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Liparis gigantea generally grows in subtropical broad-leaved evergreen forests and blooms during the rainy season with purple flowers. Our study focused on floral phenology and morphology, pollinators and their behavior, and pollination mechanism. Our observations showed that the population flowering period lasted for about 20 days, and the single flowering period was 5–6 days. The rate of artificial self-pollination was 100%, which indicated that L. gigantea was self-compatible. L. gigantea achieved reproduction success by attracting Mycomya sp. (Diptera, Mycetophilidae). There was no significant difference between pollination efficiency both at night and during the day (Premoval = 0.34, Pdeposition = 0.55). Data on the functional morphological characteristics of L. gigantea and the pollinators related to pollination showed a high match, with the height and width of the pollination tunnel were 3.10 ± 0.34 and 1.93 ± 0.22 mm, and the height and width of the pollinator's thorax were 5.84 ± 0.96 and 0.96 ± 0.23 mm. The forefoot of insects could be stretched and bent when visiting flowers, so that they could exactly enter and exit the flower with removing or depositing pollinia. While L. gigantea could be pollinated by Mycomya sp., it could also be self-pollinated with the aid of rain. With the assistance of raindrops, the pollinia of L. gigantea slowly slid to the stigma. And this rain-assisted self-pollination mechanism guaranteed the success of reproduction in L. gigantea, especially in the special habitat and flowering season. The results of our study indicated that L. gigantea had a complex pollination reproduction system for insect and rain pollination. [ABSTRACT FROM AUTHOR]

Distinct lineages of the grasshopper Chorthippus parallelus (Orthoptera: Acrididae) form well‐known hybrid zones (HZs) both in the Pyrenees and the Alps mountain ranges in South Europe. These HZs represent unique experimental systems to identify “key genes” that maintain genetic boundaries between emerging species. The Iberian endemism C. p. erythropus (Cpe) and the subspecies C. p. parallelus (Cpp), widely distributed throughout the rest of Europe, overlap and form the Pyrenean HZ. Both subspecies differ morphologically, as well as in behavioral, mitochondrial, nuclear, and chromosomal traits, and in the strains of the maternally transmitted bacterial endosymbiont Wolbachia infecting them. This results in either unidirectional and bidirectional cytoplasmic incompatibility between both grasshopper subspecies, pointing out that Wolbachia clearly affects gene expression in the infected individuals. Here we explore how Wolbachia may modify the expression of some major genes involved in relevant pathways in Cpp in the Pyrenean HZ. We have analyzed, through molecular biomarkers, the physiological responses in C. parallelus individuals infected by Wolbachia, with particular attention to the energy metabolism, the immune system response, and the reproduction. qPCR was used to evaluate the expression of selected genes in the gonads of infected and uninfected adults of both sexes, since this tissue constitutes the main target of Wolbachia infection. Transcriptional analyses also showed differential sex‐dependent responses in most of the analyzed biomarkers in infected and noninfected individuals. We identified for the first time new sensitive biomarkers that might be involved in the reproductive barrier induced by Wolbachia in the hybrid zone. [ABSTRACT FROM AUTHOR]

Lipids perform a diverse and unique array of functions in insects. Lipases are key enzymes in lipid metabolism, and their metabolic products are crucial for development and reproduction of insects. Here, a total of 110 lipase genes were identified in the genome of Spodoptera frugiperda. Cluster analysis indicated that neutral lipases constitute the majority of lipases. Tissue expression profile analysis displayed that most lipase genes were highly expressed in the larval gut of S. frugiperda. Some lipases exhibited a diet‐specific expression pattern, which implied their roles in host adaptation. Key domain analysis proved that none of the neutral lipases highly expressed in the gut has an integrated lid domain, while most lipases highly expressed in the fat body contained both the integrated lid domain and β9 loop, indicating the activity loss of neutral lipases in guts. The assay of triacylglycerol (TAG) hydrolytic activity confirmed that the gut had the lowest activity when compared to that of fat body and epidermis. Interestingly, the opposite TAG hydrolytic activity trends across mating were observed between adult males and females, implying that lipase played different roles in the reproduction of both sexes. In conclusion, neutral lipases lost TAG hydrolytic activity in S. frugiperda guts, but retained the activity in fat body. Neutral lipases would play vital roles in many physiological processes in insects, especially in insect reproduction, which provides palpable targets for novel insecticide development to control insect population growth. [ABSTRACT FROM AUTHOR]

Melanin plays a pivotal role in insect body pigmentation, significantly contributing to their adaptation to diverse biotic and abiotic environmental challenges. Several genes involved in insect melanin synthesis showed pleiotropic effects on insect development and reproduction. Among these, the N‐β‐alanyl dopamine synthetase gene (Ebony) is integral to the pigmentation process. However, the full spectrum of its pleiotropic impacts is not yet thoroughly understood. In this study, we identified and characterised the HaEbony gene in the Asian multi‐coloured ladybird beetle (Harmonia axyridis) and found that HaEbony gene is a conserved gene within the Coleoptera order. We aimed to further explore the multiple roles of HaEbony in the physiology and behaviour in H. axyridis. The CRISPR/Cas9 system was applied to generate multiple HaEbony knockout allele (HaEbony+/−), showing nucleotide deletion in the G0 and G1 generations. Remarkably, the resultant HaEbony+/− mutants consistently displayed darker pigmentation than their wild‐type counterparts across larval, pupal and adult stages. Furthermore, these HaEbony+/− individuals (G0) demonstrated an enhanced predatory efficiency, evidenced by a higher number of aphids consumed compared to the wild type. A significant finding was the reduced egg hatchability in both G0 and G1 generations of the HaEbony+/− group, highlighting a potential reproductive fitness cost associated with HaEbony deficiency. In conclusion, our study not only sheds light on the multifaceted roles of HaEbony in H. axyridis but also highlights the potential of employing CRISPR/Cas9‐targeted modifications of the Ebony gene. Such genetic interventions could enhance the environmental adaptability and predatory efficacy of ladybirds, presenting a novel strategy in biological control application. [ABSTRACT FROM AUTHOR]

In evolutionary terms, plastic traits can covary, providing adaptive value by compensating for certain characteristic costs or enhancing fitness. This combination of traits is expected in species with significant intrapopulation ecological variation, like insects. In the Phanaeini tribe, males and females have distinct nesting behaviors, and the alpha, beta, and gamma morphotypes of trimorphic males display different reproductive strategies. Although phenotypic integration of wings and protibiae associated with horn size occurs in dung beetles, this study focuses on the morphological and functional variation of these and other structures due to behavioral differences and reproductive strategies between sexes and male morphotypes. We used a geometric and functional morphometric approach to investigate the variation in plasticity of structures (clypeus, protibia, elytra, and membranous wing), their integration with horn size in males, and flight biomechanics in the trimorphic dung beetle Oxysternon palemo (Scarabaeinae: Phanaeini). Comparing different sexes and morphotypes, we tested for significant differences associated with various reproductive and behavioral strategies. Adaptive morphological differences were found in all structures in at least three of the four groups (females and alpha, beta, and gamma males), along with clear sexual dimorphism in the protibia. In alpha males, fossorial structures enhance resource partitioning and confrontations, whereas in females and gamma males, these structures optimize digging and tunnel mobility. We also found integration between the size of pronotal horns and clypeus shape, and between head horn size and wing shape. The variation in elytra morphology, covariation between membranous wings and horns, and flight biomechanics results suggests different reproductive investment and foraging strategies among groups. Alpha and beta males invest in intense flights and rapid resource colonization, whereas gamma males exhibit slower, low‐energy flights with greater reproductive investment. We discuss how trade‐offs between dispersal and reproduction in polyphenic insects shape adaptive variation through plasticity in dung beetle morphotypes. [ABSTRACT FROM AUTHOR]

