Host preferences of the gypsy moth, Lymantriadispar (L.), in southern Quebec

Abstract

Larval populations of gypsy moth were monitored from June through July 1980 in southwestern Quebec, the northern edge of the insect's North American range. Larval activity on a total of 1870 trees representing 29 tree species was studied at 13 different sites. At least some gypsy moth larvae were found on all tree species, but different larval preferences for the available host trees were evident. Gypsy moth larvae preferentially attacked Quercusrubra L., Amelanchier spp., Populusgrandidentata Michx., Salix sp., and Ostryavirginiana (Mill) K. Koch. The larvae generally avoided members of the genus Fraxinus, Acernegundo L., A. pensylvanicum L., A. rubrum L., A. saccharinum L., Betulalutea Michx. f., Caryacordiformis (Wang) K. Koch, C. ovata (Mill) K. Koch., Juglanscinerea L., Pinusstrobus L., Populusdeltoides Marsh., Prunuspensylvanica L.f., Pyrusmalus L., and Ulmusrubra Muhl. The following species are best categorized as intermediate hosts whose utilization varies with forest composition: Acersaccharum Marsh., Betulapapyrifera Marsh., B. populifolia Marsh., Fagusgrandifolia Ehrh., Populustremuloides Michx., Prunusserotina Ehrh., Tiliaamericana L., and Ulmusamericana L. Some differences were found from host preferences reported for New England. For example, Ostryavirginiana is strongly preferred in Quebec in contrast to New England where it is only an intermediate host; Betulapopulifolia and Populustremuloides are both preferred in New England but classed as intermediate hosts in our study. Overall, the forest composition appears to play only a limited role in altering gypsy moth host selection, but does especially affect the utilization of intermediate hosts.