Effect Of Host Plant Factors On Occurrence And Growing Development And Oviposition Preference Of Grapholita Molesta Busck

The oriental fruit moth (OFM), Grapholita molesta Busck (Lepidoptera:Olethreutidae), widely distributed in the world, is a serious insect pest of fruit trees innorthern China. G. molesta larvae often harm the fruit and shoot of peach, pear, apple andother Rosaceae fruit trees, which can influence fruits production greatly, and seriouslyaffect the quality of fruits. For this reason, we systematically investigated the occurrenceand transfer rule of OFM in a orchard where peach, pear and apple was adjacent planted inShen Zhou, meanwhile, we comparatively studied the influence of host plants such aspeach, pear, apple, plum, apricot and nectarine on the growth development and theinfluence of colours on oviposition behavior, the major results outlined as following:1. OFM occurred5generations one year and emerged from early April tomid-October in peach, pear and apple orchard which were adjacent planted in Shen Zhou。The peaks of its overwintering generation and1-4generations peaks respectively appearedin mid-April, late May, late June, mid-July and mid-August. The occurrence of OFM wasrelated to the host species and obvious preferred Shen Zhou Peach. Peach orchard,especially Shen Zhou Peach orchard was the main overwintering source, and OFMspreaded and transfered to other varieties peach orchards and pear, apple orchardssubsequently.The investigation found that there were significant differences in the number ofoverwintering larval of OFM between different hosts. OFM mainly overwatered in ShenZhou Peach orchard, with more than90%overwintering cocoon in total, while the cocoonoverwintering in Yali orchard and other varieties of peach orchards were less and none wasdiscovered in Fuji apple orchard. The distribution of OFM in the tree body had nosignificant difference between different hosts. OFM overwintered mainly in the trees,especially under the old skins of tree trunk, followed by the main branches, and rarely insoil. there were more overwintering chrysalis under the old skins of the sunny side andunder60cm from the ground, and less on shady side of the old skins and above60cm.There were a slight difference between different hosts on the wintering periods of OFM.OFM overwintered mainly at late September to early October and mid to late Septemberrespectively in2011and2012in Shen Zhou Peach orchard, which trapped respectively 84.62%and68.52%of the total.2. Different host plants affected the growth and reproduction of OFM. In six differenthosts (peach, pear, apple, plum, apricot, nectarine), pear, apple and nectarine were the besthost, followed by plum and peach, apricot was the worst.The results showed that the larval duration was the shortest on plum (10.58d) andfollowed by nectarine (10.73d) and apple (14.78d), while the larva survival rate was thehighest on nectarine (48.89%) and followed by plum (48.76%) and peach (32.00%).Female adults derived from larvae reared on apple and pear laid significantly more eggs(135.63and104.90eggs laid per female, respectively) compared with those reared on theother host plants, while reared on apricot laid least eggs (60.39eggs laid per female).Oviposition period was the longest on nectarine (15.17d) and the shortest on apricot(10.37d). Life-table parameters were calculated for each host plant and compared byjackknife procedures. Analysis indicated that the net reproduction rate (R0) was the greateston apple (50.6552) and followed by nectarine (31.7632) and pear (28.7056), while theintrinsic rate of increase (rm) was the greatest on pear (0.1574), followed by apple (0.1221)and the lowest on Apricot.3. Different colors affected the oviposition preference, fecundity, oviposition periodand so on, preferring yellow and green color, especially light yellow and light green, andhighest fecundity in green.The results showed that colour affected the oviposition preference significantly. OFMpreferred to the light yellow and light green laying eggs, with oviposition preferences of68.9%(white reference) and63.8%(black reference) on light yellow cards,64.1%and65.5%on light green cards. OFM showed a certain avoidance to blue and light pink cards,with oviposition preferences of47.7%and40.4%on blue cards,47.2%and42.7%on lightpink cards, and the referance colours can significantly affect the oviposition preference.Colour also affected the fecundity significantly. whether white or black referance, the eggsspawed on yellow and green cards were much more than others, especially the deep yellow,deep green and green cards. Colour affected the oviposition preference of1-7days adultssignificantly.2and3days of OFM preferred to the light yellow and light green laying eggson white reference, with oviposition preferances of86.7%and91.7%. On black reference,2day moth preferred light green laying eggs, with oviposition preferance of79.7%and6day moth preferred light yellow, with oviposition preferance of74.8%.The results showed that the pre-oviposition period was the shortest on yellowbackground of4.94d) and followed by green background of5.48d, while was the longeston purple background of7.32d. Oviposition period was the longest on green backgroundof13.53d) and shortest on purple background of8.57d. Female adults reared on yellowand green background laid significant more eggs (90.18and88.29eggs laid per female,respectively) than those reared on the other clours. Adult mating rate was the highest on green and blue background of96.08%and lowest on purple background, while femalelongevity was the longest on blue background of22.26d and followed by greenbackground of22.19d. The egg period was longest on purple background, on which thehatching rate was lowest. To comprehensive analysis, the suitability of different colourfrom high to low in turn is green, blue, red, yellow, CK, orange and purple.The innovation of this paper is clarifing the occurrence and overwintering rule ofOFM in orchard adjacent planted in Shen Zhou, also preliminarily identified the optimalhost and the oviposition preference colors. These results and discoveries laid thefoundation for further study of the OFM in occurance or infestation and the contactbetween the host, also provide a scientific basis and reference for the research anddevelopment of efficient, green monitoring and control techniques, with the importantvalue in academic and production instruction.