Test for Pesticide Resistance in Cattle

Resistance testing consists of exposing buffalo flies to a range of concentrations of insecticide to detect changes in their susceptibility to chemical concentrations outside the normal range seen in non-resistant flies. Resistance tests with buffalo flies can be conducted by a number of methods, depending on the chemical of interest and the facilities available, but desirably needs to be conducted by an experienced or trained practitioner. The most common method used on farm is to expose buffalo flies to filter papers treated with different concentrations of insecticide, for a fixed period of time, and then to count the numbers of flies alive at concentrations above a critical level (the discriminating dose).

Resistance to synthetic pyrethroids and organophosphates can also be conducted using molecular methods to detect the presence and frequency of known resistance genes. The advantage of genetic testing methods are that they don’t require the use of live flies. The potential disadvantage is that some resistance mechanisms are not currently known, so genetic tests cannot detect them.

There are currently no laboratories in Australia that offer commercial testing for chemical resistance in buffalo flies.