Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2007
Publication Date: 7/5/2007
Citation: Coudron, T.A., Ellersieck, M.R., Shelby, K. 2007. Influence of diet on long-term cold storage of the predator Podisus maculiventris (Say) (Heteroptera: Pentatomidae). Biological Control. 42(2):186-195. Interpretive Summary: Maintaining healthy colonies of insects is a costly exercise regardless of whether those insects are for research or commercial use. To reduce that cost, a highly desirable trait would be the ability to preserve insects at reduced temperatures for short- and long-term periods. Results from this study demonstrated that insect egg, immature and adult developmental stages each respond differently to short- and long-term storage at cold temperatures and that the nutrient quality affected the ability of each developmental stage to tolerate cold storage. In particular, it was more advantageous to rear insects on an artificial food source for short-term storage which is useful information prior to the shipment or release of eggs or immature stages. In contrast, it is more advantageous to rear insects on a natural food source for long-term storage which is useful information when collecting large numbers of insects for sale and release purposes or when storing a colony between uses. Commercial producers and researchers will find both of these storage regimes to be useful procedures when attempting to minimize their operational costs and to maximize the fitness of their insects.
Technical 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 10degC better than 4degC and that eggs from diet-fed insects survived storage at 10degC significantly better than eggs from prey-fed insects. The survival of nymphs to 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, for adults there was a higher survival at 10degC but different from eggs and nymphs was that the prey-fed adults survived better than diet-fed. Our results show that prey-fed adults were able to withstand cold storage at 10degC 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 4degC. For the longer intervals of storage at 10degC, 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 a diet more optimum for continuous rearing is not necessarily the better diet for cold storage.