Epizootics and behavioral alteration in the arctiid caterpillar Chionarctia nivea (Lepidoptera: Arctiidae) caused by an entomopathogenic fungus, Entomophaga aulicae (Zygomycetes: Entomophthorales)

Abstract

We observed epizootics and behavioral alteration in the arctiid caterpillar Chionarctia nivea after infection by an entomopathogenic fungus, Entomophaga aulicae , in April at a riverbank in Kyoto Prefecture, central Japan. The density of arctiid cadavers infected with E. aulicae was 1.31 individuals/m 2 . The critically ill caterpillars crawled up the dead stems of grasses and herbs such as the common reed Phragmites communis and the Japanese mugwort Artemisia indica var. maximowiczii to die at and near the highest parts of the stems, while the healthy larvae usually wandered on the ground and fed on the leaves of small herbs. This behavioral difference could be caused by infection with E. aulicae to enhance dispersal of conidia by active discharge in Entomophthorales with the aid of wind and rainfall.

First record of the entomopathogenic fungus Entomophaga aulicae on the Bihar hairy caterpillar Spilarctia obliqua in Manipur, India

“…The total number of nuclei ranged from 10 to 18 per conidium (average: 13.98± 0.28; n=50) and the number of nuclei in hyphae varied from 6 to 17 (average: 11.8±0.37; n=50). These morphological features fit well with the earlier descriptions of E. aulicae (Hajek et al 1996;Humber 1997;Keller 1987;Yamazaki et al 2004).…”

“…Moribund caterpillars infected with E. aulicae crawl up the dead stems of both grasses and herbs to die at high parts of the plants (Yamazaki et al 2004). Some fungi and viruses alter behavior of host insects, causing them to climb up vegetation and to die at a high site (Goulson 1997;Yamazaki et al 2004). These behavioral alterations have been interpreted to be adaptive for the pathogens, aiding in the dispersion of spores and viruses (Goulson 1997;Sawyer et al 1994).…”

“…2). Moribund caterpillars infected with E. aulicae crawl up the dead stems of both grasses and herbs to die at high parts of the plants (Yamazaki et al 2004). Some fungi and viruses alter behavior of host insects, causing them to climb up vegetation and to die at a high site (Goulson 1997;Yamazaki et al 2004).…”

“…This species complex includes several members that are well known for the epizootics they cause, e.g. in Euproctis chrysorrhoea (L.), Estigmene acrea (Drury), Lambdina fiscellaria Hulst, Choristoneura fumiferana Clemens, Orgyia vetusta Boisduval (see Hajek et al 1996), Chionarctia nivea (Ménétriès) (Yamazaki et al 2004), etc. In Canada, it is a naturally occurring fungal pathogen of eastern hemlock caterpillar and the eastern spruce budworm and is being used for biological control of these pests (Nolan 1993).…”

BIZARRE INTERACTIONS AND ENDGAMES: Entomopathogenic Fungi and Their Arthropod Hosts

“…Elevation seeking by insects at late stages of infection is a common phenomenon that was recognized by early insect pathologists who noted that diseased lepidopteran larvae, such as Lymantria monacha (the nun moth), infected with baculoviruses migrated to the tops of trees where they died (94). This host-altered behavior was named "Wipfelkrankheit" or "Wipfelsucht" (meaning tree top disease in German) for viral diseases (41) and "summit disease" for fungal diseases (24,57,106).…”