Comparative Life Table Parameters of the Beet Armyworm, Spodoptera exigua (Hübner) (Lepidoptera, Noctuidae) on Five Host Plants

Abstract

The beet armyworm, Spodoptera exigua (Hübner) is an important cosmopolitan insect that attacks different plant species in Iran and many parts of the world. Life table parameters of S. exigua on different host plants including Zea mays (var. 704), Gossypium hirsutum (var. Varamin), Brassica napus (var. RGS), Glycine max (var. Sahar) and Chenopodium album were studied at 26 ± 1°C, 60 ± 5% RH and a photoperiod of 16:8 (L:D) h. The larval period, development time and life span of S. exigua were longest on G. hirsutum and shortest on B. napus. The longest pupal period was on G. hirsutum and the shortest one was on G. max. Among different host plants, fecundity (total number of eggs laid per female) of S. exigua was the highest (948.0 eggs) on B. napus and lowest (426.3 eggs) on G. hirsutum. The highest net reproductive rate (R0) was on C. album (377.11 female/ female/ generation), whereas the lowest one was on G. hirsutum (126.39 female/female/generation). The intrinsic rate of increase (rm) varied from 0.1707 to 0.2644, which was the highest on B. napus and lowest on G. hirsutum. Our results indicated that G. hirsutum was the most unsuitable host plant as compared to other hosts tested.