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Many animals improve offspring survival through parental care. Research on coevolution between parents has provided key insight into the genesis and maintenance of biparental care. However, understanding family dynamics more broadly requires assessing potential male–female coevolutionary processes in the more widespread and common context of uniparental care. Here, we explore how pre-zygotic maternal contributions, jelly coats and oviposition sites, influence offspring dependency and change with the evolution of male-only care in glassfrogs. Egg care appears ubiquitous among glassfrogs, with repeated evolutionary transitions from brief female-only to extended male-only care. Glassfrogs also exhibit a diversity of sex-specific parental traits involving maternal egg-jelly contributions, oviposition-site choice, and egg-attendance behaviors. We hypothesize these form functionally interchangeable suites of traits that mediate embryos' susceptibility to environmental risk. First, using parent-removal field experiments, egg-hydration assays, and comparative analyses, we found no evidence that evolutionary transitions in caring sex or care duration alter the adaptive functions or overall benefits of care (across eight species). Rather, the jelly contributions and oviposition-site use associated with brief care influence embryo susceptibility to the same risks that are reduced by prolonged care. Next, we examined the diversity and evolutionary history of pre- and post-zygotic parental traits, applying phylogenetic comparative methods to literature records and our field observations of 40 species (71 total, ~47% of the family). Because prezygotic maternal contributions determine embryo requirements, the evolution of male care might enable and/or compensate for reduced maternal contributions. Supporting this hypothesis, we found that the repeated evolution of complex male care is always associated with reductions in egg-jelly and changes in oviposition sites. This phylogenetic pattern suggests that clutch phenotype might provide a general mechanism for the coevolution of parental investment in species with uniparental care. If different combinations of egg phenotypes and post-zygotic care are ecologically equivalent, their interchangeability could allow parental traits to coevolve between the sexes without compromising offspring survival. Male-only care is widespread in oviparous metazoans, occurring among annelids, molluscs, arthropods, fishes, and amphibians. Investigations of egg and clutch phenotypes offer new prospects for broadening research on the coevolutionary dynamics of parental care.

The Korean species of Tipula (Vestiplex) Bezzi, 1924 crane flies are taxonomically revised. Five species are recognized. Tipula (V.) coquillettiana Alexander, 1924, T. (V.) kuwayamai Alexander, 1921, T. (V.) tchukchi Alexander, 1934, and T. (V.) verecunda Alexander, 1924 are newly recorded from the Korean Peninsula, and T. (V.) serricauda Alexander, 1914 was previously recorded. The larva of T. (V.) serricauda is described and illustrated, and the larvae of the subgenus T. (Vestiplex) are divided into four groups based on spiracular lobe morphology. An identification key, redescriptions, and illustrations of Korean T. (Vestiplex) adults and grouping of known larvae are presented.

Background Insects rely on chemosensory perception, mainly olfaction, for the location of mates, food sources, and oviposition sites. Plant-released volatile compounds guide herbivorous insects to search for and locate their host plants, further helping them to identify suitable positions for oviposition. The fall armyworm Spodoptera frugiperda ( S. frugiperda ) was found to invade China in 2019 and has since seriously threatened multiple crops, particularly maize and rice. However, the chemical and molecular mechanisms underlying oviposition preference in this pest are not fully understood. Here, the oviposition preference of S. frugiperda on maize and rice plants was investigated. Results GC-EAD and GC–MS/MS techniques were used to identify the antennally active volatiles from maize and rice plants. The attraction and oviposition stimulation of identified components to female adults were tested in both laboratory and field settings. The odorant receptors (ORs) on female antennae were expressed in Xenopus oocytes , and their functions evaluated by RNAi. Ten and eleven compounds of maize and rice plants, respectively, were identified to possess electrophysiological activity from headspace volatiles. Among these compounds, ( Z )-3-hexenyl-acetate specifically presented in maize volatiles was found to play a critical role in attracting females and stimulating oviposition compared to rice volatiles. Among the cloned ORs on the antennae of both sexes, SfruOR23 with highly female-biased expression mediated the responses of females to ( Z )-3-hexenyl-acetate. Knockdown of SfruOR23 using RNAi markedly reduced the electrophysiological response of female antennae and oviposition preference to the compound. Conclusions ( Z )-3-Hexenyl-acetate is a key volatile mediating the host and oviposition preference of S. frugiperda on maize. The olfactory receptor of ( Z )-3-hexenyl-acetate was identified to be SfruOR23 , which is mainly expressed in the antennae of S. frugiperda .

