Molecular Ecology (2015) 24, 249-258

Vera I.D. Ros, Stineke van Houte, Lia Hemerik and Monique M. van Oers (2015)
Baculovirus-induced tree-top disease: how extended is the role of egt as a gene for the extended phenotype?
Molecular Ecology 24 (1), 249-258
Abstract: Many parasites alter host behaviour to enhance their chance of transmission. Recently, the ecdysteroid UDP-glucosyl transferase (egt) gene from the baculovirus Lymantria dispar multiple nucleopolyhedrovirus (LdMNPV) was identified to induce tree-top disease in L. dispar larvae. Infected gypsy moth larvae died at elevated positions (hence the term tree-top disease), which is thought to promote dissemination of the virus to lower foliage. It is, however, unknown whether egt has a conserved role among baculoviruses in inducing tree-top disease. Here, we studied tree-top disease induced by the baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) in two different host insects, Trichoplusia ni and Spodoptera exigua, and we investigated the role of the viral egt gene therein. AcMNPV induced tree-top disease in both T. ni and S. exigua larvae, although in S. exigua a moulting-dependent effect was seen. Those S. exigua larvae undergoing a larval moult during the infection process died at elevated positions, while larvae that did not moult after infection died at low positions. For both T. ni and S. exigua, infection with a mutant AcMNPV lacking egt did not change the position where the larvae died. We conclude that egt has no highly conserved role in inducing tree-top disease in lepidopteran larvae. The conclusion that egt is a 'gene for an extended phenotype' is therefore not generally applicable for all baculovirus–host interactions. We hypothesize that in some baculovirus–host systems (including LdMNPV in L. dispar), an effect of egt on tree-top disease can be observed through indirect effects of egt on moulting-related climbing behaviour.
(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): Vera I.D. Ros, Monique M. van Oers

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Spodoptera exigua
	Trichoplusia ni
Alphabaculovirus aucalifonicae (entomopathogen)	Spodoptera exigua
Alphabaculovirus aucalifonicae (entomopathogen)	Trichoplusia ni