Interpretive Summary: It is reported that some fruit fly pests are attracted to and feed on bird droppings. Flies need a source of nitrogen in their diet in order to produce eggs. This is of importance because such natural food sources compete against and thus lessen the effectiveness of fruit fly traps. Experiments were conducted to see if the Mexican fruit fly utilizes bird droppings as a source of nutrition. The results were generally negative. Flies with access to bird droppings produced no more eggs than flies without access. Furthermore, flies with access to bird droppings produced far fewer eggs than flies with access to other nitrogen rich foods such as yeast. Thus, the behavior and ecology of the Mexican fruit fly seems to be very different than that of some other fruit fly pests.
Technical Abstract: Adults of the Mexican fruit fly given access to bird droppings were not significantly more fecund than flies without access to bird droppings. Flies with access to dried torula yeast and sugar had a sevenfold increase in fecundity compared to flies maintained on sugar only. The latter result demonstrates that flies maintained on a diet of sugar alone are nutritionally deprived. Yet, bird droppings were not utilized to increase fecundity by these nutritionally challenged flies. Reports that other economically important tephritid species utilize bird droppings as a natural source of organic nitrogen do not seem to apply to the Mexican fruit fly.