Biological quality of Anisopteromalus calandrae (Hymenoptera: Pteromalidae) reared with cold-stored larvae of Lasioderma serricorne (Coleoptera: Anobiidae)

An effective storage method for larvae of the tobacco beetle Lasioderma serricorne (F.) (Coleoptera: Anobiidae) would be useful for rearing and studying its larval parasitoid Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae), which is an idiobiont ectoparasitoid. In this study, we observed the survival of L. serricorne larvae that were refrigerated under different conditions (stored at 7 °C, 10 °C, and 13 °C for 30, 45, 60, and 75 days) and the number of emerging A. calandrae under these conditions, aiming to determine the optimal temperature for L. serricorne larvae storage. Our results showed that 10 °C was the optimum temperature for storing L. serricorne larvae, with no significant differences recorded in the number of parasitoids that emerged from L. serricorne larvae that had been refrigerated for 75 days compared with the control. After refrigeration at 7 °C for 45 days, L. serricorne larvae were almost dead, with no parasitoid emergence, suggesting that dead host larvae were not used for rearing A. calandrae. Interestingly, when stored for more than 45 days at 13 °C, L. serricorne larvae developed abnormally and died, and the number of parasitoids that emerged was also significantly reduced. Subsequently, we tested the adaptive parameters of A. calandrae reared with L. serricorne larvae after cold storage at 10 °C for different periods, including development time, sex ratio, longevity, adult body length, and fecundity. These parameters were not significantly different from those of the control with the exception of fecundity, which indicated that progeny production on refrigerated hosts gradually declined with storage duration. In summary, A. calandrae could successfully parasitize and utilize L. serricorne larvae as hosts for long-term refrigeration at 10 °C for up to 45 days without considerable undesirable effects on offspring suitability. These results may have practical implications regarding the development of efficient mass-rearing systems for A. calandrae.