Ecology of the Polyhedroses of Tent Caterpillars

Abstract

Information on the polyhedrosis diseases of the tent caterpillars has been accumulating for a number of years. Howard & Fiske (1912) cite an earlier reference (New Hampshire Agr. Exp. Station Tech. Series No. 5) to a disease similar to the polyhedrosis they were studying in the gipsy moth. They state that this reference reported the destruction of a population of tent caterpillars in 1898. Davis (1903) recorded a destructive epizootic among a population of Mala.cosoma anericanum (F.) in Pennsylvania, New York, and New Jersey in 1903. Chapman and Glaser (1916) and Glaser (1927, and other reports) studied the histopathology and other aspects of polyhedrosis in M. americanum in considerable detail. As has been traced elsewhere (Clark and Thompson 1954), polyhedroses have been subsequently reported from most of the North American species of tent caterpillars. To date no real differences between the diseases have been reported. In field tests, the viruses causing the diseases have been collected from populations of Malacosoma fragile (Stretch), Malacosoma californicum (Pack.), Malacosoma disstria Hbn., or Malacosoma contrictum (Stretch), and freely used to initiate infections among populations of any of the other species. Such field cross-infections have been made both sympatrically and allopatrically. To facilitate this discussion of the ecology of the polyhedroses of tent caterpillars, a brief review of other aspects of this group of insect diseases is presented. For a detailed and historical review, the reader is referred to Steinhaus (1949).