Optimizing cold storage of Encarsia formosa (Hymenoptera: Aphelinidae) reared on yacon: enhancing fitness, flight, and biocontrol potential for effective whitefly management

Effective cold storage is a key strategy for extending the shelf life of biological control agents and ensuring a reliable and timely supply for pest management programs. In this study, we evaluated the effects of different cold storage durations (0, 10, 15, 20, 25, 30, and 35 d at 10 °C) on the performance, pest control potential, and flight capacity of Encarsia formosa Gahan (Hymenoptera: Aphelinidae) reared on yacon (Smallanthus sonchifolius Poeppig & Endlicher) as an alternative host plant. Our results showed that the parental adult emergence rate remained high (>82%) for parasitoids stored up to 20 d, while offspring emergence exceeded 95% for all treatments except the 35-d storage. Parasitoids stored up to 20 d retained body size (head width, body length, hind tibia length), and those stored up to 10 d preserved total and mature egg loads as well as parasitism and host-killing capacities comparable to the control (0 d cold storage duration). Adults from the 15-d storage treatment maintained strong host-feeding and flight abilities. These findings demonstrate that E. formosa reared on yacon can be cold-stored at 10 °C for up to 10 d without compromising key biological traits, providing practical guidance for mass-rearing, storage, and field release strategies. This work highlights the innovative use of yacon as an alternative host plant to enhance cold tolerance and biocontrol efficiency, offering a promising approach for improving the industrial production and application of E. formosa against whitefly pests.