Effect of methoprene on the progeny production of Tribolium castaneum (Coleoptera: Tenebrionidae).

BACKGROUND Tribolium castaneum (red flour beetle) is a serious insect pest of stored products around the world. Current control measures for this species have several limitations: loss of registration of insecticides, insecticide resistance and consumer concerns about chemical residues in food. The objective of this study was to determine whether methoprene affects progeny production of T. castaneum. Late-instar larvae or young adults were exposed to methoprene-treated wheat, and progeny production was determined. The pairing of male and female adults was performed as untreated × untreated, treated × untreated or treated × treated, to study sex-based effects. RESULTS There were three outcomes to late-instar larvae held on methoprene-treated wheat kernels (0.001 and 0.0165 ppm): (1) failure to emerge as an adult; (2) emergence as an adult, and almost no offspring produced; (3) emergence as an adult and normal production of offspring. Male larvae were more susceptible to methoprene than female larvae. In contrast, young adults exposed to methoprene (1.67-66.6 ppm) showed no reduction in offspring production. CONCLUSION Methoprene concentrations will decline with time following its application. However, this research indicates that methoprene can still reduce populations of T. castaneum by reducing their progeny production, even if adults emerge.