Sexual maturation of male Bactrocera correcta (Diptera: Tephritidae) and age-related responses to β-caryophyllene and methyl eugenol

Sexual maturation of male Bactrocera correcta (Bezzi) and age-related responses to β-caryophyllene (CP) and methyl eugenol (ME) were examined to identify effective attractants for sexually immature males of the species. Sexual maturation rates (100 × number of cages containing males which attained sexual maturity/total number of cages at a given day) over different ages were 0.0%, 6.7%, and 100.0% for 5-, 6-, and 13-day-old, respectively, and at all the different ages, more males were captured with CP than with ME. The capture rate (the predicted probability by logistic regression) with CP was 29.7% (30.6%) for 5-day-old males, which were still sexually immature, and 52.7% (38.2%) for 6-day-old males, for which the earliest sexual maturation was observed. In contrast, no 5-day-old males responded to ME (the probability was 12.6%), and the capture rate (the probability) of 6-day-old males was merely 0.3% (14.5%), while the rate gradually increased later. The present study revealed that certain males of B. correcta responded to CP prior to sexual maturation but not to ME under the laboratory conditions. These results imply that CP could be an effective attractant used in male annihilation techniques for B. correcta and that ME may not be useful.