Australian researchers have identified the first ever orally-active bioinsecticide from the Australian tarantula venom. The poison may become friend of us and foes of social insect pests in future
Insect pests are always a nuisance to farmers. They bring down not only the crop yield, but also rampantly loot the stored agri-produce.
Bugs from mosquitoes to wasps, and sometimes also ants annoy us, so researchers develop poisonous chemical insecticides like pyrethroids. These might be active in repelling or killing the insects in different ways, but have environmental and health risks.
Science has been looking for better insecticides, out there in Nature – bio-based or bio-inspired insecticides, for example, the controversial Bacillus thuringiensis (Bt) with its Cry proteins encoded in crops as Bt-crops.
But, the future may see that a good dose of a poisonous peptide from the Australian tarantula venom, as a solution for all these problems. A new study by Margaret Hardy and Glenn King, with their colleagues at the University of Queensland, St Lucia, Australia, covers their successful tapping of this Tarantula venom factor, named OAIP-1 (Orally Active Insecticidal Peptide). “Our study is the first example of a directed-discovery program successfully isolating a novel orally-active insecticide” Hardy told Decoded Science.
Natural Insect Poison
Spiders inject venom in their prey, and doctors even use spider venom clinically, but, scientists believed that the venom would not work orally, i.e., when the prey ‘eats’ the poison. Hardy and her colleagues have proven otherwise in this milestone study. The scientists purified the tapped venom into different fractions, and fed those to termites, mealworms that eat away the stored grains, and the cotton bollworms, a notorious crop pest. They found one particular highly lethal fraction and it was OAIP-1 that killed these insects within 2 days.
“OAIP-1 is different from other insecticides because it is potent, synergistic with an existing insecticide, and can be produced recombinantly,” says Hardy. In the study, the group has chemically synthesized the peptide, but says that it can also be produced recombinantly, in fungi, for instance. “The synthesis of OAIP-1 was primarily for the purpose of the paper, and wouldn’t be cost-effective for large-scale production. for the next part of our research we will use recombinantly-produced peptides”, Hardy tells us. They also prove that OAIP-1 works well with a commercial insecticide, imidacloprid, i.e., the presence of either of the insecticides adds up their action.
Many cash and food crops grow in warm and arid places. Thus, the stability of an insecticide in the wild is important. The group shows that the peptide is stable at high temperatures and pH, and can be used as foliar sprays for crops. The group has not done any field study yet on this. But Hardy says, “Before we do we will determine the compound is safe for use around beneficial insects (like bees) and people, livestock, pets, and in the environment.” Moreover, using their results, they say that OAIP-1 is a non-repellent insecticide, i.e., not ignored by insects, when fed, and it is another quality of an orally-active insecticide. Future works from their group might bring out the commercial exploitation of this nature of OAIP-1.
Additional information is that, like imidacloprid, OAIP-1 is also neurotoxic to the insects. Observing the activity of insects after feeding them with OAIP-1 in agar, they observed dead, or near-dead, or paralyzed insects. The insects could not manage to right themselves, when they fell on their back. With this, they say that blockage of pre- or post-synaptic voltage-gates in their nerves might be the reason.
OAIP-1: Promising Future
By comparing OAIP-1’s action with commercial pyrethroids, the scientists claim that OAIP-1 is an equally potent insecticide. Moreover, the dose required is much less than the chemical insecticides. Thus, according to them, OAIP-1 is a promising bioinsecticide.
The researchers also argue that OAIP-1 is a broad-spectrum insecticide, and being a peptide, can be engineered in plants to create GM-crops, like Bt. They suggest that Bt and OAIP-1 may act together, but with their different mechanisms, to kill the insects effectively. However, “OAIP-1 would have the same challenges any GMO has” cautions Hardy.
On the possibility of resistance by insects to OAIP-1, Hardy admits that, “With any insecticide there is potential for resistance to develop, and OAIP-1 would be no different in this regard.”
“We have filed patents and are in the process of commercialization. UniQuest is the commercialization company for The University of Queensland” says Hardy. From further studies in future, we might hear more success stories of OAIP-1, academically and commercially. However, for now, we have to live with the light the study sheds – on the agricultural use of OAIP-1. We shall hope that OAIP-1 passes all its ‘tough tests’ to become a friend of humans – in farms or at home!
Hardy, M., Daly, N., Mobli, M., Morales, R., King, G. Isolation of an Orally Active Insecticidal Toxin from the Venom of an Australian Tarantula. (2013). PLoS ONE. Accessed September 12, 2013.
Australian Museum. Australian Tarantula. (2010). Accessed September 12, 2013.
Bristol University. Applications of Spider Venom. Accessed September 12, 2013.
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