Use of Alternative Plant Species as a Monitoring Tool for the Cranberry Girdler (Lepidoptera: Pyralidae)

Abstract

Soil-dwelling larvae of the cranberry girdler, Chrysoteuchia topiaria (Zeller), are difficult to detect even at densities causing severe damage to plantings of commercial cranberry (Vaccinium macrocarpon Ait.). This study examined plant preference of this insect as a potential monitoring tool in cranberry bogs. Girdler larvae preferred grasses to Douglas fir seedlings and to cranberry plants. Among the seven grass species evaluated, foxtail (Alopecurus pratensis L.) and red top (Agrostis alba L.) were most heavily infested. Preference in these experiments is expressed as movement of larvae to these plants rather than as oviposition preference by adult females. Foxtail is suggested as a useful monitoring tool in cranberry bogs because detecting girdler larvae on this plant is easy even at very low levels of girdler infestation on cranberry plants. It is suggested that this method of attracting and monitoring also be incorporated in the protocol of experimental studies of control measures for this insect, or as a potential trap crop.