Factors affecting host finding ability of Pales murina (Diptera: Tachinidae), a Parasitoid of Thiacidas postica on jujube trees

The tachinid fly, Pales murina Mes. is a larval parasitoid of jujube tree (Ziziphus sp.) defoliator, Thiacidas postica Walker (Lep.: Noctuidae) in south of Iran. The parasitoid eggs are laid on lower surface of fresh leaves. Third and fourth instars of the host larvae are parasitic after ingesting the parasite eggs. The study was conducted to determine the affecting factors on orientation, seeking and finding the host by the parasitoid using a 4-wats olfactrometer designed by authors. The first experiment was conducted in a completely randomized design with four treatments and 10 replications each using 10 gravid females. The treatments consisted of 1- individual larva feeding on leaves, 2- individual larvae, 3- shredded leaves and 4- whole leaf sample. Results showed a significant difference between numbers of females attracted to the treatments of larvae feeding on leaves and other treatments. Although no significant difference was found between the two treatments of shredded leaves and individual larvae, they attracted more flies than the treatment of whole leaves. The second experiment was conducted in four replicates and treatments including the above treatments except for the replacing a single larvae with feces instead of larvae feeding on leaves. The results of this experiment showed a significant difference between the number of females attracted to the treatment of larvae with feces and the other treatments. However, no significant difference was observed between the single larvae and whole leaves treatments. It can be concluded that the parasitoid is attracted to host tree and pest larvae by chemical volatiles emanated from damaged leaves.