Research On The Behavioral Responses Of Bactrocera Dorsalis To The Volatile Compounds From Protein Bait

Bactrocera dorsalis (Hendel) was a major and widespread destructive pest in agriculture worldwide and had been widely distributed in southeast Asia and the Pacific region, caused serious economic losses of crops every year, had many different types of hosts.The protein bait prepared from spent brewer’s yeast enzymatic hydrolysate was effective for the adult attraction of B. dorsalis. Presumably, seven major volatile compounds of the hydrolysate attributed to the primary attraction, were 3-methyl-1-butanol, benzaldehyde, octyl acetate, phenethyl acetate, ethyl caprylate, benzyl cyanide and phenylethyl alcohol.However, the activity of volatiles in this substance had not been fully studied for attraction of B. dorsalis. Thus, on the one hand, the attractiveness of these volatile compounds were assayed with different developmental periods of adult B. dorsalis. Eventually, three volatile compounds were selected, attributed to the primary attractiveness. And then a best mixed ratio to attract B. dorsalis was obtained by orthogonal experiment. On the other hand, the electroantennogram (EAG) technology was adopted to measure the EAG response from antennae of different developmental periods of adult B. dorsalis to three volatile compounds and blends.The main results were as follows:(1) The attraction of single volatile to three different developmental periods of adult B. dorsalis, the results as showed.①Seven volatiles (except benzaldehyde) all showed a certain attraction to B. dorsalis, but attractiveness of volatile compounds varied with differences level, and most volatiles showed significant attractiveness between 100μL/mL to 200μL/mL. Octyl acetat, phenethyl acetate and ethyl caprylate in particular showed dramatic attractiveness, and the concentration of most attractiveness of these three volatiles to B. dorsalis before mating were 150μL/mL, 150μL/mL,200μL/mL, and could achieve 61.4%,64.8%,62.6%; the concentration of most attractiveness of these three volatiles to B. dorsalis after mating were 150μL/mL, 150μL/mL,200μL/mL, and could achieve 64.0%,76.6%,71.4%; the concentration of most attractiveness of volatile to B. dorsalis after oviposition were 150μL/mL, 200uL/mL,200μL/mL, and could achieve 62.8%,78.6%,76.0%.②Attraction of the blends of volatile and protein bait or torula yeast to adult B. dorsalis after oviposition were assayed indoors and the results revealed that there were no significant differences between control and treatment. ③The seven single volatiles at 200uL/mL were assayed outdoors for different developmental periods of adult B. dorsalis. The results showed that octyl acetate, phenethyl acetate, ethyl caprylate had significant attractiveness. The indoor experiments’results and outdoor experiments’results were consistent respectively.(2) Orthogonal experiment was taken to assay that the attractiveness of the blends of three good attractive volatiles to different developmental periods of adult B. dorsalis. The best attractiveness of these blends to B. dorsalis before mating was in ratio of 200μL/mL:100μL/mL:100μL/mL, and to B. dorsalis after oviposition, the blends was in ratio of 200μL/mL:200μL/mL:100μL/mL.(3) The EAG responses of different developmental periods of B. dorsalis to selected three compounds and their blends at different concentration. The results showed that EAG responses of B. dorsalis had certain differences among the same concentration of different volatiles or different concentrations of the same volatiles. For the same volatile, the EAG responses were enhanced with increasing concentrations generally, in addition to the relative EAG response values of ethyl caprylate to females after mating. The maximum relative EAG response values of octyl acetate (100μL/mL) in females before mating was 0.4150mv, ethyl caprylate (100μL/mL) in males was 0.3995mv; octyl acetate(100μL/mL) in females after mating was 0.544lmv, octyl acetate (100μL/mL) in males was 0.7634mv; octyl acetate (100μL/mL) in females after oviposition was 0.6706mv, octyl acetate (100μL/mL) in males was 0.5258mv;the EAG responses of different developmental periods of adult B. dorsalis to blends showed significant differences. The blends could evoke higher relative EAG values than single compounds. And the maximum relative EAG values of blend 1 (200μL/mL octyl acetate, 100μL/mL phenylethyl acetate, 100μL/mL ethyl caprylate were blended by volume 1:1:1) in females before mating was 0.6982mv. The relative EAG values of blend 2 (100μL/mL octyl acetate, 200μL/mL phenylethyl acetate,100μL/mLethyl caprylate were blended by volume 1:1:1)in males before mating was 0.7169mv.