Simple Summary: Ground beetle (Carabidae) spermatozoa are often aggregated in bundles of different sizes and are covered by a secretory material produced by the deferent duct epithelium. These secretions can have different shapes being either similar to a cap or to a rod (spermatostyle). Through a detailed study of the different regions of the male reproductive systems, we were able to describe the origin of this protective structure. We have obtained evidence that the secretions from the duct epithelium have initially an irregular shape, with the spermatozoa present in the duct lumen adhering to the structure with their heads on one side only. Later on, along their maturation, these structures bend, taking a cap shape. Hence, this process of secretion and successive evolution of the structures is very similar to that occurring in the spermatostyles. In conclusion, we obtained clear evidence that the two models of the sperm bundle protection share the same origin and thus they can be considered as homologous. The males of Carabus lefebvrei produce sperm bundles of quite variable size as a consequence of a sexual selection via sperm competition. The ultrastructural features of spermatogenesis of the species and the sequence of events leading to sperm bundle formation along the deferent duct lumen revealed the origin and evolution of the apical structure protecting the sperm bundles. Elongated layers of the electron-dense material of variable size and thickness are visible over the microvilli of the distal deferent duct epithelium. They likely correspond to sections through different levels of discoidal secretions. Then, the sperm present in the duct lumen attach to one side of such elongated secreted structures. Later on, these structures bent to take a cap shape and increase their size and thickness by apposition of additional secretions produced by the proximal deferent duct epithelium. These results reconcile the different opinions about the formation of the structures called the cap and the rod (spermatostyle). In our work, we in fact obtained evidence that both these structures have the same origin, even though at the end of their formation they exhibit a different appearance. The reported results indicate that, differently from the spermatostyle, in the initial stages of cap formation, the sperm adhere only to one side of the cap rather than around the whole structure, as it occurs instead along the spermatostyle rod. Under this aspect, the cap structure is similar to the protection present in the sperm of some whirligig beetle. [ABSTRACT FROM AUTHOR]

Climate change is increasing mean temperatures, and intensifying heatwaves. Natural populations may respond to stress through shorter-term acclimation via plasticity and/or longer-term inter-generational evolution. However, if the pace and/or extent of thermal change is too great, local extinctions occur; one potential cause in ectotherms is identified to be the heat-liability of male reproductive biology. Recent data from several species, including the beetle Tribolium castaneum , confirmed that male reproductive biology is vulnerable to heatwaves, which may constrain populations. However, such reproductive-damage may be overestimated, if there is potential to adapt to elevated mean temperatures associated with climate change via evolution and/or acclimation. Here, we tested this to evaluate whether pre-exposures could improve heatwave tolerance (adaptation or acclimation), by experimentally evolving Tribolium castaneum populations to divergent thermal regimes (30 °C vs. 38 °C). Findings across assays revealed that relative to 30 °C-regime males, males from the 38 °C regime, maintained constantly at 8 °C warmer for 25 generations, displayed an increase; (i) in post heatwave (42 °C) reproductive fitness by 55%, (ii) survival by 33%, and (iii) 32% larger testes volumes. Unexpectedly, in the acclimation assay, warm-adapted males' post-heatwave survival and reproduction were best if they experienced cool developmental acclimation beforehand, suggesting a cost to adapting to 38 °C. These results help progress knowledge of the potential for survival and reproduction to adapt to climate change; trait specific adaptation to divergent thermal regimes can occur over relatively few generations, but this capacity depended on the interaction of evolutionary and thermal acclimatory processes. [ABSTRACT FROM AUTHOR]

Ecdysteroids are major hormones in insects and control molting, growth, reproduction, physiology, and behavior. The biosynthesis of ecdysteroids such as 20-hydroxyecdysone (20E) from dietary sterols is well characterized, but ecdysteroid catabolism is poorly understood. Ecdysteroid kinases (EcKs) mediate the reversible phosphorylation of ecdysteroids, which has been implicated in ecdysteroid recycling during embryogenesis and reproduction in various insects. However, to date, only 2 EcK-encoding genes have been identified, in the silkworm Bombyx mori and the mosquito Anopheles gambiae. Previously, we identified 2 ecdysteroid kinase-like (EcKL) genes— Wallflower (Wall) and Pinkman (pkm)—in the model fruit fly Drosophila melanogaster that are orthologs of the ecdysteroid 22-kinase gene BmEc22K. Here, using gene knockdown, knockout, and misexpression, we explore Wall and pkm 's possible functions and genetically test the hypothesis that they encode EcKs. Wall and pkm null mutants are viable and fertile, suggesting that they are not essential for development or reproduction, whereas phenotypes arising from RNAi and somatic CRISPR appear to derive from off-target effects or other artifacts. However, misexpression of Wall results in dramatic phenotypes, including developmental arrest, and defects in trachea, cuticle, and pigmentation. Wall misexpression fails to phenocopy irreversible ecdysteroid catabolism through misexpression of Cyp18a1 , suggesting that Wall does not directly inactivate 20E. Additionally, Wall misexpression phenotypes are not attenuated in Cyp18a1 mutants, strongly suggesting that Wall is not an ecdysteroid 26-kinase. We hypothesize that the substrate of Wall in this misexpression experiment and possibly generally is an unknown, atypical ecdysteroid that plays essential roles in Drosophila development, and may highlight aspects of insect endocrinology that are as-yet uncharacterized. We also provide preliminary evidence that CG5644 encodes an ecdysteroid 22-kinase conserved across Diptera. [ABSTRACT FROM AUTHOR]

Several European and North American countries have started releasing the Japanese knotweed psyllid, Aphalara itadori (Shinji) (Hemiptera: Aphalaridae), to control the Japanese knotweed, Reynoutria japonica Houtt. (Polygonaceae), and its relatives, which are among the worst invasive exotic plants. However, establishing populations of the currently released strains in the field has not been successful, desiring newly collected lineages. Moreover, little is known about the microbiome of the current strains, which potentially impacts properties as biocontrol agents. Hence, this study analyzed the microbiota of an A. itadori strain newly collected on Honshu Island, Japan, along with related species of the family Aphalaridae, using amplicon sequencing of 16S rRNA genes. The localization of symbionts identified in A. itadori was further analyzed using fluorescence in situ hybridization. The results demonstrated that the A. itadori bacteriome, a specialized organ for microbial symbiosis, maintains a dual symbiotic system with the primary symbiont "Candidatus Carsonella ruddii" (Gammaproteobacteria: Oceanospirillales: Halomonadaceae) and the secondary symbiont Sodalis sp. (Gammaproteobacteria: Enterobacterales: Pectobacteriaceae), suggesting that they are evolutionarily stable obligate mutualists for A. itadori. The central area of the bacteriome containing Sodalis comprised uninucleate bacteriocytes with nuclei larger than those of bacteriocytes harboring Carsonella. This observation contrasted previous reports on various psyllid lineages in which secondary symbionts are housed in a central syncytium with nuclei smaller than those of bacteriocytes for Carsonella. No known plant pathogens or parasitic manipulators of insect reproduction were identified in the analyzed A. itadori strain, indicating its suitability as a biocontrol agent, posing a minimum risk to the ecosystem. Besides distinct Carsonella lineages, Sodalis independently acquired by Craspedolepta miyatakeai Klimaszewski and an ambiguous Enterobacterales symbiont in Epheloscyta kalopanacis Loginova were identified. Only Carsonella was found in Togepsylla matsumurana Kuwayama. These results indicate repeated infections and replacements of bacterial symbionts during the evolution of Psylloidea, providing deeper insights into the microbe‐psyllid interactions. [ABSTRACT FROM AUTHOR]

Ecdysone-induced protein 93 (E93), known as the 'adult-specifier' transcription factor in insects, triggers metamorphosis in both hemimetabolous and holometabolous insects. Although E93 is conserved in ametabolous insects, its spatiotemporal expression and physiological function remain poorly understood. In this study, we first discover that, in the ametabolous firebrat Thermobia domestica, the previtellogenic ovary exhibits cyclically high E93 expression, and E93 mRNA is broadly distributed in previtellogenic ovarioles. E93 homozygous mutant females of T. domestica exhibit severe fecundity deficiency due to impaired previtellogenic development of the ovarian follicles, likely because E93 induces the expression of genes involved in ECM (extracellular matrix)-receptor interactions during previtellogenesis. Moreover, we reveal that in the hemimetabolous cockroach Blattella germanica, E93 similarly promotes previtellogenic ovarian development. In addition, E93 is also essential for vitellogenesis that is necessary to guarantee ovarian maturation and promotes the vitellogenesis-previtellogenesis switch in the fat body of adult female cockroaches. Our findings deepen the understanding of the roles of E93 in controlling reproduction in insects, and of E93 expression and functional evolution, which are proposed to have made crucial contributions to the origin of insect metamorphosis. [ABSTRACT FROM AUTHOR]

