Submitted to: Bulletin of Entomological Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/1/2011
Publication Date: 10/20/2011
Citation: Pinero, J.C., Mau, R., Vargas, R.I. 2011. A comparative assessment of the response of three fruit fly species (Diptera: Tephritidae) to a spinosad-based bait: Effect of ammonium acetate, female age, and protein hunger. Bulletin of Entomological Research. 101:373-381. Interpretive Summary: Fruit flies (Diptera: Tephritidae) are among the most destructive pests of agriculture in the world. Efforts to suppress fruit fly populations around the globe relied heavily on the application of protein baits mixed with highly toxic organophosphate insecticides. Concerns for use of organophosphate insecticides in residential areas has raised serious environmental/ human health concerns. Safer alternatives to organophosphate insecticides for fruit fly monitoring and control have been developed by the Hawaii Fruit Fly Area-Wide Pest Management (AWPM) program, funded by the U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS). Recently, a low toxicity, spinosad-based bait, commercially marketed as GF-120 NF Naturalyte Fruit Fly Bait (Dow Agrosciences), has been used to suppress fruit flies. The objective of this study was to assess the relative attractiveness of three formulations of GF-120 that varied in the amounts of ammonium acetate (AA) which is found to be very attractive to fruit flies. This study conducted at Agricultural Research Service (ARS), U.S. Department of Agriculture, Pacific Basin Agricultural Research Center, Hilo, Hawaii, indicated that a comparatively small increase in the amount of AA in GF-120 was associated with an increase in the number of female C. capitata responding under field conditions. In contrast, an increase in the amount of AA did not result in an increase of the number of female B. dorsalis and B. cucurbitae responses. Information gained from this comparative study can be used to unify criteria concerning the effect of AA on the behavioral response of pestiferous fruit flies.
Technical Abstract: Ammonia-releasing substances are known to play an important role in fruit fly (Diptera: Tephritidae) attraction to food sources and this information has been exploited for the development of effective synthetic food-based lures and insecticidal baits. In field studies conducted in Hawaii, we examined the behavioural response of wild female oriental fruit fly (Bactrocera dorsalis (Hendel)), melon fly (B. cucurbitae (Coquillett)), and Mediterranean fruit fly (Ceratitis capitata (Wiedemann)) to spinosad-based GF-120 NF Fruit Fly Bait containing either, 0, 1, or 2% ammonium acetate in the bait mixture. Use of visually-attractive yellow bait stations for bait application in the field allowed for proper comparisons among bait formulations. Field cage tests were also conducted to investigate, using a comparative behavioural approach, the effects of female age and protein starvation on the subsequent response of F1 generation B. cucurbitae and B. dorsalis to the same three bait formulations that were evaluated in the field. Our field results indicate a significant positive effect of the presence, regardless of amount, of AA in GF-120 for B. dorsalis and B. cucurbitae. For C. capitata there was a significant positive linear relationship between the relative amounts of AA in bait and female response. GF-120 with no AA was significantly more attractive to female C. capitata, but not to female B. dorsalis or B. cucurbitae, than the control treatment. Our field cage results indicate that the effects of AA present in GF-120 can be modulated by the physiological stage of the females. There was an overall stronger response of female B. cucurbitae to GF-120 than B. dorsalis over the various ages and levels of protein starvation regimes evaluated. Results are discussed in light of their applications for effective fruit fly suppression.