Insect Science最新文献

Dominance contests have important implications for the allocation of limited resources among insect individuals. Prior experiences, particularly winning and losing have been well-documented to influence the performance and outcomes of future contests across various species. This experience effect is believed to arise either from alterations in an individual's self-assessment of its fighting ability based on past experiences or from social cues generated by previous experiences that are subsequently recognized by opponents. However, the influence of previous fighting experiences on dominance contests and the underlying cognitive mechanisms in insects remains underexplored. This study aims to investigate how previous fighting experiences influence the performance and outcomes of dominance contests among bumblebee workers (Bombus terrestris) and the underlying cognitive process. Our research findings indicate that prior winning experiences significantly influence individuals' behavioral decision-making during the pre-escalation phase of contests. Specifically, individuals with previous victories demonstrate a pronounced tendency to initiate and escalate contests, providing compelling evidence that such experiences enhance their self-perceived fighting ability. Furthermore, despite conflict resolution being largely contingent upon escalated contests, prior winners consistently exhibit a markedly higher probability of securing victories. This finding suggests that previous winning experiences improve individuals' actual fighting ability. This enhanced fighting ability enables smaller individuals to overcome larger opponents. Notably, the winner effect persists for a minimum duration of 3 d. In contrast, losers did not show significant changes in performance, suggesting the absence of a pronounced loser effect. These findings provide new insights into the mechanisms underlying the winner effect in insects.

Heavy metals are widespread environmental pollutants. This study investigated the growth toxicity of cadmium (Cd) stress on Chouioia cunea offspring during the parasitism period within a Cd-contaminated food chain of artificial diets-Hyphantria cunea pupae-C. cunea. After parasitizing Cd-accumulated H. cunea pupae, the offspring exhibited a significant reduction in both body length and the expression levels of most growth regulatory genes. Transcriptome analysis revealed that, during the early parasitism stage, genes responsive to Cd stress predominantly involved the endoplasmic reticulum (ER) stress, mitochondrial dysfunction, apoptosis, and calcium homeostasis. In the subsequent stages of parasitism, Cd exposure induced substantial damage to the ER and mitochondrial ultrastructure, disrupted the antioxidant defense system, activated the mitochondrial apoptotic and ER stress pathways, and decreased the expression of SLC24A3 and SLC24A4. Overexpression of SLC24A3 and SLC24A4 in Sf9 cells mitigated Cd toxicity by alleviating the Ca²⁺-mitochondrial permeability transition pore (MPTP)-mitochondrial membrane potential (MMP) collapse/apoptosis and oxidative stress cascade reaction. Overall, Cd exposure impaired the growth of C. cunea parasitic offspring through the SLC24A3/SLC24A4-mediated apoptosis and oxidative damage signaling pathways.

Cuckoo bumblebees are obligate brood parasites that must invade a colony of their host bumblebee species in order to reproduce. As the host queen is typically killed in the colony invasion process, cuckoo bumblebees are thought to severely reduce the reproductive success of the host bumblebee species. Here, we introduce a novel colony-splitting method to investigate and quantify the reproductive impact of cuckoo parasites, applying it to common bumblebee species, Bombus terrestris and its brood parasite, Bombus vestalis. The brood and workers from commercial B. terrestris colonies were divided into two boxes. One colony half was left with the original Bombus terrestris queen-forming the "queen-right" colony-and a B. vestalis cuckoo bumblebee was introduced to the second half, becoming the "cuckoo-parasitized" colony. This paired approach minimizes differences between colony success from genetic variation or other parasites and allows for comparisons between host and cuckoo reproductive success in a controlled environment. In our experiment, cuckoo parasitism resulted in a significant loss of host reproductive success as compared to queen-right colonies. We also record a significant influence of cuckoo lifespan on the number of new cuckoos and hosts produced in parasitized colony halves. In cuckoo-parasitized colonies, we observed higher reproductive success for host B. terrestris than B. vestalis, the cuckoo bumblebee species. We suggest further refinements of this method may be needed before drawing conclusions on the comparative reproductive success of host and cuckoo bumblebees in natural environments.