Insulin‐like peptides (ILPs) act as crucial reproductive neuropeptides in insects, regulating insect reproduction through the insulin signaling pathway (ISP). Our previous studies have found that the sublethal concentrations (LC1 and LC10) of lambda‐cyhalothrin (λCy) could induce severe reproductive toxicity in the lacewing, Chrysoperla sinica (Tjeder), but the toxicological mechanism remains unclear. This study discovered that λCy could inhibit CsILP transcription, leading to a decrease in insulin content and downregulation of C. sinica insulin receptor (CsInR) and C. sinica forkhead box O (CsFOXO) expression in ISP. Interference with CsILP expression resulted in downregulation of C. sinica vitellogenin (CsVg) and decreasing fecundity, while exogenous injection of bovine insulin promoted upregulation of CsVg expression and facilitated reproduction in female adults of C. sinica. Meanwhile, interference with FOXO of ILP downstream transcription factor could lead to downregulation of CsVg, hindering ovarian development and resulting in a decrease in egg production. However, exogenous injection of bovine insulin could remedy the effects caused by FOXO interference. In addition, ILP mediates juvenile hormone and 20‐hydroxyecdysone biosynthesis by acting on their synthetic regulatory enzymes and influences the signal transduction of the 2 reproductive endocrine hormones, thereby regulating the reproductive endocrine environment in C. sinica. In conclusion, λCy inhibits CsILP expression, leading to disorder of ISP, leading to the reduced fecundity of C. sinica. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

BACKGROUND: Wolbachia are widespread intracellular bacteria in insects that often have high rates of spread due to their impact on insect reproduction. These bacteria may also affect the mating behavior of their host with impacts on the fitness of host progeny. In this study, we investigated the impact of Wolbachia on a preference for mating with young or old males in the parasitoid wasp Habrobracon hebetor. RESULTS: Our results showed that uninfected females from a tetracycline‐treated line preferred to mate with young males, whereas Wolbachia‐infected females had no preference. Time to mating was relatively shorter in the infected lines. Regardless of Wolbachia infection status, progeny resulting from matings with young males showed higher fitness than those from crosses with old males, and infected females crossed with infected young males showed the highest performance. CONCLUSION: These results suggest an impact of Wolbachia on female mate preference and offspring fitness although it is unclear how this phenomenon increases Wolbachia transmission of infected wasps. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Dicer1 plays a crucial role in regulating the development and reproduction of insects. Knockout of Dicer1 causes pupal deformity, low eclosion and low fecundity in Plutella xylostella, but the mechanism behind this phenomenon is not clear. This study aims to identify differentially‐expressed genes and miRNAs in the Dicer1‐knockout strain (ΔPxDcr‐1) and assess their impact on the reproduction and development of P. xylostella. RESULTS: The knockout of Dicer1 affected the expression of genes including the adipokinetic hormone/corazonin‐related peptide receptor (PxACPR). The expression of PxACPR was upregulated, and the expression of miR‐8514‐5p was downregulated in ΔPxDcr‐1 of P. xylostella. The dual luciferase reporter assay and pull‐down assay showed that miR‐8514‐5p bound to PxACPR in vitro and in vivo. The expression profiles demonstrated a negative correlation between PxACPR mRNA and miR‐8514‐5p in different developmental stages of the wild‐type strain. Both the miR‐8514‐5p agomir and double‐stranded RNA of ACPR (dsPxACPR) injected into the pre‐pupae inhibited the mRNA level of PxACPR, causing high mortality and deformity of pupae, and low fecundity and hatching rate, which were consistent with the phenotype of ΔPxDcr‐1. The injection of miR‐8514‐5p antagomir caused a similar phenotype to the injection of miR‐8514‐5p agomir. Additionally, the injection of miR‐8514‐5p antagomir significantly rescued the phenotype caused by dsPxACPR. CONCLUSION: These results indicate that miR‐8514‐5p affects the development and reproduction of P. xylostella by regulating PxACPR, and the homeostasis of PxACPR expression is essential for the development and reproduction of P. xylostella. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

In addition to preventing precocious larval metamorphosis, juvenile hormone (JH), synthesized in corpora allata (CA), is known to stimulate female reproduction of insects. JH titer is extremely low or absent during metamorphosis, but thereafter rapidly increases in the previtellogenic stage and rises to a peak in the vitellogenic phase. However, the mechanisms underlying the biosynthesis of high levels of JH in adults remain unclear. We found in this study that 12 genes involved in JH synthesis pathway were highly expressed in the CA of adult locusts. By transcriptome analysis and quantitative real‐time – polymerase chain reaction validation, a total of 106 evolutionary conserved micro RNAs (miRNAs) and 163 species‐specific miRNAs were identified in locust CA. Dual‐luciferase assay revealed that 17 miRNAs bound to 10 JH synthesis genes (JHSGs) and downregulated their expression. These miRNAs were expressed in low levels during vitellogenic stage, which was oppositive from that of targeting JHSGs. Six miRNAs including miR‐971‐3p, miR‐31a, miR‐9‐5p, miR‐1‐3p, miR‐315, and miR‐282 were selected for function study. Co‐application of agomiRs resulted in significantly decreased levels of targeting JHSGs, accompanied by significantly reduced vitellogenin expression as well as arrested ovarian development. The data suggest that multiple miRNAs expressed synchronously at low levels in the vitellogenic phase, thereby ensuring the high levels of JHSG expression to facilitate JH biosynthesis required for JH‐dependent female reproduction. The findings provide important information for deciphering miRNA—messenger RNA modules for JH biosynthesis as well as JH regulation of insect metamorphosis and reproduction. [ABSTRACT FROM AUTHOR]

Background: The Endosomal Sorting Complex Required for Transport (ESCRT) is a highly conserved cellular machinery essential for many cellular functions, including transmembrane protein sorting, endosomal trafficking, and membrane scission. CHMP4B is a key component of ESCRT‐III subcomplex and has been thoroughly studied in the meroistic ovaries of Drosophila melanogaster showing its relevance in maintaining this reproductive organ during the life of the fly. However, the role of the CHMP4B in the most basal panoistic ovaries remains elusive. Results: Using RNAi, we examined the function of CHMP4B in the ovary of Blattella germanica in two different physiological stages: in last instar nymphs, with proliferative follicular cells, and in vitellogenic adults when follicular cells enter in polyploidy and endoreplication. In Chmp4b‐depleted specimens, the actin fibers change their distribution, appearing accumulated in the basal pole of the follicular cells, resulting in an excess of actin bundles that surround the basal ovarian follicle and modifying their shape. Depletion of Chmp4b also determines an actin accumulation in follicular cell membranes, resulting in different cell morphologies and sizes. In the end, these changes disrupt the opening of intercellular spaces between the follicular cells (patency) impeding the incorporation of yolk proteins to the growing oocyte and resulting in female sterility. In addition, the nuclei of follicular cells appeared unusually elongated, suggesting an incomplete karyokinesis. Conclusions: These results proved CHMP4B essential in preserving the proper expression of cytoskeleton proteins vital for basal ovarian follicle growth and maturation and for yolk protein incorporation. Moreover, the correct distribution of actin fibers in the basal ovarian follicle emerged as a critical factor for the successful completion of ovulation and oviposition. Significance: The overall results, obtained in two different proliferative stages, suggest that the requirement of CHMP4B in B. germanica follicular epithelium is not related to the proliferative stage of the tissue. [ABSTRACT FROM AUTHOR]

Introduction: Parasites can facilitate their own spread and reproduction by manipulating insect hosts behavior, as seen in the interaction between Thitarodes xiaojinensis and Ophiocordyceps sinensis. Infection by O. sinensis leads to the mummification of T. xiaojinensis larvae, but the underlying mechanisms remain mysterious. Methods: The morphology of O. sinensis infected larvae and fungal growth were first observed. Subsequently, the metabolite changes in the larvae before and after infection with the fungus were analyzed by LC/MS and targeted metabolomics. The expression of mannitol-related genes was detected using RT-qPCR, and morphological changes in larvae were observed after injection of different concentrations of mannitol into the O. sinensis-infected larvae. Results: Significant changes were found in phenotype, fungal morphology in hemocoel, larval hardness, and mannitol metabolites in infected, mummified 0 h larvae and larvae 5 days after mummification behavior. Surprisingly, the occurrence of mummification behavior was accompanied by fungal dimorphism, as well as the absence of mannitol in both infected and non-infected larvae, until the initial accumulation of mannitol and the expression of mannitol-associated genes occurred at the time ofmummification behavior. The presence of mannitol may promote fungal dimorphism to mediate changes in fungal toxicity or resistance, leading to the end of the fungus-insect coexistence period and the incidence of mummification behavior. Furthermore, mannitol injections increase the mummification rate of the infected larvae without significant difference from the normal mummification phenotype. Discussion: This finding suggests the importance of mannitol in the mummification of host larvae infected with O. sinensis. [ABSTRACT FROM AUTHOR]

