Insect parasitoids cold storage: A comprehensive review of factors of variability and consequences

International audienceStorage at low temperature is a valuable method for increasing the shelf-life of natural enemies such as insect parasitoids. Cold storage is usually performed under sub-optimal temperatures, and therefore it is generally associated with major fitness costs. Tolerance to cold storage is a very plastic trait influenced by a wide range of endogenous (biotic) and exogenous (abiotic) factors experienced before, during, or after cold exposure. In fact, every hierarchical level from inter-species to inter-individuals shows a high plasticity in the response to cold exposure. Mortality represents the ultimate level of a range of sub-lethal perturbations accumulating during chilling. Even if individuals remain alive after cold storage, a reduction of several fitness-related traits may be observed directly, later in development or even in the next generation. The present review focuses on cold storage of insect parasitoids. We first consider the genotypic-based plasticity in cold storage tolerance and the complex network of endogenous and exogenous factors affecting the phenotypic plasticity in cold storage tolerance. We also summarize and examine the wealth of fitness-related traits affected by cold storage in parasitoids. This review provides a comprehensive list of documented factors that must be taken into account when designing cold storage protocols