Inge Mestdagh

Variation in susceptibility to pyriproxyfen in four laboratory strains of Podisus maculiventris (Say) (Het., Pentatomidae)

Abstract: The susceptibility of four laboratory strains of the spined soldier bug, Podisus maculiventris (Say), to the juvenile hormone mimic pyriproxyfen was examined in the laboratory. Fifth instar nymphs (< 24 h old) were exposed to pyriproxyfen via ingestion of treated drinking water. LC50 values for a long‐term laboratory strain originating from Florida (FLO), a more recently introduced strain from Indiana (IND), and two mildly inbred strains (IS1, IS2) of the latter origin, were comparable, ranging from 39.8 to 61.6 mg a.i. ˙ 1−1. However, slopes of dose–mortality curves indicated that the susceptibility of the four populations of P. maculiventris decreased in order of IS2 > IS1 ≅ FLO > IND. The results of this study are discussed with respect to strain maintenance and quality control of natural enemies used to test side‐effects.