Spider venoms are usually toxic when injected into prey, but a new protein discovered in the venom of Australian tarantulas can also kill prey insects that consume the venom orally. The protein is strongly insecticidal to the cotton bollworm, an important agricultural pest, according to research published September 11 in the open access journal PLOSONE by Glenn King and Maggie Hardy from the Institute of Molecular Bioscience at the University of Queensland, Australia, and colleagues from other institutions. The small protein, named orally active insecticidal peptide‑1 (OAIP‑1), was found to be highly toxic to insects that consumed it, with potency similar to that of the synthetic insecticide imidacloprid. Cotton bollworm, a pest that attacks crop plants, was more sensitive to OAIP‑1 than termites and mealworms, which attack stored grains. “There is an urgent need for new insecticides due to insects becoming resistant to existing products and others being deregistered due to perceived ecological and human health risks,” Professor King said. “Cotton bollworms cause major economic damage to crops and the toxin we have isolated is more potent against these insects than existing chemical insecticides.” These and other insect pests reduce global crop yields by 10 – 14% annually and damage 9 – 20% of stored food crops, and several species are resistant to available insecticides. Isolated peptides from the venom of spiders or other venomous insectivorous animals, such as centipedes and scorpions, may have the potential to serve as bioinsecticides. Alternately, the authors suggest the genes encoding these peptides could be used to engineer insect-resistant plants or enhance the efficacy of microbes that attack insect pests. King elaborates, “The breakthrough discovery that spider toxins can have oral activity has implications not only for their use as bioinsecticides, but also for spider-venom peptides that are being considered for therapeutic use.” “The next step is to determine the safety of OAIP‑1 for non target organisms, including pollinators, like bees, as well as natural enemies of insect pests such as ladybird beetles”, Dr Hardy said.
Margaret C. Hardy, Norelle L. Daly, Mehdi Mobli, Rodrigo A. V. Morales, Glenn F. King. Isolation of an Orally Active Insecticidal Toxin from the Venom of an Australian Tarantula. PLoS ONE, 2013; 8 (9): e73136DOI: 10.1371/journal.pone.0073136 The Institute for Molecular Bioscience (IMB) is a research institute of The University of Queensland that aims to improve quality of life by advancing personalised medicine, drug discovery and biotechnology. The study was funded by the Australian Research Council and also involved Professor Norelle Daly, Dr Mehdi Mobli and Dr Rodrigo Morales. Source: University of Queensland