Background Gravid females assess the conditions of oviposition sites to secure the growth and survival of their offspring. Conspecific-occupied sites may signal suitable oviposition sites but may also impose risk due to competition or cannibalism at high population density or heterogeneous larval stage structure, respectively. Chemicals in the habitat, including chemicals emitted from other organisms, serve as cues for females to assess habitat conditions. Here, we investigated the attraction and oviposition preference of the Old World cutaneous leishmaniasis vector, Phlebotomus papatasi , to young and old conspecific stages, including eggs and evaluated the effect of a semiochemical associated with eggs and neonate larvae. Methods Attraction and oviposition preference of Ph. papatasi to each of various life stages (eggs, first-, second-, third-, fourth-instar larvae, pupae and male and female adults) was investigated using cage and oviposition jar behavioral assays. Identification of organic chemical compounds extracted from eggs was performed using GC-MS and chemicals were tested in the same behavioral assays in a dose-response manner. Behavioral responses were statistically analyzed using logistic models. Results Gravid Ph. papatasi females were significantly attracted to and preferred to oviposit on medium containing young life stages (eggs and first instars). This preference decreased towards older life stages. Dose effect of eggs indicated a hump-shaped response with respect to attraction but a concave-up pattern with respect to oviposition. Chemical analysis of semiochemicals from eggs and first-instar larvae revealed the presence of dodecanoic acid (DA) and isovaleric acid. Sand flies were attracted to and laid more eggs at the lowest DA dose tested followed by a negative dose-response. Conclusions Findings corroborated our hypothesis that gravid sand flies should prefer early colonized oviposition sites as indicators of site suitability but avoid sites containing older stages as indicators of potential competition. Findings also supported the predictions of our hump-shaped oviposition regulation (HSR) model, with attraction to conspecific eggs at low-medium densities and switching to repellence at high egg densities. This oviposition behavior is mediated by DA that was identified from surface extracts of both eggs and first-instar larvae. Isovaleric acid was also found in extracts of both stages.

Aedes aegypti, the primary vector of viruses such as dengue, chikungunya, and yellow fever, poses a global health challenge. Traditional vector control strategies predominantly rely on broad-spectrum insecticides, which not only contribute to development of resistance in mosquitoes but also pose significant risks to non-target organisms and the environment. Here, we assessed the potential of cigarette butt (CB) extract for the management of A. aegypti population. Globally, 4.5 trillion CBs are being wasted annually, which is expected to rise to nine trillion by 2025. So, repurposing this waste for vector control offers an innovative approach. This study evaluated the potential of CB extract to deter ovipositing females and to assess larval mortality of A. aegypti using three concentrations of CB extract (1 CB, 2 CBs, and 3 CBs) against a control (water only). Our results revealed that highest concentration (3 CBs) significantly repelled the egg-laying females and resulted in 100% mortality of younger mosquito larvae (1st and 2nd instars) within 24 h of exposure, whereas complete mortality in mature larvae (3rd and 4th instars) was observed within 48 h of exposure. GC–MS analysis of CB extracts, using acetone and methanol as solvents, revealed both qualitative and quantitative differences in the chemical composition. Identified compounds include nicotine, phthalic acid, terephthalic acid, and acetonyl dimethyl carbinol. This study presents an innovative solution for recycling cigarette butt waste to control A. aegypti population at both adult and larval stages and highlights the potential to utilize CB waste into integrated vector management programs.

