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Coccinella septempunctata L. and Harmonia axyridzs Pallas are key natural enemies of soybean aphid, Aphi3 gltjcines Matsumura, in North America. Third instars, adult females, and adult males of both C. septempunctata and H. axyridis exhibited a type H functional response for predation toward adult soybean aphids at 26 ± 1°C. In C. septempunctata, the functional response curve of adult males differed from those of third instars and adult females, but there was no difference between third instars and adult females. In H. axyridis, the functional response curves of larvae, adult females, and adult males all differed significantly. Third instars and adult females consumed significantly more soybean aphids than did adult males at prey densities of 150 and 180 aphids per arena for C. septempunctata and at prey densities of 60, 90, 120, 150, and 180 aphids per arena for H. axyridis. The theoretical maximum daily predation rate of adult aphids by C. septempunctata was predicted to be 204 per third instar, 277 per adult female, and 166 per adult male, and 244, 156, and 73, respectively, for H. axyridis. Third instars and adult females of both species consumed significantly more aphids than did adult males on soybean plants with the recommended action threshold of 250 soybean aphids per plant. Both C. septempunctata and H. axyridis have high predation capacities and are important in suppressing soybean aphid populations. [ABSTRACT FROM AUTHOR]

Survival after cold chilling and spring emergence of pea leafminer, Liriomyza huidobrensia (Blanchard), were evaluated in both the field and laboratory in 2001 and 2002. Spring emergence was evaluated through the use of traps placed in various fields and hoop-houses that had high populations of pea leafminers the previous season. No pea leafminer adults were captured in spring emergence cages during either year. To evaluate cold chilling in the laboratory, a factorial design with three. temperatures (approximately -5,0, and 5°C), eight exposure periods (0,1,2,4,8, 16,32, and 64 d), and four replicates was employed. Pupal mortality increased as the length of exposure increased, with no survival after 64 d of chilling at any temperature. Chilling exposure periods in the laboratory were compared with the number of days per month that soil temperatures in the study area fell below 5,0, and -5°C. No field-collected pupae exposed to winter field conditions survived until the spring. The pea leafminer seems to be unable to overwinter in southern Ontario, except in protected areas. [ABSTRACT FROM AUTHOR]