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Abstract
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Abstract The efficiency of biological control agents can be influenced by several factors, such as the quality of their herbivore hosts and the nutritional status of the host plants. This study focused on the parasitism capacity of Habrobracon hebetor (Hymenoptera: Braconidae) on Helicoverpa armigera (Lepidoptera: Noctuidae) reared on different nitrogen fertilized tomato plant cultivars. Four cultivars, namely Kingston, Early Urbana, Super strain-B, and Primo Early, with four nitrogen levels (0, 2.1, 3.0, 3.9 g/ pot Nitrogen as Urea 46%), were used. The results showed that the net parasitism rate (C0 ) of H. hebetor varied from 9.50 to 11.04 and 10.3 to 12.34 host/parasitoid on H. armigera reared on four host plant cultivars with the lowest and highest N levels, respectively. The transformation rate (Q p) on treatments was close to 1. The total parasitism capacity of a stable population (ψ) ranged from 0.224 to 0.358 host/parasitoid. Moreover, the highest recorded values of the finite parasitism rate (ω) included 0.281, 0.390, 0.329 and 0.431 day −1 on the hosts reared on Early Urbana, Super strain-B, Primo Early and Kingston at the highest N levels, respectively. Based on the estimated biological attributes in the current study, the optimum performance for H. hebetor belonged to the hosts fed on Kingston and Super strain-B cultivars. Moreover, the parasitism capacity of the parasitoid was positively influenced by nitrogen fertilized treatments as an effective bottom-up factor.
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