WEED SEED PREDATION BY CARABID BEETLES AND CRICKETS FOR BIOLOGICAL CONTROL OF WEEDS IN WILD BLUEBERRY FIELDS

Abstract

Weeds are a major pest problem of wild blueberry. Granivorous insects may consume weed seeds, contributing to pest control. In the laboratory, the ground beetle Harpalus rufipes and field cricket Gryllus pennsylvanicus consumed a significant number of seeds of sheep sorrel and hairy fescue, two important weeds of wild blueberry. In a prey vs. seed preference experiment, H. rufipes preferred aphids over sheep sorrel seeds. Field experiments also found considerable weed seed granivory by invertebrate herbivores. There was generally no effect of distance from field edge and type of field (“crop” or “vegetative”) on the weed seed granivory. In experiments with insecticides used in blueberry production, H. rufipes was highly susceptible to field rates of phosmet (Imidan) and acetamiprid (Assail) by topical exposure and ingestion of treated seeds, whereas no mortality was seen with spirotetramat (Movento).