Submitted to: Entomophaga
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 2, 1998
Publication Date: N/A
Interpretive Summary: The Colorado potato beetle (CPB) is an economically important pest of potato, tomato and eggplant crops in North America and Europe. CPB costs growers hundreds of millions of dollars every year. After the mass release of the parasitic wasp, E. puttleri, in New Jersey eggplant fields, the population of CPB was greatly reduced, and no additional applications of chemical pesticides were required. In addition the fruit was of higher quality than fruit harvested from fields treated with chemical pesticides. However, the high cost of mass rearing the parasite on CPB eggs is a major obstacle to its practical use in the field. A cost-effective in vitro rearing system could permit lower cost production of large numbers of E. puttleri adults for use as a biological control agent. We now report the development of an artificial diet and an artificial egg which will support the development of E. puttleri through the pupal stage. A diet which is free of insect products (expensive ingredients) has also been developed. It will support parasite growth through the prepupal stage. The artificial egg and diets are major breakthroughs for the augmentative rearing of this beneficial wasp, and will permit the testing of alternative nutritional sources in the development of a cost-effective rearing system for E. puttleri.
A variety of semidefined artificial diets were developed and tested for their ability to support the in vitro development of E. puttleri. In the most effective diet, 2.6% of E. puttleri pupated. This diet contained high levels of hen egg yolk combined with M. sexta larval hemolymph, or with a mixture of M. sexta egg homogenate and larval hemolymph. Egg homogenate alone (without the addition of hemolymph) was not capable of supporting the parasitoid's development. Thus, hemolymph appears to contain material(s)/factor(s) which is (are) important for inducing pupation of the wasp. Addition of M. sexta pupal fat body tissue extract (in place of hemolymph) also promoted pupation of E. puttleri. Gypsy moth larval hemolymph could not replace M. sexta larval hemolymph. Fractionation irreversibly reduced the growth-promoting effects of M. sexta larval hemolymph. However the most beneficial fraction contained components whose molecular weights were ò 1000 kd. In diets that were devoid of insect materials, the best results were achieved when hen egg yolk, FreAmine, yeast extract, lactalbumin, trehalose, fetal bovine serum and bovine milk were included. This is the first report of an artificial diet for in vitro rearing an eulophid parasitoid from the egg through the pupal stage.