Destruction of bacteria in the digestive tract of the maggot of Lucilia sericata (Diptera : Calliphoridae)

Green fluorescent protein-producing Escherichia coli were used to investiga te the fate of bacteria in the alimentary tract of sterile grown maggots, L ucilia sericata (Meigen), using a laser scanning confocal microscope. A com puter program was used to analyze the intensity of the fluorescence and to quantify the number of bacteria. The crop and the anterior midgut were the most heavily infected areas of the intestine. A significant decrease in the amount of bacteria was observed in the posterior midgut. The number of bac teria decreased even more significantly in the anterior hindgut and practic ally no bacteria were seen in the posterior end, near the anus. The viabili ty of bacteria in the different gut sections was examined. It was shown tha t 66.7% of the crops, 52.8% of the midguts, 55.6% of the anterior hindguts, and 17.8% of posterior hindguts harbored living bacteria. In conclusion, d uring their passage through the digestive tract the majority of E. coli was destroyed in the midgut. Most of the remaining bacteria were killed in the hindgut, indicating that the feces were either sterile or contained only s mall numbers of bacteria.