THE IMPACT OF SPERM PRECEDENCE IN MALATHION RESISTANCE TRANSMISSION IN POPULATIONS OF THE RED FLOUR BEETLE TRIBOLIUM-CASTANEUM (HERBST) (COLEOPTERA, TENEBRIONIDAE)

Malathion resistance in the red flour beetle Tribolium castaneum (Herb st) (Coleoptera: Tenebrionidae) is actually a worldwide problem, and s tudies on resistance transmission are needed to improve insecticide re sistance management. Females of Tribolium castaneum commonly mate with several males, and the last batch of male sperm preferentially fertil izes subsequent eggs. This phenomenon, a particular form of sexual sel ection, helps to increase resistance transmission in populations of st ored product insects. We confirmed the last male sperm precedence and, in the absence of further matings, examined the evolution of mixed su sceptible and malathion-resistant progeny during a 3-month period. The proportion of resistant phenotypes in female progeny was 99.6 and 3%, respectively, after the first mating with a resistant male and the se cond mating with a susceptible one. When females thus mated twice were isolated from males, the proportion of the resistant phenotype increa sed to 34.1% after 30 days. From 72 days onwards, this proportion rang ed from 14.2 to 29.7%. (C) 1997, Published by Elsevier Science Ltd.