Repellency and oviposition deterrence effects of plant essential and vegetable oils against female Q ueensland fruit fly B actrocera tryoni( F roggatt) ( D iptera: T ephritidae)

Eight plant essential oils and five vegetable oils were evaluated under laboratory conditions for their repellency and oviposition deterrence effects against femaleQueensland fruit flyBactrocera tryoni, using artificial substrates and apple fruits. The results showed that vegetable oils were more effective than essential oils in deterring oviposition. The oil with most potential was that of safflowerCarthamus tinctorius. This vegetable oil, at a concentration of 10 mL/L, significantly reduced oviposition in apples by 56.4% in a 24 h choice test, but none of the tested essential and vegetable oils had a significant effect on oviposition in apples in a no‐choice test. Based on the number of fruit flies landing on treated apples, vegetable oils were not repellents but deterred oviposition. The likely mechanism is that safflower and other vegetable oils created a slippery surface, and females were unable to make punctures in the fruit for egg deposition. Essential oils, especially lemon‐scented tea treeLeptospermum petersonii, peppermintMentha piperitaand honey myrtleMelaleuca teretifolia, repelled femaleB. tryoni, but their persistence on apple fruits was very low, only for a few hours.