Wastewater sludges as novel growth substrates for rearing codling moth larvae

Abstract

Codling moth (CM), Cydia pomonella (L) is a pest of numerous fruit species and is also used as a host for baculovirus (granulovirus) and hence the high rate production of CM is important for their biological control. In this research, different wastewater residues from cheese industry, starch industry and municipal wastes (eight different types of larval diets) were investigated as potential substitutes for protein ingredient (principal component) of insect diet. CM larvae were produced with 65–75% survival rate and were healthy as observed under the microscope. Hence, use of cheaper alternatives in the diet derived from agriculture and/or municipal wastes was feasible. Moreover, the preparation steps involved, sterilization, mixing and homogenization and hence the simplicity of these steps makes it practical to scale-up the diet to industrial scale in future. There was no contamination all during the process development. Dryness of all larval diets increased with time, however, even after 26 days, the dryness was ≤18% which is an acceptable norm. Weight, length and diameter of CM larvae was higher when 50% of protein was replaced by cheese industry sludge and corresponded to 145 ± 5, 174 ± 5, and 103 ± 3% increase, respectively. Cheese industry sludge gave highest fecundity of 340 eggs/adult/g of larval diet and the values were higher for other alternative larval diets too. Hence, CM insect diet can be developed using alternative protein substitutes (wastewater residues) is feasible, by adopting simplified scheme with scope for industrial scale-up.