Frozen lepidopteran larvae as promising alternative factitious prey for rearing of Orius species.

Orius predators are important natural enemies of thrips, whiteflies and mites and are reared as commercial biological agents. Due to the importance of food sources in natural-enemy mass-rearing programs, researchers have been screening efficient food sources for the rearing of such enemies. In this study, we compared the demographic fitness of Orius strigicollis reared on 3 foods (i) frozen 48h-old eggs (FE) of Spodoptera frugiperda, (ii) frozen 24h-old 2^nd instar larvae (FL) of S. frugiperda, and (iii) 2^nd instar larvae of Frankliniella occidentalis (western flower thrips, WFT) using the age-stage, two-sex life table. According to the life table analysis results, O. strigicollis were successfully maintained on FL for consecutive generations, and the reproductive performance of individuals from the 1^st (G1) and 6^th (G6) generations was evaluated. Among the 3 tested foods, FE was the lowest suitable food, leading to slower development and lower O. strigicollis fecundity than with other foods. In overall, O. strigicollis showed similar fitness when reared on WFT and on FL (no difference in fecundity), although the intrinsic rate of increase (r) and finite rate of increase (λ) was lower on FL. The fecundity and longevity of G6 O. strigicollis reared on FL were not significantly different from those of G1. The results indicate that frozen S. frugiperda larvae could be a promising factitious food for the long-term rearing of O. strigicollis and more broadly that frozen larvae of Lepidoptera may be potential new factitious food sources for Orius spp. rearing. [ABSTRACT FROM AUTHOR]