Bacteria as food had no effect on fecundity during domestication of the fruit fly, Bactrocera tryoni

Adult Bactrocera tryoni from different generations of domestication were given various diets to determine whether either or both the bacteria Klebsiella oxytoca and Klebsiella pneumoniae could provide a source of proteinaceous material sufficient to allow the female flies to produce mature oocytes and eggs or alternatively, whether the bacteria could act as a beneficial supplementary food when given in addition to the usual laboratory proteinaceous food that consisted of a paste of sucrose and yeast autolysate. Overall, there was no evidence from any generation studied that female flies could produce eggs or mature oocytes on a bacterial diet above the levels attained with access to culture medium without bacteria. Similarly, there was no evidence that bacterial supplementation to a diet that included a paste of sucrose and yeast autolysate was more beneficial than when the paste was the sole source of proteinaceous food. There was an increase in mature oocytes per female with the number of generations of culture but the extent of increase was greater when sugar/yeast paste was included in the diet. There was no evidence that mixtures of either bacterium species in nutrient broth or the broth itself was attractive to female B. tryoni over a distance of a few centimetres when the tested flies were caged at low density but flies of later generations did feed when offered either type of food at very close range.