Background: The genus Ichthyurus Westwood, 1848 is a large cantharid group consisting of approximately 200 species worldwide, with only 10 species hitherto found in China. Despite its expansive area, the Chinese fauna has historically received little attention from specialists, leading to a lack of knowledge even about some common Ichthyurus species in this region. New information: A new species of Ichthyurus Westwood, 1848 is described under the name of I. longulus sp. nov., which is widely distributed in mainland China, including Shannxi, Gansu, Hubei, Chongqing, Guizhou and Guangxi. Although there are some variations in the pronotum colouration within the species, this new species could be easily distinguished from all others of Ichthyurus by the large-sized body, uniformly black elytra, mesotibiae each with an apical spur in male, terminal abdominal tergite of male with long and cylindrical lateral projections that are about 3/5 the length of the tergite, terminal abdominal ventrite of male saddle-shaped and deeply cleft in middle of apical 2/3 part and aedeagus with a long setifore extension that is as long as the parameres. The habitus, terminal abdominal ventrite and tergites and genitalia of both sexes are illustrated. In addition, a distribution map of this species and a list of the Ichthyurus species from mainland China are provided. [ABSTRACT FROM AUTHOR]

Flight muscle histolysis is a widespread strategy used by insects to break down functional flight muscle and modulate the energetic costs associated with flight muscle use and maintenance. The variable field cricket, Gryllus lineaticeps , undergoes histolysis during their transition between dispersal flight and reproduction. Despite the importance of histolysis on insect reproduction and fitness, the molecular mechanisms driving this flight muscle breakdown are not well understood. Here, we show that beclin -mediated autophagy, a conserved lysosomal-dependent degradation process, drives breakdown of dorsal longitudinal flight muscle in female flight-capable G. lineaticeps. We found that female G. lineaticeps activate autophagy in their dorsal longitudinal flight muscle (DLM), but to a greater extent than the neighboring dorsoventral flight muscle (DVM) during histolysis. RNA interference knockdown of beclin , a gene that encodes a critical autophagy initiation protein, delayed DLM histolysis, but did not affect DVM histolysis. This suggests that crickets selectively activate autophagy to break down the DLMs, while maintaining DVM function for other fitness-relevant activities such as walking. Overall, we confirmed that autophagy is a critical pathway used to remodel flight muscle cells during flight muscle histolysis, providing novel insights into the mechanisms underlying a major life history transition between dispersal and reproduction. [ABSTRACT FROM AUTHOR]

Ultraviolet radiation (UVR) has positive and negative impacts on organisms and affects entire ecosystems. It is currently receiving attention because of the interactions of UVR with changes in climate that are likely to affect agriculture and food security.A review is provided on the effects of different types of UVR on the survival, development and reproduction of insects, collembolans and mites. The foci are on how UVR is used in pest control and how it affects arthropod coloration and distribution.Direct exposure to UV‐A, UV‐B and UV‐C delays development and reduces survival and host‐seeking ability of arthropods; immature stages are more sensitive than the adults. Increased exposure of crops to UVR has indirect effects on herbivory, and regions with high UVR levels may permit crop production in the absence of certain pest insect species.The Bunsen‐Roscoe law of reciprocity was upheld for Diaphorina citri and Tetranychus urticae under the range of irradiances and durations of exposure used in two studies, which showed that, for a constant dose, the effects of low irradiances of long durations were equivalent to those of higher irradiances of shorter durations.DNA damage caused by UV‐C and UV‐B can be repaired by photoreactivation; both white light and UV‐A are effective. [ABSTRACT FROM AUTHOR]

Exportin 1 (XPO1) is the major karyopherin‐β nuclear receptor mediating the nuclear export of hundreds of proteins and some classes of RNA and regulates several critical processes in the cell, including cell‐cycle progression, transcription and translation. Viruses have co‐opted XPO1 to promote nucleocytoplasmic transport of viral proteins and RNA. Maize mosaic virus (MMV) is a plant‐infecting rhabdovirus transmitted in a circulative propagative manner by the corn planthopper, Peregrinus maidis. MMV replicates in the nucleus of plant and insect hosts, and it remains unknown whether MMV co‐opts P. maidis XPO1 (PmXPO1) to complete its life cycle. Because XPO1 plays multiple regulatory roles in cell functions and virus infection, we hypothesized that RNAi‐mediated silencing of XPO1 would negatively affect MMV accumulation and insect physiology. Although PmXPO1 expression was not modulated during MMV infection, PmXPO1 knockdown negatively affected MMV accumulation in P. maidis at 12 and 15 days after microinjection. Likewise, PmXPO1 knockdown negatively affected P. maidis survival and reproduction. PmXPO1 exhibited tissue‐specific expression patterns with higher expression in the ovaries compared with the guts of adult females. Survival rate was significantly lower for PmXPO1 knockdown females, compared with controls, but no effect was observed for males. PmXPO1 knockdown experiments revealed a role for PmXPO1 in ovary function and egg production. Oviposition and egg hatch on plants were dramatically reduced in females treated with dsRNA PmXPO1. These results suggest that PmXPO1 is a positive regulator of P. maidis reproduction and that it plays a proviral role in the insect vector supporting MMV infection. [ABSTRACT FROM AUTHOR]

In insects, biogenic amines function as neurotransmitters, neuromodulators, and neurohormones, influencing various behaviors, including those related to reproduction such as response to sex pheromones, oogenesis, oviposition, courtship, and mating. Octopamine (OA), an analog of the vertebrate norepinephrine, is synthesized from the biogenic amine tyramine by the enzyme tyramine β-hydroxylase (TβH). Here, we investigate the mechanisms and target genes underlying the role of OA in successful reproduction in females of Rhodnius prolixus, a vector of Chagas disease, by downregulating TβH mRNA expression (thereby reducing OA content) using RNA interference (RNAi), and in vivo and ex vivo application of OA. Injection of females with dsTβH impairs successful reproduction at least in part, by decreasing the transcript expression of enzymes involved in juvenile hormone biosynthesis, the primary hormone for oogenesis in R. prolixus, thereby interfering with oogenesis, ovulation and oviposition. This study offers valuable insights into the involvement of OA for successful reproduction in R. prolixus females. Understanding the reproductive biology of R. prolixus is crucial in a medical context for controlling the spread of the disease. [ABSTRACT FROM AUTHOR]

Background: Accurate detection of pheromones is crucial for chemical communication and reproduction in insects. In holometabolous flies and moths, the sensory neuron membrane protein 1 (SNMP1) is essential for detecting long-chain aliphatic pheromones by olfactory neurons. However, its function in hemimetabolous insects and its role for detecting pheromones of a different chemical nature remain elusive. Therefore, we investigated the relevance of SNMP1 for pheromone detection in a hemimetabolous insect pest of considerable economic importance, the desert locust Schistocerca gregaria, which moreover employs the aromatic pheromone phenylacetonitrile (PAN) to govern reproductive behaviors. Results: Employing CRISPR/Cas-mediated gene editing, a mutant locust line lacking functional SNMP1 was established. In electroantennography experiments and single sensillum recordings, we found significantly decreased electrical responses to PAN in SNMP1-deficient (SNMP1−/−) locusts. Moreover, calcium imaging in the antennal lobe of the brain revealed a substantially reduced activation of projection neurons in SNMP1−/− individuals upon exposure to PAN, indicating that the diminished antennal responsiveness to PAN in mutants affects pheromone-evoked neuronal activity in the brain. Furthermore, in behavioral experiments, PAN-induced effects on pairing and mate choice were altered in SNMP1−/− locusts. Conclusions: Our findings emphasize the importance of SNMP1 for chemical communication in a hemimetabolous insect pest. Moreover, they show that SNMP1 plays a crucial role in pheromone detection that goes beyond long-chain aliphatic substances and includes aromatic compounds controlling reproductive behaviors. [ABSTRACT FROM AUTHOR]