The venom gland is a remarkable organ of the parasitoid wasps, which produces venom that controls the host and is important for the survival and reproduction of the parasitoid. But little is known about how venom gland cells precisely regulate venom synthesis. Here, we used single-nucleus RNA sequencing to construct the cell atlases of the venom gland and ovary of the Pteromalus puparum, a natural enemy of vegetable pests. The cells in the venom gland were clustered into six subsets, and the main cell types in the ovary were follicle cells, germline cells and nurse cells. The cellular function of venom gland subsets named VgC1 to VgC6 was enriched in the production and secretion of venom. In addition, the expression pattern of identified venom genes that 77 genes expressed across all six VgCs and 46 genes in five VgCs, demonstrated that most venom genes expressed widely in VgCs. Finally, hdWGCNA analysis of venom gland cells identified a set of co-expressed venom and non-venom genes that include putative regulators of venom production in P. puparum. Our analysis of transcription factor (TF) binding sites within the venom modules revealed that TFs such as AP-1 and EHF are potential regulators of venom genes. This work reveals the cellular heterogeneity, venom gene expression patterns, and transcriptional regulatory networks in the venom gland of P. puparum at single-cell resolution. These findings provide fundamental insights into the biology of venom-producing organs and establish a molecular foundation for developing novel biopesticides based on venom proteins.

Coastal dunes are highly vulnerable ecosystems that require adequate bioindicators for effective biodiversity monitoring. Although moths are recognized as good bioindicators in many contexts, their diversity patterns in these habitats remain understudied. This research examines the taxonomic and functional diversity of noctuoid moths in a well-preserved, protected dune system in Central Italy (Adriatic coast). Specifically, the study aimed at investigating how vegetation composition, and hence dune zonation, influences noctuoid diversity and traits. Moth sampling was carried out on an annual basis using UV LED traps in both shifting and fixed dune zones. Vegetation surveys were conducted in spring using 4 m × 4 m plots. We compared noctuoid species richness, species abundance distribution patterns, and trait attributes between the two dune zones in relation to vegetation characteristics. We also evaluated the congruence in species composition and abundance between dune zones for both moths and plants. Sampled noctuoids included 98 species (78 Noctuidae, 18 Erebidae, 1 Nolidae, and 1 Notodontidae). The presence of habitat-exclusive species underscores the influence of both abiotic and biotic filtering processes in shaping noctuoid assemblages across the seashore-inland zonation. Trait-based analyses and diversity patterns showed clear ecological links between noctuoid assemblages and dune zones. This congruence supports the use of noctuoid moths as effective bioindicators and stresses the need to conserve the entire dune system as an integrated ecological unit.

The tortoise scale insect (Toumeyella parvicornis) is rapidly spreading in stone pine (Pinus pinea) forests and urban parks of Mediterranean Europe. Its current distribution and potential spread is concerning as, so far, it already includes three different European countries. Pest management strategies based on endotherapic treatments have a limited time coverage and are unfeasible on large scales. Biological control can be a valuable alternative to contain the spread of T. parvicornis, as highlighted by some recent studies conducted with predators under controlled conditions. Although promising outcomes, open-field efficacy is still poorly explored. This study aimed to fill this gap in knowledge through an open-field assessment of the predation impact of Exochomus quadripustulatus and its capability of reducing T. parvicornis infestation level. Adult ladybug females were released on stone pine groups divided as follows: (i) plants treated only with ladybugs, (ii) plants pre-treated with bio-insecticide prior the release of the ladybugs, and (iii) an untreated control. The stone pine groups that received the ladybugs application, showed a lower infestation level (in terms of T. parvicornis adult females) than the untreated control, for most of the evaluation period. Results showed, for the first time, evidence of E. quadripustulatus efficacy in open-field applications, confirming the previously positive outcomes observed under laboratory and semi-field conditions. The outcomes of this study, accordingly, open the door to future biological control programs.

Bursicon is indispensable for wing expansion in Bactrocera dorsalis, acting through PKA-mediated regulation of the wing-development gene Bdhh. Although cuticular proteins are recognized as critical regulators of insect wing development, it remains unclear whether they directly respond to the bursicon signaling pathway. Here, we conducted a functional dissection of cuticular protein genes during wing expansion. Transmission-electron-microscopy (TEM) analysis revealed that bursicon controls endocuticle development in the wing cuticle. Genome-wide mining uncovered sixteen CPR-type endocuticle structural glycoprotein genes, of which three cuticular protein genes (BdABD-4a, BdABD-4b, and BdABD-4c) were selected for RNAi on the basis of their expression profiles. Silencing of each gene via dsRNA injection at the 5-d-old pupal stage produced wing malformations in 37.5%, 32.5%, and 40% of adults, respectively, and reduced cuticle thickness by 40.4%, 42.4%, and 44.2% relative to controls. TEM confirmed the presence of thinner endocuticle in malformed wings. Furthermore, expression levels of all three endocuticle structural glycoprotein genes were markedly altered following knock-down of Bursicon genes, Bdhh and after PKA inhibition, indicating that these proteins operate downstream of the bursicon signaling cascade. The results in this study demonstrated that the functional role of BdABD-4a, BdABD-4b, and BdABD-4c in wing expansion, and provide new insights into the molecular mechanism underlying bursicon regulated wing expansion in B. dorsalis.

