Seasonal incidence of H. coriandari on fennel and their correlation with biotic and abiotic factors

Abstract

Seasonal incidence of aphid, Hyadaphis coriandari on fennel and their correlation with biotic and abiotic factors were studied at Research Farm, College of Agriculture, SKRAU, Bikaner during two consecutive years i.e., Rabi, 2016-17 and 2017-18. The infestation of H. coriandari commenced in the second week of Feb (7th SMW) and remained active throughout the crop season i.e. upto first week of April during both the years. The population of H. coriandari attained to its peak in last week of February/first week of March i.e. 9th SMW during both the years. After the peak population, the population of H. coriandari started to decline and reached to low level in the 13th SMW near maturity of the crop during both the years. Simultaneously the occurrence of predator, C. septempunctata coincides with the population of aphids during both the years. Maximum temperature had significant negative correlation and minimum temperature had non significant negative correlation with aphid population during 2016-17 where as maximum and minimum temperature had non significant negative correlation with aphid population during 2017-18. Relative humidity morning and C. septempunctata had significant positive correlation with aphid population during both the years. Whereas, relative humidity evening and rainfall had non significant positive correlation with aphid population during both the years (2016-17 and 2017-18).