Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-22T18:49:15.268Z Has data issue: false hasContentIssue false
  • English
  • Français

Population fluctuations of the African armyworm, Spodoptera exempta (Walker) (Lepidoptera: Noctuidae), in Outdoor Cages in Kenya

Published online by Cambridge University Press:  10 July 2009

B. Persson
B. Persson
Affiliation:
The International Centre of Insect Physiology and Ecology, P.O. Box 30772, Nairobi, Kenya
Get access Rights & Permissions [Opens in a new window]

Abstract

Spodoptera exempta (Wlk.) was reared for one year at three locations in Kenya: Msabaha on the coast, Nairobi, and Mbita Point on Lake Victoria. The potential yearly number of generations was 15·8 at Msabaha, 6·6 at Nairobi and 13·1 at Mbita Point. Average developmental time from egg deposition to adult emergence was 23·1, 54·9 and 27·8 days, respectively. The longest, 77·3 days, was recorded in Nairobi and the shortest, 19·4 days, at Msabaha. The survival rate varied little seasonally at the coast but was erratic inland, with some generations failing and others very successful. Larvae offered a choice of maize and stargrass (Cynodon dactylon) showed a preference for stargrass. Survival was higher on stargrass than on maize but the developmental time was longer. Mortality was highest in the larval stage. In all generations and at all locations, death was usually caused by a nuclear polyhedrosis virus. There was a positive relationship between larval mortality and rainfall, and a negative one between larval mortality and sunshine. Mating was restricted to after midnight. Females oviposited and then mated during the same night. Peak egg-laying took place before midnight, with a smaller peak at about 02·00–04·00 h.

Type
Original Articles
Information
Bulletin of Entomological Research , Volume 71 , Issue 2 , June 1981 , pp. 289 - 297
Copyright
Copyright © Cambridge University Press 1981

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Brown, E. S. & Swaine, G. (1965). Virus disease of the African armyworm, Spodoptera exempta (Wlk.).—Bull. ent. Res. 56, 95–116.CrossRefGoogle Scholar
Brown, E. S. & Swaine, G. (1966). New evidence of the migration of moths of the African armyworm, Spodoptera exempta (Wlk.) (Lepidoptera, Noctuidae).—Bull. ent. Res. 56, 671–684.CrossRefGoogle Scholar
Brown, E. S., Betts, E. & Rainey, R. C. (1969). Seasonal changes in distribution of the African armyworm, Spodoptera exempta (Wlk.) (Lep., Noctuidae), with special reference to Eastern Africa.—Bull. ent. Res. 58, 661–728.CrossRefGoogle Scholar
Brown, E. S. (1970). Control of the African armyworm, Spodoptera exempta (Walk.).—An appreciation of the problem.—E. Afr. agric. For. J. 35, 237–245.Google Scholar
Hattingh, C. C. (1941). The biology and ecology of the armyworm (Laphygma exempta) and its control in South Africa.—Sci. Bull. Dep. Agric. For. Un. S. Afr. no. 217, 50 pp.Google Scholar
Khasimuddin, S. & Lubega, M. C. (1979). Behavioural ecology of the African armyworm Spodoptera exempta (Walker) (Lepidoptera: Noctuidae); evidence of successive generations from Kenya.—Bull. ent. Res. 69, 275–282.Google Scholar
Odindo, M. O. (1977). Comparative studies on the histopathology and the symptomatology of a nuclear polyhedrosis of Spodoptera exempta (Walk.) (Noctuidae, Lepidoptera).—E. Afr. agric. For. J. 42, 287–295.CrossRefGoogle Scholar
Persson, B. (1977). Distribution of catch in relation to emergence of adults in some noctuid pest species in south coastal Queensland.—Aust. J. Zool. 25, 95–102.CrossRefGoogle Scholar
Rose, D. J. W. (1975). Field development and quality changes in successive generations of Spodoptera exempta Wlk., the African armyworm.—J. appl. Ecol. 12, 727–739.CrossRefGoogle Scholar
Rose, D. J. W. & Law, A. B. (1976). The synoptic weather in relation to an outbreak of the African armyworm, Spodoptera exempta (Wlk.).—J. ent. Soc. sth. Afr. 39, 125–130.Google Scholar