ESTABLISHING A FRUIT-FLY FREE-ZONE IN SOUTHWESTERN PUERTO RICO I: FEASIBILITY ASSESSMENT
Location: Tropical Crops and Germplasm Research
Title: Forest fragments as barriers to fruit fly dispersal: Anastrepha (Diptera: Tephritidae) populations in orchards and adjacent forest fragments in Puerto Rico
Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 18, 2012
Publication Date: April 10, 2013
Citation: Jenkins, D.A., Kendra, P.E., Van Bloem, S., Whitmire, S., Mizell, R., Goenaga, R.J. 2013. Forest fragments as barriers to fruit fly dispersal: Anastrepha (Diptera: Tephritidae) populations in orchards and adjacent forest fragments in Puerto Rico. Environmental Entomology. 42(2):283-292.
Interpretive Summary: Fruit fly populations were monitored for sixteen months in orchards and natural areas in southern Puerto Rico. Some natural areas harbored populations of economically important fruit flies, but others had very low populations, especially compared with populations in orchards containing host fruit. Abundance of fruit flies was seasonal, usually highest in the summer when host fruits, such as mango, were available. The distribution of flies among traps in orchards was more or less equal, but in all natural areas, certain traps accounted for more flies than would be expected by chance, indicating that proximity to a host is very important in trap placement. The low levels of flies trapped in natural areas suggest that these areas are barriers to the dispersal of fruit flies and may be used in the creation of a fruit fly-free zone or an area-wide suppression program.
McPhail-type traps baited with ammonium acetate and putrescine were used to monitor populations of Anastrepha obliqua and A. suspensa at four sites in Guánica, Puerto Rico; one forest fragment in Ponce, Puerto Rico; in a commercial mango orchard in Guayanilla, PR; and an experimental carambola orchard in Juana Diaz, PR; as well as in the forest fragments bordering these orchards. Intensive trapping (transects of 30 traps at each site, each trap within 15 m of adjacent traps) for sixteen months demonstrated very low (one fly captured) to moderate populations (56-146 flies captured) of the economically important species of Anastrepha in the forest fragments, whereas the two fruit orchards harbored large populations of these species (1826 flies captured in the carambola orchard and 365 flies captured in the mango orchard). The forest fragments adjacent to orchards harbored very low (13 flies captured next to the mango orchard) or moderately low (167 flies were captured next to the carambola orchard) populations of the fruit flies. The number of flies captured in the forest fragment adjacent to the carambola orchard was not correlated with distance from the orchard, but proximity to host trees in the forest fragment; two traps in proximity to known hosts accounted for 67% of all the A. obliqua captured in this forest fragment. Sampling fleshy fruit from native trees in these forest fragments did not yield Anastrepha pupae, except for Amyris elemifera, which yielded one adult male A. suspensa from a total of 300 collected fruit. During this experiment, we also trapped Anastrepha antilliensis, a native fly about which very little is known. Our results demonstrate that populations of Anastrepha species are highly variable in southern Puerto Rico. The results are discussed as they pertain to monitoring and detecting Anastrepha spp. with the McPhail-type trap, ammonium acetate, and putrescine baiting system and the dispersal of these flies within Puerto Rico.