Biology and Partial Ecological Life Table of the Cotton Bollworm in Ethiopia

Abstract

The biology and partial ecological life tables o f Helicoverpa armigera were studied during 2001 to 2002 at Werer, Ethiopia under controlled condition (30+ 3°C). Egg development period lasted 2-3 days and the observed infertility was 47.20 %. Total larval period (1-6 instar) was 12-16 days. Pre-pupal period ranged between 1-2 days. Pupation lasted 7-12 days and 48 % of the pupae emerged within 9 days. Recorded average adult longevity was 7.4 days while average number of eggs per female was 256. Disease (unidentified) was the major mortality factor o f larvae and prepupae, while desiccation was found to cause mortality over pupae. The calculated netreproductive rate (Ro), the intrinsic rate o f increase (r) and cohort generation time (Tc) was 77.98, 0.78 and 26.5 days, respectively. The utility o f these results in planning the management strategy for H. armigera in Ethiopia is discussed.