Insect Science最新文献

Fungus farming in termites is vulnerable to invasions by opportunistic and specialized fungi that may compromise the Termitomyces fungal crop that these termites rely on for food. Both termite and symbiont defenses contribute to suppressing such fungal infections, and here we build on past efforts to help understand these defenses. We demonstrate that gardens without Macrotermes annandalei termites are rapidly colonized by weedy fungi, initially dominated by opportunistic Aspergillus and Trichoderma molds and later by co-evolved Xylaria that outcompete these molds. In some cases, termite presence suppresses molds but not Xylaria infections. We then demonstrate that termite burying behavior, a defense response to weeds, increases in the presence of Termitomyces, suggesting that the perception of weeds as threats is most pronounced when there is a risk of garden exposure. The burying response was strongest toward Aspergillus and Trichoderma, suggesting that coevolved Xylaria may to some extent evade this defense. Lastly, we document antifungal properties of Bacillus and Burkholderia bacteria, and 21 fungi isolated from the symbiotic environment, in support that both hosts and fungistatic microbes contribute to keeping fungal gardens free from unwanted fungi. Although our findings suggest a multi-partnered defense, further work is needed to determine the compounds responsible and their ecological significance in protecting termite gardens.

The fall webworm (Hyphantria cunea) is a globally recognized quarantine pest with a wide host range, causing serious ecological and economic damage. Olfactory-based pest control using semiochemicals is an environmentally sound strategy, but little is known about larval olfactory mechanisms. Here, we identified 48 Odorant Binding Protein (OBP) genes in H. cunea larvae and investigated their roles in perceiving its adult sex pheromone components. Behavioral assays revealed that two female-produced sex pheromone components, Z9,Z12-18Ald and Z9,Z12,Z15-18Ald, significantly attracted H. cunea larvae. Exposure to these compounds upregulated six larval OBPs. Fluorescence binding assays confirmed that both HcunOBP36 and HcunGOBP2 bind to these two pheromone components. Larvae injected with dsGOBP2 showed significantly reduced attraction to the two pheromone components, whereas injection of dsOBP36 had little effect; co-silencing both genes further diminished attraction compared with the dsGOBP2 alone. These findings indicate that HcunGOBP2 was essential in the larval orientation toward adult sex pheromone-containing food sources, while HcunOBP36 had an auxiliary role. This study offers novel insights into the pheromone perception of insect larvae, thereby enhancing our understanding of larval olfactory biology and pheromone-mediated ecological interactions.

The adequate supply of oxygen is critical for the embryonic development in insects. However, oxygen transport in embryo when the tracheal system is not fully developed remains elusive. Herein, we investigated the relationships between hemocyanin and tracheal development in locust embryo. The results showed that hemocyanin expression and tracheal development display a seesaw pattern during the process of embryonic development (i.e., the two show an inverse relationship: as the tracheal system gradually matures, the expression level of hemocyanin gradually decreases). The hemocyanin proteins, Hemocyanin subunits I (Hc1) and II (Hc2), possess oxygen-binding capabilities and their expression positively respond to the hypoxia in locust embryo. RNA interference (RNAi)-mediated silencing of Hc1 and Hc2 genes in the early embryo leads to hypoxia-induced malformations and mortality, thereby underscoring their essential function in embryonic oxygen transport. Once tracheal system developed, the hemocyanin gene expression rapidly declined. Intriguingly, the genes involved in tracheal system development was knockdown by RNAi, the higher expression of hemocyanin is prolonged by 1-2 d extending oxygen transport in early embryo. The tracheal system functions earlier in locust embryo than that we expected. Therefore, the hemocyanin is pivotal to transfer oxygen in early embryo of locusts. Our findings reveal that the mechanism of hemocyanin function in oxygen transport before tracheal system development in locust embryo, and provide an insight into hemocyanin function in insects.

As the catalytic subunit of the Elongator complex, Elongator protein 3 (Elp3) plays a crucial role in multiple physiological processes, including growth, development and immune responses. Previous studies on Elp3 have focused on Caenorhabditis elegans, Drosophila melanogaster, Homo sapiens (human) or Mus musculus (mouse), whereas there are few reports on Elp3 in agricultural pests. Here, the role of TcElp3 in reproduction in the red flour beetle, Tribolium castaneum, was investigated, and the underlying mechanisms were explored. The results showed that RNA interference (RNAi)-mediated knockdown of TcElp3 in female pupae led to decreased fecundity in female adults. Consistently, the injection of dsTcElp3 into female pupae decreased the mRNA levels of the vitellogenin (Vg)-encoding genes TcVg1 and TcVg2 in female adults. Notably, knockdown of TcElp3 upregulated the expression of forkhead box protein O (FOXO) at both the mRNA and the protein level in T. castaneum, and promoted the nuclear translocation of TcFOXO. Additionally, TcElp3 directly interacts with TcFOXO and the silencing of TcElp3 significantly decreased the acetylation level of TcFOXO. Overall, our studies reveal that Elp3 regulates beetle reproduction by interacting with FOXO and modulating its acetylation status.

