Does a Polyphagous Predator Prefer Prey Species That Confer Reproductive Advantage?: Case Study ofPodisus maculiventris

Abstract

The purpose of this study was to determine whether preferred prey of Podisus macu- liventris (Say) (Heteroptera: Pentatomidae) adult females also conferred maximal fecundity. We also studied egg development and maturation as a function of predator age, i.e., ovigeny as used predominantly in the context of parasitoids. To determine prey preference, adult females were simultaneously offered Þve pest prey: 1) beet armyworm, Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae); 2) fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae); 3) cabbage looper, Trichoplusia ni (Hubner) (Lepidoptera: Noctuidae); 4) greater wax moth, Galleria mellonella (L.) (Lepidoptera: Pyralidae); and 5) yellow mealworm, Tenebrio molitor (L.) (Coleoptera: Tenebrionidae) (n 20). In a second experiment, adult P.maculiventris females were provided a single species of prey (for each of the Þve prey species, n 10). This experiment was repeated over four durations: 7, 15, 22, and 30d. After each time trial, egg load dissections were performed, and numbers of mature and immature eggs were recorded. P. maculiventris displayed a preference of beet army- worm, whether measured as numbers attacked or estimated biomass consumed. However, no signif- icant differences were found in cumulative numbers of eggs laid under the different prey treatments, with the exception of the 22-d trial where signiÞcantly more eggs were laid when feeding on the cabbage looper. During the 22-d trial, the number of egg clutches and numbers of eggs per clutch were highest when fed cabbage looper and lowest with yellow mealworm. Percentage of egg hatch combined across time trials was highest in cabbage looper (81.7%) and lowest in greater wax moth (63.8%). Egg load dissections revealed that the total number of eggs and numbers of mature eggs declined signiÞcantly with predator age. However, numbers of immature eggs increased. The mean number of mature eggs in 7-d-old predators represented only 5% of mean cumulative numbers of eggs laid by 30-d-old predators, indicating that P. maculiventris is strongly synovigenic, where egg development and maturation continues during adulthood. The implications of these results are discussed from the context of P. maculiventris as a biological control agent.