Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2004
Publication Date: 3/1/2005
Citation: Puche, H., Midgarden, D.G., Ovalle, O., Kendra, P.E., Epsky, N.D., Rendon, P., Heath, R.R. 2005. Effect of elevation and host availability on sterile and wild Mediterranean Fruit Flies (Diptera: tephritidae) distribution. Florida Entomologist. 88(1): 83-90. Interpretive Summary: Localized isolated populations or "hot spots" of the Mediterranean fruit fly have been found to persist in certain areas in Guatemala where successful eradication of this fly was obtained by the sterile insect technique (SIT) in combination with bait sprays. To identify possible causes for the "hot spots" due to elevation and host plant availability, scientists from the USDA Subtropical Horticulture Research Station (SHRS), USDA/APHIS-International Services, and USDA/APHIS-PPQ, GUATEMALA, evaluated the distribution of endemic wild and released sterile medfly by deploying cylindrical traps baited with a three-component lure in the Santa Maria valley, Guatemala. The investigation showed that wild medfly populations appeared to decrease when 40 sterile males/trap with wild females/ week were captured, and identified that coffee was a preferred host plant, and that, medflies were most abundant at 1273 m elevation range than at other elevations. This discovery is essential for management purposes to reduce costs of treatment effects by directing control efforts to those identified areas where the wild populations are most abundant.
Technical Abstract: Effects of elevation and host fruit availability on the distribution of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), were evaluated using cylindrical traps baited with a female-biased food-based synthetic lure. Tests were conducted in the Santa María valley, Guatemala during a sterile male release program. Traps were placed in or near host trees (primarily coffee & citrus) and in non-host shade trees when no hosts were available. Trap locations were grouped according to elevation every 170 m. Elevation group midpoints were 1103, 1273, 1443, and 1613 m above sea level. The spatial distributions of sterile males, wild males and females were clumped throughout the 13 wk of sampling. More wild female flies were captured in coffee in the 1273 m elevation and on non-host shade trees in the 1103 m elevation. The number of wild males was directly related to the number of wild females captured, and the sex ratio (female: male) was highest at the 1443 and 1613 m elevation ranges. There was no relationship between the number of sterile males and number of wild females in the traps at any elevation. At all elevation ranges, an inverse relationship was observed between the numbers of wild females and males with the mean numbers of sterile males / trap. Wild C. capitata populations appeared to decrease when 40 sterile males were captured per trap with wild females per week. The results indicated that coffee is a preferred host plant, and that, at least during the sampling period evaluated, the C. capitata were more abundant at the 1273 elevation range than at other elevations.