摘要: The house fly, Musca domestica, is a cosmopolitan species known for its pestiferous nature and potential to mechanically vector numerous human and animal pathogens. Control of adult house flies often relies on insecticides formulated into food baits. However, due to the overuse of these baits, insecticide resistance has developed to all insecticide classes currently registered for use in the United States. Field populations of house flies have developed resistance to imidacloprid, the most widely used neonicotinoid insecticide for fly control, through both physiological and behavioral resistance mechanisms. In the current study, we conducted a comprehensive analysis of the inheritance and dominance of behavioral resistance to imidacloprid in a lab-selected behaviorally resistant house fly strain. Additionally, we conducted feeding preference assays to assess the feeding responses of genetic cross progeny to imidacloprid. Our results confirmed that behavioral resistance to imidacloprid is inherited as a polygenic trait, though it is inherited differently between male and female flies. We also demonstrated that feeding preference assays can be instrumental in future genetic inheritance studies as they provide direct insight into the behavior of different strains under controlled conditions that reveal, interactions between the organism and the insecticide. The findings of this study carry significant implications for pest management and underscore the need for integrated pest control approaches that consider genetic and ecological factors contributing to resistance.

摘要: The gregarious lifestyle of lepidopteran larvae is diverse and shaped by a complex interplay of ecological and evolutionary factors. Our review showed that the larval-aggregation behavior has been reported in 23 lepidopteran families, indicating multiple evolution of this behavior. Some larvae live in sibling groups throughout all larval instars and even pupation stages, which may result from the kin-selection. In contrast, group fusion may occur among different sibling or foraging groups of larvae and form larger aggregates, and the gregariousness of these species might be driven by the group-selection. While group size and foraging patterns vary greatly across species, it is generally associated with improved larval survivorship and accelerated development. However, the advantages of group living, such as facilitating feeding activities, adjusting the temperature, and defending natural enemies, may diminish along with development, with strong intraspecific competition occurring at later instars, even when food is abundant. Therefore, the group sizes and fission-fusion dynamics of certain gregarious lepidopteran larvae may be a consequence of their cost-benefit balance depending on various biotic and abiotic factors. Trail and aggregation pheromones, silk trails, or body contact contribute to collective movement and group cohesion of gregarious lepidopteran larvae. However, frequent contact among group members may cause the horizontal transmission of pathogens and pesticides, which may bring an integrated pest management strategy controlling gregarious lepidopteran pests. This review focuses on physiological, ecological, and behavioral characteristics of aggregation behaviors of lepidopteran larvae, which have been reported in 23 Lepidoptera families. This figure provides examples of gregarious lepidopteran larvae, including Heortia vitessoides (Lepidoptera: Crambidae), Pieris brassicae (Lepidoptera: Pieridae), Cricula variabilis (Lepidoptera: Saturniidae), and Hyphantria cunea (Lepidoptera: Erebidae).image

摘要: Black soldier fly larvae (Hermetia illucens) receive growing interest as a potential alternative animal feed source. These insects may be exposed to insecticide residues in the rearing substrate. This study aimed to investigate the effects of six different pyrethroid and organophosphate insecticides on this insect species' performance. The toxicity of two model substances for each of these classes (cypermethrin; pirimiphosmethyl) was quantified, with and without the synergist piperonyl butoxide (PBO). Critical effect doses corresponding to 10% yield (CED10) for cypermethrin (0.4 mg/kg) and pirimiphos-methyl (4.8 mg/kg) were determined. The addition of PBO to cypermethrin enhanced its relative potency with a factor 2.6. These data were compared against the relative toxicity of two analogue substances in each class (permethrin, deltamethrin; chlorpyrifosmethyl, malathion). Results suggest that exposure to concentrations complying with legal limits can cause significant reductions in yield. Exposure to multiple substances at lower concentrations resulted in negative additive and synergistic effects. Of the tested substances, deltamethrin was most toxic, causing 94% yield at 0.5 mg/kg. Analytical results suggested that transfer of tested substances to the larval biomass was substance-and concentration-specific, but appeared to be correlated to reduced yields and the presence of PBO. Transfer of organophosphates was overall low (<2%), but ranged from 8% to 75% for pyrethroids. Due to very low limits in insect biomass (similar to 0.01 mg/kg), high transfer may result in noncompliance. It is recommended that rearing companies implement lower contractual thresholds, and that policymakers consider adjusting legally allowed maximum residue levels in insect feed.

