摘要: Bombyx mori ELAV-like-1 (BmEL-1) and B. mori ELAV-like-2 (BmEL-2) are 2 members of the ELAV-like family of RNA-binding proteins. Mutations in Bmel-1 and Bmel-2 resulted in 5.8% and 28.5% decreases in larval weight on the 3rd day of the 5th instar larva (L5D3), respectively. Triglycerides (TG) are the most important energy resource and are the main component of neutral fat (NF) in animals. To investigate the role of Bmelav-like genes in the synthesis and decomposition of TG, transcriptomic, and metabolic analyses were performed on the whole bodies on the 1st day of the 2nd instar larvae (L2D1) and on fat bodies on L5D3 of Bmel-1- and Bmel-2- mutants, respectively. As compared with the control silkworm, differentially expressed genes generated in both mutants were mainly enriched in lysine degradation, fatty acid (FA) metabolism, and unsaturated FAs biosynthesis. The diglyceride and phosphatide contents were significantly lower in Bmel-1- and Bmel-2- fat bodies than those of the control group. Consistently, the NF content of both mutants' fat bodies were reduced by 50% and 60%, respectively. BmEL-2 positively regulates BmAGPAT gamma (B. mori 1-acyl-sn-glycerol-3-phosphate acyltransferase gamma, LOC101741736) and BmFaF2 (B. mori fatty acid synthetase-associated factor 2, LOC101739090) expression by binding to the specific regions of their 3 ' untranslated regions in BmN cells. This study suggests that BmEL-2 may be an important regulator of BmAGPAT gamma and BmFAF2 expression and thereby participates in TG metabolism in the silkworm fat body.

摘要: The gut is not only used by insects as an organ for the digestion of food and absorption of nutrients but also as an important barrier against the invasion and proliferation of pathogenic microorganisms. Bombyx mori cytoplasmic polyhedrosis virus (BmCPV), an insect-specific virus, predominantly colonizes the midgut epithelial cells of the silkworm, thereby jeopardizing its normal growth. However, there is limited knowledge of the cellular immune responses to viral infection and whether the infection is promoted or inhibited by different types of cells in the silkworm midgut. In this study, we used single-nucleus RNA sequencing to identify representative enteroendocrine cells, enterocytes, and muscle cell types in the silkworm midgut. In addition, by analyzing the transcriptional profiles of various subpopulations in the infected and uninfected groups, we found that BmCPV infection suppresses the response of the antiviral pathways and induces the expression of BmHSP70, which plays a role in promoting BmCPV replication. However, certain immune genes in the midgut of the silkworm, such as BmLebocin3, were induced upon viral infection, and downregulation of BmLEB3 using RNA interference promoted BmCPV replication in the midgut of B. mori. These results suggest that viral immune evasion and active host resistance coexist in BmCPV-infected silkworms. We reveal the richness of cellular diversity in the midgut of B. mori larvae by single-nucleus RNA sequencing analysis and provide new insights into the complex interactions between the host and the virus at the single-cell level.

摘要:

摘要:

