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Temperature thresholds and thermal requirements for egg hatching in an Illinois population of western corn rootworms, Diabrotica virgifera virgifera LeConte, were determined under controlled conditions. Developmental rate for first hatch increased linearly with increasing temperature. The threshold temperature (t) and thermal constant (K) for first hatch were t = 12.7°C and K = 209.7 degree-days (DD), respectively. The respective values for 50% hatch were y = 0.235x - 2.616, R2 = 0.97, t = 11.2°C,and K = 426.2 DD. Developmental times were longer than those reported for Minnesota and South Dakota populations at similar temperatures, suggesting significant physiological differences among populations. Based on 4-yr mean monthly temperatures that simulated those at the lO-cm depth at Champaign, 1L, first hatch occurred on 7 June (176.5DD, t = 12.7°C), 50% hatch occurred by 18June (353.8 DD, t = 1l.2°C), and last hatch took place on 4 July, 27 d after first hatch. In separate studies in Illinois and Ontario, Canada, a small percentage of eggs from both locations underwent prolonged diapause. In Illinois, 0.14% of 4,202 D. virgifera virgifera eggs hatched only after passing through two simulated winters. Similarly, in studies in Ontario, 0.21%of 1,446D. virgifera virgifera eggs hatched only after the passage of a second winter. Ours is the first report of prolonged diapause in the western corn rootwoml.
Document Type: Research Article
Publication date: December 1, 1992
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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.