Age-related responsiveness of male Bactrocera latifrons (Diptera: Tephritidae) to α-ionol+cade oil relative to age of sexual maturity

Abstract

Bactrocera latifrons (Hendel) is a tephritid fruit fly of primarily Asian distribution that became established in Hawaii in 1983 and recently invaded Africa, being detected in Tanzania in 2006 and in Kenya in 2007. Although males of the majority of dacine fruit flies respond to either methyl eugenol or cuelure, B. latifrons shows little to no response to these lures. Instead, B. latifrons males respond to α-ionol+cade oil. Male age-related responsiveness to α-ionol+cade oil (using wind tunnel bioassays) relative to the age of sexual maturity (assessed through spermathecal dissections) was documented using wild B. latifrons adults. Relative to the peak response observed at day 28, males exceeded 50, 75 and 90% of the peak response at days 7, 14 and 21, respectively. No females younger than 16 days old were mated. Based on a sigmoidal regression of the percentage of inseminated females versus age, 50% of females were inseminated when 18.8 days old, with the percentage increasing to 75 and 90% at 19.8 and 20.9 days of age, respectively. At 24 days and older, 100% of females were mated. The observation that no female B. latifrons were mated by day 14, while 14-day-old male flies achieved over 75% of the peak response to α-ionol+cade oil, suggests that α-ionol+cade oil mass trapping has some potential to remove males from the field before they can contribute to increasing field populations through matings, as previously found with the oriental fruit fly, B. dorsalis (Hendel), and its respective male lure, methyl eugenol. The effectiveness of the removal of males before they mate, though, would be expected to be less for B. latifrons than the male annihilation achieved in the use of methyl eugenol with B. dorsalis because the male lure for B. latifrons is weaker overall.