摘要: In insects, the juvenile hormone (JH) and 20-hydroxyecdysone (20E) pathways jointly regulate fecundity, but only methyl farnesoate (MF) and ponasterone A exist in mites. Comparative transcriptomic analysis in Panonychus citri showed that E75B was significantly downregulated when exposed to lufenuron. Knockdown of E75B significantly affects the expression of vitellogenin (Vg), Fushi tarazu factor 1 (Ftz-f1) and juvenile hormone acid O-methyltransferase (JHAMT), reducing fecundity in mites. The knockdown of Ftz-f1 produced a more significant effect than the knockdown of E75B, indicating that the ponasterone A pathway positively regulates fecundity in P. citri. After the knockdown of JHAMT, the expression levels of both Vg and Ftz-f1 and fecundity were significantly increased, along with the inhibition of Kr-h1, suggesting that JHAMT was negatively correlated with fecundity in the regulatory network. Knockdown of Kr-h1 inhibited the expression of Vg and Ftz-f1 and fecundity, and whether the drop in fecundity is caused by Kr-h1 or Ftz-f1 is unclear. Subsequent feeding with MF induced Kr-h1 and Vg expression, whereas no significant effects were observed for JHAMT and Ftz-f1. Therefore, the MF pathway stimulates fecundity independently. RNA interference (RNAi) showed that JHAMT and Ftz-f1 inhibited each other, resulting in opposite effects of MF and ponasterone A pathways on steady-state fecundity when either factor changed. Meanwhile, JHAMT knockdown led to increased fecundity, indicating that the stimulating effect of the ponasterone A pathway was greater than the inhibiting effect of the MF pathway, and demonstrating the dominant role of the ponasterone A pathway. Therefore, the interaction between JHAMT and Ftz-f1 may be closely associated with the maintenance of MF-ponasterone A regulatory network homeostasis and is involved in the reduction of fecundity in P. citri induced by exposure to lufenuron.

摘要: Entomopathogenic fungi have been widely used as the main mycoinsecticide for controlling agricultural and forest pests. The effector molecules of these mycopathogens have evolved to adapt to their hosts. The role of fungal effectors in evading the host immune system in insects remains mainly unclear. We characterized the widely distributed fungal effector necrosis-inducing-like secreted protein 1 (NLS1) in the entomopathogenic fungus Metarhizium robertsii. Our findings revealed the presence of M. robertsii NLS1 (MrNLS1) in host hemocytes during the early stage of hemocoel infection. MrNLS1 knock down (Delta MrNLS1) reduced fungal pathogenicity during infection and altered the expression of host immune genes. The molecular docking results and the yeast 2-hybrid assay confirmed that MrNLS1 interacts with the host defense protein Hdd11. The phylogenetic analysis indicated that Hdd11 is conserved across a broad range of Lepidoptera species. Knock down of hdd11 in Helicoverpa armigera, Bombyx mori, and Galleria mellonella markedly suppressed their immune responses against M. robertsii. However, no significant difference was observed in the mean lethal time between hdd11-knockdown Lepidoptera species infected with Delta MrNLS1 and those infected with wild-type M. robertsii. Therefore, in Lepidoptera insects, Hdd11 is essential for fungal defense. In conclusion, M. robertsii infects Lepidoptera insects by targeting host Hdd11 through its protein MrNLS1, thereby suppressing the host immune response. Our findings clarify the molecular mechanisms underlying fungal infection pathogenesis.

摘要: Oviposition preferences of plant-feeding predators remain a complex topic, as such omnivores choose oviposition sites by assessing both plant characteristics and the quality and quantity of nearby animal food sources. Orius predators are omnivores that oviposit endophytically, thus plant characteristics play an important role in their oviposition choices. In this study, we assessed the oviposition and foraging preferences of O. laevigatus and O. majusculus on vegetative and flowering chrysanthemum plants, and assessed the survival of their offspring on differently aged tissues. Our results show a preference of O. laevigatus for young and tender chrysanthemum tissues, where the survival of the nymphs was longer on a plant diet. In contrast, O. majusculus selected older plant parts when laying its eggs, and nymphs did not survive long on any of the plant tissues offered. The foraging activity of Orius females for animal prey (Ephestia kuehniella eggs) did not reveal any specific pattern for either of the two predators. Furthermore, we tested the plasticity of the within-plant oviposition preferences of O. laevigatus, by offering sentinel prey (E. kuehniella eggs) on distinct plant parts. We found that more eggs were laid in older plant tissue when animal prey was offered lower on the plant. Overall, our findings show that oviposition choices of Orius predators are based on a dynamic interplay between plant characteristics, presence of animal and/or floral food sources among other factors, and that differences may well occur between closely related species based on the importance of plant resources in their diet.

