Journal of economic entomology最新文献

Though a minor forest pest in its native range in Asia, the emerald ash borer (EAB), Agrilus planipennis Fairmaire, causes widespread ash (Fraxinus spp) mortality throughout its invaded range in North America and Europe. The rapid range expansion demonstrated by EAB suggests this beetle possesses extraordinary tolerance for a broad range of climatic conditions. While previous studies have measured the cold tolerance of overwintering EAB larvae, none have considered the effect of developmental stage or diapause condition on cold hardiness. By testing the supercooling point (SCP) of lab-reared and field-collected larvae, we evaluated EAB cold hardiness at multiple developmental stages and diapause phases following exposure to different temperature regimes. Results of SCP testing indicated feeding larval stages and larvae in late diapause may be most susceptible to freeze-induced mortality, suggesting that semivoltinism and late-winter freeze events may limit winter survival within EAB populations. Results of field studies confirmed that cold hardiness in EAB is a plastic trait that increases with exposure to lower temperatures, but indicated plasticity may differ between populations. Together, these findings indicate that developmental stage, diapause phase, induction of cold hardiness, and geographic origin may all contribute to the ability of EAB larvae to acclimatize to and survive cold temperatures. Our findings contribute to our understanding of how environmental and physiological factors interact to impact winter survival of EAB and therefore, may improve estimates of the potential invasive range of EAB.

Wireworms, the larval stage of click beetles (Coleoptera: Elateridae), cause substantial damage to potato tubers, particularly during the ripening phase. Management strategies such as early harvest and the use of less susceptible cultivars have been shown to reduce feeding damage. However, the mechanisms driving cultivar susceptibility and the key factors influencing wireworm feeding during ripening remain poorly understood. To address this gap in knowledge, we compared the effects of harvest date, soil moisture, tuber mass, and wireworm abundance on feeding damage of wireworms (Agriotes spp.) during ripening in 2 potato cultivars. Additionally, we investigated whether differences in potato tuber CO2 respiration are responsible for cultivar susceptibility to wireworm damage. Feeding damage significantly varied between cultivars and harvest dates. Early harvest reduced damage in the highly susceptible cultivar but had no effect on the less susceptible cultivar. Soil moisture primarily affected wireworm abundance in the ridge, which decreased under low soil moisture conditions. In the susceptible cultivar, feeding marks increased significantly under low compared to high soil moisture. Tuber mass was positively related to damage, with heavier tubers showing more damage. Differences in tuber CO2 respiration between cultivars neither influenced wireworm feeding nor explained differences in susceptibility. These findings highlight the potential of selecting suitable cultivars and managing soil moisture, harvest timing, and tuber mass to reduce wireworm damage during potato tuber ripening. Understanding the mechanisms of cultivar resistance and breeding more resistant varieties will help minimize wireworm-related crop losses in potatoes.

To assess how climate warming affects the phenology and occurrence patterns of Scirpophaga incertulas, historical phenological records and corresponding temperature data were analyzed using linear regression and Pearson correlation to detect interannual trends and associations with temperature. Results indicated that climate warming has produced significant, region- and generation-specific shifts in the phenology of S. incertulas across Southern, Eastern, and Southwestern China. Results derived from simple linear regression analysis indicated that Southern China showed interannual delays in population peaks across generations, but analyses against rising mean annual temperature indicated peak adult emergence advancement; Pearson correlations revealed strong negative associations with spring, autumn, winter, and annual temperatures. Eastern China exhibited generally earlier first occurrences and overall advancement of population peaks, although some later generations showed delayed first-occurrence dates; phenology correlated negatively with seasonal and annual temperatures. Southwestern China displayed mixed responses: interannual trends included delayed first-generation occurrence and delayed all population peaks, and advanced end occurrence, while temperature-based analyses showed generally earlier first occurrences, a delayed first-generation peak but an advanced second-generation peak and all first occurrence and end occurrence, and a combination of positive and negative temperature correlations. These findings improve understanding of likely occurrence dynamics under future warming and can inform optimization of integrated pest-management timing and strategies.

