Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2004
Publication Date: 9/20/2005
Citation: Prokopy, R.J., Miller, N.W., Pinero, J., Oride, L.K., Chaney, N.L., Revis, H., Vargas, R.I. 2005. How effective is GF-120 fruit fly bait spray applied to border area sorghum plants for control of melon flies (Diptera: Tephritidae)?. Florida Entomologist. 87:3. P354-360. Interpretive Summary: Insecticidal bait sprays are often applied to border crops around cucurbit fields in Hawaii to control melon flies. We applied GF-120 Fruit Fly Bait to one-sided and two-sided field borders to evaluate the ability of this bait to protect cucumbers from female melon flies. In addition we evaluated responsiveness of mature melon fly females fed continuously with protein and those deprived of protein for 24 hours, to GF-120. We found no significant differences in control between one sided and two sided borders. We found no significant differences in responsiveness between the two types of flies. It seems likely that our findings were due to our use of very narrow swaths of sorghum. Wider swaths would likely be more effective at controlling melon fly.
Technical Abstract: Application of bait spray to non-host sorghum plants bordering host plants of melon flies, Bactrocera cucurbitae Coquillet, is a common practice for melon fly control in Hawaii. In a field study conducted in 2003 in Hawaii, we first asked whether GF-120 Fruit Fly bait spray applied to sorghum plants that bordered only two (opposite) sides of a patch of cucumbers was as effective in protecting cucumbers against melon flies as similar spray applied to sorghum plants that bordered all four sides of a cucumber patch. Second, we asked whether mature melon fly females carrying a high egg load but deprived of protein during the previous 24 h were more responsive to bait spray than mature females having continuous access to protein. Color-marked melon fly females were released outside of patches of sorghum-bordered cucumbers. We found no significant differences between two-sided and four-sided patches of sorghum or between protein-deprived (for 24 h) and protein-fed (continuously) mature females in percentages of released females that found cucumbers in bait-sprayed plots. Moreover, none of these percentages was significantly less than percentages of released females that found cucumbers in unsprayed plots, indicating an overall ineffectiveness of bait spray application. During the 24 h after alighting on cucumbers, released females that were captured alive on cucumbers and placed in cups with cucumbers laid on average almost as many eggs (insignificantly fewer) when taken from bait-sprayed plots as when taken from unsprayed plots. An overriding factor may have been the presence of just a narrow swath of sorghum (arising from a single row of plants), which may have permitted females easy access to cucumbers and masked potential differences among treatments. Bait spray applied to broader swaths of sorghum may be more effective.