Abstract

The mean population densities of dominant insects (pest and beneficial) associated with watermelon (Citrullus lanatus Thunb.) in a field experiment conducted in 2016 early- and late-season were subjected to statistical models to determine the average relative length of their presence period (ARLPP) and spatial distribution pattern (using Lloyd’s index of patchiness [m*/m] and Green’s coefficient of dispersion [Cx]). The ARLPP ranged from 41.67 – 66.67% with pest species/taxa having overall slightly higher values of 62.50 and 59.38% on early- and late-crop, respectively vis-à-vis 59.52 and 54.76% for beneficial species. But for Camponotus sp. on the seedling stage of early-crop, all the other dominant insects had m*/m values > 1 which indicates aggregated dispersion. Similarly, aside Camponotus sp. with Cx value of -0.050, all the other dominant insects had values that ranged from 0.001 – 0.466 indicating that the aggregation were weak since maximum clumping is 1. Even though the results from the dispersion models herein used corroborates previous results on this same study which used other models (variance to mean ratio [S 2 /m], Taylor’s power law [S 2 = am b ] and Iwao’s patchiness regression [m * = α + βm]), we recommend validation of the results on large field trials and with different varieties.