In vitro rearing of Edovum puttleri, an egg parasitoid of the Colorado potato beetle, from egg to pupal stage in artificial diets devoid of insect sources: Effects of dietary amino acid and carbohydrate levels

Previous studies have demonstrated that Edovum puttleri, an egg parasitoid of the Colorado potato beetle, can be reared through the pupal stage in an artificial diet containing either hemolymph from Manduca sexta or CPB embry onic cell line-conditioned medium. In order to improve the diet and reduce production costs, i.e., eliminate the insect-derived components, the effect s of 13 amino acids and 20 carbohydrates on the growth and development of t he parasitoid were determined. In the presence of any one of five of the am ino acids (arginine, glutamine, lysine, threonine and valine) at a concentr ation of 1%, or eight of the carbohydrates (cellobiose, fructose, gentiobio se, glucose, lactose, melinbiose, sorbitol and threhalose), also at a conce ntration of 1%, more than 75% of the larvae molted to the second instar. At higher concentrations (2 and 3%), all five of the amino acids and most of the eight sugars promoted third instar formation. Prepupal formation was al so observed. In the presence of threonine (at 2 and 3%) or glutamine (at 3% ), between 22 and 29% of the parasitoids formed prepupae. Of the six sugars (at 3%) that promoted prepupal formation, lactose and sorbitol which promo ted 18 and 20% prepupation, respectively, were the most effective. In the p resence of all 13 amino acids teach at 3%) or all 20 carbohydrates teach at 3%), 36 and 39%, respectively, of the parasitoids formed prepupae. At lowe r concentrations, reduced percentages of prepupal formation were observed. Since the amino acids, glutamine and threonine, and the sugars, fructose,,g entiobiose, glucose, lactose, sorbitol and trehalose, when added individual ly to the diet (at a concentration of 3%) were most effective in promoting prepupal formation, the effect of one of these two amino acids in combinati on with each of the six sugars was tested. Glutamine in combination with la ctose or sorbitol was able to promote pupation (less than or equal to6.3%), and threonine in combination with any one of five of the sugars (lactose a nd sorbitol were most effective) supported pupal formation (less than or eq ual to6.7%). Our study demonstrated that E. puttleri can be successfully re ared from the egg through the pupal stage in an artificial diet devoid of i nsect materials.