Sometimes it's the smallest creatures that create the biggest problems for beef producers. In fact, cattle ticks can cost the Australian beef industry more than $160 million/year, with buffalo flies presenting a similar problem.
According to Professor Joel Mackay from the University of Sydney, an effective strategy to deal with cattle ticks and buffalo flies would include more potent and effective pesticides. However, most pesticides on the market work non-selectively against both pests and also beneficial arthropods. A selective pesticide that is harmful to cattle ticks and buffalo flies but safe for beneficial insects such as dung beetles, would be a valuable asset for producers, and be a starting point for developing pesticides that target other harmful mites.
A target-based approach
MLA-funded research at The University of Sydney, led by Professor Joel Mackay, Professor Ron Hill and Dr Emily Remnant, aims to develop such selective pesticides, and considerable progress made already.
A target-based approach must be employed to design a pesticide with significant selectivity. Leveraging protein biochemistry, genomics, structural biology, toxicology and chemistry molecules interacting with specific biological targets can be identified. In cattle ticks (and all other arthropods), there is a hormone binding protein called the ecdysone receptor which is a promising target for pesticide development. This protein interacts with the hormone ecdysone to regulate tick development, reproduction and behaviour. Disrupting this interaction through custom designed chemicals would significantly impair tick development and reproduction, making such chemicals great candidates for pesticides.
So far, the team has purified significant quantities of the ecdysone receptor protein and demonstrated that the lab-generated protein can bind to the native ecdysone hormone and can therefore be used as a target for pesticide development, with further research commencing to find chemicals that can hit that target.
The search for a needle in a haystack
The search for selective chemicals will take advantage of subtle differences in the shape of the receptor protein found in the cattle tick, compared to the equivalent protein from the dung beetle. By searching through hundreds of thousands of commercially available chemicals, it is hoped that the needle in the haystack can be found: a chemical that interferes with the cattle tick ecdysone receptor while leaving the equivalent protein in the dung beetle untouched. The same strategy will be used to target the buffalo fly – again without harming the dung beetle.
This new approach to pesticide discovery is hoped to offer a competitive route to the development of safe, more selective, and environmentally friendly agents for the control of insect and arachnid pests and help protect global agricultural systems.
