Spider venom - a natural born insect killer
“Spiders are the ‘quintessential insect predator’ with a venom that is rich in insecticidal neurotoxins, so it makes sense to explore the reasons why their venom remains so potent,” he says.
“Our results have shown that spider venom can be used as a stand-alone insecticide or used to engineer insect-resistant crops. ”With the decline in the insecticide arsenal in recent years from both resistance and legislation, it is an area that is of increasing interest to growers.” He explains that these venoms are a complex chemical cocktail of inorganic salts, small organic molecules, peptides and proteins that act together in the nervous system of the spider’s prey, the insect.
“Nature has developed and perfected this bio-insecticide over many millions of years, so spider venoms are an excellent source of natural insecticide compounds such as disulphide-rich peptides.” These peptides can act individually or as part as a larger toxin cabal, which is a group of venom peptides that act synergistically to enhance venom potency.
“However, one of the challenges we still need to overcome is how to improve oral and contact insecticidal activity. Because these venoms are normally injected into the prey by the spider using a hypodermic needle-like fang that penetrates the protective exoskeleton, scant contact activity has evolved,” he continues. “We are therefore looking at ways of using vectors to introduce the toxins or to encourage the target insects to ingest them – but for them to be effective oral insecticidal activity is crucial.”
Another promising option is to fuse spider venom peptides with a carrier protein that facilitates transport across the gut. Going on to discuss resistance, he remarks that despite an apparently vast array of chemical insecticides, these insecticides work on a very small number of molecular targets , which has led to insecticide resistance.
“More than 600 insects and mites, including some key disease vectors, are now resistant to one or more classes of chemical insecticides,” he discloses. “However, we know that products from spiders have a wide range of insect-killing abilities that prevent insects becoming resistant to spider bites, so researchers are investigating whether we can mimic those peptide compounds.”
“Because most spiders do not feed on a restricted prey type, their venoms have evolved to contain an array of compounds that target a broad spectrum of prey. Moreover, although some large spiders consume small vertebrates, very few are toxic to humans.
“The project is still in its infancy but we are hopeful that the outcomes will be of enormous long-term benefit to the cropping industry in Australia and around the world,” Prof King says. The research on spider venom is sponsored by the Australian Research Council (ARC) and the Australian Grains Research and Development Corporation (GRDC).