| The citrus fruit fly Bactrocera minax is commonly known as the “orangemaggots”,mainly distributed in Sichuan,Chongqing,Hunan,Hubei,Guizhou,Yunnan,Guangxi and other citrus producing areas,the citrus fruit fly are thedestructive pests.The pest occurred a generation of one year,although many kinds of prevent and control measures are took,but it is diffcult to solve theproblem basically.In order to find an effective measure to prevent and control the pests,we studied the adult oviposition and larval feeding preference for different citrus varieties in B.minax,to clear the relationship of adultoviposition and larval feeding preference,we compared the difference of number of eggs laying marks and eggs laid by B.minax on different parts of citrus fruits,we analyzed the chemical constituents of the basal hemisphere and distal hemisphere peels of different varieties citrus,and choosed some chemicals to test B.minax by Y-tube olfactometer.We lured the B.minax by self-made food lures and other attractants in orchard,and found the self-made food lures can lure the most pests than other attractants.We have made a preliminary study on the sex pheromone of B.minax,to obtain the active compounds which can lure the B.minax and comprehensive management the B.minax.The main results are as follows: 1.Adult oviposition and larval feeding preference for different citrus varieties in Bactrocera minax(Diptera: Tephritidae)This study aims to understand the preference of Bactrocera minax for several citrus varieties.We investigated the diseased citrus ratio in citrus orchards of different citrus varieties under natural conditions by five-point sampling method,and examined the larval feeding preference of B.minax to host odorants of citrus petals by the selection tests in the laboratory.The results showed that the oviposition preference of B.minax found was Citrus sinensis cv.Navel and C.aurantium>C.sinensis cv.Bingtang,Amakusa,and C.reticulata cv.Satsuma >C.maxima cv.Shatian>C.reticulata cv.Ponkan.The numbers of egg-laying marks and eggs laid on oranges(C.sinensis cv.Navel,C.aurantium and C.sinensis cv.Bingtang)were higher than those on tangerines(Amakusa,C.reticulata cv.Satsuma,C.reticulata cv.Ponkan)and C.maxima cv.Shatian(P<0.05).Larval feeding preference was closely correlated with adult oviposition preference.Our results suggest that oviposition preference of B.minax is related to larval feeding preference.2.Oviposition preference of Bactrocera minax and its response to the compounds of host citrus peels volatilesAimed at knowning the relationship of chemical cues produced by the host with oviposition preference of Bactrocera minax(Enderlein)(Diptera:Tephritidae),the egg-laying marks counted and Y-tube olfactometer attraction assays were used.In the oviposition choice survey,the females significantly preferred laying eggs on the distal hemisphere of Navel(Citrus sinensis),Sour oranges(C.sinensis),Bingtang sweet oranges(C.sinensis)fruit,Amakusa,Shatian you(C.maxima).However,more egg-laying marks of B.minax were found on basal hemisphere than on the distal hemisphere of Satsumas(C.reticulata)fruit.The chemical analysis of volatiles from the different hemisphere of the three varieties host oranges peel by GC-MS showed that the main compounds on the basal were different from the distal of the three tested oranges fruit in some extent.Furthermore,thirteen compounds of the oranges peels volatiles were chosen to lure the females by Y-tube olfactometer attraction assays.Four compounds among them,including nonanal,citral,limonene and linalool lured the female flies obviously(P<0.05),furfuryl alcohol and guaiastil expeled the females obviously(P<0.05).The percentage composition of nonanal,citral,limonene and linalool on different part of peel displayed positive correlation and furfuryl alcohol and guaiastil displayed negative correlation with the numbers of egg marks lay by the females.These results suggested that the oviposition preference of B.minax females were highly related to or depended on the chemical compounds of its host orange peel volatiles.3.The trapping experiments of Bactrocera minax in the fieldIn order to test the attraction effect of some saccharides and the food lures to Bactrocera minax,we used brown sugar,white sugar,honey,acetic acid and ethyl acetate lure the B.minax,and found brown sugar,acetic acid and ethyl acetate can lure B.minax significantly(P<0.05).We conducted trapping experiments in the field by using the food lures we had designed.We set bottles in the field three times,five positions in the three orchards were chosed in the three experiments.Totally,we catched 223 adults in Linan and Yiwan,and the number of those catched by our food lures were 129(84 females and 45 males),which made up 57.8% of the total adults we had catched.56 adults(41 females,15 males)were catched by the using of Guoruite,making up 25.1% of the total number.we also used the protein lure and catched 29 adults(22 females and 7 males),making up 13.0% of the total number.only 5 adults(3 females and 2 males)were catched by using Liewang,and four(two in each sex)by using Dusipi.From the total number of those catched in each time,the highest number occured in late June,and the lowest occured in early July,The number of the May went in the middle.we haven't set bottles in early June.These results showed that the effect of our special-designed lure in attracting injurious insects was obviously superior to Guoruite,Dusipi and protein lure.Late May to Late June was the rush hours of B.minax to return to the orchards.However in July,the number of B.minax decreased drastically.4.A preliminary study on the sex pheromone of Bactrocera minax.In order to determin the constituent of the sex pheromone of Bactrocera minax,we test the lure of sex of B.minax with Y-tube olfactometer,getting the glands of female,testing if these glands can lure males,we extract the volitale chemical compounds from glands of female B.minax using the n-hexane.We analysed the compounds through the use of Gas chromatography–mass spectrometry,and we also conducted Electrophysiological experiments(GC-EAD)to test the reaction of the male antennal to these compounds.the result showed that the females can lure males(P<0.05)but males can not(P>0.05),the glands also can lure males and males can show sexual behaviour(P<0.05),part of compounds extracted from glands induced responses in the antennal of male B.minax. |
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