Cold Hardiness and Overwintering Survival of the Sugarbeet Root Maggot (Diptera: Otitidae) in Southern Alberta

Publisher： Entomological Society of America

ISSN： 1938-2901

Source： Annals of the Entomological Society of America, Vol.78, Iss.4, 1985-07, pp. : 501-505

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Abstract

Mature third instar larvae of the sugarbeet root maggot, Tetanops myopaeformis (Röder), were exposed to constant temperatures of −15, −10, −5, 0.5, 2.5, and 5°C for 6 months. Larval survival and pupation were greatest at 5°C and significantly less survival was observed at temperatures below 0.5°C. Supercooling point determination indicated that although larvae can supercool to −11°C, mortality may occur at temperatures above the supercooling point, especially under extended periods (6 months) of low temperatures. There were significant differences in the vertical distribution of larvae in the soil; the majority of larvae were observed to occur at a depth of 10–20 cm in September, 5–15 cm in January and February, and 0–15 cm in April. Survival and pupation of larvae averaged 87.1 and 74.1%, respectively, and there were no significant differences in larval survival at soil depths of 5–30 cm. High overwintering survival of the larvae is attributed to their low supercooling points, freezing tolerance, and the ability of larvae to move within the soil to take advantage of the thermal damping properties of soil throughout the season.