Genetically engineered crop plants for enhanced emission of herbivore-induced plant volatiles (HIPVs) offer great potential in reducing the herbivore load on crops by repelling insect herbivores directly or attracting their natural enemies. Plant volatile organic compounds (VOCs) are also essential for pollination, insect reproduction, allelopathy, and serve as antimicrobial agents. Existing research in this field revolves around the routine chemical ecological experiments like identifying VOCs, HIPVs, and synthetic blends. Therefore, a deeper understanding of the role of enhanced volatile emissions and volatile biosynthetic pathways involved in chemical communication can lead to the development of behavior-based novel pest management strategies and lay the foundation for future research in these approaches. Recent discoveries in identifying and isolating the enzymes and genes associated with the biosynthetic pathways of volatiles have opened new avenues for the genetic engineering of crops. Genetically engineered plants could be developed to release volatiles only with an herbivore attack to conserve plant resources by mimicking a natural defensive strategy for direct repellence and/or recruitment of natural enemies. Crops engineered for sustainable volatile production can also serve as companion plants in the push and pull strategies and modify insect behavior to reduce the pest damage. A crop bioengineered for enhanced repellence of oviposition and increased release of insect pheromone-resembling compounds could benefit pest management programs. Further advanced research under field conditions is required to assess the physiological and ecological consequences, especially to the crop and the environment. [ABSTRACT FROM AUTHOR]

The silkworm is an economically important insect known for its unique silk production. Oviposition is an important aspect of insect reproduction which needs in-depth study. The aim of this study was to determine the effect of the mating period on the fecundity, egg fertility, and performance of bivoltine silkworm (Bombyx mori L). Adult males and females were allowed to mate for 1, 2, 3, 4, 5, and 6 hours respectively. The eggs laid by the mother moth were acid treated, incubated, and subsequent hatched larvae were reared following standard protocols. The treatments were replicated five times and placed in a completely randomized design. Data were collected on female fecundity, egg fertility, larval and pupal weights, larval survival, and cocoon parameters. Data were subjected to analysis of variance and means were separated using DMRT (P <0.05). The results showed that the number of eggs laid, larval weight, number of cocoons harvested, shell ratio, and effective rate of rearing were significantly higher in progeny whose parents were allowed to mate for one hour. The cocoon weight, pupal weight, and shell weight were highest in progeny whose parents were allowed to mate for five hours, but not significantly different from the ones of other mating durations. There was a negative linear relationship between mating duration and hatchability (r=-0.88) at P<0.05. The study conclusively established that mating duration of one hour in bivoltine silkworms is enough to produce the best larval and cocoon performance. Hence, one-hour mating duration can be recommended for silkworm producers in the sericulture industry. [ABSTRACT FROM AUTHOR]

Simple Summary: Spermatogenesis, which is regulated by many different genes, is a conserved process across species to produce mature sperm for animal reproduction. Fox transcription factors can bind to DNA sequences in the promoters to regulate gene expression. FoxD subfamily members are mainly involved in metabolism and early organ development. In Drosophila melanogaster, FoxD subfamily member Fd59a may regulate the development of the nervous system and control the egg-laying behavior of females. However, the functions of insect FoxD members are still largely unknown. In this study, we investigated the role of Fd59a in the spermatogenesis of Drosophila. We found that mutations in Fd59a caused swelling of the apical region in the testis, resulting in fewer mature sperm in the seminal vesicle and significantly lower fertility of Fd59a mutant males compared to the control flies. We also found that the homeostasis of the testis stem cell niche in Fd59a mutant and RNAi flies was disrupted, causing increased apoptosis of sperm bundles. RNA sequencing and qRT-PCR results suggested that Fd59a can regulate the expression of genes related to reproductive process and cell death. Our collective results indicated that Fd59a plays a key role in Drosophila spermatogenesis, which will help to understand the role of FoxD members in insect spermatogenesis. Spermatogenesis is critical for insect reproduction and is regulated by many different genes. In this study, we found that Forkhead transcription factor Fd59a functions as a key factor in the spermatogenesis of Drosophila melanogaster. Fd59a contains a conversed Forkhead domain, and it is clustered to the FoxD subfamily with other FoxD members from some insect and vertebrate species. Mutations in Fd59a caused swelling in the apical region of the testis. More importantly, fewer mature sperm were present in the seminal vesicle of Fd59a mutant flies compared to the control flies, and the fertility of Fd59a2/2 mutant males was significantly lower than that of the control flies. Immunofluorescence staining showed that the homeostasis of the testis stem cell niche in Fd59a2/2 mutant and Fd59a RNAi flies was disrupted and the apoptosis of sperm bundles was increased. Furthermore, results from RNA sequencing and qRT-PCR suggested that Fd59a can regulate the expression of genes related to reproductive process and cell death. Taken together, our results indicated that Fd59a plays a key role in the spermatogenesis of Drosophila. [ABSTRACT FROM AUTHOR]

BACKGROUND: Mating is an essential factor that governs the size of insect populations that reproduce sexually. The extensive application of insecticides has both lethal and sublethal effects on the physiology and mating behavior of insect natural enemies. The predatory bug Cyrtorhinus lividipennis is a natural enemy of planthopper and leafhopper populations in the rice ecosystem. Unfortunately, the effects of insecticides on the mating behavior of C. lividipennis are not well‐understood. RESULTS: The mating behavior of C. livdipennis consisted of mounting, antennal touch and mating attempts, genital insertion, adjustment of posture, and separation of the mating pair. Approximately 82.5% of the C. lividipennis mating pairs displayed their first mating at 12–36 h postemergence. Mating activity occurred throughout a 24‐h period, with peak activity at 12:00–14:00 h, and the mean duration of mating was 48.75 min. Sublethal exposure to imidacloprid increased mating latency. Compared with the controls, the duration of courtship, pre‐mating and adjusting posture for males treated with imidacloprid were prolonged. The duration of mating for females treated with imidacloprid was prolonged relative to untreated controls. The fecundity and daily spawning capacity of females treated with imidacloprid were higher than the untreated controls. CONCLUSION: Our results provide insight into the mating process of C. lividipennis. Imidacloprid prolonged the duration of mating, which may explain the enhanced reproductive output in C. lividipennis females treated with imidacloprid. These findings will be useful in both rearing C. lividipennis and deploying this natural enemy in rice fields. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Oogenesis is a complex pathway necessary for proper female reproduction in insects. Ovary‐serine protease (Osp) is a homologous gene of serine protease Nudel (SpNudel) and plays an essential role in the oogenesis and ovary development of Drosophila melanogaster. However, the function of Osp is not determined in Plutella xylostella, a highly destructive pest of cruciferous crops. RESULTS: The PxOsp gene comprises a 5883‐bp open‐reading frame that encodes a protein consisting of 1994 amino acids, which contain four conserved domains. PxOsp exhibited a high relative expression in adult females with a specific expression in the ovary. Through the utilization of CRISPR/Cas9 technology, homozygous mutants of PxOsp were generated. These homozygous mutant females produced fewer eggs (average of 56 eggs/female) than wild‐type (WT) females (average of 97 eggs/female) when crossed with WT males, and these eggs failed to hatch. Conversely, mutant males produced normal progeny when crossed with WT females. The ovarioles in homozygous mutant females were significantly shorter (5.02 mm in length) and contained fewer eggs (average of 3 eggs/ovariole) than WT ovarioles (8.09 mm in length with an average of 8 eggs/ovariole). Moreover, eggs laid by homozygous mutant females were fragile, with irregular shapes, and were unable to maintain structural integrity due to eggshell ruptures. However, no significant differences were observed between WT and mutant individuals regarding developmental duration, pupal weight, and mating behavior. CONCLUSION: Our study suggesteds that PxOsp plays a vital role in female reproduction, particularly in ovary and egg development. Disrupting PxOsp results in recessive female sterility while leaving the male reproductive capability unaffected. This report represents the first study of a haplosufficient gene responsible for female fertility in lepidopteran insects. Additionally, these findings emphasize PxOsp as a potential target for genetically‐based pest management of P. xylostella. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Biotremology, officially coined in 2016, has rapidly emerged as a distinct scientific discipline, focusing on the study of substrate‐borne mechanical waves in animal communication, particularly among insects. Initially seen as a niche within bioacoustics, biotremology is now recognized for its broad significance, rivalling chemical communication in its prevalence. This special issue highlights the multidisciplinary nature of biotremology, with research spanning insect behaviour, ecology and pest management. Studies showcase advances in understanding vibrational communication across diverse insect taxa, the development of new tools for reliable playback experiments and the growing potential of biotremology in applied pest control. This collection provides a snapshot of a dynamic field in rapid expansion, pushing the boundaries of both fundamental research and practical applications. [ABSTRACT FROM AUTHOR]

