Environmental Entomology (1992) 21, 706-713

Ann E. Hajek and Donald W. Roberts (1992)
Field diagnosis of gypsy moth (Lepidoptera: Lymantriidae) larval mortality caused by Entomophaga maimaiga and the gypsy moth nuclear polyhedrosis virus
Environmental Entomology 21 (4), 706-713
Abstract: Cadavers of late instars of the gypsy moth, Lymantria dispar (L.), that were attached to tree boles were examined to determine cause of death. Cadavers of gypsy moth larvae killed by the fungal pathogen Entomophaga maimaiga Humber, Shimazu and Soper were predominantly oriented vertically with heads downward, all prolegs were frequently at a 90° angle to the axis of the body, and older cadavers were usually dry in appearance. By contrast, larvae killed by the L. dispar nuclear polyhedrosis virus (NPV) were predominantly positioned with anterior prolegs attached to the bole, the anterior section of the body hanging unattached, and the body bending at an angle of <90°. Cadavers of NPV-killed larvae remained soft and moist when older, and all prolegs were seldom at a 90° angle to the body. In 4.4% of cadavers analyzed, mixed infections with both fungus and virus were evident. Individual samplers with little field experience with these pathogens averaged correct field diagnosis of 69.9% of cadavers of pathogen-killed larvae in the field using these criteria. Cadavers of larvae that had died only recently were more frequently incorrectly diagnosed. It is concluded that. field diagnosis of the cause of death of gypsy moth larvae due to E. maimaiga or NPV leads to an unacceptably high level of error for quantitative ecological studies. Nevertheless, cadaver signs and symptoms can provide generalized information on the occurrence of these pathogens.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Ann E. Hajek, Donald W. Roberts

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
surveys/distribution/isolation
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Lymantria dispar
Alphabaculovirus lydisparis (entomopathogen)	Lymantria dispar
Entomophaga maimaiga (entomopathogen)	Lymantria dispar