Urban green spaces (UGS) are vital habitats for maintaining insect diversity within cities. However, the key factors driving insect biodiversity under accelerating urbanization remain poorly understood. This study systematically investigates insect diversity and its environmental drivers across 200 sampling sites distributed along an urban-to-rural gradient in 4 climatically distinct cities of China: Changchun, Beijing, Hangzhou, and Haikou. We identified 102 common insect species across 8 orders, with Diptera dominating overall abundance. Species richness was highest in farmland and well-managed urban parks, while roadside and residential habitats exhibited reduced or variable diversity. Insect abundance and composition showed significant spatial variation, strongly influenced by UGS type and urbanization intensity. Diptera emerged as key indicator taxa, responding sensitively to urbanization gradients. A generalized linear mixed-effects model framework was developed to integrate large-scale urban environmental variables with local habitat characteristics, enabling a comprehensive assessment of how urbanization and climate combinedly influence insect diversity across cities. Principal coordinate analysis and non-metric multidimensional scaling revealed that both land use and climate zone contributed to community differentiation, with the strongest effects observed in transitional habitats. Mantel tests and random forest models demonstrated that the key environmental drivers of diversity were taxon- and city-specific, including geographic location, particulate matter, wind speed, and floral diversity. Maximum ecological niche model analysis revealed divergent trends in future habitat suitability, driven by distinct climatic variables in each city. Overall, our findings underscore the importance of region-specific conservation strategies in sustaining insect diversity in urban ecosystems.

The invasive white-footed ant Technomyrmex difficilis has emerged as a rising pest in several regions, yet its invasion dynamics remain underexplored. This species outcompetes native ants and causes agricultural losses by tending pest insects, including aphids and mealybugs. This study provides the first integrated analysis of the species' behavioral, chemical, and genetic variation across Texas and Florida populations. Observations suggest that the recently discovered Texas population of white-footed ants originated from Florida. Microsatellite and mitochondrial DNA analyses revealed low genetic diversity in both populations, with a shared haplotype consistent with the Texas population originating from Florida. STRUCTURE analysis further supported genetic clustering between the two regions. Despite similar within-colony coefficients of relatedness for workers, the populations differed in reproductive strategy: Florida colonies showed signs of inbreeding and high inter-colony aggression, whereas Texas colonies exhibited potential localized outbreeding, low aggression, and more uniform cuticular hydrocarbon profiles. Aggression was positively correlated with chemical divergence but not with genetic differentiation. This study establishes a foundational understanding and highlights the importance of integrating multiple types of data to understand the invasion biology of Technomyrmex difficilis.

Pathogens are shared between wild bees and wasps but little is known about how urbanization affects their occurrence. Here, the role of temperature and fragmentation of green areas, both associated with urbanization, in modulating pathogen loads was investigated. Twelve pathogens were investigated in the bees Anthophora plumipes Pallas, 1772, Halictus scabiosae (Rossi, 1790), Osmia cornuta (Latreille, 1805), and the wasp Polistes dominula (Christ, 1791) sampled across an urbanization gradient in a metropolitan area of northern Italy. Overall, the relative presence/abundance of the pathogens were found to be species specific, as were the responses to urbanization. Anthophora plumipes and O. cornuta had a higher occurrence probability of the neogregarine protozoan Apicystis bombi in more fragmented urban areas. In the same bee species, both temperature and the fragmentation of green areas reduced the number of copies of the deformed wing virus (DWV). In H. scabiosae and P. dominula, higher temperature increased respectively the likelihood of occurrence of DWV and chronic bee paralysis virus (CBPV). In addition, the viruses were found to be replicative in all samples tested. The results show a consistent presence of pathogens in the four target species, and that urbanization plays a role in modulating the pathogen load. Although transmission pathways could not be considered here, it may be suggested that appropriate management of urban areas may buffer wild insects from potentially harmful pathogens. Whether the presence of such pathogens also results in symptomatic phenotypes remains to be determined in laboratory experiments.

Urbanization significantly impacts genetic connectivity and imposes selective pressures on insect populations, particularly in urban habitats. Although these effects are well documented at the scale of individual cities, the impact of mega-urbanization on species occupying large urban agglomerations remains poorly understood. Here, we investigate the population structure and detect selection signals associated with local adaptation in the white butterfly Pieris latouchei across the Yangtze River Delta Megalopolis (YRDM), a region comprising 27 contiguous cities and adjacent areas. Using genome-wide 2b-RADseq data, we demonstrate that urbanization reduces genetic diversity but not gene flow in the pest populations. Compared to peripheral populations, we observed population homogenization and identified selected genes related to detoxification, immune response, and thermal stress resistance in YRDM populations. Mega-urbanization, driven by habitat modifications and an extensive transport system, facilitated the expansion of a specific population with adaptive genes, leading to the loss of genetic diversity in YRDM. This study provides genomic evidence for low genetic divergence and the genetic basis of adaptation to megalopolitan environments in an urban insect pest.