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.

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.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), commonly known as spotted-wing Drosophila (SWD), is an invasive insect pest threatening the economy of many small fruit farms in the Americas and Europe. Biological control using parasitoids is a promising strategy for improving the sustainable management of SWD. To use the parasitoids as biocontrol agents, recognizing and understanding the presence and preference of North American native parasitoids and their local adaptation is necessary. We conducted 2 season-long field explorations of North American native parasitoids of SWD during 2021 and 2022 at major blueberry-producing locations in southeast GA, USA. A total of 371 parasitoids of Drosophila were collected using fruit-baited sentinel traps and classified into 3 families: Figitidae, Pteromalidae, and Diapriidae. Leptopilina boulardi (Hymenoptera: Figitidae) and Pachycrepoideus vindemmiae (Hymenoptera: Pteromalidae) were the most abundant species. The abundance of parasitoids was higher during the peak blueberry ripening period through the end of the harvest season compared to all other phenological stages. Out of the North American native parasitoids of SWD that we collected, Pachycrepoideus vindemmiae successfully parasitized SWD in its natural habitat, and L. boulardi only parasitized SWD larvae at a low rate of 7% in the laboratory, but it failed to emerge from all the parasitized SWD. Ultimately, we found that the existing North American native parasitoids were inadequate to suppress the SWD in these locations. Planned intervention with the classical release of Asian native specialist parasitoids in addition to the existing SWD management approaches was deemed necessary in these areas.

Psyllids (Hemiptera: Psylloidea) are herbivores that feed and reproduce on narrow subsets of hosts within a few related genera. During surveys of Solanum umbelliferum (Eschsch) (Solanaceae), we collected multiple life stages of Bactericera maculipennis (Crawford), a species exclusively associated with bindweeds (Convolvulaceae). We hypothesized that B. maculipennis has expanded its host range to include this solanaceous host. To test this, we quantified egg to adult development time on S. umbelliferum, 2 other solanaceous hosts, and Convolvulus arvensis L., the most suitable host for B. maculipennis in North America. B. maculipennis failed to develop on additional solanaceous hosts but developed significantly faster on S. umbelliferum than on C. arvensis. We also sampled for B. maculipennis at 27 S. umbelliferum populations and collected 24 individuals directly from S. umbelliferum plants. We confirmed all individuals are B. maculipennis and found that 10/24 were infected with the plant pathogen 'Candidatus Liberibacter solanacearum' (CLso), which is transmitted by the potato psyllid, B. cockerelli (Šulc). Half of infected individuals harbored CLso haplotype B, which is dominant in crops, but rare in S. umbelliferum. The other 50% harbored CLso haplotype Sumb2, previously documented in S. umbelliferum, but never in crops. Our results suggest that the host range of B. maculipennis has expanded to include a key wild host plant of B. cockerelli. This may create opportunities for exchange of multiple haplotypes of CLso between these 2 species, possibly facilitating the emergence of CLso variants as pathogens of plants in the Convolvulaceae.

Changing climate patterns will likely affect insect pressure on many agricultural crops. Mild winters may decrease the number of insects that experience reduced fecundity or that are killed during hard freezes. This may result in larger populations in subsequent years and allow for range expansion. Direct effects from pests are compounded by indirect effects, such as crop damage resulting from insect-vectored diseases. Corn flea beetle (Chaetocnema pulicaria) infestations have both direct and indirect effects on crops. This beetle is a pest on all types of corn in the United States, including sweet corn and grain corn (sometimes referred to as dent corn). It is responsible for damage to plant foliage and also serves as the primary overwintering vector for Pantoea stewartii bacterium, which causes Stewart's Wilt, a disease that can severely impact the health and productivity of corn. Evidence suggests that warmer winters will contribute to a geographic range expansion for the corn flea beetle. Here we show the projected northward expansion of economically damaging crop losses caused by Stewart's Wilt: (A) from 1980 to 2011, (B) projected by mid-century, and (C) projected by end-century. Our work suggests that climate change and associated increasing winter temperatures in the United States will lead to a dramatic increase in the probability of severe damage from corn flea beetle across the United States, including the Corn Belt. Predicted increases in pest and disease pressure will have negative ramifications for corn production and are likely to exacerbate issues associated with specific management tactics, such as pesticide application.

Mason bees, subgenus Osmia Panzer (Hymenoptera: Megachilidae), are economically and ecologically significant pollinators. In eastern North America, the rapid spread of 2 non-native species from Asia, Osmia cornifrons Radoszkowski and Osmia taurus Smith, has coincided with declines in native Osmia populations, raising concern about the effects of further exotic arrivals. Here we investigate the recent establishment in British Columbia, Canada of the European orchard bee, Osmia cornuta Latreille, previously thought to be limited to Europe and its periphery. We document O. cornuta records ranging more than 170 km, including sightings of live adults and the discovery of a multigenerational nest with hundreds of cocoons. We tested whether these cocoons could be discriminated from other Osmia species by training a machine learning classifier on features extracted from images. The best performing model could not reliably discriminate cocoons by species, raising the possibility O. cornuta could be inadvertently intermingled in future commercial shipments. Recent occurrence records of O. cornifrons and O. taurus were spatially isolated, suggesting ongoing anthropogenic dispersal of these species. We predicted the suitability of North American habitats for O. cornuta by estimating its native climate niche. This analysis indicated broad regions of the Pacific Northwest and eastern North America contain potentially suitable habitat. Our findings document the establishment of O. cornuta in North America and the potential for its expansion. Our study demonstrates the utility of accessible biodiversity data archives and public observation programs in tracking non-native species spread and highlights the need for future monitoring of exotic Osmia.

