A group of researchers in Mexico report observing sexual differences in some body parts of the Mexican fruit fly that may play a role in regurgitation in a recent study the authors believe is the first of its kind. The research team led by Martin Aluja and including entomologist John Stoffolano of the Stockbridge School of Agriculture say regurgitation is a behavior that may help adult flies eliminate toxins such as insecticides that they have ingested.
“Our findings shed light on an interesting phenomenon that has important practical implications,” they write, adding that more research is now needed. “If indeed it is proven that regurgitation may also be associated with possibly eliminating toxicants ingested by the insect, our findings can lead the way to better understanding why fruit fly chemical control is not always as efficient as expected.” Stoffolano adds, “At the moment, we do not understand all of the systems of the fly.”
As he explains, the teams basic goal was to understand mechanisms involved in regurgitation behavior of the economically important Mexican fruit fly pest, Anastrepha ludens Loew. Using optical scanning electronic microscopy (SEM) and transmission electron microscopy (TEM) to study digestive structures, plus a feeding assay, Aluja and colleagues found male crop duct nerve bundles are larger than in the female, but these techniques failed to find a direct structural connection to regurgitation. However, the feeding assay did indicate that males regurgitate significantly more than females.
Stoffolano says they wanted “to completely identify using SEM/TEM, all of the structures both externally and internally of the Mexican fruit fly. Other than the common vinegar fly, Drosophila melanogaster, this has not been done for any other fruit fly.”
He adds that this long-term collaboration will serve as a platform for future studies aimed at “controlling the pest in the most logical ways based on the previous studies at the INECOL laboratory.” Good biological control may result in lower pesticide use, better acceptance by American consumers and lower costs for Mexican farmers, he points out.
Based on earlier studies of tropical fruit flies, Stoffolano says that Aluja was able to show the U.S. Department of Agriculture that it is safe to import Mexican avocados, which has pleased U.S. consumers and helped Mexican farmers. Further, success at INECOL could be helpful in controlling U.S. fly pests such as Bactrocera, which attacks fruits in Florida, the entomologist adds.