Beneficial arthropod behavior mediated by airborne semiochemicals : IV. Influence of host diet on host-oriented flight chamber responses ofMicroplitis demolitor Wilkinson.

Microplitis demolitor Wilkinson were reared fromHeliothis zea larvae fed either an artificial diet or a diet of cowpea seedlings. Responses of females from these two sources to semiochemicals from the insect hostcowpea complex were compared in a flight tunnel. Very limited responses were obtained from females reared from hosts fed artificial diet unless they first had preflight contact with frass from plant-fed hosts. Female parasite is reared from plant-fed hosts were generally responsive without preflight contact. Contact with cocoons containing frass of the plant fed host at the time of emergence was an important source of stimulation. It increased their subsequent responsiveness to the volatile semiochemicals of the insect host-plant complex. The cocoons of females reared from artificial diet-fed hosts were apparently lacking plant chemicals that are vital to their subsequent responsiveness. Imprinting of the adults at time of emergence from the cocoon is strongly indicated.