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Dispersal characteristics of the armoured ground cricket, Acanthoplus speiseri Brancsik, 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 dispersal characteristics of a population of 124 marked adult individuals (62 males and 62 females) of the armoured ground cricket (AGC), Acantliophis speiseri Brancsik (Orthoptera: Tettigoniidae, Hetrodinae), released at the centre of a circular study site, were investigated using the capture-mark-release-recapture method for five successive days. The 110 m-diameter study site comprised five grass-trap annuii (each 1 m wide) spaced at 10-m intervals from the centre.

The frequency curve of numbers derived from recapture data for day 1 departed from normal (Kurtosis = 2.7), indicating that the released AGC population was heterogeneous in its dispersing behaviour. A comparison of mean numbers of recaptures from grass-traps per quarter portion of the study site revealed no drift in the dispersal of the population (P > 0.05), though differences in the variances of the recapture frequencies indicated a tendency towards non-random movement in the AGC population.

The population covered a mean distance of 24.47 m in the first 24 h following release and the rate of dispersal changed daily in the five-day study. The implications of the dispersal characteristics observed in this study to future design of control strategies for the pest in Zambia are discussed.

Résumé

Les caractéristiques de dispersion d'une population de 124 individus adultes (62 mâles et 62 femelles) du criquet-de-sol à armure (AGC) Acanthoplus speiseri Brancsik (Orthoptera: Tettigoniidae, Hetrodinae), relâchés au centre d'un espace d'étude circulaire (diamètre 110 m), étaient examinées en utilisant la méthode de capturer-marquer-relacher-recapturer (durant cinq jours consécutifs). Cinq pièges d'herbes appellés annuli (chacun ayant 1 metrè de largeur) étaient placés l'un de l'autre (10 m à part) sur une distance croissante à partir du centre de l'espace en étude. La courbe de fréquence des nombres dérivés des résultats du recapture pendant le premier jour dévia du norme (Kurtosis = 2.7). Une comparaison des moyennes des recaptures par les pièges d'herbes dans chaque quart de l'espace d'étude revéla qu'il n'y avait pas d'amassement dans la dispersion de la population. Il n'y avait pas de difference significative entre les moyennes (P > 0.05). Quoique les differences des variances entre les fréquences des recaptures revéla qu'il y avait une tendance vers le fait que le mouvement de dispersion des AGC n'était pas un hasard.

En se dispersant la population des AGC couvrit une distance moyenne de 24.47 m durant les premières 24 heures après la relache et la vitesse de dispersion changea chaque jour durant les cinq jours d'étude. Les implications des caractéristiques de dispersion observée dans cette étude pour le project futur des stratégie de control de la peste en Zambie sont examinées.

Type
Research Articles
Copyright
Copyright © ICIPE 1998

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