As natural landscapes are modified and converted into simplified agricultural landscapes, the community composition and interactions of organisms persisting in these modified landscapes are altered. While many studies examine the consequences of these changing interactions for crops, few have evaluated the effects on wild plants. Here, we examine how pollinator and herbivore interactions affect reproductive success for wild resident and phytometer plants at sites along a landscape gradient ranging from natural to highly simplified. We tested the direct and indirect effects of landscape composition on plant traits and reproduction mediated by insect interactions. For phytometer plants exposed to herbivores, we found that greater landscape complexity corresponded with elevated herbivore damage, which reduced total flower production but increased individual flower size. Though larger flowers increased pollination, the reduction in flowers ultimately reduced plant reproductive success. Herbivory was also higher in complex landscapes for resident plants, but overall damage was low and therefore did not have a cascading effect on floral display and reproduction. This work highlights that landscape composition directly affects patterns of herbivory with cascading effects on pollination and wild plant reproduction. Further, the absence of an effect on reproduction for resident plants suggests that they may be adapted to their local insect community. [ABSTRACT FROM AUTHOR]

Chironomidae (Diptera) are one of the most abundant aquatic insects in freshwater habitats and play key roles in aquatic ecosystems. Many studies have assessed chironomid longevity under varying conditions to estimate potential consequences of climate change on longevity. However, these studies did not account for behavioral changes that may affect the ability of chironomids to find a mate or return to the water for oviposition. Longevity estimates may therefore underestimate the effects of climate change on chironomids by neglecting behavior-related fitness losses. To better understand how chironomid behaviors relate to survivorship, we used previously identified behaviors to determine how behavior patterns changed as the chironomid Diamesa mendotae aged. We found that D. mendotae exhibited age-related behaviors that correlated with a decrease in mobility over time. Additionally, behaviors performed early post-collection in D. mendotae adult lifespans were predictive of total chironomid longevity. These findings will help improve estimates of chironomid longevity and our understanding of age-related behaviors in other invertebrates. Improved methods for determining longevity and age-specific fitness-linked behaviors will allow us to better understand climate change's impacts on aquatic insect survival and reproduction, which has broad ramifications for the aquatic ecosystems where they are abundant. [ABSTRACT FROM AUTHOR]

B chromosomes are intriguing "selfish" genetic elements, many of which exhibit higher-than-Mendelian transmission. This perspective highlights a group of B chromosomes known as Paternal Sex Ratio chromosomes (PSRs), which are found in several insects with haplo-diploid reproduction. PSRs harshly alter the organism's reproduction to facilitate their own inheritance. A manifestation of this effect is the conversion of female destined individuals into males. Key to this conversion is the mysterious ability of PSRs to cause elimination of the sperm-inherited half of the genome during zygote formation. Here we discuss how PSRs were discovered, what is known about how they alter paternal chromatin dynamics to cause sex conversion, and how PSR-induced genome elimination is different from other forms of programmed genome elimination in different insects. PSRs also stand out because their DNA sequence compositions differ in remarkable ways from their insect's essential chromosomes, a characteristic suggestive of interspecies origins. Broadly, we also highlight poorly understood aspects of PSR dynamics that need to be investigated. [ABSTRACT FROM AUTHOR]

Cockroaches, widespread pests found in metropolitan areas, are known as vectors of various disease agents, including viruses, fungi and antibiotic‐resistant bacteria, as well as causing allergies in humans. Insect growth regulators have been used in pest management for several decades. These insecticides disrupt insect development and reproduction. Chitin synthesis inhibitors interfere with chitin biosynthesis in insects, causing abortive moulting and mortality, as well as inhibiting egg fertility, and larval hatching in insects. In this research, we evaluated the various effects of diflubenzuron, a chitin synthesis inhibitor, on synthetic pyrethroid‐resistant German cockroach (Blattella germanica L. Blattodea: Ectobiidae), including ootheca production, oothecal viability, ootheca incubation time, the number of nymphs emerging from the ootheca and survivorship of nymphs. The cockroaches were fed diets that contained diflubenzuron, which was added to solid bait (impregnated fish food) and ingestible aqueous bait (impregnated cotton). Three concentrations (0.5%, 1% and 2%) were used in the experiments. As a result, diflubenzuron treatment led to ootheca production ranging from 60% to 100%; statistically, no difference was found between the treatment and the control groups. The number of nymphs emerging from the first and second ootheca was reduced by 40%–100% in the diflubenzuron‐treated groups compared with the control. Nymphs exposed to diflubenzuron‐impregnated solid bait and ingestible aqueous bait experienced mortality exceeding 92.1% and 66.27% within 15 days, respectively. In conclusion, diflubenzuron is a potential insecticide for use in cockroach baits to control B. germanica, as it caused high nymphal and embryonic mortality in the synthetic pyrethroid‐resistant population and decreased the number of nymphs emerging from the ootheca. [ABSTRACT FROM AUTHOR]

The effect of pesticides on insects is often discussed in terms of acute and chronic toxicity, but an important and often overlooked aspect is the impact of sublethal doses on insect physiology and behavior. Pesticides can influence various physiological parameters of insects, including the innate immune system, development, and reproduction, through a combination of direct effects on specific exposed tissues and the modification of behaviors that contribute to health and reproductive success. Such behaviors include mobility, feeding, oviposition, navigation, and the ability to detect pheromones. Pesticides also have a profound effect on insect learning and memory. The precise effects depend on many different factors, including the insect species, age, sex, caste, physiological condition, as well as the type and concentration of the active ingredients and the exposure route. More studies are needed to assess the effects of different active ingredients (and combinations thereof) on a wider range of species to understand how sublethal doses of pesticides can contribute to insect decline. This review reflects our current knowledge about sublethal effects of pesticides on insects and advancements in the development of innovative methods to detect them. [ABSTRACT FROM AUTHOR]

Temperature influences nearly all aspects of fitness. However, reproduction is often more thermally sensitive than survival. Thermoregulation must maintain performance in both components of fitness to buffer populations from environmental change.We assessed the fitness benefits of thermoregulation in Enchenopa binotata treehoppers. Under realistic mesocosm conditions, we quantified fine‐scale microclimates using 3D‐printed operative temperature models. We then compared operative temperatures to treehopper body temperatures and translated patterns of thermoregulation into variation in survival and reproduction. We also assessed two thermoregulatory mechanisms: precise microclimate choice and heat‐escape behaviours. Finally, we applied our results to evaluate if arthropod thermoregulation is accurately characterized by two theoretical models commonly used to simulate responses to environmental change.We found substantial thermal variation at fine spatial scales relevant to insects: at a single point in time, temperatures within 30‐cm‐tall plants spanned ranges up to 19°C (23–42°C).Lethal operative temperatures were common when air temperatures were high. However, heat escapes allowed treehoppers to almost entirely avoid lethal temperatures.By contrast, individuals thermoconformed in the absence of lethal operative temperatures. This finding suggests that precise microclimate choice imposes high costs due to thermal uncertainty at fine spatial scales. Furthermore, given the narrow range of temperatures in which reproduction occurs, thermoregulation is unlikely to maintain reproduction.Thermoregulation was most effective in the lowest‐quality and most spatially variable thermal habitats. Treehopper thermoregulation therefore more closely follows cost–benefit models of thermoregulation compared to models that account for inhibited movement at extreme temperatures.Overall, even if thermoregulation can prevent lethal heat stress, it may have limited capacity to buffer arthropods and other small ectotherms from environmental change if it cannot maintain reproductive performance. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

This article explores the use of social insects, like ants, bees, and wasps, as models for studying reproductive longevity. Social insect queens have long lifespans and high fertility, which challenges the typical trade-off between lifespan and reproduction. These insects provide valuable insights into the molecular and cellular mechanisms that allow for high fecundity and long lifespans. The article also discusses the plasticity of senescence and fertility in social insects and raises questions about the deviations from conventional aging theories. Further research in social insects could provide important insights into reproductive senescence and aging. Additionally, the article mentions the relevance of non-insect eusocial species, like mole rats, in bridging the gap between social insects and humans. Overall, social insects offer valuable perspectives and potential applications for studying reproductive longevity in diverse species. [Extracted from the article]

