Population Dynamics of Red Ant Dorylus Orientalis in Potato Grown Under Flood Free/Prone Conditions

Experiments were carried out in the farmer’s field at Jorhat during 2015-16 and 2016-17 to study the population dynamics of red ant Dorylus orientalis Westwood in potato crop. The incidence of D. orientalis was observed both under flood free/and prone conditions in three villages each, during potato growing season. These data were correlated with weather factors. The effect on population buildup was studied with observations at fortnightly interval starting from 1^st fortnight of October to 2^nd fortnight of February through fixed plot surveys. The observations revealed that maximum incidence (36.5, 33.2 and 30.1; 35.2, 32.5 and 29.8/pit) was observed in Charaibahi, Karangia and Hokai Khangia villages, respectively during the 1^st fortnight of January. In contrast, in the flood prone villages, incidence was observed to be negligible. Correlation coefficients of incidence with weather factors revealed that minimum temperature, soil temperature (morning and evening) and evaporation rate show a significantly negative correlation; whereas relative humidity (RH) (morning and evening) exhibited significant positive correlation in flood free villages. In flood prone villages minimum temperature as well as morning soil temperature showed significant negative correlation (2015-16); in contrast, in flood prone villages, RH (morning and evening) showed significant positive correlation (2016-17).