EVALUATION OF PROTEIN BAIT FORMULATIONS FOR THE CARIBBEAN FRUIT-FLY (DIPTERA, TEPHRITIDAE)

Laboratory and field trials were conducted to determine the preference of the Caribbean fruit fly, Anastrepha suspensa (Loew), for aqueous f ormulations of the protein bait NuLure(R) and standard torula yeast pl us sodium borate (HTY-borax) pellets. Addition of 1-10% borax to 10% N uLure solution increased bait pH, and this increase was directly corre lated with increase in number of female flies trapped in two-choice la boratory bioassays and in field trials conducted in three locations in south Florida during the spring of 1992. Overall, significantly more flies were attracted to volatiles from HTY-borax solution than to vola tiles from any of the NuLure solutions. There was variation in the res ponse of flies to baits observed among the three test locations. Age s tructures of the populations at the different locations were compared by determining the percentage of females mated among the trapped femal es. There were significant differences in the percentage of mated fema les at the 3 locations, which ranged from 26-65% mated. In the locatio ns with a high percentage of unmated female flies, the flies were less discriminating, at least among the protein baits offered in this stud y. Thus, age structure of the target population may alter response to bait. There was also variation in the pH of the baits at different loc ations due to the pH of the water used to prepare the solutions. Bait pH may be a significant factor that has been overlooked in field tests conducted at different locations or at different times as changes in water pH, as well as bait protein pH, may strongly affect trap efficac y.