Dispersal characteristics of the armoured ground cricket, Acanthoplus speiseri Brancsik, a pest of grain crops in Zambia

Abstract

The dispersal characteristics of a population of 124 marked adult individuals (62 males and 62 females) of the armoured ground cricket (AGC), Acanthoplus 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 annuli (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.