ARS | Publication request: Sex pheromone investigation of Anastrepha serpentina (Diptera: Tephritidae)

Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 2, 2008
Publication Date: N/A

Interpretive Summary: This research determined that further investigation of pheromone chemicals for development of lures for the Sapote fruit fly is not warranted. The Sapote fruit fly, which has been reported as a potential pest of citrus, has been found increasingly often in Texas during recent years. These finds have raised awareness and fear of this insect, prompting studies to find ways to identify outbreaks quickly so that steps can be taken to eliminate the threat before damage occurs. As part of our response to this threat, we began investigations into the sexual behavior of this fly with the hope of identifying chemicals produced by males that attract females for the purpose of mating. Initially, we identified several chemicals produced by males including one chemical that had never been encountered in nature. In the current work, we tested the attractiveness of those chemicals to females with the hope that an attractant could be developed that would effectively draw females to traps for early detection of incipient populations. Unfortunately, none of the chemicals elicited olfactory responses on female antennae nor did they attract females in great numbers. These results indicate that further investigation of these chemicals for development of lures for the Sapote fruit fly is not warranted.

Technical Abstract: Attraction of virgin females to odor of calling males was demonstrated. This sex pheromone mediated attraction occurred during the latter half of a 13-h photophase but not during the first half of the day. Two major components of emissions of calling males, 2,5-dimethylpyrazine (DMP) and 2,5-dihydro-3,6-dimethylpyrazine (DHDMP), and trimethylpyrazine (TMP), a minor component, were tested for pheromonal activity. DMP and TMP elicited antennal responses using (GC-EAD) electroantennogram assays, but no response was observed for DHDMP. DMP and combinations of DMP and TMP were not attractive in laboratory bioassays. Bioassays of DHDMP were complicated by its instability making purification of the compound unfeasible. Bioassays of DHDMP in unpurified form were further complicated by the presence of reaction byproducts and unreacted reagent in crude preparations of the DHDMP. However, statistical analysis indicated that combinations of 100-500 ng of DHDMP in mixtures with DMP as the major component elicited attraction in laboratory bioassays with sexually active female flies. Taking into account all of the data, we could not conclude that any of the chemicals emitted by males are pheromones, but based on female fly responses to mixtures of DHDMP and DMP, this is the most likely scenario.