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 formulations of the protein bait NuLure(R) and standard torula yeast plus sodium borate (HTY-borax) pellets. Addition of 1-10% borax to 10% NuLure solution increased bait pH, and this increase was directly correlated with increase in number of female flies trapped in two-choice laboratory 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 volatiles from any of the NuLure solutions. There was variation in the response of flies to baits observed among the three test locations. Age structures of the populations at the different locations were compared by determining the percentage of females mated among the trapped females. There were significant differences in the percentage of mated females at the 3 locations, which ranged from 26-65% mated. In the locations with a high percentage of unmated female flies, the flies were less discriminating, at least among the protein baits offered in this study. Thus, age structure of the target population may alter response to bait. There was also variation in the pH of the baits at different locations 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 efficacy.