Effect of Acyclovir on the Microbial Contamination in the Artifical and Natural Diets for Rearing of Galleria mellonella L. larvae

Abstract

The effects of clinically important antiviral agent, acyclovir, on microbial contamination sources in the artificial (Bronskill diet) and natural diets (dark old honeycomb) used for rearing of a serious pest in the honey bee hives, greater wax moth Galleria mellonella L. The larvae were reared on diets conatining different concentrations of acyclovir (0.001-3.0 %). Control larvae were reared on diet without acyclovir. The diet with 1.0% of acyclovir had no significant negative effects on biological parameters of immature stages and adult stage. Therefore, dietary antimicrobial effects of this safe concentration on insect were tested. Antimicrobial effects varied with the rearing media, initial microbial sources in diets and microorganism types. Acyclovir at 1.0 g in artificial diet was significantly capable of reducing the number of yeast and molds from 6000 ± 565.6 and 800 ± 20.6 CFU to 800 ± 35.3 and 50 ± 2.3 CFU respectively. Proliferation of Stahylococcus aureus (3200 ± 141.4 CFU) inhabiting this diet were completely inhibited by 1.0 g of acyclovir. Coliform bacteria are not seen in the artificial diet. This concentration of acyclovir completely inhibited proliferation of coliform in natural diet while the artificial diet lacks coliform bacteria. Acyclovir at a level of 1.0% was also of capable of preventing the bacterium, mold and yeast growth in both artificial diet and natural food. We infer from these results that the importance of determining the antimicrobial effect of an antimicrobial agent before adding it as a food additive to the diet during laboratory rearing of insects.