Forewarning models of tea mosquito bug {Helopeltis antonii (Signoret)} in cashew

Abstract

Field experiment was conducted to monitor tea mosquito bug damage with respect to weather variables for seven years from 2013 to 2020 at Cashew Research Station, Madakkathara. A seasonal pattern was observed in tea mosquito bug incidence, coinciding the crop phenophase, initiating from 24th October to 5th November, continuing till 18th to 30th March of the succeeding year. Peak damage and high seasonal indices were recorded during 16th to 28th December, 28th December to 10th January and11th to 23rd January respectively in early, mid and late flowering types. Night temperature between 19.2 and 22.50C, morning relative humidity of 70-80 per cent, evening relative humidity between 40 and 60 per cent, a day length of 11.5 to11.7 hours, sunshine within 7 to 9 hours, and prevalence of low or no rainfall were the triggering factors for pest build up and infestation. The best fit regression with minimum temperature and morning relative humidity predicted the damage with 80-83 per cent accuracy. The models were validated with dataset for the year 2019-20 and RMSE, and other validation statistics revealed no significance difference between observed and predicted values of tea mosquito bug damage. Hence, the models could be utilized to disseminate the insect advisories to the farmers.