Predicting insecticide resistance

Student post submitted by Philip Lockton

This article is a good example of the effects of evolution on current day pests and parasites. In regards to pest management, pesticides and insecticides have been developed in the last century to deter the effects of parasitic damage. In agriculture, insecticide use is critical in managing and controlling both crop and livestock production. The development of chemical insecticides has allowed humans to produce more reliable agricultural goods with greater quality and quantity. However, with the increased use of insecticides arises another problem, which is ‘insecticide resistance.’ The article talks about insecticide use on sheep, which is intended to control ectoparasites. With persistent use of chemical agents, resistance can evolve in an organism. This article addresses the concept of predicting such resistance mechanisms.

Many strategies have arisen to manage resistance to particular insecticides. Although, as the article notes, management strategies to resistance of a particular insecticide are typically devised after the resistance has already evolved. The goal is to be able to predict and correct possible resistance problems before they ever occur. This would allow us to manage susceptibility in various organisms.

In sheep, a common ectoparasite is the Australian sheep blowfly, Lucilia cuprina. Sheep are used in agriculture for their wool primarily. Lucilia cuprina agitate the dermis of the sheep causing the fur (wool) to fall out or become discolored or damaged causing quality to drop. Management of this problem has been done by the use of insecticides. Using Lucilia cuprina in lab, blowflies were introduced to insecticides such as dieldrin, diazinon and malathion. These were then compared to previously evolved flies (resistant) from a natural population in order to predict resistance capacity. Using this approach with known capacities, it was used to predict possible mechanisms for resistance of another insecticide, cyromazine. Cyromazine has been used as an effective insecticide against L. cuprina for over almost twenty years. Using the laboratory-generated resistant variants, these researchers found that they showed low levels of resistance. According to adjusting insecticide concentration, resistance occurred at different rates.

Resistance is a major problem in our modern day society. Insecticide resistance is a good example of such a problem. Other types of resistance occur such as herbicide resistance and antibiotic resistance. Resistance is one of the best examples of evolution in action. The purpose of this experiment is to try to predict possible resistance problems before they happen, rather than trying to assess the damage after. The goal is to be able predict resistance for the control purposes and to ‘minimize evolution of resistance.’ Current methods of resistance control include increased concentration and strength of such things as pesticides and antibiotics, however, these methods only further contribute to the evolution of increased resistance. We need to come up with more effective ways of fighting resistances, rather than just increasing it in the long run. Being able to predict resistance is a wonderful concept, and may soon help us better control for various types of ‘unwanted’ resistances’ before they have a chance to evolve, or at least slow it down.

Reference:

McKenzie, J.A., Batterham, P. (1998). Predicting insecticide resistance: mutagenesis, selection and response. Philosophical Transactions of the Royal Society B: Biological Sciences, 353(1376), 1729-1734. DOI: 10.1098/rstb.1998.0325