Impact of host plants on the efficacy of nucleopolyhedrovirus as a biopesticide against insect pest Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

The present study evaluated the effect of three host plants: chickpea, Cicer arietinum, tomato, Lycopersicon esculentum and cotton, Gossypium hirsutum, on the efficacy of Helicoverpa armigera nucleopolyhedrovirus (HearNPV). The results showed that HearNPV was inactivated within one hour when sprayed on to the leaf surface of chickpea indicating that leaf surface factors on this plant were responsible for the effect. In contrast, virus that has been sprayed onto the leaf surface of cotton and tomato was not significantly affected compared to untreated HearNPV. This study also showed that HearNPV was inactivated on the chickpea leaf surface in field experiments. One compound was shown to be induced on the chickpea leaf surface in response to spraying with 0.02% Triton X-100 which was used as a surfactant. The induced compound was isolated and identified as sissotrin, and isoflavonoid. Sissotrin was shown to reduce the efficacy of HearNPV, although not by as much as when the virus was exposed to the chickpea leaf surface. The results indicated that sissotrin was partially responsible for the inactivation of HearNPV and that other compounds which accumulated on the leaf surface after spraying with HearNPV must also have an additional effect in combination with sissotrin. This is the first study to show that isoflavonoids reduce the efficacy of baculovirus against Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). Field trials were also conducted with different low cost additives mixed with HearNPV on chickpea crop and these increased the efficacy and persistence of HearNPV under field conditions. This study may therefore help to improve biopesticide based pest management on chickpea.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Greenwich

Year dc:date.issued

2007

Author dc:creator

• D'Cunha, Reju Francis

• S Agriculture (General)
• SB Plant culture