Document Type : Research Paper
Authors
1
Asistant Professor, Department of Plant Protection, Faculty of Agriculture, Azarbaijan Shahid Madani University
2
Associate Professor, Department of Plant Protection, Faculty of Agriculture, University of Tabriz.
3
Professor, Department of Plant Protection, Faculty of Agriculture, University of Tabriz
Abstract
The cotton bollworm (CBW), Helicoverpa armigera (Hübner) is a major pest of cotton in Iran. Nowadays, integrated control of CBW is done using Bacillus thuringiensis Berliner and Trichogramma or Habrobracon. To determine indirect effects of the bacteria on Habrobracon hebetor (Say), its life table in two treatments of cotton bollworm, one a control (larvae fed by normal artificial diet without Bt) and the other Bt treated (the 3rd instar larvae of CBW that fed by artificial diet involving LC20 concentration of B. thuringiensis) at 26±1 ˚C, 65±5% RH and 16: 8 (light: darkness) was studied. Intrinsic rate of increase (rm), finite rate of increase (λ), net reproductive rate (R0), mean generation time (T), doubling time (DT) for control and Bt treatment were evaluated as 0.2051±0.017, 0.1644±0.017 d-1, 1.227±0.021,1.178±0.021 d-1, 61.863±17.60, 28.32±6.81 per generation, 20.10±0.70, 20.33±0.70 d, 3.37±0.15, 4.21±0.36 d, respectively. The life expectancy of H. hebetor at the beginning of the cohort life was 25.5 and 16.83 d in control and Bt treatment, respectively. The results suggested that B. thuringiensis has an inverse effect on biological parameters of H. hebetor and caused a decrease in parasitism as well as intrinsic rate of increase.
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