Assessment of spatial distribution of Plutella xylostella on Cabbage (Brassica oleracea var. capitata)

The present investigation aimed to study the distribution pattern of larvae and pupae of diamondback moth (DMB) on cabbage (Brassica oleracea var. capitata L.). The experiment was laid out in randomized block design at the Horticulture farm, Rajasthan College of Agriculture, Maharana Pratap University of Agriculture and Technology, Udaipur, Rajasthan during rabi 2019-20 and 2020-21. The present study was carried out to understand the pattern and behaviour of the spatial distribution of DBM in cabbage. The prevalence of DBM incidence was recorded in terms of the number of larvae and pupae per plant on ten randomly selected plants in each replication at weekly intervals. The various indices, viz. variance to mean ratio, exponent-K, patchiness index, clumping index, mean colony size, mean clump size, Iwao's patchiness regression and Taylor's power law were analyzed to test the dispersion behaviour of diamondback moth. The value of various indices exceeded unity in most of the weekly observations indicating clumped type of distribution of diamondback moth larvae and pupae on cabbage. Clumped distribution behaviour of DBM population can aid the understanding of the pest ecology and its management.