Journal of Insect Science最新文献

Aedes albopictus (Skuse) is an invasive mosquito species which has rapidly expanded across the Americas since the 1980s. This species has significant implications for public health. This study aimed to assess the genetic diversity and potential invasion routes of Ae. albopictus populations in El Salvador and throughout the Americas using the mitochondrial DNA (mtDNA) CO1 barcode. The mtDNA CO1 was sequenced from 52 samples from 5 departments in El Salvador. Analyses included the El Salvador populations, and an additional 205 GenBank sequences from the American continent and Asia, the region of origin. Haplotype and nucleotide diversity assessments, genetic differentiation, and phylogenetic clustering were performed. Genetic diversity in populations of Ae. albopictus from El Salvador and from most countries in America was generally low; El Salvador had 3 haplotypes. One exception was Colombia, where 12 haplotypes were detected. In the Americas, 22 haplotypes were found overall. Phylogenetic analyses grouped American samples into 2 major clusters, 1 centered around haplotype 19, which was the most abundant and widely distributed. El Salvador shared 2 haplotypes with North America. Ae. albopictus from Puerto Rico was genetically distinct from other groups and grouped together with Asian samples. The Asian outgroups were more diverse than samples from America. The analysis highlighted the presence of ancestral lineages in El Salvador and their role in early and complex colonization patterns of this species across the Americas, providing critical data for future management and control strategies against this invasive vector.

Chilo sacchariphagus Bojer and Chilo infuscatellus Snellen are 2 major sugarcane pests in southern China. Both species are nocturnal moths that exhibit sexual activity during the night. However, the rhythms of their sexual activities remain poorly documented. In this study, we investigated the sex pheromone titers of both species to determine the effect of age on pheromone production and to characterize the rhythms of pheromone production during the scotophase, when the highest levels are expected to occur. Gas chromatography-mass spectrometry analysis of hexane extracts from female pheromone glands revealed that the titers of 3 sex pheromone components, (Z)-11-hexadecenyl acetate (Z11-16: Ac), (Z)-13-octadecenyl acetate (Z13-18: Ac), and (Z)-13-octadecen-1-ol (Z13-18: OH) were very low on the first night after eclosion, peaked on the second night, and then decreased with age, becoming nearly undetectable by the fourth night in C. sacchariphagus. A similar trend was observed in C. infuscatellus, in which the titer of (Z)-11-hexadecenol (Z11-16: OH) also peaked on the second scotophase. During the second scotophase, the titers of the 3 sex pheromone components in C. sacchariphagus increased rapidly over time from 21:00 to 05:00, peaking between 03:00 and 05:00, and then declined sharply. In contrast, the pheromone titer in C. infuscatellus remained stable during the first 4 h of the scotophase, then rose sharply between 01:00 and 03:00 before declining. These findings contribute to a better understanding of the sexual behavior of these 2 moths and provide a theoretical basis for precise monitoring strategies in the field.

In insect reproduction, vitellogenesis is a prerequisite to oocyte maturation and critically depends on nutrient acquisition, supporting reproductive success. In Helicoverpa armigera (Hübner 1809), a hallmark of female reproduction is that vitellogenin (Vg) synthesis is initiated following adult eclosion, and juvenile hormone (JH) plays a principal role in this process. The adults commonly visit flowers to feed on nectar, which implies the possible linkage between adult nutrient and vitellogenesis. The preliminary experiment demonstrated that the supplemental nutrition with 10% honey during vitellogenesis significantly shortened the preoviposition period, extended the oviposition duration, and improved female fecundity. Ovary dissection showed that the ovarian development was somewhat delayed in water-fed females, while their ovarian degradation occurred in advance. Consistent with this, on days 1 and 2 of vitellogenesis, the water-fed females possessed a larger proportion of previtellogenic follicles in the ovaries and higher triglyceride content than those in honey-fed individuals. On days 3 and 4, the Vg transcription was significantly downregulated in the fat body of water-fed females. Besides, the water feeding during vitellogenesis resulted in an attenuated JH biosynthesis and a notable decline in intrinsic JH content. The expressions of JH pathway genes, Met and Kr-h1, in the fat body were reinforced in honey-fed females at day 4 of vitellogenesis. These results elucidated the promoting effect of adult nutrient on female reproduction, and we proposed that the adult nutrient shortage impairs female vitellogenesis partly via the attenuated JH signaling.

