Fitness consequences of artificial diets with different macronutrient composition for the predatory bugOrius majusculus

The commercial production ofOriusspp. (Hemiptera: Anthocoridae), includingOrius majusculus(Reuter), relies on the use of eggs ofEphestia kuehniella(Zeller) (Lepidoptera: Pyralidae) as rearing diet. However,E. kuehniellaeggs have become an expensive fodder thus increasing the price of these key biological control agents. The use of artificial diets potentially decreases the production costs. In this regard, establishing a link between dietary composition and fitness could advance the development of an optimum alternative artificial diet for these predatory insects. The aim of the current study was to test the effect of six artificial diets with different macronutrient composition on the development and reproductive fitness ofO. majusculuswhen compared with the effect ofE. kuehniellaeggs. In general, nymphal survival was not affected by diet, whereas development was slightly delayed on artificial diets. However, female body mass and fecundity were significantly lower on all of the artificial diets compared with theE. kuehniellaeggs diet, suggesting that artificial diets were of inferior quality. Within artificial diets, females fed the viable diet with highest content in lipid laid more eggs than those raised on the most protein-rich diets. We found there was some variation in carcass composition between theO. majusculusfed the various diets, but these variations did not match the differences found in the fitness parameters measured.