Study on Olfactory Behavior of Spodoptera exigua on Rosa chinensis Infected by Podosphaera pannosa

The influence and its spacial effect of Podosphaera pannosa-infection on Spodoptera exigua adult on Rosa chinensis plant were determined by using olfactometer.According to the number of response insects,the beet armyworm moths were significantly attracted by the volatiles emitted from healthy leaf tissues of roses(P=0.002),while the females were obviously repelled by the volatiles emitted from infected leaves(P=0.006),when compared to the clean air control.And the moths showed the significant differences between healthy and infected leaves(P=0.000).Therefore,the female's choosing for oviposition site was significantly inhibited by P.pannosa-infection.Further bioassays were conducted to elucidate the spacial scale of the effect of this inhibition.In consequence,the obviously local and systemic effects were found: the local effect expanded within one leaf and the systemic effect expanded one leaf position up and down.The study will provide further basis for further study on selection mechanism of oviposition.