Life History Parameters of the Gregarious Phase of the South American locust, Schistocerca cancellata (Serville) (Orthoptera: Acrididae), under Laboratory Conditions

Abstract

A laboratory study was conducted to determine some life history parameters of the gregarious phase of the South American locust, Schistocerca cancellata. An age-specific life table was constructed based on laboratory data. Duration of egg, nymphal and adult female and male stages was 15?1.005, 33.24?1.302, 87.60+34.84, and 89.80?26.85 days, respectively. The mean life of the cohort was 175 days, and sex ratio of emerging adults was 1:1. Survivorship curve showed a high survival during most of the life time of the cohort. 9.10 % of the cohort mortality occurred during nymphal instars V and VI and 90.90 % during adult stage, most of it during the last 5 weeks. Mean fecundity was 160.7+93.10 eggs/female and the number of eggs per pod was 73+18.94. Maximum values of the fecundity rates were reached at the age of 17 and 18 weeks. The reproductive values curve indicated that the highest contribution to the future population occurred at week 17. The values of the intrinsic rate of increase (r), the net reproductive rate ( R 0) and the mean generation time ( T ) were 0.2906 _ 0.0027, 130.43 ? 9.71, and 17.78 ? 0.2281, respectively.