Studies On The Pattern Of Transferring Damage And Host Preference Of Bactrocera Dorsalis(Hendel) In The Guava Producing Area

Bactrocera dorsalis(Hendel)has extensive host,and can transfer damage within different host species.However,the pattern of transferring damage and host preference of this pest in the guava producing area of Guangxi is still unclear.Therefore,Yulin city as guava producing area in Guangxi was chosen as experimental site to explore the population dynamics of B.dorsalis in different orchards of their host were investigated to determine the pattern of transferring damage;meanwhile,the relationship between population dynamics and meteorological factors were analyzed.Subsequently,oviposition preference of B.dorsalis to host fruit from the guava producing area in different months were conducted to understand their hobby-host.Lastly,effects of physicochemical properties and volatile of hobby-host’ fruits on oviposition preference were studied.Results could provide information for B.dorsalis to forecast and formulate reasonable strategy of integrate pest management.The main results were as follows:(1)The damage situation and the pattern of transferring damage of B.dorsalis in guava producing area were clarified.A total of 15 species of fruits matured in different months in the guava producing area were investigated,of 10 species of fruits were damaged by B.dorsalis.Among of all damaged fruits,percentages of damaged fruit of two varieties of Psidium guajava were the highest(80.65% and 84.00%).The pattern of transfering damage of B.dorsalis in guava producing area was: P.guajava and Averrhoa carambola(January to Februarry)→P.guajava,A.carambola and Morus alba(March and April)→ P.guajava and Citrus limon(May)→ P.guajava,A.carambola,C.limon,Litchi chinensis and Dimocarpus longan(June)→ P.guajava,A.carambola,C.limon and Clausena lansium(July to September)→ P.guajava,A.carambola,C.limon,Fortunella margarita and Zizyphus mauritiana(October to December).(2)Understanding the population dynamics of B.dorsalis in guava producing area.The male of B.dorsalis could be trapped by sex pheromone all year round in Xi’an village of Yuzhou district and Caiwang village of Beiliu City,and three occurrence peaks of B.dorsalis adults were observed,i.e.,May,July to September and November to December.B.dorsalis adults captured was the lowest from December to March of the next year.This pest overwinter as pupal and adult’s stages.Temperature was the most important meteorological factors affecting the population dynamics of B.dorsalis in Yulin City,Guangxi.(3)Bactrocera dorsalis prefer to oviposite on fruit expansion and maturation period of P.guajava.This pest has no obvious oviposition pererence between the two varities of P.guajava.Oviposition rate of B.dorsalis was significant negative correlation with fruit hardness and soluble protein content,and positive correlation with soluble sugar content of P.guajava.(4)Response of adults B.dorsalis to volatile components isolated from P.guajava fruits were studied.volatile components isolated from P.guajava fruits refers terpenes,esters,and alkanes.Obvious electroantennogram responses of B.dorsalis adults to isoamyl acetate,3-hexen-1-yl acetate,ethyl hexanoate,ethyl caprylate,(+)-limonene and β-caryophyllene were observed.Among of the 6 volatile components,Isoamyl acetate,3-hexen-1-yl acetate,ethyl hexanoate,and ethyl caprylate have significant attracting effect to male and female adults of B.dorsalis.However,there has no significant difference between both sexes response to these volatile components.