Attractions of volatiles from wax-apple fruit to the oriental fruit fly

Objective To study the attractions of volatiles from Syzyzgium samarangense (Blume) fruit to Bactrocera dorsalis (Hendel).

Method The ripe fruits of five wax-apple varieties (black pearl, Indian red, big leaf, Thailand red diamond, palm) and five different developmental stages of the black pearl fruit were selected as materials. The behavioral responses of the oriental fruit fly to their volatiles were examined with the Y-tube olfactometer, and ovipositional preference of the insect to five wax-apple varieties were conducted. The volatile components from the ripe fruit of five wax-apple varieties were analyzed with the method of solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) technology. Based on the change of volatile components of different developmental stages of black pearl and combined with the volatile components of five varieties, lure experiments of B. dorsalis to 9 types of synthetic monomer compounds were performed.

Result and conclusion Five wax-apple varieties and different developmental stages of the black pearl fruit had no attraction to males (P > 0.05). Different varieties had different degrees of attractions to females: black pearl (40.75%) > Indian red (39.40%) > big leaf (34.76%) > Thailand red diamond (23.02%) > palm (15.54%). Attractions of different developmental stages of the black pearl fruit to mature females increased gradually with the maturity. The results of ovipositional preference black pearl (517.0), Indian red (433.0), big leaf (357.0), Thailand red diamond (305.7), palm (200.0) were basically the same as olfactory responses. Main components and relative contents of volatiles were black pearl (12, 80.27%), Indian red (6, 23.56%), big leaf (6, 69.90%), Thailand red diamond (11, 96.97%) and palm (9, 95.1%), which indicated that their volatile components had great differences. Isobutyl acetate, decanal, β-caryophyllene and camphor had significant attractions to females. γ-terpinene, α-farnesene and 1, 2-benzenedicarboxylic acid bis(2-methylpropyl) ester had obvious attractions to the mature females. Isobutyl acetate, γ-terpinene and camphor had attractions to males. As for the same compound, the attraction to the mature adults was stronger than that to the immature adults, while the attraction to females was considerably greater than that to males, with the attraction to the mature females being the strongest.