Oviposition behaviour and life-history performance of Epiphyas postvittana (Lepidoptera: Tortricidae) on the leaves of Vitis vinifera (Vitales: Vitaceae) infected with Botrytis cinerea (Helotiales: Sclerotiniaceae)
In three-way interaction systems involving an insect and a plant-pathogenic fungus, both occurring on the same plant, the insects generally gain in terms of their growth and metabolism. In this study we have tested how the infection by Botrytis cinerea on the leaves of Vitis vinifera influences the life-history performance of larvae and the oviposition behaviour of Epiphyas postvittana. We conducted free-choice and two-choice experiments to test the oviposition behaviour of gravid E. postvittana. We also characterized the effects of B. cinerea-infected leaves of V. vinifera on the growth and development of E. postvittana. We found that the oviposition preference of E. postvittana was strongly influenced by the olfactory and tactile cues. Volatiles from B. cinerea-infected plants significantly deterred oviposition and in consequence, adult females laid fewer number of eggs on B. cinerea-infected leaves of V. vinifera compared with uninfected leaves. The mortality rate of larvae fed on B. cinerea-infected leaves were not significantly different from the larvae fed on uninfected leaves of V. vinifera. Whereas, the larvae of E. postvittana fed on B. cinerea-infected leaves had significantly shorter developmental period, attained heavier pupal mass, and on becoming adults they laid more numbers of eggs than the larvae that were enabled to feed on uninfected leaves of V. vinifera. We also reared the larvae of E. postvittana on exclusive-fungus diet but all larvae died before pupation indicating that for a better larval performance and adult reproductive output of E. postvittana, the V. vinifera-B. cinerea interacting system is but imperative
