Female and male Grapholita molesta (Busck) adults responding to various acetic acid and ethanol lure ratios.

Grapholita molesta (Busck) is a menacing pest of fruit trees worldwide. A mixture of glucose, acetic acid, ethanol, and water (GAEWM) has been widely used for monitoring or trapping G. molesta adults. Previous research has shown that acetic acid captures more moths compared to ethanol; however, the respective roles of acetic acid and ethanol in bisexual attraction remain unknown. This study investigated the olfactory behaviours of virgin females, virgin males, and gravid females to variations in nine concentration levels of acetic acid (A) and ethanol (E) for GAEWM using electroantennography, a wind tunnel experiment, and a field test. There was a significant dose‐dependent response by moths to the GAEWM lure variations that affected the range of lure detection and the probability of a moth being trapped. In contrast, adult sex and mating status had the strongest effect on the behaviours associated with flying close to the trap. For medium level dosages of A and E, one combination with acetic acid exceeding ethanol content (A > E; #3, A:E = 3:1) elicited antennal detection by the test adults, and upwind flight of the females. In another combination with ethanol predominating (E > A; #7, A:E = 1:3), the lured traps caught more males than control groups. For low dosages, with the acetic acid level equal to ethanol (A = E; #1, A:E = 1:1), females flew upwind, and virgin females flew around the lure. For high level dosages, with A > E (#6, A:E = 3:2), the antennae of gravid females and virgin males reacted to the lure. These results concluded that the acetic acid to ethanol ratios of either 3:1 or 1:3 in GAEWM has the potential to improve the attraction of both G. molesta sexes to traps. [ABSTRACT FROM AUTHOR]