Multitactic Resistance Management: An Approach that is Long Overdue?
“Resistance management” tactics have been much discussed, but such tactics have provided surprisingly limited practical results for pest management programs to date. We have learned a great deal about pesticide resistance mechanisms, the mode of inheritance of resistances, the molecular basis of resistance and cross resistance mechanisms, and how to evaluate the impact of resistance on fitness. However, it remains difficult to “manage” resistance once resistant individuals make up more than 5 to 10% of the population. Generally, the best that can be achieved is to delay the development of high levels of resistance for a few years, most often by using the product less often. A more effective resistance management strategy will combine a variety of effective pest management tactics along with a reduction in numbers and rates of pesticides applied. Effective pest management tactics include monitoring, evaluating economic injury levels so that pesticides are applied only when needed, biological control, host plant resistance, cultural controls, biorational pest controls, and genetic control methods. As a part of this multi-tactic strategy, it is crucial to evaluate the impact of pesticides on natural enemies. Sometimes, pesticide-resistant natural enemies can be effective components of a program to delay the development of resistance in pest arthropods.