摘要: The clustered regularly interspaced small palindromic repeats (CRISPR) / CRISPR-associated nuclease 9 (Cas9)-mediated gene editing technology has revolutionized the study of fundamental biological questions in various insects. Diverse approaches have been developed to deliver the single-guide RNA (sgRNA) and Cas9 to the nucleus of insect embryos or oocytes to achieve gene editing, including the predominant embryonic injection methods and alternative protocols through parental ovary delivery. However, a systematic comparative study of these approaches is limited, especially within a given insect. Here, we focused on revealing the detailed differences in CRISPR/Cas9-mediated gene editing between the embryo and ovary delivery methods in the beetle Tribolium castaneum, using the cardinal and tyrosine hydroxylase (TH) as reporter genes. We demonstrated that both genes could be efficiently edited by delivering Cas9/sgRNA ribonucleoproteins to the embryos by microinjection, leading to the mutant phenotypes and indels in the target gene sites. Next, the Cas9/sgRNA complex, coupled with a nanocarrier called Branched Amphiphilic Peptide Capsules (BAPC), were delivered to the ovaries of parental females to examine the efficacy of BAPC-mediated gene editing. Although we observed that a small number of beetles' progeny targeting the cardinal exhibited the expected white-eye phenotype, unexpectedly, no target DNA indels were found following subsequent sequencing analysis. In addition, we adopted a novel approach termed direct parental CRISPR (DIPA-CRISPR). However, we still failed to find gene-editing events in the cardinal or TH gene-targeted insects. Our results indicate that the conventional embryonic injection of CRISPR is an effective method to initiate genome editing in T. castaneum. However, it is inefficient by the parental ovary delivery approach.

摘要: Species distributed across wide elevational gradients are likely to experience local thermal adaptation and exhibit high thermal plasticity, as these gradients are characterised by steep environmental changes over short geographic distances (i.e., strong selection differentials). The prevalence of adaptive intraspecific variation in thermal tolerance with elevation remains unclear, however, particularly in freshwater taxa. We explored variation in upper and lower thermal limits and acclimation capacity among Iberian populations of adults of the widespread water beetle Agabus bipustulatus (Dytiscidae) across a 2000 m elevational gradient, from lowland to alpine areas. Since mean and extreme temperatures decline with elevation, we predicted that populations at higher elevations will show lower heat tolerance and higher cold tolerance than lowland ones. We also explored whether acclimation capacity is positively related with climatic variability across elevations. We found significant variation in thermal limits between populations of A. bipustulatus, but no evidence of local adaptation to different thermal conditions across the altitudinal gradient, as relationships between thermal limits and elevation or climatic variables were largely nonsignificant. Furthermore, plasticities of both upper and lower thermal limits were consistently low in all populations. These results suggest thermal niche conservatism in this species, likely due to gene flow counteracting the effects of divergent selection, or adaptations in other traits that buffer exposure to climate extremes. The limited adaptive potential and plasticity of thermal tolerance observed in A. bipustulatus suggest that even generalist species, distributed across wide environmental gradients, may have limited resilience to global warming.

摘要: Juvenile hormones (JHs) play a crucial role in regulating development and reproduction in insects. Most insects predominantly synthesize JH III, which typically involves esterification followed by epoxidation, lepidopteran insects use a pathway of epoxidation followed by esterification. Although hemipteran insects have JH III and JH skipped bisepoxide III (JH SB3), the synthesis pathway and key epoxidases remain unclear. This study was conducted on Aphis craccivora, and demonstrated that corpora allata, microsomes, Ac-CYP15C1, and Ac-JHAMT catalyze JH III production in vitro, establishing the pathway of epoxidation followed by esterification. These findings were further confirmed through RNA interference and molecular docking. The presence of JH III and JH SB3 in A. craccivora was identified, and their synthesis pathway was elucidated as follows: Ac-CYP15C1 oxidizes farnesic acid to JH A, followed by methylation to JH III by Ac-JHAMT, possibly providing an epoxidation site on the second carbon for JH SB3. This alteration may significantly contribute to the differentiation and functional diversification of JH types in insects.