During winter months, a significant portion of commercial honey bee (Apis mellifera L.) colonies are stored indoors to overwinter in climate-controlled conditions. However, refrigerated bee storage facilities could be a useful tool at other times of the year in an integrated pest management approach to control the infamous Varroa destructor Anderson and Trueman. Here, we investigated the efficacy of using refrigerated bee storage in the spring to temporarily disrupt honey bee brood production, followed by treating colonies with miticides that perform best in times of low brood production. Immediately following commercial spring pollination in California almonds, colonies were moved to refrigerated bee storage or an apiary as a control. After 18 d, colonies in refrigerated bee storage were relocated to the apiary, and all colonies were treated with a miticide. Bee samples, frames of bees, and hive weights were recorded at the time of miticide application and 37 d later. While there were no statistically significant differences in hive weight or number of frames of bees, colonies that experienced an induced brood break had significantly lower Varroa loads (mites per 100 bees) than colonies that did not experience a brood break. This study demonstrates a viable large-scale method to increase the efficacy of and decrease the need for reapplication of miticides for Varroa control.

Spodoptera eridania (Stoll) is a key pest of soybean crops in Brazil. However, information about the physiology, behavior, and ecology of S. eridania, including its genetic variability within the agricultural landscape, remains scarce. In this study, we conducted an exploratory analysis of the genetic diversity, population structure, and demographic patterns of S. eridania in Brazil. A cytochrome c oxidase I (COI) gene fragment of 866 bp was sequenced from 89 S. eridania individuals collected in Brazilian soybean macroregions. We identified 33 COI haplotypes with high haplotype diversity and moderate nucleotide diversity distributed throughout the country. The genetic relationships among COI haplotypes show a recent divergence with no evidence of distinct haplogroups. Spodoptera eridania collected on soybean crops showed a lack of population genetic structure associated with soybean macroregions or Brazilian states. Overall, our data suggest that S. eridania populations are undergoing demographic and spatial expansion in Brazil, with an increasing effective population size in the last 200 years. This study provides the first insights into the population diversity and demography of S. eridania in the Americas, shedding light on the dynamics and evolution of this species and further supporting integrated pest management strategies in Brazilian soybean crops.

The Mediterranean fruit fly (Ceratitis capitata Wiedemann, medfly) is a highly invasive agricultural pest with a considerable threat to global fruit production. Its olfactory system, mediated by odorant-binding proteins (OBPs), plays a fundamental role in key behaviors such as host localization, mate recognition, and oviposition site selection. This study presents a comprehensive homologation and systematic reclassification of CcapOBPs through comparative genomic analyses with the model organism Drosophila melanogaster Meigen and 8 Tephritidae species (tribes Dacini, Toxotrypanini, and Trypetini), supported by Bayesian phylogenetic inference. By integrating 2 genome assemblies (Ccap_2.1 and EGII-3.2.1), additional GenBank entries, a de novo head transcriptome from sexually mature wild males, and comparative analyses with D. melanogaster orthologs, we consolidated 156 candidate sequences into a homologized repertoire of 48 CcapOBPs. RT-PCR validation of 21 representative CcapObps confirmed their expression in male heads and highlighted how the de novo transcriptome recovered genes missing from individual genome assemblies, demonstrating consistency across all data sources. Phylogenetic reconstruction of CcapOBP and tephritid species revealed clustering patterns consistent with the established evolutionary relationships within the family, enabling the identification of ortholog genes, lineage-specific diversification events, gene duplications, expansions in C. capitata. However, limitations were identified in datasets for the other fruit fly species, and the need for nomenclature adjustments based on chromosomal localization. This study represents the most comprehensive OBP homologation in medfly to date, providing a robust framework for understanding the molecular evolution of chemosensory systems in Tephritidae and supporting the development of species-specific and environmentally sustainable pest management strategies.

