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1 June 2000 Risk of Infection by the Fungal Pathogen Entomophaga maimaiga Among Lepidoptera on the Forest Floor
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The entomopathogenic fungus Entomophaga maimaiga causes epizootics in gypsy moth, Lymantria dispar (L.), populations and persists in forests as a reservoir of spores in soil at the bases of trees. To investigate whether E. maimaiga infects Lepidoptera living in leaf litter, we collected and reared larvae in leaf litter, understory vegetation, and on tree boles within a 200-cm radius around trunks of red oak, Quercus rubra L., trees. Among the 358 lepidopteran larvae reared, only one gelechiid larva (out of 84 collected) and one larva of the noctuid Sunira bicolorago (out of 20 individuals from this species) were infected by E. maimaiga. Our collections included 67 gypsy moth larvae, of which 25 (37%) were infected by E. maimaiga. The majority of infected gypsy moth larvae were collected during the second half of June, when few nontarget Lepidoptera were present in the oak leaf litter. A bioassay of Zanclognatha laevigata Grote, a herminiine noctuid whose larvae spend their entire lives in leaf litter, yielded no infection. Because laboratory host specificity studies had demonstrated high levels of infection only in lymantriid larvae, we also caged larvae of the lymantriid Orgyia leucostigma (J. E. Smith) over soil at the bases of trees or in understory vegetation. Levels of infection for O. leucostigma remained consistently lower than among caged gypsy moth larvae, and infection was always higher in the soil than on the understory vegetation. We conclude that, aside from gypsy moth larvae, E. maimaiga infections among litter-dwelling lepidopteran larvae were rare, and we hypothesize that infection of other lymantriids in the field will depend on whether they visit the ground level for a significant period of time.

Ann E. Hajek, Linda Butler, James K. Liebherr, and Micheal M. Wheeler "Risk of Infection by the Fungal Pathogen Entomophaga maimaiga Among Lepidoptera on the Forest Floor," Environmental Entomology 29(3), 645-650, (1 June 2000).
Received: 5 January 2000; Accepted: 1 March 2000; Published: 1 June 2000

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