Olfactory response of Anastrepha striata （Diptera： Tephritidae） to guava and sweet orange volatiles

The behavioral responses of virgin and mated female Anastrepha striata Schiner （Diptera： Tephritidae） to guava （Psidium guajava L.） or sweet orange （Citrus sinensis L.） were evaluated separately using multilure traps in two-choice tests in field cages. The results showed that flies were more attracted to guava and sweet orange volatiles than to control （unbaited trap）. The physiological state （virgin or mated） of females did not affect their attraction to the fruit volatiles. Combined analysis of gas chromatography coupled with electroantennography （GC-EAD） of volatile extracts of both fruits showed that 1 and 6 compounds from orange and guava, respectively elicited repeatable antennal responses from mated females. The EAD active compounds in guava volatile extracts were identified by gas chromatography-mass spectrometry （GC-MS） as ethyl butyrate, （Z）-3-hexenol, hexanol, ethyl hexanoate, hexyl acetate, and ethyl octanoate. Linalool was identified as the only antennal active compound in sweet orange extracts. In field cage tests, there were no significant differences between the number of mated flies captured by the traps baited with guava extracts and the number caught by traps baited with the 6-component blend that was formulated according to the relative proportions in the guava extracts. Similar results occurred when synthetic linalool was evaluated against orange extracts. From a practical point of view, the compounds identified in this study could be used for monitoring A. striata populations.

Sexual behavior and male volatile compounds in wild and mass-reared strains of the Mexican fruit fly Anastrepha ludens （Diptera： Tephritidae） held under different colony management regimes

We compared the calling and mating behavior and volatile release of wild males Anastrepha ludens （Loew） with males from 4 mass-reared strains： （i） a stan- dard mass-reared colony （control）, （ii） a genetic sexing strain （Tap-7）, （iii） a colony started from males selected on their survival and mating competitiveness abilities （selected）, and （iv） a hybrid colony started by crossing wild males with control females. Selected and wild males were more competitive, achieving more matings under field cage conditions. Mass-reared strains showed higher percentages of pheromone calling males under field conditions except for Tap-7 males, which showed the highest percentages of pheromone calling males under laboratory cage conditions. For mature males of all strains, field-cage calling behavior increased during the last hour before sunset, with almost a 2 fold increase exhibited by wild males during the last half hour. The highest peak mating activity of the 4 mass-reared strains occurred 30 rain earlier than for wild males. By means of solid phase microextraction （SPME） plus gas chromatography-mass spectrometry （GC- MS）, the composition of volatiles released by males was analyzed and quantified, Wild males emitted significantly less amounts of （E,E）-α-farnesene but emitted significantly more amounts of （E,E）-suspensolide as they aged than mass-reared males. Within the 4 mass-reared strains, Tap-7 released significantly more amounts of （E,E）-α-farnesene and hybrid more of （E,E）-suspensolide. Differences in chemical composition could be ex- plained by the intrinsic characteristics of the strains and the colony management regimes. Characterization of calling behavior and age changes of volatile composition between wild and mass-reared strains could explain the differences in mating competitiveness and may be useful for optimizing the sterile insect technique in A. ludens.