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A Preliminary Life Table of the Armoured Ground Cricket, Acanthoplus speiseri Brancsik (Orthoptera: Tettigoniidae, Hetrodinae), a Pest of Grain Crops in Zambia

Published online by Cambridge University Press:  19 September 2011

Keith J. Mbata
Affiliation:
Department of Biological Sciences, University of Zambia, P. O. Box 32379, Lusaka, Zambia, E-mail: [email protected]
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Abstract

The development of a single cohort of the armoured ground cricket, Acanthoplus speiseri Brancsik was followed in the environs of the University of Zambia campus, Lusaka and a preliminary life table of the grain pest constructed. The pest's total generation mortality was influenced by: failed egg eclosion, failed ecdysis, cannibalism/predation and parasitism. The egg stage had the highest percent real mortality (98.57%) and sub-mortality k-value, indicating that this was the main contributor to the total generation mortality. The rest of the developmental stages suffered lower mortalities, although that of the 6th instar was comparatively higher. A mermithid nematode, Mermis sp., and another unidentified nematode species caused 2.61% sub-mortality in the 6th nymphal instar. The constructed preliminary life table of A. speiseri is analysed and the possible causes of the observed high mortalities in the egg and 6th instar stages are discussed.

Résumé

Le développement biologique d'une seule cohorte du criquet terricole à bouclier, Acanthoplus speiseri Blancsik a fait objet de suivi dans les alentours du campus de l'Université de Zambie à Lusaka, et une table préliminaire de vie du ravageur a été construite. La mortalité totale enregistrée au cours d'une génération du ravageur était influencée par des éclosions avortées des oeufs, des mues larvaires ratées de même qu'un cannibalisme/ prédation et parasitisme. Le stade oeuf avait le pourcentage de mortalité réelle le plus élevé (98,57%) et la plus haute valeur de k de sous-mortalité, ce qui indique que la mortalité à ce stade contribue grandement à la mortalité totale au sein d'une génération. Les autres stades de développement subissaient moins de mortalité, même si les nymphes du sixième stade avaient une mortalité plus élevée comparativement aux autres stades larvaires. Mermis sp. et un nématode mermétide et un autre nématode non identifié ont causé 2,61% de sous-mortalité chez les nymphes du sixième stade. La table préliminaire de vie de A. speiseri ainsi construite est analysée et des raisons possibles des hautes mortalités observées au stade oeuf et au sein des nymphes du sixième stade de développement sont discutées.

Type
Research Articles
Copyright
Copyright © ICIPE 1999

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