized that novaluron would have a direct effect on mortality in nymphs and could decrease fecundity in adult stink bugs. Although the effect on fecundity was counter to our hypothesis, this study shows effective control of nymphs in our model insect, the southern green stink bug, Nezara viridula (Hemiptera: Pentatomidae). Future evaluation of proper timing of novaluron applications could make this a valuable tool for residual control of stink bugs in cotton.

Climate change has been repeatedly linked to phenological shifts in many taxa, but the factors that drive variation in phenological sensitivity remain unclear. For example, relatively little is known about phenological responses in areas that have not exhibited a consistent warming trend, making it difficult to project phenological responses in response to future climate scenarios for these regions. We used an extensive community science dataset to examine changes in the adult flight onset dates of 38 butterfly species with interannual variation in spring temperatures in the Piedmont region of North Carolina, a region that did not experience a significant overall warming trend in the second half of the 20th century. We also explored whether voltinism, overwintering stage, and mean adult flight onset dates explain interspecific variation in phenological sensitivity to spring temperature. We found that 12 out of 38 species exhibited a significant advance in adult flight onset dates with higher spring temperatures. In comparison, none of the 38 species exhibited a significant advance with year. There was a significant interaction between mean onset flight date and voltinism, such that late-emerging, multivoltine species tended to be the most sensitive to spring temperature changes. We did not observe a significant correlation between phenological sensitivity and the overwintering stage. These results suggest that butterfly arrival dates may shift as temperatures are projected to rise in the southeastern United States, with late-emerging, multivoltine species potentially exhibiting the greatest shifts in adult flight onset dates.

Many endosymbionts of insects have been shown to manipulate and alter their hosts' reproduction with implications for agriculture, disease transmission, and ecological systems. Less studied are the microbiota of classical biological control agents and the implications of inadvertent endosymbionts in laboratory colonies for field establishment and effects on target pests or nontarget organisms. While native-range field populations of agents may have a low incidence of vertically transmitted endosymbionts, quarantine and laboratory rearing of inbred populations may increase this low prevalence to fixation in relatively few generations. Fixation of detrimental endosymbionts in founding biological control agent populations prior to release may have far-reaching effects. Significant female-biased sex-ratio distortion was found within laboratory populations of the weevil Ceratapion basicorne (Illiger), a classical biological control agent that was recently approved for use against yellow starthistle (Centaurea solstitialis L.). This sex-ratio distortion was observed to be vertically inherited and reversible through antibiotic treatment of the host insect. Molecular diagnostics identified a Rickettsia sp. as the only bacterial endosymbiont present in breeding lines with distorted sex ratios and implicated this as the first reported Rickettsia associated with sex-ratio distortion within the superfamily Curculionoidea.

In recent years, the damage caused by thrips has become a key factor impacting the winter and spring production of fruits and vegetables in Hainan Province, China. This study aimed to elucidate the effects of different pupation environments on pupal development and eclosion of chilli thrips (Scirtothrips dorsalis Hood) by analyzing pupal development and eclosion of chilli thrips in an indoor environment with simulated natural soils and water content. Soil type, soil water content, and temperature substantially affected the eclosion of chilli thrips during the pupal stage. Both a low soil water content of 1% and a high soil water content of 15% were not conducive to the pupation and eclosion of chilli thrips. Moreover, the results indicated an interaction between soil type and soil water and temperature and soil water content, affecting the eclosion of chilli thrips. Chilli thrips not only pupated in soil but also completed pupation and eclosion in other soil-less environments, such as tender mango leaves, stalks, plastic mulch, and weed fabric. This study suggests that in addition to adopting pest control measures that target the canopy layer of crops, appropriate measures such as increasing soil water content can also be implemented in the ground layer to enhance the overall effectiveness of pest control.

Wild bee communities are the target of various conservation and ecological restoration programs. Strategic conservation can influence bee communities visiting fields and help mitigate pollinator limitations in fruit production. However, planning compatible conservation strategies and gauging their effectiveness requires understanding how local communities vary across space and time in crops and adjacent semi-natural areas. Here, we assessed the spatiotemporal changes in the composition of wild bee communities in blueberry fields and adjacent forests. In partnership with commercial farms in southeast Georgia, USA, we deployed blue vane traps at the interior and edge of blueberry fields and within adjacent forests of 8 fields, from March to October over 2 yr. We identified 72 wild bee species across 26 genera. The most common were Melissodes communis (Cresson, Hymenoptera: Apidae), Bombus bimaculatus (Cresson, Apidae), Melissodes bimaculatus (Lepeletier), Ceratina floridana (Mitchell, Apidae), Lasioglossum pectorale (Smith, Halictidae), and Lasioglossum nymphale (Smith), which accounted for nearly 60% of the wild bees caught. Bee diversity and richness fluctuated over time, with peaks in all 3 habitat types occurring after the blueberry blooming. Bee abundance in the adjacent forest was relatively constant throughout the season, while in the field interior and edge assemblages, abundance peaked between May and June. We observed dissimilarity in species composition related to month and field location. This difference was explained by fluctuation in the identity and relative abundance of the most abundant species. Together, our study advances foundational knowledge of wild bee community dynamics and species identity in blueberry fields which will help inform and prioritize conservation practices.