Insects touch their proximal environment with their tarsi. The immediate contact with xenobiotics occurs with the tarsal cuticle surface that is covered with cuticular hydrocarbons (CHCs). In this work, we tested the hypothesis that xenobiotics entry through the tarsi depended on CHC amounts and composition. Applying RNA interference, we suppressed the expression of genes coding for the key enzymes of CHC production Cyp4G1 (total CHC), desat1 (unsaturated CHCs) and FASN2 (branched CHCs) in lipid producing oenocytes and analyzed the penetration efficiency of the insecticides DDT and chlorantraniliprole and of the inert dye Eosin Y in the respective flies. As expected, in walking experiments, reduction of CHC amounts (cyp4G1^RNAi) enhanced insecticide and dye penetration into the tarsi. In the same assay, we identified unsaturated CHCs as the main CHC component attenuating DDT and chlorantraniliprole at low concentrations. Likewise, tarsal adhesion and uptake of Eosin Y depended rather on unsaturated than on branched CHCs. Extrapolating from our data, we propose a two-step model of xenobiotics penetration through the tarsal cuticle: first, modulated by unsaturated CHCs, the molecule is repelled or adheres to the cuticle surface; upon adhesion, the molecule penetrates the cuticle and accumulates in the tarsal lumen in a second step. Whether these mechanisms apply to molecules other than Eosin Y remains to be investigated. Taken together, the tarsal cuticle constitutes a selective bipartite barrier against uncontrolled uptake of contact xenobiotics.

Farnesoic acid O-methyltransferase (FAMeT) and juvenile hormone acid O-methyltransferase (JHAMT) are key enzymes in the isoprene branch pathway, a specialized downstream biosynthetic pathway for juvenile hormone (JH). Both enzymes play crucial roles in insect egg production. While their mechanisms have been well characterized in model insects, this study aims to elucidate their specific functions in the reproductive process of the small brown planthopper (SBPH), Laodelphax striatellus. Here, we cloned the full-length cDNA encoding a putative FAMeT (LsFAMeT) from SBPH. The deduced protein sequence has a conserved Methyltransf_farnesoic acid domain and shares high identity with other insect FAMeTs. To gain further insight, we silenced LsFAMeT and LsJHAMT in SBPH and found that LsJHAMT expression increased when LsFAMeT was knocked down, and vice versa, suggesting a potential coordinated relationship between LsFAMeT and LsJHAMT in JH biosynthesis. In addition, RNAi-mediated silencing of LsFAMeT, LsJHAMT, or both genes significantly reduced female fecundity while simultaneously decreasing JH III titers. This was associated with reduced levels of total protein, cholesterol, triacylglyceride, and four carbohydrates (glucose, fructose, sucrose, and trehalose), as well as decreased ovarian cell mitosis, increased ovarian cell apoptosis, and downregulation of the JH receptor Met and its early-responsive gene Kr-h1. Together, these data suggest that LsFAMeT- and LsJHAMT-mediated JH biosynthesis regulates the reproductive capabilities of SBPH through energy mobilization, and ovarian cell activity. Our findings help elucidate the role of JH in insect reproduction and provide insights into key enzymes that may serve as potential targets for the development of selective insect growth regulators.

Feeding behavior determines insect survival and reproductive success. As insects process multimodal olfactory and gustatory cues to guide their feeding decisions, appetitive odors not only attract insects to food sources but also directly increase food ingestion. However, the mechanisms that coordinate chemosensory integration to regulate these behaviors remain poorly characterized. The silkworm mainly feeds on mulberry leaves. We previously identified GS01 as a natural mutant that consumes an expanded range of non-mulberry diets and exhibits compromised olfactory specificity for mulberry leaves. Thus, GS01 is an excellent model for studying the genetic basis of interactions between olfaction and gustation. Combining the results of molecular mapping, transcriptome sequencing, and DNA sequencing, we determined that the gustatory receptor Gr66, and odorant receptors Or39 and OrJ are involved in the euryphagous phenotype of GS01. Next, we generated a series of mutants by single or combined gene knockout using CRISPR/Cas9 and studied the interactions between the affected genes in regulating feeding behavior. We showed that a single knockout of Gr66 increases intake of an artificial diet containing no mulberry leaves, while individual or simultaneous knockouts of genes Or39 and OrJ do not increase consumption of this diet. However, the combined knockout of genes Gr66, Or39, and OrJ significantly enhances uptake of the artificial diet beyond levels exhibited by the Gr66 knockout alone. This study demonstrates the synergy between gustatory and odorant receptors in regulating silkworm feeding preference and food uptake, and sheds light on understanding the complexity of regulation of feeding behavior in insects.