caa a22 4500 388093382 CHVBK 20180307125257.0 cr unu---uuuuu 161130e199904 xx s 000 0 eng 10.4039/Ent131243-2 doi S0008347X0000986X pii (NATIONALLICENCE)cambridge-10.4039/Ent131243-2 BIOLOGY OF CYPHOCLEONVS ACHATES (COLEOPTERA: CURCULIONIDAE), PROPAGATED FOR THE BIOLOGICAL CONTROL OF KNAPWEEDS (ASTERACEAE) [Elektronische Daten] Cyphocleonus achates (Fahraeus) is a weevil used for the biological control of diffuse knapweed, Centaurea diffusa Monnet Del La Marck, and spotted knapweed, Centaurea maculosa Monnet Del La Marck, in North America. This research provided specific information on the biology of this insect in British Columbia. Adult weevils were released at six densities (1, 2, 4, 8, 16, and 32 male-female pairs) in each of 2 years into plots containing spotted knapweed. Larvae per plant, larval mass, larval survival, adult emergence, and air temperature were measured. Larval production increased with the release density of weevils in both the 1992 cohort and the 1993 cohort. Larval mass did not differ between years. Larval mass also did not vary with the release density of adults or the number of larvae per root. Larval survival of the 1993 cohort ranged from 17 to 48%, whereas that of the 1994 cohort ranged from 0 to 91%. Adult emergence began after the accumulation of 726-1144 degree-days. For both cohorts the date of first emergence occurred earlier, as the average number of larvae per plant increased for both cohorts. Increasing competition for food or space in the roots can induce early emergence. Sex ratios did not vary with date of emergence or release density of adult weevils. Adult emergence increased with the release density in the 1992 cohort, suggesting the average larval densities did not exceed the carrying capacity of the roots. The peak emergence rate increased with the release density in the 1992 cohort, but not in the 1993 cohort because of lower larval survival. Copyright © Entomological Society of Canada 1999 Wikeem Brian M. Research Branch, British Columbia Ministry of Forests, 3015 Ord Road, Kamloops, British Columbia, Canada V2B 8A9 Powell George W. Research Branch, British Columbia Ministry of Forests, 3015 Ord Road, Kamloops, British Columbia, Canada V2B 8A9 Sturko Allen Range Branch, British Columbia Ministry of Forests, P.O. Box 9513, Station Provincial Government, Victoria, British Columbia, Canada V8W 9C3 The Canadian Entomologist Cambridge University Press 131/2(1999-04), 243-250 0008-347X 131:2<243 1999 131 TCE https://doi.org/10.4039/Ent131243-2 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.4039/Ent131243-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Wikeem Brian M. Research Branch, British Columbia Ministry of Forests, 3015 Ord Road, Kamloops, British Columbia, Canada V2B 8A9 NATIONALLICENCE 700 1- Powell George W. Research Branch, British Columbia Ministry of Forests, 3015 Ord Road, Kamloops, British Columbia, Canada V2B 8A9 NATIONALLICENCE 700 1- Sturko Allen Range Branch, British Columbia Ministry of Forests, P.O. Box 9513, Station Provincial Government, Victoria, British Columbia, Canada V8W 9C3 NATIONALLICENCE 773 0- The Canadian Entomologist Cambridge University Press 131/2(1999-04), 243-250 0008-347X 131:2<243 1999 131 TCE CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge