Effects of trophic levels on Host-Finding behavior of Pales murina a tachinid parasitoid of Streblote siva

Pales murina Mes. (Tachinidae) which is parasitoid of Jujube Lappet moth Streblote siva (Lefebvre) (Lasiocampidae) in south of Iran, deposits numerous very small eggs (microtype) on the foliages of their caterpillar hosts. Parasitization is successful when the S. siva larva swallow the eggs. To increase parasitization some factors are involved: choosing suitable plants, laying their eggs near the hosts, ingesting eggs by caterpillar host. The behavioral responses of P. murina were investigated to odors from its host and hosts plants infested with the fly’s host, S. siva, in an olfactometer and wind tunnel. It was studied to determine the factors which effect on orientation, searching and host-finding. In this way, they can be detected more readily than volatile cues emitted from herbivores, Semiochemicals infested plants (Conocarpus erectus and Calotropis procera) and frass. Results of olfactometer showed a significantly higher rate of landing of P. murina on caterpillar infested Conocarpus erectus than on rest (χ2=12.019, P=0.007, df=3). Also differences were detected between treatments fresh frass with the rests (χ2=9.940, P=.019, df=3). Results of bioassay of wind tunnel showed that there was significant difference between caterpillar infested and mechanically wounded C. erectus (χ2=14.40, df=1, P=0.000), caterpillar infested C. erectus vs. C. procera (χ2=18.667, df=1, P=0.000) and fresh frass vs. sand (χ2=4.90, df=1, P=0.027). The results show that P. murina exploits a different host- finding strategy to make use of specific Semiochemicals coming from suitable plant–herbivore interaction as odors and fresh frass of host in order to increase their parasitization success.