The effects of global climate change on the biocontrol of agricultural pests remain unclear. Understanding the geographical distribution and genetic differentiation of parasitoid wasps in past and current environments can help predict how the future environment will affect these wasps. Diglyphus albiscapus (Hymenoptera: Eulophidae) is a dominant parasitoid wasp of agromyzid leaf miners. Our study analyzed the intraspecific diversity, population structure, and historical population dynamics of D. albiscapus based on cytochrome c oxidase subunit I and internal transcribed spacer II genes. The current and future potential geographical distributions (PGD) of D. albiscapus in China were predicted using an ensemble model. Although the genetic diversity of D. albiscapus in China was relatively high, its genetic variation was relatively low. The fixation indices (FST) and gene flow (Nm) for the D. albiscapus population were 0.09823 and 2.29505, respectively, indicating that interpopulation gene exchange was adequate. The effective population size of D. albiscapus expanded approximately twofold during the early stadial of the last glacial period (MIS 4), and 3 populations expanded substantially. Currently, this species occurs mainly in northeast, northwest, and southern China. The PGD of D. albiscapus would be expected to spread outward from its current potential distribution range under global climate change. The predicted results of population genetics and PGD showed that anthropogenic activities may have promoted the spread of D. albiscapus, enhancing gene exchange within the species and reducing genetic differentiation. This study provided a reference for the conservation and application of D. albiscapus in the field.

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is one of the major pests infesting squash (Cucurbita spp.). The present study examined the interactions between combined applications of 2 insecticides, imidacloprid and cyantraniliprole, with 2 entomopathogenic fungi (EPF), Beauveria bassiana (GHA strain) and Cordyceps javanica (wfGA17 strain), across 8 squash cultivars infested with B. tabaci. The insecticides were tested for compatibility with EPF at three concentrations using in vitro bioassays. A compatible rate based on the survival of the EPF was subsequently selected for evaluating the lethality against B. tabaci. The combined application of EPF and either of the insecticides resulted in higher B. tabaci nymphal mortality than when either agent was applied alone. Although some reduction in fungal viability was observed, some combinations still produced enhanced efficacy, particularly with imidacloprid. Among all treatments, the combinations involving imidacloprid yielded the highest percentage mortality. The nature of EPF-chemical interactions (synergy, additivity, or antagonism) varied by cultivar. Additive interactions were consistently recorded on the cultivars Early Summer, Fortune, Gray Summer, and Green Eclipse where both EPF species showed enhanced effectiveness when combined with imidacloprid, and to a similar extent, with cyantraniliprole. However, antagonistic interactions were found when C. javanica was combined with cyantraniliprole on the cultivars, Gentry, Grey Summer, Lioness, and Respect, or B. bassiana and imidacloprid on the cultivar Golden glory. Overall, the results emphasized the potential of combining EPF with selective insecticides and the importance of cultivar-specific responses in optimizing B. tabaci control.

The neuropeptide pigment-dispersing factor (PDF) is essential for the circadian rhythm of Drosophila and other insects. Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) is a transcontinental pest that threatens the global agricultural supply. However, the functional study of PDF in S. frugiperda larvae remains unexamined. The study demonstrated that the Sf-PDF coding sequence spans 330 bp, and a highly conserved mature peptide sequence was found in the predicted protein. A spatiotemporal expression analysis revealed that Sf-PDF was predominantly expressed in female adults and 1st instars, with the lowest expression level noted during the pupal stage. Sf-PDF exhibited significant expression in the larval head and midgut tissues. A marked reduction in the expression of Sf-PDF was also noted in the larval midgut following azadirachtin treatments. The Sf-PDF mature peptide injection enhanced larval food consumption and weight gain during 2 days of treatment, while also mitigating the antifeedant impact caused by 1.0 μg/g azadirachtin. Our research indicates that Sf-PDF is associated with feeding behavior in S. frugiperda larvae and modulates the antifeedant effects caused by azadirachtin. These findings elucidate a novel understanding of the role of PDF protein and enhance comprehension of the antifeedant mechanism of azadirachtin in insect larvae.

There is an imported fire ant (IFA) quarantine in the USA to prevent human assisted spread of the invasive, red IFA (Solenopsis invicta Buren), black IFA (Solenopsis richteri Forel), and the S. invicta × S. richteri hybrid. Quarantine regulated articles must be treated following approved protocols and must not be infested with IFA queens or reproducing colonies. Large, post-harvest field-grown nursery plants are an infestation risk because they are difficult to treat effectively with approved insecticide treatments of (i) immersing in chlorpyrifos or bifenthrin solutions, or (ii) thoroughly drenching root balls with chlorpyrifos. To improve quarantine treatments, the efficacies of drenching and injecting (D&I) large (60 cm diameter) root balls with bifenthrin or lambda-cyhalothrin to disinfest them of IFA were determined and compared with chlorpyrifos drench (standard), and water drench (control). Bifenthrin and lambda-cyhalothrin D&I treatments eliminated all IFA colonies in 2 wk, while >70% of the chlorpyrifos drench-only and control root balls were infested. Bioassays of red IFA female alates (surrogates of colony founding queens) in soil sampled from various root ball positions receiving the above treatments resulted in no survival of alates exposed to bifenthrin after 10 d. With lambda-cyhalothrin and chlorpyrifos, 10% and 11% of the soil samples had ≥1 surviving alate, respectively. The complete IFA colony disinfestation of root balls and the death of all alates in soil samples indicated bifenthrin D&I could provide additional and effective quarantine level control of IFA in large, post-harvest field-grown nursery plants.