摘要: C-type lectins (CTLs) are a family of proteins that contain 1 or more carbohydrate-recognition domains (CRDs) and bind to a broad repertoire of ligands in the presence of calcium ions. CTLs play important roles in innate immune defenses against microorganisms by acting as pattern-recognition receptors (PRRs) for invading pathogens, such as bacteria, viruses, and parasites. After binding to pathogen-associated ligands, CTLs mediate immune responses, such as agglutination, phagocytosis, and the activation of phenol oxidase progenitors, thereby clearing pathogens. CTLs are an evolutionarily conserved family found in almost all vertebrates and invertebrates. Medical arthropods can acquire and transmit a range pathogens through various approaches, such as bloodsucking, lancing, and parasitism, thus infecting humans and animals with related diseases, some of which can be life-threatening. Recent studies have shown that lectins are important components of the arthropod immune system and are essential for the immune responses of arthropods to arthropod-borne pathogens. This article reviews the current understanding of the structure, function, and signaling pathways involved in CTLs derived from important medical arthropods.

摘要: ATAD3A is a mitochondrial membrane protein belonging to the ATPase family that contains the AAA+ domain. It is widely involved in mitochondrial metabolism, protein transport, cell growth, development and other important life processes. It has previously been reported that the deletion of ATAD3A causes growth and development defects in humans, mice and Caenorhabditis elegans. To delve into the mechanism underlying ATAD3A defects and their impact on development, we constructed a Bombyx mori ATAD3A (BmATAD3A) defect model in silkworm larvae. We aim to offer a reference for understanding ATAD3A genetic defects and elucidating the molecular regulatory mechanisms. The results showed that knockout of the BmATAD3A gene significantly affected the weight, survival rate, ATPase production and mitochondrial metabolism of individuals after 24 h of incubation. Combined metabolomics and transcriptomics analysis further demonstrated that BmATAD3A knockout inhibits amino acid biosynthesis through the regulation of mitochondrial ribosomal protein expression. Simultaneously, our findings indicate that BmATAD3A knockout impeded mitochondrial activity and ATPase synthesis and suppressed the mitochondrial oxidative phosphorylation pathway through B. mori mitochondrial ribosomal protein L11 (BmmRpL11). These results provide novel insights into the molecular mechanisms involved in the inhibition of development caused by ATAD3A deficiency, offering a potential direction for targeted therapy in diseases associated with abnormal ATAD3A expression.

摘要: Advanced DNA structures, such as the G-quadruplex (G4) and the i-motif, are widely but not randomly present in the genomes of many organisms. A G4 structure was identified in the promoter of the silk gland factor-1 gene (SGF1), which is the main regulatory gene for silk production in Bombyx mori. In this study, a BmSGF1 G4(-/-) homozygous mutant was generated with the G4 sequence knocked out. The promoter activity of BmSGF1 was lowered in the BmSGF1 G4(-/-) mutant. Pyridostatin (PDS) stabilized the G4 structure and increased the promoter activity of BmSGF1, whereas anti-sense oligonucleotide (ASO) complementary to the G4 sequence suppressed the promoter activity of BmSGF1. Compared with wild-type larvae, the deletion of the BmSGF1 G4 structure decreased both the expression of BmSGF1 and the fibroin heavy chain gene BmFib-H in the posterior silk gland and the weight of the cocoons. Overall, these results suggest that the promoter G4 structure of BmSGF1 participates in the transcription regulation of the BmSGF1 gene in the silkworm.

摘要: Pollination networks are increasingly used to model the complexity of interactions between pollinators and flowering plants in communities. Different methods exist to sample these interactions, with direct observations of plant-pollinator contacts in the field being by far the most common. Although the identification of pollen carried by pollinators allows uncovering interactions and increasing sample sizes, the methods used to build pollen-transport networks are variable and their effect on network structure remains unclear. To understand how interaction sampling influences the structure of networks, we analyzed the pollen found on wild bees from eight communities across Mallorca Island and investigated the differences in pollen loads between bee body parts (scopa vs. body) and sexes. We then assessed how these differences, as well as the uncovered interactions not detected in the field, influenced the structure of wild bee-plant networks. We identified a higher quantity and diversity of pollen in the scopa than in the rest of the female body, but these differences did not lead to differences in structure between plant-pollination (excluding scopa pollen) and bee-feeding interaction (including scopa pollen) networks. However, networks built with pollen data were richer in plant species and interactions and showed lower modularity and specialization (H2'), and higher nestedness than visitation networks based on field observations. Female interactions with plants were stronger compared to those of males, although not richer. Accordingly, females were more generalist (low d') and tended to be more central in interaction networks, indicating their more key role structuring pollination networks in comparison to males. Our study highlights the importance of palynological data to increase the resolution of networks, as well as to understand important ecological questions such as the differences between plant-pollination and bee-feeding interaction networks, and the role of sexes in pollination. This study shows that pollen-transport networks built with pollen carried by wild bees were richer in plant species and interactions, showed lower modularity and specialization, and higher nestedness compared to visitation networks built with interactions detected in the field. Although female wild bees carried more and more diverse pollen in the scopa than in the rest of the body, this did not lead to strong differences in structure between plant-pollination (excluding scopa pollen) and bee-feeding (including scopa pollen) interaction networks. Females were more generalist and tended to be more central in interaction networks compared to males, indicating their more important role structuring networks.image

