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In laboratory experiments, a freeze-dried concentrated form of the icenucleating active bacteria, Pseudomonas syringae, was used to decrease the supercooling capacity of field-collected diapausing Colorado potato beetles, Leptinotarsa decemlineata (Say). Application of the P. syringae to adult beetles increased their mean supercooling point values from -7.6 ± 0.2°C (untreated) to -3.7 ± 0.1°C (1,000 ppm). No beetles survived cooling to temperatures below their supercooling point, indicating that this species is freeze-intolerant. During tests conducted in 1991 and 1992, the increase in the supercooling point was directly dependent on the amount of P. syringae added to soil containing the beetles. Cumulative freezing distributions indicated that 80% of beetles treated with 100ppm of P. syringae would be expected to freeze and die when exposed to -5°C; in contrast, none or very few of the untreated control beetles would be expected to freeze at this temperature. Other experiments demonstrated that the capacity of P. syringae treatments to increase the supercooling point of the beetles decreased after 2 wk of exposure at 4°C and when experiments were done at 10°C. If delivery systems were developed that would expose adult beetles to ice nucleating agents and preserve their ice nucleating activity until critical low-temperature exposure occurs in mid-winter, these nucleating agents could be used in conjunction with cultural control strategies for increasing winter mortality.
Document Type: Research Article
Publication date: April 1, 1994
More about this publication?
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.