The spatiotemporal variability in resistance to Sitobion miscanthi (Takahashi) among wheat germplasm poses a substantial challenge for wheat breeders attempting to efficiently select and utilize existing germplasm in the development of aphid-resistant wheat varieties. The genetic composition and phenotypic traits of aphid populations within the same wheat field exhibit annual fluctuations, which may explain the unstable field resistance of wheat germplasms to S. miscanthi. In this study, the host adaptability of 4 aphid populations collected from the same wheat field in Yangling, Shaanxi Province, at different time points was evaluated across 5 wheat varieties and 3 barley varieties. The results showed that, following aphid infestation on day 14, the 4 aphid populations exhibited significant differences in their abundance on all host plants except the barley variety Xiyin-2. On day 24, the 4 aphid populations differed significantly in their abundance, total biomass, and mean individual biomass across all host plants. Distinct host-specific differentiation patterns were observed among the 4 populations based on their abundance on days 14 and 24, as well as total and mean individual biomass on day 24. Overall, significant differences in host adaptability were observed among populations sampled from the same field at different times, providing preliminary evidence that temporal variation in aphid population composition may directly contribute to the unstable resistance performance of wheat germplasm under field conditions.

Longevity critically influences biocontrol efficacy, yet direct artificial selection for lifespan extension has rarely been documented in natural enemies. Here, we established long-lived lines of the parasitoid wasp Pachycrepoideus vindemmiae through artificial selection and investigated their phenotypic and genomic consequences. Two longevity-selected lines (LL1 and LL2) and their corresponding original control lines (OL1 and OL2) were generated. Females of LL1 showed a significantly extended lifespan by the fifth generation, whereas LL2 did not respond to selection. Notably, the longevity advantage of LL1 females persisted at generations 15 and 33 after cessation of selection. LL1 females also exhibited increased lifetime fecundity and enhanced resistance to cold and starvation, without changes in developmental duration, sex ratio, or body size. To explore the genetic basis of these traits, whole-genome resequencing was conducted on females and males from LL1 and OL1 at generation 33. Population genomic analyses revealed clear genetic differentiation between lines but not between sexes within lines. Selective sweep analyses in females identified genomic regions under selection enriched in energy metabolism and stress regulation, and integration with expression data revealed SNP variation and line-specific cold-induced expression of heat shock protein genes. Together, these results indicate that artificial selection can potentially produce a stable extension of female lifespan in P. vindemmiae, accompanied by distinct genomic signatures in the responsive line. Our findings provide insights into the genetic architecture of longevity and stress resistance in parasitoid wasps while highlighting both the opportunities and constraints of artificial selection for biological control improvement.

Insects possess an intricate and efficient olfactory system that plays a critical role in navigating their environment, facilitating host location, defensive maneuvers, and reproductive behaviors. In the present study, 12 biological samples were successfully sequenced, yielding a total of 79.92 G data. This led to the assembly of 46,291 Unigenes, with a cumulative length of 47,102,395 base pairs. These Unigenes were subsequently annotated across seven functional databases, including NR (22,104), Swissprot (16,203), KEGG (7,652), KOG (14,597), eggNOG (19,129), GO (14,852), and Pfam (15,267). Central to our findings, 33 genes associated with olfaction were identified, comprising 16 odorant binding proteins (OBPs), 13 chemosensory proteins (CSPs), 3 ionotropic receptors (IRs), and 1 sensory neuron membrane protein (SNMP). Given the critical role of volatile organic compounds emitted by ancient tea leaves in host plant location, the volatile components of these trees using HS-SPEM-GC-MS were further analyzed. The primary volatile identified were alcohols, aldehydes, esters, alkanes, olefins, ketones, and nitriles, with linalool (14.02%), (E)-hexenal (2.84%), and α-farnesene (6.75%) emerging as the predominant compounds. To understand the molecular interactions underlying the recognition of these compounds, molecular docking simulations were conducted, focusing on the three aforementioned compounds and three specific OBPs (OBP3, OBP4, and OBP7) from the tea green leafhoppers. Notably, α-farnesene exhibited the highest binding affinity with OBP7, with the binding process stabilized by the synergistic effects of hydrophobic and hydrogen bonding forces. These findings deepen our understanding of the olfactory recognition mechanisms employed by tea green leafhoppers in their interaction with ancient tea plants.