Spatio-temporal distribution of planthopper and predator mirid in two rice granary areas of Malaysia

H. Mohd Norowi

Abstract

Spatial and temporal distributions of planthopper and predator mirid bug were analysed and quantified. The study, conducted at Pasir Panjang and Limbat, was to evaluate the roles of non-rice habitats on the conservation of beneficial arthropods in rice ecosystem. The landscape of the rice ecosystem differed at these two sites whereby the non-rice habitat was larger at Limbat than at Pasir Panjang. The temporal pattern of planthopper was dissimilar between the two sites. At Pasir Panjang, planthopper populations varied between and within season. Its peak adult densities were 3 planthoppers/m2 in the first season and increased to 45 planthoppers/m2 in the third season. Population of predator mirid bug (PMB) was low and lagged behind the planthopper population. At Limbat, the density of planthopper adult was consistently low. Its peak density was less than 5 planthoppers/m2 in all seasons. PMB density was relatively higher at Limbat. Analysis of the spatial pattern and spatial association between planthopper and PMB indicated that planthopper patches consistently occurred in the middle of the area at both sites. Generalist predators inhibiting the non-rice habitat might have killed the planthopper present near the vicinity resulting in the formation of gaps. However, these predators were slow to move to the middle of the field resulting in the formation of patches of planthopper in the central areas. These results suggested that spatial heterogeneity, in the form of non-rice habitats within rice landscapes could be manipulated to conserve predator populations and help control the planthopper population in the rice ecosystem.

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