Analysis of Historical Recapture Rates in the Anastrepha ludens (Loew), Mexican Fruit Fly (Diptera: Tephritidae) Program in Texas, USA

The Mexican fruit fly (Anastrepha ludens (Loew), Mexfly) SIT control program in the Lower Rio Grande Valley, Texas, has been jointly operated by USDA and Texas Department of Agriculture since 1984. In this chapter, we analyze historical fluctuations in Mexfly sterile release, sterile recapture, and wild fly capture. Approximately 84% of Texas commercial citrus is in Hidalgo County, 12% in Cameron County, and 4% in Willacy County, with extensive citrus and other host material found in backyards or noncommercial sites (called “dooryards”). Aerially released sterile fly numbers fluctuated from ~107.9 million to ~716.8 million with a mean of 452.1 ± 8.5 million per month. Since 2007, aerial release rate for standard Mexfly is 123,550 flies and all male strain is 61,775 flies per km2, safeguarding 109.3 km2 (27,000 acres) of citrus. Recaptured sterile flies in traps fluctuated from ~5.6 thousand to ~494.1 thousand with a mean of 120.1 ± 6.6 thousand flies per month. Since 2012, there are 1840.6 ± 3.6 Mexfly surveillance traps in Hidalgo County, 953.6 ± 5.6 in Cameron County, and 168.5 ± 1.0 in Willacy County. Higher numbers of sterile, wild, and larval Mexfly are captured from October to June and smaller numbers from July to September.