The blue orchard bee (Osmia lignaria Say) is a solitary bee native to North America that is increasingly propagated, sold, and used for pollination of rosaceous orchard crops. While methods exist to rear blue orchard bees in a laboratory setting, present protocols vary in diet manipulation and fail to progress bees to adult emergence. Variability in published methods also makes standardized comparisons within or across species challenging. Here, we present a validation of a rearing protocol for O. lignaria in a laboratory setting, with the study employed over a 2-year period that mirrored the bees' phenology in northern Utah (United States). Our protocol used 3D printed well plates with a well diameter that we recommend as appropriate for rearing O. lignaria in a laboratory. Each well permits the user to observe detailed life stages of individual O. lignaria bees without disturbing their development. To validate the protocol, we monitored O. lignaria development across 3 larval instars (first, second, and fifth), prepupal, pupal, and adult stages using a dissection scope and X-ray imaging. We confirm that diapause duration can be altered and affects the percent weight loss. Our data demonstrate that we can successfully rear bees to the adult stage (74%). Our protocol can be altered to fit any laboratory experiment and adapted to investigate other above-ground cavity-nesting bee species in a laboratory setting. Such investigations might include how multiple environmental conditions, nutritional factors, and stressors influence bee health.

Temperature-induced changes in the physiological signals altered the wing coloration in Bicyclus anynana (Butler, 1879). The morphogenetic hormone 20-hydroxyecdysone (20E) increases with temperature and regulates the seasonal morph formation of the species. Although melanization in Idea leuconoe clara Butler (Lepidoptera: Nymphalidae) can be induced by temperature shock at 10, 35, and 40 °C, the relationship between this phenomenon and 20E remains unexplored. This study hypothesizes that the melanic phenotype of I. leuconoe clara is affected by distinct hormonal responses under extreme temperatures. The 20E levels were measured at the 3% and 20% pupal development stages of I. leuconoe clara under temperature shock. The relationship between 20E and melanization was investigated through hormone injection. The results demonstrated that the relationship between melanization under cold shock and 20E was negative and that 20E regulated the degree of melanin deposition rather than the patterning of melanized areas. This study investigates the effects 20E on wing melanization under extreme temperatures in I. leuconoe clara. Future studies could further determine the melanic changes in pigment and structural coloration through transcriptomic analysis and scanning electron microscopy based on the temperature shock procedure.

Dealation is a critical biological process in the life cycle of Solenopsis invicta Buren, playing a pivotal role in reproduction, population dispersal, and survival strategies. However, over the past 30 years, there have been few studies on the patterns and underlying mechanisms of dealation in S. invicta. Existing research has mainly focused on the monogyne form, and there are certain limitations in terms of data collection density and sample size. In this study, 1,000 alate virgin females (hereafter "AV-females") of the polygyne form were individually isolated from queen pheromone exposure and monitored for independent dealation at 2-h intervals over 15 consecutive days. Results indicated that the peak dealation period for AV-females occurred between days 3 and 5, with 93.3% completing wing shedding within 2 to 6 days. The relationship between "dealation rate and dealation time" could be well fitted by a logistic model. Furthermore, dealation primarily occurred during the daytime, with 59.1% of AV-females completing dealation between 9:00 AM and 2:00 PM, as well as between 7:00 PM and 8:00 PM These findings provide foundational insights for advancing research into the mechanistic basis of dealation in S. invicta.

Stable isotope analysis is scarcely utilized among bee researchers. One reason for this scarcity is ambiguity when determining whether to utilize the entire insect/arthropod or certain body parts for isotope analysis. Here, we analyzed δ15N and δ13C isotopic compositions of the abdomens, heads, and legs of 3 bee species native to North America [Centris pallida Fox, Melissodes bimaculatus (Lepeletier), and Bombus griseocollis (De Geer)]. We hypothesized that the abdomen δ15N and δ13C values would differ significantly from those of the heads and legs because the abdomen contains metabolically active organs, while the heads and legs, with less active tissues, would show no differences in isotopic compositions. Overall, we found varying degrees of statistical differences among the different body parts for isotope values. However, variations equivalent in magnitude to trophic level differences were not observed, resulting in the ability to use a single body part rather than a whole insect body for stable isotope analysis. To strengthen this finding, correlation analyses revealed paralleled patterns in responses by species. Finally, we suggest that when designing experiments using stable isotope analysis, it is important to focus on being consistent with selected body parts to reduce inter-individual variability. We also recommend using a relatively large sample size (n ≥ 20) due to the wide variance observed within individuals, especially if the goal is to characterize population-level ecological differences.