Genetics of Insecticide Resistance
Professor Phil Batterham is expert in molecular, population and developmental genetics.
Advances in chemistry powered much of the agricultural and industrial development in the twentieth century.
In agriculture chemical insecticides have been applied liberally, reducing production losses caused by insect pests and dramatically improving productivity. However, insects invariably evolve resistance to these insecticides. This imposes a significant economic burden as farmers may need to use more chemical to exert control and industry engages in expensive research and development to discover new insecticides.
Insecticides kill by binding to a key target protein in the insect pest. The binding of the insecticide may prevent the target protein from carrying out an essential function and the insect dies. Alternatively the insecticide may cause death by inappropriately modifying the activity of the target.
Resistance can evolve through mutations in the gene encoding the target protein, reducing or removing the capacity for insecticide binding. However, it can also evolve through mutations that change the substrate specificity or expression levels of detoxification enzymes. The enzyme products of three large multi-gene families (carboxylesterases, cytochrome P450s and glutathione-s-transferases) have been linked to many cases of insecticide resistance in the field.
At this point in time the capacity to prevent the evolution of insecticide resistance does not exist because of a lack of knowledge about either the insecticide targets or detoxification systems in insects.
We go to war against insect pests deploying our insecticidal weapons against unknown targets, totally ignorant of the capacity of the insect’s defence (detoxification) systems. Our weapons often kill our allies, the beneficial insects. Given the lack of intelligence in this approach, it is totally unsurprising that the insects win so many battles. In days gone by this was the best that could be done. This is no longer the case. Using SRC and other funding we are studying insecticide targets and detoxification and the molecular genetic basis of field resistance. The model genetic organism, the vinegar fly (Drosophila melanogaster), is used for fundamental research.
Our group also works on a number of key insect pests including the Australian sheep blowfly (Lucilia cuprina) and the cotton bollworm (Helicoverpa armigera). L. cuprina is the cause of strike in sheep. Control costs and production losses in Australia are estimated at $150-500 million per annum.
H. armigera attacks over 100 species of agricultural plants inflicting global costs of approximately $5 billion dollars. It is particularly troublesome in developing nations where farmers spend a signficant percentage of their income on insecticides. Our genomic characterization of these pests underpins our capacity to investigate insecticide resistance in these species.
Date Created: 01 May 1995