The assassin bug venom system plays diverse roles in prey capture, defence and extra-oral digestion, but it is poorly characterised, partly due to its anatomical complexity. Here we demonstrate that this complexity results from numerous adaptations that enable assassin bugs to modulate the composition of their venom in a context-dependent manner. Gland reconstructions from multimodal imaging reveal three distinct venom gland lumens: the anterior main gland (AMG); posterior main gland (PMG); and accessory gland (AG). Transcriptomic and proteomic experiments demonstrate that the AMG and PMG produce and accumulate distinct sets of venom proteins and peptides. PMG venom, which can be elicited by electrostimulation, potently paralyses and kills prey insects. In contrast, AMG venom elicited by harassment does not paralyse prey insects, suggesting a defensive role. Our data suggest that assassin bugs produce offensive and defensive venoms in anatomically distinct glands, an evolutionary adaptation that, to our knowledge, has not been described for any other venomous animal.

Assassin bugs (Hemiptera: Heteroptera: Reduviidae) are venomous insects, most of which prey on invertebrates. Assassin bug venom has features in common with venoms from other animals, such as paralyzing and lethal activity when injected, and a molecular composition that includes disulfide-rich peptide neurotoxins. Uniquely, this venom also has strong liquefying activity that has been hypothesized to facilitate feeding through the narrow channel of the proboscis-a structure inherited from sapand phloem-feeding phytophagous hemipterans and adapted during the evolution of Heteroptera into a fang and feeding structure. However, further understanding of the function of assassin bug venom is impeded by the lack of proteomic studies detailing its molecular composition.By using a combined transcriptomic/proteomic approach, we show that the venom proteome of the harpactorine assassin bug Pristhesancus plagipennis includes a complex suite of >100 proteins comprising disulfide-rich peptides, CUB domain proteins, cystatins, putative cytolytic toxins, triabin-like protein, odorant-binding protein, S1 proteases, catabolic enzymes, putative nutrient-binding proteins, plus eight families of proteins without homology to characterized proteins. S1 proteases, CUB domain proteins, putative cytolytic toxins, and other novel proteins in the 10 -16-kDa mass range, were the most abundant venom components. Thus, in addition to putative neurotoxins, assassin bug venom includes a high proportion of enzymatic and cytolytic venom components likely to be well suited to tissue liquefaction. Our results also provide insight into the trophic switch to blood-feeding by the kissing bugs (Reduviidae: Triatominae). Although some protein families such as triabins occur in the venoms of both predaceous and blood-feeding reduviids, the composition of venoms produced by these two groups is revealed to differ markedly. These results provide insights into the venom evolution in the insect suborder Heteroptera. Venoms are chemical arsenals injected by one animal into another to disrupt the homeostasis of the injected animal in ways that assist predation, defense, or feeding by the injecting animal (1). Typically, venoms are composed of multiple toxins, including peptides, enzymes, and small molecules, such as polyamines, that bind to and affect the function of multiple molecular targets in the injected animal. Because of their key role governing life-or-death interactions between animals, venom toxins are subject to selection pressures that have resulted in unique evolutionary patterns such as massive duplication and accelerated evolution of toxin-encoding genes (2-5). In addition, the properties that ensure that toxins confer a fitness advantage to the animals that produce them, including high stability and potency, make them well suited for use as insecticides, therapeutics, and pharmacological tools (6 -11). However, our understanding of the factors shaping venom evolution, and our ability to repurpose venom toxins for biotechnological use, is limited ...

Nickel oxide nanoparticles with an average diameter of about 9 nm were synthesized via thermal decomposition of NiC2O4 precursor at 450 °C. The nanoparticles were investigated using XRD, TEM, TGA, and UV–vis spectrophotometry. The optical absorption spectrum indicates that the NiO nanoparticles have a direct band gap of 3.56 eV. The electrochemical tests show that the ultrafine NiO nanoparticles, as a promising electrode material, can deliver a large reversible discharge capacity of about 610 mA h g−1.

Assassin bugs (Reduviidae) produce venoms that are insecticidal, and which induce pain in predators, but the composition and function of their individual venom components is poorly understood. We report findings on the venom system of the red-spotted assassin bug Platymeris rhadamanthus, a large species of African origin that is unique in propelling venom as a projectile weapon when threatened. We performed RNA sequencing experiments on venom glands (separate transcriptomes of the posterior main gland, PMG, and the anterior main gland, AMG), and proteomic experiments on venom that was either defensively propelled or collected from the proboscis in response to electrostimulation. We resolved a venom proteome comprising 166 polypeptides. Both defensively propelled venom and most venom samples collected in response to electrostimulation show a protein profile similar to the predicted secretory products of the PMG, with a smaller contribution from the AMG. Pooled venom samples induce calcium influx via membrane lysis when applied to mammalian neuronal cells, consistent with their ability to cause pain when propelled into the eyes or mucus membranes of potential predators. The same venom induces rapid paralysis and death when injected into fruit flies. These data suggest that the cytolytic, insecticidal venom used by reduviids to capture prey is also a highly effective defensive weapon when propelled at predators.

The insects are a hyperdiverse class containing more species than all other animal groups combined-many of which employ venom to capture prey, deter predators and microorganisms , or facilitate parasitism or extra-oral digestion. However, with the exception of those made by Hymenoptera (wasps, ants and bees), little is known about insect venoms. Here, we review the current literature on insects that use venom for prey capture and predator deterrence, finding evidence for fourteen independent origins of venom usage among insects, mostly among the hyperdiverse holometabolan orders. Many lineages, including the True Bugs (Heteroptera), robber flies (Asilidae), and larvae of many Neuroptera, Coleoptera and Diptera, use mouthpart-associated venoms to paralyse and pre-digest prey during hunting. In contrast, some Hymenoptera and larval Lepidoptera, and one species of beetle, use non-mouthpart structures to inject venom in order to cause pain to deter potential predators. Several recently published insect venom proteomes indicate molecular convergence between insects and other venomous animal groups, with all insect venoms studied so far being potently bioactive cocktails containing both peptides and larger proteins, including novel peptide and protein families. This review summarises the current state of the field of entomo-venomics. 1. Multiple independent origins of venom use among insects The >5 million species of insects estimated to exist on earth today make up the majority of eukaryotic species (May, 1988; Stork, 2018). Moreover, insect diversity goes further than just vast numbers of species. Hexapods (including insects) diverged from their closest relatives, the cave-dwelling remipede crustaceans, ~479 mya, and true insects (Ectognatha) emerged ~440 mya when they diverged from the entognathous hexapods (Collembola, Diplura and Protura) (Misof et al., 2014). Since their early evolution as one of the first animal groups to adapt to terrestrial lifestyles, the insects have undergone a spectacular evolutionary radiation and today occupy a diverse array of ecological niches. Major adaptations powering this radiation include the early adoption of powered flight and copulation for sperm transfer by the early Pterygota, a group that includes all orders except Archaeognatha (jumping bristletails) and Zygentoma (silverfish). Holometabolous development-in which larvae must pass through metamorphosis to become adults which differ markedly in their morphology-probably further drove diversification by allowing a single species to occupy multiple niches at different life stages. Of the 34 extant orders, 18 are descended from a holometabolous ancestor that lived ~345 mya (Misof et al., 2014), including the hyperdiverse insectan orders Hymenoptera, Diptera, Coleoptera and Lepidoptera. Only one of the hyperdiverse orders, Hemiptera, is hemimetabolous. Alongside these major trends, a multitude of trophic strategies, mating systems and life histories evolved, entailing adaptations spanning the biochemical, morphological and behavi...