Submitted to: Biocontrol
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2009
Publication Date: 7/9/2009
Citation: Coudron, T.A., Popham, H.J., Ellersieck, M.R. 2009. Influence of Diet on Cold Storage of the Predator Perillus bioculatus (F.). Biocontrol 54:773-783.
Interpretive Summary: More efficient and effective methods to store insects for short and extended periods would help reduce the costs associated with rearing and transporting insects. Placing insects at reduced temperatures is a common storage practice. However, the response of insects to storage at cold temperatures is not well understood and consequently this method has not been perfected. Results from this study demonstrated that eggs, immature and adult developmental stages of the beneficial predatory two spotted stink bug respond differently to short and extended periods of storage at cold temperatures and that nutrition affected the ability of each developmental stage to tolerate cold storage. In particular, for extended cold storage it was more advantageous to rear insects on natural prey and to hold insects at 10 deg C than at 4 deg C. In contrast, for short periods of cold storage neither the temperature nor the food source affected the response to cold storage, with the exception that the diet-fed immatures survived better than prey-fed immatures. Commercial producers and researchers will find this information useful when developing storage regimes that minimize their operational costs and maximize the fitness of their insects for sale and release purposes or when storing a colony between uses.
Technical Abstract: Placing insects at reduced temperatures is a common practice to reduce growth rates while storing insects. Cold storage of insects is often used when transporting insects or to assist with efforts to increase the size of a colony. The response of insects to storage at reduced temperatures for short or extended periods has been shown to be effected by temperature, length of time exposed to the cold, developmental stage and food source. Cold storage effects egg, nymphal and adult survival, adult fecundity, and egg viability. We evaluated the influence of nutrient source on the response of eggs, nymphs and adults of Perillus bioculatus when exposed to two temperatures most likely to be used for short and extended storage by comparing natural prey-fed insects to artificial diet-fed insects. The results of our study showed that the survival of eggs from either prey-fed or diet-fed insects declined at both 4 deg C and 10 deg C as the length of storage exceeded 1 week. The survival of nymphs exposed to cold storage treatment was slightly higher than for eggs, with a similar response to time of storage. Unique to the nymphal stage was the superior performance of diet-fed insects over prey-fed insects. However, of the three developmental stages tested, the best survival was obtained with adults. Our results show that both prey-fed and diet-fed adults were able to withstand cold storage at 10 deg C for 3 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 deg C. Outcross mating of cold stored adults with adults held at 26 deg C indicated that adult females were more detrimentally affected by cold storage than males. There were differences in the response of P. bioculatus to cold storage compared to previously reported responses of P. maculiventris. However, the most notable difference is that P. maculiventris did better at almost all parameters than P. bioculatus. Collectively, these results demonstrate a nutrient influence on the response to cold storage at different developmental stages.