Insecticidal action of plant essential oils has been an area of intensive research in the new millennium, according to a recent bibliometric analysis. Despite this overwhelming research effort, commercialization of bioinsecticides based on essential oils has lagged far behind, although such products have now been used in the USA for over a decade, and in the EU in the last 4–5 years. Recent progress in commercialization of these products is reviewed here. Essential oils and their mono- and sesquiterpenoid constituents are fast-acting neurotoxins in insects, possibly interacting with multiple receptor types. These compounds also display potentially important sublethal behavioural effects in pest insects, including feeding and oviposition deterrence and repellence. Synergy among essential oil terpenoids appears to be a common phenomenon, and a mechanism for this action in rosemary oil has recently been demonstrated. Commercial development of bioinsecticides based on plant essential oils can follow several different pathways producing products with active ingredients differing in their genesis. These include products whose active ingredients consist of (1) a mixture of essential oils; (2) a single essential oil, or a single terpenoid constituent; (3) a blend of terpenoids, synthetically produced, that emulate those in a plant essential oil; and (4) a novel (non-natural) blend of terpenoids obtained from different plant sources. Examples of each of these are provided.

The sense of smell enables insects to recognize and discriminate a broad range of volatile chemicals in their environment originating from prey, host plants and conspecifics. These olfactory cues are received by olfactory sensory neurons (OSNs) that relay information about food sources, oviposition sites and mates to the brain and thus elicit distinct odor-evoked behaviors. Research over the last decades has greatly advanced our knowledge concerning the molecular basis underlying the reception of odorous compounds and the mechanisms of signal transduction in OSNs. The emerging picture clearly indicates that OSNs of insects recognize odorants and pheromones by means of ligand-binding membrane proteins encoded by large and diverse families of receptor genes. In contrast, the mechanisms of the chemo-electrical transduction process are not fully understood; the present status suggests a contribution of ionotropic as well as metabotropic mechanisms. In this review, we will summarize current knowledge on the peripheral mechanisms of odor sensing in insects focusing on olfactory receptors and their specific role in the recognition and transduction of odorant and pheromone signals by OSNs.

Sexual dimorphism is a crucial aspect of morphological and behavioral traits in animals. Unlike males, adult female locusts, i.e., Locusta migratoria , have highly extensible abdominal intersegmental membranes (ISMs) that facilitate deep oviposition into the soil, displaying an iconic sexual dimorphism, but the underlying mechanisms remain largely unknown. Here, we reveal that the extremely extensible ISMs in adult females are predominantly controlled by two female-specific proteins, LmAbd-1 and LmAbd-6, ensuring the oviposition behavior. Moreover, we discovered that LmJHBP, a juvenile hormone (JH) binding protein specifically expressed in adult female ISMs, mediates JH signaling to induce LmAbd-1 and LmAbd-6 expression. Importantly, the sex differentiation pathway (i.e., Tra-2 and Dsx ) determines the female-specific expression pattern of LmJHBP, and thus those of JH signaling and LmAbd-1 and LmAbd-6 expression. The finding of Tra/Dsx-JHBP axis significantly advanced understanding of sexual dimorphism and the adaptation of oviposition behavior in insects, the evolutionarily successful “segmentation” animals.

The preference-performance hypothesis (PPH) states that herbivorous female insects prefer to oviposit on those host plants that are best for their offspring. Yet, past attempts to show the adaptiveness of host selection decisions by herbivores often failed. Here, we tested the PPH by including often neglected oviposition-induced plant responses, and how they may affect both egg survival and larval weight. We used seven Brassicaceae species of which most are common hosts of two cabbage white butterfly species, the solitary Pieris rapae and gregarious P. brassicae. Brassicaceous species can respond to Pieris eggs with leaf necrosis, which can lower egg survival. Moreover, plant-mediated responses to eggs can affect larval performance. We show a positive correlation between P. brassicae preference and performance only when including the egg phase: 7-day-old caterpillars gained higher weight on those plant species which had received most eggs. Pieris eggs frequently induced necrosis in the tested plant species. Survival of clustered P. brassicae eggs was unaffected by the necrosis in most tested species and no relationship between P. brassicae egg survival and oviposition preference was found. Pieris rapae preferred to oviposit on plant species most frequently expressing necrosis although egg survival was lower on those plants. In contrast to the lower egg survival on plants expressing necrosis, larval biomass on these plants was higher than on plants without a necrosis. We conclude that egg survival is not a crucial factor for oviposition choices but rather egg-mediated responses affecting larval performance explained the preference-performance relationship of the two butterfly species.