Spatial distribution of red palm weevil Rhynchophorus ferrugineus Oliv. (Coleoptera: Curculionidae) in coconut plantations

Abstract

The spatial distribution of red palm weevil, Rhynchophorus ferrugineus Oliv. in coconut plantations was studied by applying a series of statistical tests. Population dispersion parameters and also different dispersion indices were calculated for monthly weevil counts obtained through 40 pheromone (Ferrolure+) trap captures, between August, 1999 and July, 2000. The dispersion parameters, viz. mean-variance test, clumping parameter (K) and statistic t tests revealed that red palm weevil population followed the negative binomial distribution pattern and was highly aggregated or clumped. Further, the different dispersion indices, viz. variance to mean ratio, Cole's index, David and Moore's index, 'K' of negative binomial and Lloyd's index of mean crowding went on to confirm the aggregated or contagious distribution pattern of red palm weevil. Due to the clumped nature of palm weevil population, these results emphasize the need of adopting preventive management practices in and around plantations infested by red palm weevil. © 2002 Elsevier Science Ltd. All rights reserved.