Effect of Weather on Diamond Back Moth, Plutella xylostella (L.) (Lepidoptera: plutilidae) in District Haripur

Under unprotected condition study was carried out during the months from July to November in the year 2012 and 2013 to investigate population dynamics and observe the impact of temperature, relative humidity and rainfall on population of Plutella xylostella (L.) in Cauliflower, Brassica oleracea crop at District Haripur of Khyber Pakhtunkhwa. Field studies results showed that the population of P. xylostella gradually increased from mid of July where the population was 2.1 and 2.0 larvae and pupae per plant in the year 2012 and 2013 respectively. The population increased in September to highest number of larvae and pupae per plant (8.25 and 8.4) were recorded in the years 2012 and 2013 respectively. Then population declined from September to November 3.5 and 3.1 larvae and pupae was recorded per plant in both years as the lowest number. In the year 2012, mean maximum and minimum temp showed non- significant negative and positive association (r=-0.32 and 0.07) with population of P. xylostella respectively. Similarly R.H (r=0.89) exhibited positive highly significant whereas RF (r=-0.96) showed negative highly significant relationship with P. xylostella during the year 2012. Likewise, during the year 2013, mean maximum temperature showed non-significant negative relation (r=-0.21) whereas mean minimum temperature showed positive non-significant association with P. xylostella population. Mean relative humidity (RH) also exhibited non-significant positive association (r=0.06), while the population effectively influenced by total rainfall (r=-0.82) which exhibited highly significant negative association. Regression analysis showed 87-96% (R2) variability due to weather parameters on the population dynamics of P. xylostella at District Haripur.