We calculated conversion factors, based on instar complement or degree-day accumulation, for use with the shake-bucket technique for sampling alfalfa weevil, Hypera postica (Gyllenhal), larvae. Proportions of larvae recovered in shake-bucket samples for each instar were consistent across years for second through fourth instars but differed between instars. Early instars (first and second), which feed within growing tips of alfalfa, were much less susceptible to shaking out than older instars (third and fourth). Therefore, recovery was reduced early in the sampling season when early instars were abundant. Conversion factors for instars two to four are presented to estimate total larvae per six-stem sample from shakebucket counts. Estimates of total larval numbers from a regression of the proportion of recovered larvae on cumulative degree-days were inconsistent between years because of differences between degree-day estimates.
Document Type: Research Article
Publication date: June 1, 1989
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Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.