Optimizing Mass Rearing of the Egg Parasitoid, Telenomus podisi, for Control of the Brown Stink Bug, Euschistus heros

SIMPLE SUMMARY: Biological control programs are used to effectively manage pests in a more sustainable way, such as the case of the microwasp parasitoid Telenomus podisi for managing eggs of the brown stink bug Euschistus heros, a key pest in South American soybean. A biological control program requires continuous production of the parasitoids and thus, artificial diets and freezing of host eggs are necessary. We evaluated the parasitism capacity of T. podisi reared on fresh or previously frozen eggs from E. heros fed on natural or two artificial diets. Seven constant temperatures were tested for each condition. We measured biological parameters of wasps and the rates of parasitism. We found that 24 °C had better parasitism and viability parameters, and was most-favorable to T. podisi production. We also found that both tested artificial diets for E. heros produced eggs that support mass rearing of this egg parasitoid. ABSTRACT: The parasitoid Telenomus podisi Ashmead, 1893 is used in biological control programs in Brazil against eggs of Euschistus heros (Fabricius, 1798), a key pest of soybean, Glycine max (L.) Merr. To optimize the mass production of parasitoids, artificial diets and storage of host eggs at low temperatures have been developed; however, direct comparisons of the effects of these conditions have not occurred. We assessed a double factorial arrangement composed of six treatments (fresh or cryopreserved E. heros eggs from adults fed on natural or two artificial diets). We evaluated the biological characteristics and parasitism capacity of T. podisi produced from these treatments across seven temperatures. The thermal range between 21 and 30 °C resulted in satisfactory daily parasitism in all treatments tested, with an inverse relationship between temperature and female survival. The best parasitoid biological parameters were found between 21 and 27 °C, where all tested diets supported T. podisi development, with the best results from artificial diets. Fresh eggs and those frozen in liquid nitrogen and stored at −196 °C until use supported parasitoid development. These results suggest that the best method to mass rear T. podisi is to use artificial diets to rear E. heros and store eggs until needed, and then rear parasitoids at 24 °C.