Recent developments within the IUCN and the Convention on Biological Diversity have affirmed the increasingly key role that effective population size (Ne) and the effective size: census size ratio (Ne/N) play in applied conservation and management of global biodiversity. This paper reviews and synthesizes information regarding the definition of Ne and demographic and genetic methods for estimating effective size, census size, and their ratio. Emphasis is on single‐generation estimates of contemporary Ne/N, which are the most informative for practical applications. It is crucial to clearly define which individuals are included in the census size (N). Defining N as the number of adults alive at a given time facilitates comparisons across species. For a wide range of applications and experimental designs, inbreeding Ne is simpler to calculate and interpret than variance Ne. Effects of skewed sex ratio are generally modest, so most reductions to Ne/N arise from overdispersed (greater‐than‐Poisson) variance in offspring number (σk2$$ {\sigma}_k^2 $$). Even when fecundity changes with age, overdispersed within‐age variance generally contributes most to overall σk2$$ {\sigma}_k^2 $$, and both random and deterministic (mediated by selection) factors can be important. Most species are age‐structured, so it is important to distinguish between effective size per generation (Ne) and the effective number of breeders in one season or year (Nb). Both Ne and Nb are important for applied conservation and management. For iteroparous species, a key metric is variance in lifetime reproductive success (σk•2$$ {\sigma}_{k\bullet}^2 $$), which can be affected by a variety of additional factors, including variation in longevity, skip or intermittent breeding, and persistent individual differences in reproductive success. Additional factors that can be important for some species are also discussed, including mating systems, population structure, sex reversal, reproductive compensation, captive propagation, and delayed maturity. [ABSTRACT FROM AUTHOR]

Lipid and sugar homeostasis is critical for insect development and survival. In this study, we characterized an acetyl coenzyme A carboxylase gene in Blattella germanica (BgACC) that is involved in both lipogenesis and sugar homeostasis. We found that BgACC was dominantly expressed in the fat body and integument, and was significantly upregulated after molting. Knockdown of BgACC in 5th‐instar nymphs did not affect their normal molting to the next nymphal stage, but it caused a lethal phenotype during adult emergence. BgACC‐RNA interference (RNAi) significantly downregulated total free fatty acid (FFA) and triacylglycerol (TAG) levels, and also caused a significant decrease of cuticular hydrocarbons (CHCs). Repression of BgACC in adult females affected the development of oocytes and resulted in sterile females, but BgACC‐RNAi did not affect the reproductive ability of males. Interestingly, knockdown of BgACC also changed the expression of insulin‐like peptide genes (BgILPs), which mimicked a physiological state of high sugar uptake. In addition, BgACC was upregulated when B. germanica were fed on a high sucrose diet, and repression of BgACC upregulated the expression of the glycogen synthase gene (BgGlyS). Moreover, BgACC‐RNAi increased the circulating sugar levels and glycogen storage, and a longevity assay suggested that BgACC was important for the survival of B. germanica under conditions of high sucrose uptake. Our results confirm that BgACC is involved in multiple lipid biogenesis and sugar homeostasis processes, which further modulates insect reproduction and sugar tolerance. This study benefits our understanding of the crosstalk between lipid and sugar metabolism. [ABSTRACT FROM AUTHOR]

The rice stripe virus (RSV) is transmitted by the small brown planthopper Laodelphax striatellus in a persistent and circulative–propagative manner. During the last few decades, RSV has caused serious disease outbreaks in rice fields in China. The results of long-term coevolution have led to complex and diverse relationships between viruses and vector insects, and understanding these interactions is critical for the management of diseases and vector organisms. In this study, three groups of comparative experiments were performed to investigate the effects of RSV infection on the reproductive parameters, vitellogenin (Vg), and Vg receptor (VgR) expressions of L. striatellus. The results showed that RSV infection promoted the fecundity, hatchability, and Vg and VgR expressions of L. striatellus but had no effect on the preoviposition period and oviposition period. Furthermore, the RNA interference of the nucleocapsid protein (CP) gene and the injection of the CP antibody in RSV-viruliferous L. striatellus reduced the fecundity, hatchability, and Vg and VgR expressions, further strengthening the hypothesis that RSV may manipulate the reproductive behavior of insect vectors to promote its own transmission. The results of this study can further reveal the interaction mechanism of virus–vector insects in reproduction and virus transmission, and provide new insights for the control of insect-borne viruses. [ABSTRACT FROM AUTHOR]

Simple Summary: The peach fruit moth, Carposina sasakii Matsumura, is a significant fruit-boring pest that negatively impacts the East Asian agricultural economy. To aid the development of pest control strategies, peach fruit moths are raised and studied for multiple generations in laboratory. It is important when maintaining a laboratory moth colony to consider the effects of nutrition on the colony's growth, survival, and reproduction. In this study, adult peach fruit moths (F0) were divided into separate groups, and each group was fed one of seven different nutrient solutions under laboratory conditions. The development and fitness of the moths' offspring (F1) were then analyzed. The results showed that F0 adult peach fruit moths fed with 10 grams per liter sucrose had F1 offspring with significantly higher fitness and reproductive parameters, suggesting that this concentration of sucrose is more suitable for raising laboratory peach fruit moths. Thus, appropriate nutrition during the adult stage of the peach fruit moth's life cycle could play an important role in the development of future offspring in laboratory studies and in turn influence the future of East Asian agriculture. Nutrients consumed during the adult stage are a key factor affecting the growth, development, and reproduction of insect offspring and thus could play an important role in insect population research. However, there is absence of conclusive evidence regarding the direct effects of parental (F0) nutritional status on offspring (F1) fitness in insects. Carposina sasakii Matsumura is a serious, widespread fruit-boring pest that negatively impacts orchards and the agricultural economy across East Asia. In this study, life history data of F1 directly descended from F0 C. sasakii fed with seven different nutrients (water as control, 5 g·L−1 honey solution, 10 g·L−1 honey solution, 5 g·L−1 sucrose solution, 10 g·L−1 sucrose solution, 15 g·L−1 sucrose solution, and 20 g·L−1 sucrose solution) were collected under laboratory conditions. The growth and development indices, age-stage specific survival rate, age-stage specific fecundity, age-stage specific life expectancy, age-stage specific reproductive value, and population parameters of these offspring were analyzed according to the age-stage, two-sex life table theory. The results showed that the nutritional status of F0 differentially affects the growth, development, and reproduction of F1. The F1 offspring of F0 adult C. sasakii fed with 10 g·L−1 sucrose had significantly higher life table parameters than those of other treatments (intrinsic rate of increase, r = 0.0615 ± 0.0076; finite rate of increase, λ = 1.0634 ± 0.0081; net reproductive rate, R0 = 12.61 ± 3.57); thus, 10 g·L−1 sucrose was more suitable for raising C. sasakii in the laboratory than other treatments. This study not only provides clear evidence for the implications of altering F0 nutritional conditions on the fitness of F1 in insects, but also lays the foundation for the implementation of feeding technologies within the context of a well-conceived laboratory rearing strategy for C. sasakii. [ABSTRACT FROM AUTHOR]

Simple Summary: Temperature is an important factor that affects the growth and reproduction of insects. The silkworm is an economically important insect, and as a representative insect of Lepidoptera, it is particularly important to investigate its extreme-temperature resistance mechanisms. In this article, we identified a gene in B. mori, the B. mori singed (Bmsn) gene, which is involved in the high-temperature resistance of silkworms. We demonstrated that the Bmsn gene can increase the proliferation activity of silkworm cells and enhance their tolerance to high temperatures. Furthermore, we constructed a transgenic B. mori strain that overexpressed the Bmsn gene and demonstrated that its overexpression can increase high-temperature resistance and improve the economic characteristics of silkworms. Temperature is an important factor in the growth, development, survival, and reproduction of organisms. The high-temperature resistance mechanism of insects may be significant for use in the prevention and control of insect pests. The silkworm, Bombyx mori, is an important Lepidoptera model species for studies on pest control in agriculture and forestry. We identified a gene in B. mori, the B. mori singed (Bmsn) gene, which is involved in the high-temperature resistance of silkworms. Sn proteins are highly conserved among species in many taxonomic groups. The overexpression of the Bmsn gene promoted the proliferation of silkworm cells, reduced oxidation, and reduced the accumulation of reactive oxygen species under stress. Interfering with the Bmsn gene had the opposite result. We constructed a transgenic B. mori strain that overexpressed the Bmsn gene. The physiological traits of the transgenic strain were significantly improved, and it had stronger high-temperature resistance. The Bmsn gene is involved in the process by which fat bodies respond to high-temperature stress. These findings provide insights into the mechanism of high-temperature resistance of insects and offer a new perspective on agricultural and forestry pest control. [ABSTRACT FROM AUTHOR]

