General principles of insecticide and miticide resistance

N.A. Martin
Crop & Food Research, Private Bag 92169, Auckland, New Zealand

Resistance management

Insecticide and miticide resistance prevention and management strategies are based on two principles. Firstly, preventing resistance to pesticides is much better in the long term than trying to manage resistance once control failures occur. Secondly, if the insect or mite population is not exposed to the pesticide, the proportion of resistant organisms declines (Roush & Daly 1990), either because the resistant organisms are less fit or because of interbreeding with susceptible organisms. In some situations resistance within a population

The key components of insecticide and miticide resistance prevention and management strategies are:

maximise use of non-pesticide controls
only apply pesticides when their use can be justified
time pesticide applications appropriately and target applications of pesticide to the specific parts of the plant or crop where it will be most effective
use good application technique and apply when environmental conditions are favourable
use each pesticide (or only one member of a group of pesticides) no more than the specified maximum number of times per year or growing season
rotate chemical groups of pesticides

Insecticide and miticide resistance management strategies must consider the whole crop, or even the grower's whole property, because a pesticide applied to control one pest can impact on another pest and the future options for its control.

Non-insecticide and miticide control techniques include:

quarantine (keeping the pest off the property)
plant resistance
agronomic and cultural techniques
correct identification of the problem
monitoring populations of the pest
biological control, and methods to enhance biological control

Components of the insecticide and miticide resistance strategies

The strategies for insecticides and miticides are based on individual pest species since the biology of each pest varies widely. All the insecticide and miticide strategies are organised in the same way, although there may be substantial differences in content depending on the number of species and crops involved. Some strategies only involve one species of insect, e.g. tomato fruitworm, while others cover a group of pests such as thrips.

Each strategy has the following sections:

Reason for strategy and update
Background biological information on the pest(s)
Products with label claims for the pest(s) in New Zealand
Current status of resistance by the pest(s) in New Zealand
Resistance management strategy
Implementation
References to literature cited

Product information is summarised in a table giving the recommended names for IRAC chemical groups, the IRAC numbers, each active ingredient and products containing that active ingredient and the label claims for each relevant crop.

The tables that include the label claims indicate clearly the nature of the claim. For example, in the strategy for green peach aphid, the table lists claims specifically for green peach aphid control in a crop, aphid control in a crop, or for aphid control for a particular stage of crop development or only for the crop grown in greenhouses.

The resistance management strategy section starts with the general strategy for the pest(s) and where appropriate it has specific recommendations for crops and/or pests. There may also be research recommendations.

The implementation section usually has recommendations for growers and for the chemical companies. The latter usually concerns information to be put on product labels.

Reference

Roush RT, Daly JC 1990. The role of population genetics in resistance research and management. In: Roush RT, Tabashnik BE ed. Pesticide Resistance in Arthropods. Chapman and Hall, New York, USA. Pp. 97-152.