Entomologia Experimentalis et Applicata (2010) 135, 56-67

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Liljana Georgievska, Nina Joosten, Kelli Hoover, Jenny S. Cory, Just M. Vlak and Wopke van der Werf (2010)
Effects of single and mixed infections with wild type and genetically modified Helicoverpa armigera nucleopolyhedrovirus on movement behaviour of cotton bollworm larvae
Entomologia Experimentalis et Applicata 135 (1), 56-67
Abstract: Naturally occurring insect viruses can modify the behaviour of infected insects and thereby modulate virus transmission. Modifications of the virus genome could alter these behavioural effects. We studied the distance moved and the position of virus-killed cadavers of fourth instars of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) infected with a wild-type genotype of H. armigera nucleopolyhedrovirus (HaSNPV) or with one of two recombinant genotypes of this virus on cotton plants. The behavioural effects of virus infection were examined both in larvae infected with a single virus genotype, and in larvae challenged with mixtures of the wild-type and one of the recombinant viruses. An egt-negative virus variant caused more rapid death and lower virus yield in fourth instars, but egt-deletion did not produce consistent behavioural effects over three experiments, two under controlled glasshouse conditions and one in field cages. A recombinant virus containing the AaIT-(Androctonus australis Hector) insect-selective toxin gene, which expresses a neurotoxin derived from a scorpion, caused faster death and cadavers were found lower down the plant than insects infected with unmodified virus. Larvae that died from mixed infections of the AaIT-expressing recombinant and the wild-type virus died at positions significantly lower, compared to infection with the pure wild-type viral strain. The results indicate that transmission of egt-negative variants of HaSNPV are likely to be affected by lower virus yield, but not by behavioural effects of egt gene deletion. By contrast, the AaIT recombinant will produce lower virus yields as well as modified behaviour, which together can contribute to reduced virus transmission under field conditions. In addition, larvae infected with both the wild-type virus and the toxin recombinant behaved as larvae infected with the toxin recombinant only, which might be a positive factor for the risk assessment of such toxin recombinants in the environment.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Wopke van der Werf, Just M. Vlak, Kelli Hoover

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution
genetical engin./transgenic plants

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Helicoverpa armigera Cotton (Gossypium)
Helicoverpa armigera nucleopolyhedrovirus (entomopathogen) Helicoverpa armigera Cotton (Gossypium)