Does larval diet prior to Hass avocado seed consumption and seed size impact the fitness of adult Heilipus lauri (Coleoptera: Curculionidae)?

Abstract

Heilipus lauri Boheman (Coleoptera: Curculionidae) is a specialist avocado seed feeder and a pest of economic importance in native (México) and invaded (Colombia) regions. Despite being a well-recognized pest of avocados, relatively little is known about factors affecting the developmental biology of weevil larvae infesting fruit. Laboratory studies investigated the effects of 4 pre-seed diets, 0, 1, and 3 d of feeding on avocado pulp, and consumption of conspecific first instar larvae on adult weevil fitness (ie size). Following these pre-seed diets, larvae were artificially inoculated into pre-weighed Hass avocado seeds. The effects of pre-seed diet and the size (ie weight) of inoculated seeds were analyzed for effects on the estimated mean amount of avocado seed consumed by larvae to complete development, mean time to complete development and emerge as adult weevils, and the mean weight (ie size) of adult male and female weevils. Pre-seed diet and seed size had no significant effects on seed consumption, development times, and size of adult weevils. Avocado seed size, which greatly exceeds amounts consumed to complete larval-to-adult development, may explain, in part, these observed outcomes, including purported fitness benefits that arise from consumption of conspecifics by herbivorous insects. This is the first study to confirm cannibalism by first instar H. lauri.