Diaphorina citri serves as the primary vector for ‘Candidatus Liberibacter asiaticus (CLas),’ the bacterium associated with the severe Asian form of huanglongbing. CLas-positive D. citri are more fecund than their CLas-negative counterparts and require extra energy expenditure. Therefore, understanding the molecular mechanisms linking metabolism and reproduction is of particular importance. In this study, we found adipokinetic hormone (DcAKH) and its receptor (DcAKHR) were essential for increasing lipid metabolism and fecundity in response to CLas infection in D. citri. Knockdown of DcAKH and DcAKHR not only resulted in the accumulation of triacylglycerol and a decline of glycogen, but also significantly decreased fecundity and CLas titer in ovaries. Combined in vivo and in vitro experiments showed that miR-34 suppresses DcAKHR expression by binding to its 3’ untranslated region, whilst overexpression of miR-34 resulted in a decline of DcAKHR expression and CLas titer in ovaries and caused defects that mimicked DcAKHR knockdown phenotypes. Additionally, knockdown of DcAKH and DcAKHR significantly reduced juvenile hormone (JH) titer and JH signaling pathway genes in fat bodies and ovaries, including the JH receptor, methoprene-tolerant (DcMet), and the transcription factor, Krüppel homolog 1 (DcKr-h1), that acts downstream of it, as well as the egg development related genes vitellogenin 1-like (DcVg-1-like), vitellogenin A1-like (DcVg-A1-like) and the vitellogenin receptor (DcVgR). As a result, CLas hijacks AKH/AKHR-miR-34-JH signaling to improve D. citri lipid metabolism and fecundity, while simultaneously increasing the replication of CLas, suggesting a mutualistic interaction between CLas and D. citri ovaries.

The males of Carabus lefebvrei produce sperm bundles of quite variable size as a consequence of a sexual selection via sperm competition. The ultrastructural features of spermatogenesis of the species and the sequence of events leading to sperm bundle formation along the deferent duct lumen revealed the origin and evolution of the apical structure protecting the sperm bundles. Elongated layers of the electron-dense material of variable size and thickness are visible over the microvilli of the distal deferent duct epithelium. They likely correspond to sections through different levels of discoidal secretions. Then, the sperm present in the duct lumen attach to one side of such elongated secreted structures. Later on, these structures bent to take a cap shape and increase their size and thickness by apposition of additional secretions produced by the proximal deferent duct epithelium. These results reconcile the different opinions about the formation of the structures called the cap and the rod (spermatostyle). In our work, we in fact obtained evidence that both these structures have the same origin, even though at the end of their formation they exhibit a different appearance. The reported results indicate that, differently from the spermatostyle, in the initial stages of cap formation, the sperm adhere only to one side of the cap rather than around the whole structure, as it occurs instead along the spermatostyle rod. Under this aspect, the cap structure is similar to the protection present in the sperm of some whirligig beetle.

Bacteria have a profound influence on life history and reproduction of numerous insects, while the associations between hosts and bacteria are substantially influenced by environmental pressures. Cold storage is crucial for extending the shelf life of insects used as tools for biological control, but mostly causes detrimental effects. In this study, we observed a great decrease in egg hatch rate of cold-stored Harmonia axyridis during the later oviposition periods. Furthermore, most eggs produced by their F1 offspring exhibited complete loss of hatchability. We hypothesized that long-term exposure to cold may greatly alter the bacterial community within the reproductive tracts of H. axyridis, which may be an important factor contributing to the loss of egg viability. Through sequencing of the 16S rRNA gene, we discovered considerable changes in the bacterial structure within the reproductive tracts of female cold-stored beetles (LCS_F) compared to non-stored beetles (Control_F), with a notable increase in unclassified_f_Enterobacteriaceae in LCS_F. Furthermore, in accordance with the change of egg hatchability, we observed a slight variation in the microbial community of eggs produced by cold-stored beetles in early (Egg_E) and later (Egg_L) oviposition periods as well as in eggs produced by their F1 offspring (Egg_ F1). Functional predictions of the microbial communities revealed a significant decrease in the relative abundance of substance dependence pathway in LCS_F. Moreover, this pathway exhibited relatively lower abundance levels in both Egg_L and Egg_F1 compared to Egg_E. These findings validate that long-term cold storage can greatly modify the bacterial composition within H. axyridis, thereby expanding our understanding of the intricate bacteria-insect host interactions. [ABSTRACT FROM AUTHOR]

Background: Ecosystems are brimming with myriad compounds, including some at very low concentrations that are indispensable for insect survival and reproduction. Screening strategies for identifying active compounds are typically based on bioassay-guided approaches. Results: Here, we selected two candidate odorant receptors from a major pest of cruciferous plants—the diamondback moth Plutella xylostella—as targets to screen for active semiochemicals. One of these ORs, PxylOR16, exhibited a specific, sensitive response to heptanal, with both larvae and adult P. xylostella displaying heptanal avoidance behavior. Gene knockout studies based on CRISPR/Cas9 experimentally confirmed that PxylOR16 mediates this avoidance. Intriguingly, rather than being involved in P. xylostella–host plant interaction, we discovered that P. xylostella recognizes heptanal from the cuticular volatiles of the parasitoid wasp Cotesia vestalis, possibly to avoid parasitization. Conclusions: Our study thus showcases how the deorphanization of odorant receptors can drive discoveries about their complex functions in mediating insect survival. We also demonstrate that the use of odorant receptors as a screening platform could be efficient in identifying new behavioral regulators for application in pest management. [ABSTRACT FROM AUTHOR]

Simple Summary: Transmembrane emp24 domain (TMED) proteins serve as cellular "delivery workers", facilitating the transport and folding of specific proteins. TMED6, a member of the TMED protein γ subfamily, is highly expressed in various tissues in silkworms. In our study, we investigated expression in male and female tissues, as well as in pupal ovaries at different developmental stages. We observe that decreased TMED6 expression significantly reduces the number of eggs laid by female moths, leading to the accumulation of unlaid eggs in the abdomen. Furthermore, through in vivo and in vitro experiments in silkworms, we have discovered a close relationship between TMED6 and dopamine D2-like receptors (Dop2R). Dop2R plays a crucial role in neural signal transmission and can influence reproductive behavior in insects. BmTMED6 is closely associated with the dopamine receptor, suggesting its potential involvement in regulating the oviposition behavior of the moth through dopamine-related pathways. Our findings will have important implications for sericulture production in the future. Transmembrane emp24 domain (TMED) proteins have been extensively studied in mammalian embryonic development, immune regulation, and signal transduction. However, their role in insects, apart from Drosophila melanogaster, remains largely unexplored. Our previous study demonstrated the abundant expression of BmTMED6 across all stages and tissues of the silkworm. In this study, we investigate the function of BmTMED6 in reproduction. We observe significant differences in the expression of BmTMED6 between male and female silkworms, particularly in the head and fatboby, during the larval stage. Furthermore, qRT-PCR and WB analysis reveal substantial variation in BmTMED6 levels in the ovaries during pupal development, suggesting a potential association with silkworm female reproduction. We find that reducing TMED6 expression significantly decreases the number of eggs laid by female moths, leading to an accumulation of unlaid eggs in the abdomen. Moreover, downregulation of BmTMED6 leads to a decrease in the expression of BmDop2R1 and BmDop2R2, while overexpression of BmTMED6 in vitro has the opposite effect. These indicate that BmTMED6 plays a role in oviposition in female moths, potentially through the dopamine signaling pathway. This study provides a new regulatory mechanism for female reproduction in insects. [ABSTRACT FROM AUTHOR]

Premise: Understanding the factors that limit reproductive success is a key component of plant biology. Carnivorous plants rely on insects as both nutrient sources and pollinators, providing a unique system for studying the effects of both resource and pollen limitation on plant reproduction. Methods: We conducted a field experiment using wild‐growing Dionaea muscipula J. Ellis (Droseraceae) in which we manipulated prey and pollen in a factorial design and measured flower production, number of fruits, and number of seeds. Because understanding reproduction requires knowledge of a plant species' reproductive and pollination biology, we also examined the pollination system, per‐visit pollinator effectiveness, and pollen‐ovule (P/O) ratio of D. muscipula. Results: Plants that received supplemental prey produced more flowers than control plants. They also had a higher overall fitness estimate (number of flowers × fruit set (total fruits/total flowers) × seeds per fruit), although this benefit was significant only when prey supplementation occurred in the previous growing season. Neither pollen supplementation nor the interaction between pollen and prey supplementation significantly affected overall plant fitness. Conclusions: This study reinforces the reliance of D. muscipula on adequate prey capture for flower, fruit, and seed production and a mobile pollen vector for reproduction, indicating the importance of considering insects as part of an effective conservation management plan for this species. [ABSTRACT FROM AUTHOR]

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