Spatial distribution of thrips, Thrips palmi Karny on potato (Solanum tuberosum) under subtropical conditions of Madhya Pradesh

A field experiment was carried out during 2006–07 and 2007–08 at Central Potato Research Station (CPRS), Gwalior, India to study the spatial distribution of thrips (Thrips palmi Karny) in potato (Solanum tuberosum) crop. The various indices of dispersion, viz., variance mean ratio, exponent k and common k (kc), Lloyd's indices of mean crowding (x*) and patchiness index (x * “x) and Taylor's power law revealed that the potato thrips exhibited aggregated or contagious pattern of distribution in the field. In study of Taylor's power law, slop parameter (b = 0.7617 and 0.702 for respective years) was < 1 indicating contagious distribution. This also indicates that thrips population followed negative binomial distribution pattern as an alternative of poisson or random distribution. The intercept also justified that the distribution of thrips was contagious in nature. Spatial distribution parameters are useful to out line the sampling programme as well as to estimate the population density of T. palmi.