摘要: How organ size is determined is a fundamental question in life sciences. Recent studies have highlighted the importance of the Hippo pathway in regulating organ size. This pathway controls cell proliferation and cell death to maintain the proper number of cells. The activity of the Hippo pathway is tightly fine-tuned through various post-translational modifications, such as phosphorylation and ubiquitination. Here, we discover that miR-927 is a novel regulator of wing size. Overexpression of miR-927 decreases wing size, which can be rescued by co-expressing miR-927-sponge. Next, we show that miR-927 stimulates apoptosis and suppresses the expression of Drosophila inhibitor of apoptosis protein 1, a well-known target gene of the Hippo pathway. Genetic epistatic analyses position miR-927 upstream of Yorkie (Yki) to modulate the Hippo pathway. In addition, there is a matching miR-927 seed site in the yki 3 ' untranslated region (3 '-UTR), and we demonstrate that yki 3 '-UTR is the direct target of miR-927. Ultimately, our study reveals that the targeting of yki by miR-927 to regulate the Hippo pathway is conserved in Helicoverpa armigera. Administration of miR-927 via star polycation (SPc) nanocarrier effectively inhibits wing development in H. armigera. Taken together, our findings uncover a novel mechanism by which Yki is silenced at the post-transcriptional level by miR-927, and provide a new perspective on pest management.

摘要: Insect hemocytes eliminate foreign substances from the hemocoel through various immune reactions. Integrins, receptor proteins present on the cell membrane, are formed as a heterodimer from alpha and beta subunits and are known to be involved in various immune reactions. To elucidate the role of integrins in the immunity of the lepidoptera Mythimna separata, genes encoding integrins were screened from the genome, resulting in the identification of eight alpha and four beta integrin genes. The expression levels of the integrin genes did not change in response to the injection of small abiotic beads undergoing phagocytosis in M. separata larvae. However, significant inductions of some integrin gene expressions were observed in hemocytes that formed capsules around large abiotic beads during encapsulation, especially in MysInt alpha 2. Under biotic stimulation, induction of the MysInt alpha 2 was evident after exposures to Gram-negative bacteria (Escherichia coli) and entomopathogenic nematodes (Steinernema carpocapsae), but not to Gram-positive bacteria (Micrococcus luteus). Immunostaining analysis revealed that MysInt alpha 2 was specifically localized to hemocytes surrounding the beads during the encapsulation reaction. Furthermore, the spreading and encapsulation abilities of hemocytes were significantly inhibited by incubation with MysInt alpha 2 antibodies. Suppression of MysInt alpha 2 expression in M. separata larvae by injecting double-stranded RNA also resulted in a decrease in encapsulation activity. Collectively, these results indicate that MysInt alpha 2 plays pivotal roles in the cellular immune response of M. separata, particularly during encapsulation. This likely occurs through the regulation of hemocyte spreading activity, thereby facilitating the formation of multilayered capsules around large invaders.

摘要: Circadian rhythms are self-sustained endogenous oscillations that are found in all living organisms. In insects, circadian rhythms control a wide variety of behavioral and physiological processes, including feeding, locomotion, mating, and metabolism. While the role of circadian rhythms in adult insects is well-understood, it is largely unexplored in larvae. This study investigates the potential for larval synchronized activity in the red flour beetle (Tribolium castaneum), a species exhibiting solitary and aggregation phases. We hypothesized that, similar to adults, larvae would exhibit a daily activity pattern governed by an endogenous circadian clock. We further predicted that the transition between the solitary and gregarious phases extends to unique temporal activity patterns. Our results revealed unique timekeeper gene expression in larvae, leading to a distinct daily rhythm characterized by nocturnal activity. Cues indicating on potential cannibalism did not change daily activity peak. However, the absence of these cues significantly reduced the proportion of rhythmic larvae and led to higher variation in peak activity, highlighting the crucial role of social interactions in shaping their rhythmicity. This study sheds light on the evolution and function of larval synchronization in group-living insects, offering novel insights into this complex behavior.