Factors Influencing Insecticide Resistance in Psylla pyricola (Homoptera: Psyllidae) and Susceptibility in the Predator Deraeocoris brevis (Heteroptera: Miridae)

Abstract

Insecticide susceptibility and resistance in populations of pear psylla, Psylla pyricola Foerster, and the mirid predator, Deraeocoris brevis Knight, were evaluated through biochemical and computer simulation analyses. Pear psylla were resistant to azinphosmethyl and fenvalerate, whereas D. brevis were susceptible. Although esterase detoxification activity was higher in pear psylla than in D. brevis , glutathione S-transferase and cytochrome P-450 monooxygenase activities were similar in predator and prey. Sensitivity analyses predicted that high fecundity and low immigration of susceptible individuals into populations selected by insecticides contributed greatly to the development of rapid resistance in pear psylla. Conversely, lower fecundity and high immigration of susceptible individuals contributed greatly to the lack of resistance in D. brevis . Thus, it appears that life history and ecological factors explain resistance in pear psylla and the lack thereof in D. brevis better than do detoxification attributes.