In Hymenoptera species, the reproductive mode is usually arrhenotoky, where haploid males arise from unfertilized eggs and diploid females from fertilized eggs. In addition, a few species reproduce by thelytoky, where diploid females arise from unfertilized eggs. Diploid females can be derived through various cytological mechanisms in thelytokous Hymenoptera species. Hitherto, these mechanisms were revealed mainly in endosymbiont-induced thelytokous Hymenoptera species. In contrast, thelytokous Hymenoptera species in which a reproductive manipulator has not been verified or several common endosymbionts have been excluded were paid less attention in their cytological mechanisms, for instance, Diglyphus wani (Hymenoptera: Eulophidae). Here, we investigated the cytological mechanism of D. wani using cytological methods and genetic markers. Our observations indicated that the diploid karyotypes of two strains of D. wani consist of four pairs of relatively large metacentric chromosomes and one pair of short submetacentric chromosomes (2n = 10). The arrhenotokous strains could complete normal meiosis, whereas the thelytokous strain lacked meiosis and did not expulse any polar bodies. This reproductive type of lacking meiosis is classified as apomictic thelytoky. Moreover, a total of 636 microsatellite sequences were obtained from thelytokous D. wani, dominated by dinucleotide repeats. Genetic markers results showed all three generations of offspring from thelytokous strain maintained the same genotype as their parents. Our results revealed that D. wani is the first eulophid parasitoid wasp in Hymenoptera whose thelytoky was not induced by bacteria to form an apomictic thelytoky. These findings provide a baseline for future inner molecular genetic studies of ameiotic thelytoky.

Spodoptera exempta, known as the black armyworm, has been extensively documented as an invasive agricultural pest prevalent across various crop planting regions globally. However, the potential geographical distribution and the threat it poses to host crops of remains unknown at present. Therefore, we used an optimized MaxEnt model based on 841 occurrence records and 19 bioclimatic variables to predict the potential suitable areas of S. exempta under current and future climatic conditions, and the overlap with wheat, rice, and maize planting areas was assessed. The optimized model was highly reliable in predicting potential suitable areas for this pest. The results showed that high-risk distribution areas for S. exempta were mainly in developing countries, including Latin America, central South America, central Africa, and southern Asia. Moreover, for the three major global food crops, S. exempta posed the greatest risk to maize planting areas (510.78 × 10⁴ km²), followed by rice and wheat planting areas. Under future climate scenarios, global warming will limit the distribution of S. exempta. Overall, S. exempta had the strongest effect on global maize production areas and the least on global wheat planting areas. Our study offers a scientific basis for global prevention of S. exempta and protection of agricultural crops.

Insect mating behaviors are complex, diverse, and primarily regulated by neuropeptides and their receptors. Neuropeptides are peptide signaling molecules mainly secreted by insects’ central nervous system (CNS) to reach target organs. A substantial body of research on the role of neuropeptides in regulating mating behaviors in insects has been undertaken. This review aims to (1) synthesize existing knowledge on insect mating behaviors, (2) elucidate the neuropeptidergic mechanisms governing these behaviors, and (3) identify knowledge gaps and propose future research directions. The mating process, covering mate attraction, courtship rituals, copulation, and post-mating behaviors, was elucidated with appropriate examples. Additionally, specific neuropeptides involved at each stage of the mating process, their functions, and mechanistic aspects were discussed as demonstrated in research. The review highlights that insects display behavioral dimorphism in the mating process driven by a complex underlying neuropeptidergic mechanism. While previous publications have generally addressed the role of neuropeptides in insect behavior, none has intensively and methodically examined their role in mating behaviors. In this review, we synthesized 18 neuropeptides that we found to regulate mating behaviors in insects. We note that some of the neuropeptides are malfunctional in their regulatory roles, while others are specific. We also note that these neuropeptides execute their regulatory functions through the G protein-coupled receptor (GPCR) signaling pathway but may take different routes and messengers downstream to effect behavioral change. Neuropeptides also interact with other regulatory systems, such as the endocrine system, to discharge their functions. Given their significance in mediating mating and reproduction, targeted manipulation of the signaling system of neuropeptides could serve as viable targets in the production of ecologically friendly pest management tools. Tools that could disrupt the mating process would be applied in crop production systems to reduce the population pressure of destructive pests, consequently reducing the urge to use chemical pesticides that are ecologically unfriendly. Our findings not only advance the understanding of neuropeptide-mediated mating regulation but also highlight their potential as eco-friendly pest control targets.

Insects, as the most diverse and numerous group in the animal kingdom, are at least partly dependent on the reproduction process, which is strictly regulated by the ‘classic’ insect hormones: juvenile hormone (JH), and 20-hydroxyecdysone (20E). However, the regulatory mechanism governing the reproduction of JH and 20E in Spodoptera frugiperda remains unclear. In this study, ovarian development and ovulation in female S. frugiperda were assessed through dissection of the ovaries following treatment with JH analog (JHA) and 20E. Moreover, the expression patterns of the JH-signal and 20E-signal-related genes were determined by quantitative PCR (qPCR), and RNA interference (RNAi) was used to investigate the role of JH and 20E-induced genes. Ovarian development was observed by microdissection, and JH and 20E titers were determined by ELISA. Kr-h1, Vg, and USP expression were determined by qPCR. Dissection and qPCR results showed that JHA and 20E promoted ovarian development, egg maturation, and egg laying by upregulating Methoprene-Tolerant (Met) and Ecdysone Receptor (EcR)expression. Additionally, the RNAi results showed that the injection of dsMet and dsEcR markedly delayed ovarian development, inhibited egg maturation, and halted egg production. Knockdown of Met and EcR significantly reduced JH and 20E content and inhibited the transcription of Kr-h1 and USP. These results indicate that JH and 20E facilitate adult reproduction through the methoprene-tolerant gene and ecdysone receptor gene in female S. frugiperda.

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), which is native to tropical Africa, has invaded more than 100 countries and constitutes a risk to the citrus sector. Studying its potential geographical distribution (PGD) in the context of global climate change is important for prevention and control efforts worldwide. Therefore, we used the CLIMEX model to project and assess the risk of global invasion by C. capitata under current (1981–2010) and future (2040–2059) climates. In the prevailing climatic conditions, the area of PGD for C. capitata was approximately 664.8 × 10⁵ km² and was concentrated in South America, southern Africa, southern North America, eastern Asia, and southern Europe. Under future climate conditions, the area of PGD for C. capitata is projected to decrease to approximately 544.1 × 10⁵ km² and shift to higher latitudes. Cold stress was shown to affect distribution at high latitudes, and heat stress was the main factor affecting distribution under current and future climates. According to the predicted results, countries with highly suitable habitats for C. capitata that have not yet been invaded, such as China, Myanmar, and Vietnam, must strengthen quarantine measures to prevent the introduction of this pest.