Studies on seasonal abundance of diamondback moth Plutella xylostella (Lepidoptera: Yponomeutidae) on cauliflower crop

Abstract

The studies on seasonal abundance of diamondback moth Plutella xylostella were conducted in two years 2004-2005 and 2005-2006. Survey data of three localities of Aligarh district showed that initial infestation by P. xylostella occurred when the farmers started transplantation of cauliflower seedlings, the density of P. xylostella ranged between 0.90 to 2.38 and 0.27 to 5.84 larvae and pupae/plant in I week of July, 2004 and 2005, respectively, and the rate of parasitization was quite low. Temperature and humidity recorded maximum and minimum i.e. 24.15° to 32.91°C and 68.60 to 91.30 percent, respectively. Population build up is usually observed in II to IV week of September. Cotesia plutellae was found to be a dominant larval parasitoid while, Oomyzus sokolowskii parasitized relatively few pupae of P. xylostella. 34.77°C significantly (p < 0.01) enhanced the population of DBM also on 8th September, 8th October, 2004 and 26th January, 2005. Rainfall negatively affected the DBM population in 2004-2005 and 2005-2006.