Fall army worm resistance

Glutathione S-transferases have received considerable attention because of their roles in insecticide detoxification and resistance in insects. Cytosolic glutathione S-transferases have been purified from more than two dozen insect species, including Lepidoptera, Diptera, Coleoptera, Dictyoptera, and Hymenoptera. These transferases exist in multiple forms as many as nine isozymes were found in midguts and fat bodies of fall army worm... 

A single gene may be responsible for the resistance, and in these cases the level of resistance can be quite high. Well-known examples are the 2000-fold resistance to organophosphates in spider mites, spinosad resistance in western flower thrips, DDT resistance in houseflies, and dieldrin resistance in several Diptera. In other cases, multiple genes are clearly involved in the resistance. Examples are carbaryl resistance in houseflies (Georghiou, 1972), carbaryl resistance in fall army worms (Yu et al., 2003), and malathion resistance in oriental houseflies (Yeoh et al., 1981). 

Population mobility is a very important behavioral factor for resistance development. The influx of migrants tends to dilute the frequency of resistance among survivors of treatments, especially for highly mobile insects such as the fall army worm and velvetbean caterpillar. Computer simulation indicated that a moderate rate of immigration of susceptible individuals could ensure the containment of resistance if the initial population was of low density and if a short-lived pesticide was used in regular treatments. 

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