LAUSR

Successful long-term cryopreservation of lepidopteran eggs for the mass production of parasitoids of the genus Trichogramma Westwood (Hymenoptera: Trichogrammatidae) requires a more tolerant species to withstand ultra-low temperatures. We compared the viability of eggs of Anticarsia gemmatalis Hubner (Lepidoptera: Erebidae) and Mythimna sequax Franclemont (Lepidoptera: Noctuidae), cryopreserved in liquid nitrogen, and evaluated the viability of M. sequax eggs to support the large-scale production of high-quality Trichogramma species. The presence of anti-freezing metabolites in lepidopteran eggs was detected and quantified by 1H nuclear magnetic resonance (NMR) spectroscopy. Parasitism by Trichogramma pretiosum Riley of M. sequax eggs stored for 30 days was significantly higher (84.2%) in comparison to A. gemmatalis (6.7%). The 1H NMR spectrum showed that the amounts of anti-freezing metabolites maltodextrin and trehalose were greater in M. sequax eggs, a possible explanation for their suitability to cryopreservation in comparison to A. gemmatalis. Eggs of M. sequax cryopreserved for up to 12 months maintained a mean rate of parasitism between 80 and 90% by Trichogramma atopovirilia Oatman and Platner and T. pretiosum, the latter declining to 79% after 12 months. Both Trichogramma species can exploit long-term storage of M. sequax eggs at ultra-low temperatures, without any apparent fitness penalty to the first generation. This is the first record of eggs of a noctuid species being cryopreserved for up to one year and remaining susceptible to parasitism by Trichogramma species. This procedure should enable large-scale production of hosts with high nutritional quality, and the production of parasitoids that is synchronized better with their use as biological control agents in annual crops.