Nitidulid beetles (Coleoptera: Nitidulidae), the overland vectors of the Bretziella fagacearum fungus that causes oak wilt, were monitored in infection centers in Quercus rubra stands in northern Michigan, USA using baited, wind-oriented traps for 2 years. First nitidulid captures, accounting for <1.5% of total annual captures, occurred in late April in both years (<50 cumulative degree days [DDs]; base 10°C). A total of 1,188 and 735 beetles representing 19 and 18 species were captured in 2018 (18 traps; 3 sites) and 2019 (16 traps; 4 sites), respectively. Ground traps (1.5 m high) captured more beetles and species than traps on canopy branches of red oaks. Most nitidulids (81-86%) were captured in May and June, but frequent precipitation and cool spring temperatures extended activity into early July in 2019. In 2018, 336 beetles representing 12 species were screened for B. fagacearum spores, but only 20 beetles from 4 species bore viable spores. Mycelial mats on red oaks killed were 4-fold more abundant in 2019 than in 2018. Of the 225 beetles screened in 2019, 56 beetles representing 6 species had viable spores. Nearly all (96%) spore-bearing beetles in both years were captured in late May or June. In bimonthly xylem samples collected from healthy trees, large earlywood vessels, presumably more vulnerable to infection than latewood, were present from May to June in 2018 and until early July in 2019. Results are consistent with mid-May to mid-July high-risk periods designated in current state and regional guidelines for oak wilt management.

Management solutions for waste in southern Thailand, such as fly larvae, are tested in a laboratory using different substrates and wastes from the Thai agricultural sector. The nutritional content of the immature stages of Musca domestica Linnaeus (Diptera: Muscidae) and Hermetia illucens (Linnaeus) (Diptera: Stratiomyidae) larvae, especially their protein and fat contents, makes them a potential animal feed. Laboratory strains of M. domestica and H. illucens were reared on selected substrates to examine how diet influenced their performance and nutritional composition. Waste from aquaculture, vegetables, and fruits in southern Thailand was examined for larval diet and showed promise as a rearing substrate for these insects. Musca domestica larvae reared on fishery waste achieved the highest larval weight and fat content, whereas H. illucens larvae reared on an aquaculture waste diet had the highest protein content. These findings imply aquaculture waste could be the best choice for large-scale fly larvae production, particularly as a protein feed additive.

Batocera horsfieldi is the primary stemboring pest of timber forests and economic forests in China, belonging to the Coleoptera Cerambycidae. In this study, gas chromatography-mass spectrometry was used to analyze the volatile components in the supplementary feeding hosts and oviposition hosts of B. horsfieldi, and characteristic fingerprints were constructed. A total of 168 compounds were detected, primarily consisting of terpenes, hydrocarbons, and aldehydes, with 75, 23, and 14 compounds, respectively. Hierarchical cluster analysis and principal component analysis yielded consistent results. The similarity evaluation results showed that the similarity range between healthy poplar tree bark and healthy poplar leaves was the highest, reaching 0.953-0.98, and 10 common peaks were identified. The analysis of the correlation with climatic factors shows that most compounds are positively correlated with mean annual humidity, mean annual temperature, mean annual minimum temperature, and mean annual maximum temperature. Only caryophyllene and alpha-guaiene are negatively correlated with temperature-related climatic factors. Pathway analysis also reveals differences in the direct effects of different compounds. These analytical results provide a theoretical basis for further studying the selection mechanism of B. horsfieldi on hosts and offer theoretical guidance for identifying plant-derived attractants with biological activity.

Temperature is an elementary component in mathematical models for predicting the biotic potential of insects. In this study, the objective was to evaluate the impact of different constant temperatures of 8, 10, 15, 20, 25, 30, and 32°C on the biological parameters, lower temperature thresholds (TT), and estimating the number of annual generations (NAG) of Rachiplusia nu and Chrysodeixis includens, both pests associated with the soybean crop in Brazil. There was no development of the immature stages of R. nu at 8°C, as was also found for C. includens at 8 and 10°C. However, at 10°C all stages of R. nu developed. In general, temperatures of 20 and 25°C were the most suitable for the development of R. nu and C. includens, providing egg to adult viability of over 60% and the highest total fecundities. However, the temperature of 32°C negatively affected the parameters of the fertility life table. Rachiplusia nu showed the lowest TT (eggs: 4.9°C; larvae: 10.8°C; pupa: 14.1°C; and egg to adult: 8.9°C) when compared with C. includens (eggs: 7.5°C; larvae: 15.3°C; pupa: 16.1°C; and egg to adult: 11.3°C). Based on TT values, the NAG varied from 3.9 in cold regions to 7.5 in warm regions. However, for C. includens, we can infer that the species can reach up to 8.8 generations in warm regions. The results of the present study are important for understanding the occurrence of R. nu and C. includens in field conditions and can help with the implications of management strategies.