| Chinese citrus fly [Bactrocera minax (Enderlein)], commonly known as " Maggots tangerine " Diptera, belongs to Dacinae in Diptera. The insect occurs widely and heavily in China in recent years. Present management of Chinese citrus fly mainly depends on the combination of food attractants and insecticides, which is not efficient enough with environmental pollution. Therefore, looking for a green and efficient method to control the fly is necessary. Insect sex pheromone is a kind of secreted chemicals passing information between conspecific male and female individuals during copulation. Insect sex pheromone traps baited with sex phewmones are employed worldwidely in pest management because of its high efficiency and environmental compatibility. In order to make clear pheromone secreting organ and promote the use of sex pheromone trap in the management of Chinsese citrus fly. Pheromonal activity of rectal crude extracts in Bactrocera minax were studied. This study was supported in order to by the national public sector specific research (200903047-4) funding, mainly obtains the following results:1Emergency dynamics of the Chinese citrus flyEmergence dynamics of collected pupae in outdoor conditions were compared with dynamics of adults trapped by food attractants in the filed. The beginning day, the beginning period, the peak day, the end of the peak period of emergency of collected pupae’s were14,29,31,35days earlier than that of field adults, respectively. The results showed that it is more rliable to predict the natural emergency of the fly, based on the observation of collected pupae’s eclosion. It also provides the gudiance for planning the field experiment of sex pheromone traps.Additionally field observation of mating behaviors of the fly showed, the mating peak occurs from11:00to17:00. Therefore, sex pheromone extracts were suggested to be collected during this period.2EAG and field trapping trials. Under a microscope, morphology and relative location of rectum in digestion system of adult flies were observed. The rectum of Chinese citrus fly is located at the distal part of digestion system, between hind gut and anus. The rectum is morphologically similar as that of other species in Bactrocera. Rectums and bodies with rectum excised from both males and females of5,10and15-day-old adult flies were extracted with n-hexane and methanol. Male and female bodies with rectum excised were also extracted. EAG responses of male and female adults to rectum extracts and body extracts were recorded. Field attractiveness of rectum extracts from15-day-old male and female adults were also investigated. EAG responses of male and female adults to heterosexual n-hexane rectum extracts were highest among all extracts. Meanwhile, male and female adults also showed relatively high EAG responses to homosexual rectum extracts. In field tests,15-day-old female rectum extracts attracted significantly more adults than any one attractant of protein lure, suger solution with wine and vinegar mixture, and15-day-old male rectum extracts. Meanwhile, even attractiveness of15-day-old male rectum extracts was much lower than that of15-day-old female rectum extracts, male rectum extracts still attracted a small number of adults. Sex ratio of adults attracted by15-day-old female rectum extracts was0.82:1, while any of other attractants attracted more females than males.3GC-MS analysisChemical structures of components in the female, the male rectal crude extracts were tentatively identified by GC-MS. In female crude extracts, detected47compounds were detected mainly of which were alkenes, alcohols and esters; Five compounds (1-Pentadecene、1,2-O ctanediol、1-Hexadecanol、Ethyl9-hexadecenoate、Hexadecanoic acid, ethyl ester) in female rectal gland ectracts, with similar structures to reported pheromones in other species in Tephritidae, were worthy of futher study. Meanwhile,31compounds were tentatively identified on male extracts. |
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