Influence of diet on long-term cold storage of the predator Podisus maculiventris (Say) (Heteroptera: Pentatomidae)

Abstract

Abstract Long-term storage could aid in the cost-effective mass production of beneficial insects. Pre-conditioning, insect developmental stage and environmental conditions should be considered when selecting storage conditions in order to obtain the highest performance after storage. We evaluated the influence of nutrient quality on the response of eggs, nymphs and adults of Podisus maculiventris when exposed to two temperatures most likely to be used for long-term storage. Natural prey-fed insects were compared to artificial diet-fed insects. The results of our study showed that eggs survived storage at 10 °C better than 4 °C, and that eggs from diet-fed insects survived storage at 10 °C significantly better than eggs from prey-fed insects. Nymphal survival of cold storage treatment was slightly higher than for eggs, with a similar pattern of response to temperature, nutrient quality and time of storage. However, of the three developmental stages tested, the best survival was obtained with adults. Similar to eggs and nymphs, adults survival was higher at 10 °C. However, different from eggs and nymphs was that the prey-fed adults survived better than diet-fed adults. Our results show that prey-fed adults were able to withstand cold storage at 10 °C for 4 weeks with very little loss of survival, fecundity or viability of eggs oviposited by those adults. Longer periods of storage resulted in a decline in survival, fecundity and egg viability and that decline was greatest at 4 °C. For the longer intervals of storage at 10 °C, egg viability was highest for eggs from diet-fed adults. Collectively, these results demonstrate an influence of nutrient quality on the response to cold storage at different developmental stages, and that an optimal food source for continuous rearing is not necessarily an optimal food source for cold storage.