Production and storage of mealworm beetle as prey for predatory stinkbug

Abstract

Arthropod predators can be produced using alternative prey, but the availability of a constant supply of prey at low cost is necessary to support large-scale production. The use of stored prey can be advantageous for maintaining a constant food supply, but its quality may decline in storage. Thus, we tested the effect of using stored pupae of the alternative prey Tenebrio molitor L. at low temperature (mean of 3.6°C) on the performance of predatory stinkbug Podisus nigrispinus (Dallas). The treatment conditions we tested were: pupae stored for exactly 30 days before being used as prey (30-d pupae); pupae stored for either 20 or 35 days prior to the initiation of their use as prey, with continued storage during nymphal and adult stages (20-d+ or 35-d+ pupae); and 2-day-old newly moulted pupae as the control treatment. The duration of the nymphal stage of females and the weight of males were lower for nymphs fed 20-d+ and 35-d+ pupae, respectively. The pupal weight consumed and the rate of eggs and nymphs produced per gram of consumed pupae were also lower for adult females fed 35-d+ pupae compared to females that were fed 2-day-old pupae. These measures, however, were similar for females fed 30-d and 20-d+ pupae. The greatest consumption of pupae was observed for 20-d+ and 35-d+ treatments during nymphal and adult stages, respectively. The use of stored T. molitor pupae supported the development and reproduction of P. nigrispinus, regardless of the period of storage but with variable results among treatments. Therefore, among any of the tested treatments those pupae that were stored for exactly 30 days produced the highest fitness for P. nigrispinus.