Orally active acaricidal peptide toxins from spider venom

Numerous species of ticks and mites (collectively known as acarines) are serious pests of animals, humans, and crops. There are few commercially available acaricides and major classes of these chemicals continue to be lost from the marketplace due to resistance development or deregistration by regulatory agencies. There is consequently a pressing need to isolate new and safe acaricidal compounds. In this study, we show that two families of peptide neurotoxins isolated from the venom of the Australian funnel-web spider Hadronyche versuta are lethal to the lone star tick Amblyomma antericanum. These toxins, which are specific blockers of arthropod voltage-gated calcium channels, induce a pronounced phenotype characterized by an unusual gait that is rapidly followed by paralysis and death. Remarkably, one of these toxins, the calcium channel blocker omega-atracotoxin-Hv1a, is virtually equipotent whether the toxin is injected or fed to A. americanum. (c) 2005 Elsevier Ltd. All rights reserved

Spider toxins and their potential for insect control

Insects are the most diverse and successful animals on the planet, with the number of extant species estimated to be not, vert, similar5 million (Novotny et al., 2002). However, the ability of insects to inhabit a wide variety of ecological niches has inevitably brought them into conflict with humans. Although only a small minority of insects are classified as pests, they nevertheless destroy 20–30% of the world's food supply ( Oerke, 1994) and transmit a diverse array of human and animal pathogens. In terms of agronomic importance, lepidopterans are the most pernicious insects, with not, vert, similar40% of all chemical insecticides directed against heliothine species (Brooks and Hines, 1999). However, from a global human health perspective, mosquitoes are the most problematic arthropods, being responsible for the transmission of malaria, filariasis, and numerous arboviruses. Although malaria is unquestionably the most devastating insect-borne disease, causing an estimated 2 million deaths per year ( Gubler, 1998), the increasing incidence of epidemics caused by mosquito-borne arboviruses (e.g., dengue, West Nile, Japanese encephalitis, yellow fever, and Rift Valley fever) is a mounting public health issue ( Gubler, 2002). Other insects of significant public health importance include sandflies, tsetse flies, fleas, and triatomid bugs, which transmit the causative agents of leishmaniasis, trypanosomiasis (African sleeping sickness), plague, and Chagas disease, respectively ( Gubler 1998 and Gratz 1999)

Diversification of a single ancestral gene into a successful toxin superfamily in highly venomous Australian funnel-web spiders

Background: Spiders have evolved pharmacologically complex venoms that serve to rapidly subdue prey and deter predators. The major toxic factors in most spider venoms are small, disulfide-rich peptides. While there is abundant evidence that snake venoms evolved by recruitment of genes encoding normal body proteins followed by extensive gene duplication accompanied by explosive structural and functional diversification, the evolutionary trajectory of spider-venom peptides is less clear