Journal of Insect Science最新文献

Nasonovia ribisnigri (Mosley) is a severe aphid pest of outdoor lettuce, and the combination of sporadic and unpredictable colonization on outdoor lettuce, along with the breakdown of cultivar resistance, has left few effective control methods. The population structure (spatially and temporally) of N. ribisnigri is currently unknown in England, and therefore microsatellite markers were designed to estimate the impacts of host plant selection pressure (including host plant resistance) and environmental change. Biological samples collected between 2003 and 2020 from 10 sites across England were typed with microsatellite markers. The analysis of 8 microsatellites indicated a clear east-west divide between N. ribisnigri populations, which corresponds with current outdoor lettuce cultivation distribution in England, one of the aphid's summer hosts. Analysis of gene flow indicated that aphids did not leave the eastern region; instead, there was strong evidence for aphids migrating from the West into the secondary host eastern region, possibly from the winter host (Ribes spp.) in Spring. This result suggests that although N. ribisnigri has the potential for long-distance migration, strong ties to the summer host (lettuce) determine migratory behavior at the population level. N. ribisnigri are mostly holocyclic and show a high level of inbreeding. Long-term trends revealed relatively stable populations, despite a recent breakdown of host plant resistance and other environmental changes, including favorable temperatures. The geographic and temporal structure of the N. ribisnigri population is discussed in relation to future pest management strategies.

Behavioral differences between related insects may inform how pest management strategies or conservation efforts are tailored to specific species. Movement behavior is particularly important, but few studies have undertaken head-to-head comparisons to evaluate differences in interspecific movement. This study used harmonic radar to simultaneously track 2 agriculturally important tephritid fruit fly species, Bactrocera dorsalis (Hendel) and Ceratitis capitata (Wiedemann), in an outdoor cage (experiment 1) and a coffee field (experiments 2 and 3) to assess fly directional movement, distance, and speed parameters. In general, both fly species have similar movement parameters. However, experiment 2 showed B. dorsalis to be more active with fewer induced movements and less time needed to record the target number of movement steps. This was supported by a laboratory bioassay (experiment 4) that confirmed B. dorsalis were more active. Mean step-distances only differed in experiment 2 and were longer for C. capitata. Experiment 3 tracked tagged flies over time with 2 B. dorsalis located after 3 d post-release while no C. capitata were located after 48 h. Both species generally move with the prevailing wind. While this study found some differences in movement behaviors between these 2 fly pests, fly movement parameters were more similar than expected, suggesting that it may be possible to characterize the movement of key insect species and then generalize these findings to related taxa. If this is possible, control and detection strategies optimized with movement data from one species may be transferable to other pests, thereby increasing the impact of movement research.

Jackfruit borer, Diaphania caesalis (Walker), is a major boring pest of Artocarpus plants (Moraceae). Biological control is considered an environmentally sustainable means of managing pests. However, parasitoids of D. caesalis in China are unknown. Here, we investigated the parasitoids of D. caesalis through field monitoring and surveys and identified them through morphological observation and DNA barcoding technology. Two hymenopteran parasitoid species, Dolichogenidea sp. and Eulophidae undet. sp., were identified on D. caesalis. The parasitism rate of Dolichogenidea sp. (21.0 ± 1.8%) was significantly higher than that of Eulophidae undet. sp. (3.8 ± 2.2%). The field incidence of Dolichogenidea sp. in the Artocarpus integer and Artocarpus heterophyllus orchards was 30.8 ± 2.5% and 22.3 ± 7.6%, respectively, but there was no significant difference. Overall, Dolichogenidea sp. was the dominant parasitoid of D. caesalis in China. Further research is needed to determine the species' identity, and their biological characteristics should be evaluated to determine their potential applications in biocontrol programs.

The hemolymph and fat body tissues are essential for energy storage, metabolism, and immune defense in larval Hermetia illucens (L.). We analyzed the diverse proteins and genes expressed in the hemolymph and fat body of larval H. illucens in both naïve and pathogen-challenged conditions using the entomopathogenic fungus, Beauveria bassiana (Siemaszko). Notably, odorant-binding-like and cuticle-related proteins were abundant, with pathogen exposure leading to significant regulatory changes, highlighting their potential roles in immune defense. We examined the genes associated with key metabolic pathways in H. illucens, such as lipid storage, protein storage, fatty acid metabolism, and gluconeogenesis. Interestingly, eight different storage protein-encoding genes (hexamerins/larval serum proteins) with considerable sequence differences were expressed in the fat body. Exposure to B. bassiana resulted in significant downregulation of most of these storage protein-encoding genes, which was correlated with reduced larval body weight and probably fewer energy reserves for pupal development. These findings deepen our understanding of the physiological mechanisms by which larval H. illucens responds to pathogens and highlight the vulnerability of key metabolic pathways to stress. This study underscores the importance of the fat body and hemolymph in the metabolic and immune functions of insects, paving the way for future research into the molecular pathways governing their adaptation and resilience.

