Abstract: 【Aim】 This study aims to identify maize ( Zea mays L.) volatiles and cuticular volatiles of larval Helicoverpa armigera (Hübner) for host-habitat location and host location of Microplitis mediator (Haliday). The tritrophic interaction among maize, H. armigera, and M. mediator was investigated in the context of chemical ecology, and the mechanisms of chemical communications in host location of M. mediator were illustrated. The work has some implications for the “pull-push” approach in integrated pest management.【Methods】 Semiochemicals from maize volatiles and cuticular volatiles of H. armigera larvae were identified by using electroantennogram (EAG), gas chromatographic-electroantennographic detection (GC-EAD), gas chromatograph-mass spectrometer (GC-MS), and Ytube olfactometer test equipment. Standard semiochemicals and the mimetic compounds of maize volatiles and cuticlular volatiles of H. armigera larvae were used to test behavioral responses of M. mediator with Y-tube olfactometer in the laboratory.【Results】 Tested by GC-MS and GC-EAD, totally 11 compounds of maize volatiles and 6 compounds from cuticular volatiles of H. armigera larvae were found to be electrophysiologically active, of which 4 electrophysiologically active compounds were identified from both maize volatiles and cuticular volatiles of H. armigera larvae. Behavioral response tests in the laboratory showed that compared with the control of n-hexane male and female wasps were significantly attracted to the mimetic compounds of maize volatiles (P<0.05). Female wasps were significantly attracted to the mimetic compounds of cuticular volatiles of the 1st instar (P<0.01) and the 2nd instar larvae of H. armigera (P<0.05). Male wasps were significantly attracted to the synthesized compounds of cuticular volatiles of the 1st instar larvae of H. armigera (P<0.05). 【Conclusion】 These results demonstrated that 11 compounds (heptanal, 2-hexanol, 1-hexanol, 1-octen-3-ol, nonanal, decanal, benzaldehyde, E-2-nonen-1-ol, hexanoic acid, phenyethyl alcohol, and 1-dodecanol) from maize volatiles and six compounds (2-hexanol, ethyl hexanoate, 1-hexanol, nonanal, ethyl caprylate, and decanal) from cuticular volatiles of H. armigera larvae are responsible for host-habitat location and host location of M. mediator.

Key words: Microplitis mediator, Helicoverpa armigera, Zea mays, host location, semiochemical, EAG response, behavioral response, GC-EAD, GC-MS