The Effect Of Host Fruit On The Infestation And Growth Development Of Grapholita Molesta Busck And The Primary Physic-chemical Mechanism

Oriental fruit moth (Grapholitha molesta Busck) is one of the most serious fruit boring insects inthe world. It has a wide host range in the family Rosaceae, in which primary host is considered to be thestone fruit peach(Prun us persica L.), whereas the pome fruits pear (Pyrus communis L.) and apple(Malus domestica L.) are considered secondary hosts. Oriental fruit moth larva often bores the fruit andshoot, which can directly or indirectly influence quality and production of fruits. Oriental fruit mothoccurred five generations one year in the adjacent peach, apple and pear orchard in Shenzhou. Orientalfruit moth larva can infest host fruits except the overwintering generation, but the extent of damage wasdifferent. For that reason, we systematically investigated the boring fruit rate of oriental fruit moth inthe adjacent orchards, and studied its effect on growing development and reproduction of peach(Shazizaosheng, Jiubao, No.14beijing, Shenzhoumitao), apple (Fuji) and pear (Yali pear) indoor，thenanalysised the physical-chemical factors and mechanism of host fruits, the major results outlined wereas follows:1.The boring fruit rates were significantly different among different peach varieties, which wereaffected by the Oriental fruit moth generation. The investigation result as following: the boring fruit rateorder of the second generation oriental fruit moth was: Shazizaosheng (4.00%)> Shenzhou Peach(2.20%)> Jiubao (1.80%)> No.14Beijing(1.00%)>Fuji Apple(0.00%)=Yali pear (0.00%). The thirdgeneration was: Shazizaosheng(7.26%)> No.14Beijing(2.20%)> Jiubao(1.80%)> ShenzhouPeach(0.10%)>Fuji Apple(0.00%)=Yali pear (0.00%). The forth generation was ShenzhouPeach(14.00%)> No.14Beijing(10.60%)>Jiubao(7.20%)>Fuji Apple(0.00%)=Yali pear (0.00%). Thefifth generation was Shenzhou Peach(12.00%)> Yali pear (0.80%)>Fuji Apple(0.00%).2.The development and reproduction of Grapholitha molesta Busck on different host fruit wasaffected by the host fruit species. The most prefered host plants of the second and third generation wereShazizaosheng Peach. The forth and fifth respectively chose Shenhzhou Peach and Yali Pear.The study found the second and third generation Grapholitha molesta Busck had the highest boringrates(22.33%,30.56%), the shortest larval period(11.28d,10.13), the highest spawning (207.71/female,165.27/female),the largest intrinsic rate of increase and net reproduction rate (rm=0.0714,R0=10.02andrm=0.0874,R0=14.25)on the Shazizaosheng Peach. The forth generation oriental fruit moth on the Fujiapple had the highest boring rate(57.22%),followed by Shenzhou Peach(36.67%),Oriental fruit mothlarvae period on Jiubao peach was the shortest(10.26d),followed by Shenzhou peach(10.44d),andOriental fruit moth had the highest spawning(151.90/female), the largest intrinsic rate of increase andnet reproduction rate rm=0.0999,R0=19.42）on the Shenzhou peach.The fifth generation oriental fruitmoth on the Yali pear had the highest boring rate(63.89%).Grapholitha molesta Busck on Shenzhoupeach was the shortest larvae period (10.26d),followed by Yali pear(13.60d).And oriental fruit moth had the highest spawning(181.12/female), the largest intrinsic rate of increase and net reproduction raterm=0.1117, R0=47.44）on the Yali pear.3.The content of nutrients such as soluble suger, protein, free amino acid and secondary substancescondsused tannins and flavonoid substance in the host fruit peach, apple and pear was different, and wasrelated with the boring fruit rate of different generation,but the relateion was related with the generationof oriental fruit moth.The study shows the content of soluble suger had no correlation with the boring rate of orientalfruit moth. There was no correlation between content of protein and free amino acid and the boring fruitrate of the second, third and forth generation oriental fruit moth,but the content of protein and freeamino acid had significant negative correlation with the boring rate of the fifth oriental fruit moth (Y（%）boring5=-2.341Xprotein5＋70.924,Y(%)boring5=-3.845Xamino5+66.137). the content of tannins had nocorrelation with the boring rate of oriental fruit moth. There was no correlation between content offlavonoid substance and the boring fruit rate of the second, third and forth generation oriental fruitmoth,but the content of flavonoid substance had significant negative correlation with the boring rateof the fifth oriental fruit moth (Y(%)boring5=-1.352Xflavonoid5+81.249).The result showed nutrients andsecondary substances in the fruit can resist boring fruit to some extent, but only the fruits which hadhigher protein, condsused tannins and flavonoid substance were bad for boring of the fifthgeneration.One of material bases and main reasons of Grapholitha molesta Busck infestation were thecontent and the content dynamic change with time.4.The fruit hardness, trichome density and length in the host fruit peach, apple and peach wasdifferent, which were related with the boring of G.molesta Busck, but the relation was related with thegeneration of oriental fruit moth. The fruit hardness showed significant negative correlation with theboring rate of the second and third generation oriental fruit moth（Yboring1%=-5.40Xhardness1＋93.00，Yboring2%=-0.262Xhardness2＋13.257）, but the forth and fifth didn’t.There were not correlations betweenthe trichome density and length and the boring rate of oriental fruit moth.The results showed the hostfruits hardness affected infestation of oriental fruit moth,but only played a resisting part in earlygeneration oriental fruit moth.The innovation of this paper combined two typical biological characteristics, that G.molesta Busckoccurred more than one generation a year and its extesive range of host fruit. And the adjacent orchardswas tested medium. We gradually expored the effect of the host fruit on the infestion and developmentof G.molesta Busck, and illustrated the primary physic-chemical mechanism. The result laid a solidfoundation for the further study of the connection between Grapholitha molesta Busck and host plant,provided the basis for tranference of oriental fruit moth,and indicated the direcation for the developmentof resistant varieties,which has the important value in academic and instruction.