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Sexual differences in electrophysiological and behavioral responses of Cydia molesta to peach and pear volatiles

Lu, Peng‐Fei, Wang, Rong, Wang, Chen‐Zhu, Luo, You‐Qing, Qiao, Hai‐Li
Entomologia experimentalis et applicata 2015 v.157 no.3 pp. 279-290
Cydia, Grapholita molesta, Prunus persica, Pyrus bretschneideri, bioassays, electrophysiology, females, field experimentation, fruits, intermediate hosts, males, migratory behavior, monitoring, orchards, peaches, pears, pests, shoots, traps, volatile organic compounds
The oriental fruit moth (OFM), Cydia (= Grapholita) molesta (Busck) (Lepidoptera: Tortricidae), is a serious invasive pest. The stone fruit peach, Prunus persica (L.) Batsch, is its primary host, and the pome fruit pear, Pyrus bretschneideri Rehder (both Rosaceae), is its secondary host. Electrophysiological and behavioral responses of C. molesta females and males to peach shoot and pear fruit volatiles were compared in laboratory and field bioassays. Based on gas chromatography–electroantennographic detection (GC–EAD) activity, 13 compounds in the headspaces of peach and pear volatiles elicited female antennal responses. Of these, eight compounds also elicited male antennal response. Four lures were developed based on male and female EAD responses to pear and peach‐derived volatile organic compounds (VOCs). More males than females were captured for all four lures during field trials, even in traps with lures that emitted VOCs based on female EAD responses. Lures based on female EAD responses to pear fruit VOCs consistently caught more females than lures based on male EAD responses to pear fruit VOCs in either peach or pear orchards. Peach shoot VOC lures based on female EAD responses did not attract more females than lures based on male EAD response to peach shoots. The two pear‐derived VOC lures were highly attractive to both sexes in peach orchards, whereas conversely, the two peach‐derived VOC lures showed stronger attraction in pear orchards. Seasonal population monitoring indicated both sexes made inter‐orchard flights during the late peach‐ and pear‐fruiting periods. A possible hypothesis that could explain different response profiles in females and males and seasonal migration for herbivores with multiple generations per year is discussed.