Abstract
We tested the suppression of bacterial contamination of artificial diet by 5-min submersion of Euscepes postfasciatus eggs in 70% ethanol before a simple egg-seeding method that is used for mass-rearing of other weevil species. In this egg-seeding method, eggs are suspended evenly in a sterile furcellaran solution (a viscous liquid): the mixture is then dropped onto the surface of the diet. When weevil eggs rinsed only with sterile water were mixed with the solution and placed on the diet, bacterial colonies formed in all replicates within 3 days. Ethanol treatment of the eggs before mixing with the solution significantly reduced and delayed formation of bacterial colonies on the surface of the diet by 29% and 8d, respectively. However, these values were significantly less than those achieved by an ordinary egg sterilization method (20-min submersion in 5% formaldehyde; 71% and 13d). Therefore, it appears that ethanol treatment of E. postfasciatus eggs alone is insufficient for preventing bacterial contamination of diet in the mass-rearing of E. postfasciatus.
