Raspberry ketone supplement promotes early sexual maturation in male Queensland fruit fly, Bactrocera tryoni (Diptera Tephritidae)

BACKGROUND: Raspberry ketone (RK) is highly attractive to sexually mature, but not immature, males of many Bactrocera species, including Queensland fruit fly ('Qfly', Bactrocera tryoni), and acts as a metabolic enhancer in a wide diversity of animals. We considered the possibility that, as a metabolic enhancer, RK in adult diet might accelerate sexual maturation of male Qflies. RESULTS: Recently emerged adult Qfly males (0-24h old) were exposed to RK-treated food for 48h and were then provided only sugar and water. Four doses of RK (1.25, 2.5, 3.75 and 5%) along with control (0%) were tested with two types of food: sugar alone and sugar mixed with yeast hydrolysate (3:1). For flies tested when 4-10 days old all RK doses increased mating probability of flies fed sugar mixed with yeast hydrolysate but did not show any effect on mating probability of flies fed only sugar. No effects of RK were found for flies tested when 10-30 days old for either diet group. There was no evidence that RK affected longevity at any of the doses tested. CONCLUSION: Feeding of RK together with yeast hydrolysate to immature Qfly increases mating propensity at young ages and accordingly shows significant potential as a pre-release supplement that might increase the proportion of released flies that attain sexual maturation in Sterile Insect Technique programmes.