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is a major economic pest that is difficult to manage with current strategies. New strategies will depend on better understanding the biology of whiteflies. For example, little is known about factors that affect primary sex ratio and embryological development in the haplodiploid system of B. tabaci, which may provide an entry point into new control strategies. In this study, we show that expression of DNA methyltransferase 1 (Dnmt1) is required for early embryogenesis in B. tabaci. First, we show that reduction of Dnmt1 expression using RNA interference decreased the number of eggs laid and the viability of eggs but did not affect the adult sex ratio. We also identify key developmental stages during embryogenesis, which have been shown to be consistent in both sexes. Embryos produced from dsDnmt1-treated females failed to form a germ rudiment and had smaller sized nuclei, suggesting inhibition of the cell cycle early in development. Although the specific mechanism by which DNMT1 affects embryogenesis remains elusive, that is, whether the effect is methylation dependent or independent, our study provides insights into DNMT1's function based on when and how DNMT1 is needed.

The Queensland fruit fly (Q-fly) Bactrocera tryoni is the most economically destructive tephritid pest in eastern Australia, inflicting substantial damage to diverse fruit and vegetable crops. Broad-spectrum, persistent, synthetic insecticides have been used to manage tephritid fruit flies. However, the adverse effects of these insecticides on human health, the environment, and nontarget organisms, as well as regulatory restrictions, have prompted the search for alternative control methods. This study explores the potential of essential oils as alternatives by evaluating their toxicity and behavior-modifying properties against adult Queensland fruit flies. We evaluated 16 essential oils for contact and fumigation toxicity, oviposition inhibition, and repellence. The chemical profiles of the essential oils were analyzed with Gas Chromatography-Mass Spectrometry and antennal responses were assessed by gas chromatography-electroantennographic detection. Chamomile, lemon-scented tea tree, and citronella exhibited notable contact toxicity (ED50 0.054 to 0.068 mg/µl) after a 24-h exposure, while garlic, aniseed, pennyroyal, basil, and peppermint exhibited high fumigation toxicity (ED50 3.293 to 4.950 µl/liter air) over the same period. Aniseed, cumin, and pennyroyal essential oils repelled both Queensland fruit fly sexes in 4-arm olfactometer assay. Aniseed, basil, chamomile, citronella, cumin, dill, garlic, lemon-scented tea tree, pennyroyal, peppermint, thyme, and yarrow essential oils inhibited oviposition. This study demonstrates essential oils as toxicants, oviposition deterrents and repellents, offering promising alternatives to conventional pest control methods for managing Queensland fruit fly populations.

Bark beetles (Coleoptera: Curculionidae: Scolytinae) are some of the most destructive forest insect pests in the world. Methods literature is largely limited to trapping, including pheromones and volatiles, and remote sensing. Conversely, little work has been done on methods for quantifying bark beetle development under the bark. Assessing larval development involves marking and measuring each gallery using rulers or mapping tools, which takes much time and effort. We developed a novel graphite rubbing method on rice paper to quickly and accurately map larval bark beetle development under the bark of infested pine logs. We were then able to transpose the log surface onto a 2D plane, allowing photography and image analysis. We also describe alternative methods tested that were not successful. This method allows researchers to quickly collect data on gallery area and, therefore, larval development to have an additional piece of information to better predict and manage future outbreaks.

Climate change is having a disproportionate impact on the winter period, although little is known about the implications of shifts in extreme warming events. Changes in the intensity or duration of warm-ups, for instance, may significantly influence insects given their sensitivity to temperature fluctuations. Both ecological and economic implications may be particularly pertinent for pest species such as the spruce budworm (Choristoneura fumiferana [Clem.]), the most destructive defoliator of spruce-fir forests in North America. We subjected the spruce budworm to warming events (factorial combination of 4 warming intensities and 4 durations) during the early winter dormancy phase and measured impacts on survival, development time, body condition, and biochemistry. Results suggested that survival was minimally impacted by either treatment, and there were no effects on development. Body condition varied by sex, but was similarly unaffected by warming. However, both warming treatments influenced energy reserves measured at the end of the winter period; more intense warming reduced lipid concentrations, whereas glycogen concentrations were highest at intermediate treatment levels. Overall, our findings suggest that the impacts of early winter warming events had minimal impact on insect performance. Moreover, the ultimate consequences of shifts in metabolite concentrations likely depend on their contribution to insect energetics following the resumption of development post-dormancy.

The declining diversity of pollinators is a major threat to ecosystem conservation, pollination services, and global food security. Honey bees (Apis mellifera L.) dominate managed pollination, but their dominance can affect other pollinators. Competition for resources can lead to decreased foraging success and survival rates for other bee species, including other eusocial bees such as bumble bees. This study explores the floral diet of honey bees and buff-tailed bumble bees (Bombus terrestris L.) using metabarcoding of honey (for honey bees) and of wax pots' contents (for bumble bees), based on 3 molecular markers (ITS2, trnL g-h, and trnL c-h) in Médoc, France. Molecular markers detected different species pools, indicating a high diversity of plants visited by both species. The 'marker' effect was more important than the 'pollinator' effect in distinguishing plant taxa. The Schoener index revealed a diet overlap in plant taxa used by honey bees and bumble bees, but the value was highly dependent on the molecular marker. Thus, metabarcoding on different biological matrices for both species proved to be efficient, despite some biases. Although the matrices enabled avoiding capturing individuals and disturbing colonies, and were easy to sample, comparisons of results between 2 different matrices should be made with caution due to different storage and consumption strategies used by both studied bees. Nonetheless, this study provides a fast and inexpensive approach to study eusocial bees floral resource sharing, and gives insights to improve metabarcoding effectiveness in order to better describe dietary niche of eusocial pollinators by noninvasive sampling.