author(s)
Patel RM, Chaudhari SJ, Rabari PH, Patel BC and Dodia DA

abstract
Infestation of aphid (Lipaphis erysimi Kalten) in mustard crop was studied at Sardarkrushinagar in North Gujarat during Rabi season of 2016. Mustard aphid population commenced from 4th week of December (51st SMW i.e. 7th WAS) with aphid index of 0.4 and reached to its peak during 4th week of February (8th SMW i.e. 16th WAS) with aphid index of 5.0. The parasitization by braconid endoparasite, Diaeretiella rapae MacIntosh on mustard aphid, Lipaphis erysimi Kalten was started during 4th week of January (4th SMW i.e. 12th WAS) and it was the highest (54.17 per cent) during the last week of February (8th SMW i.e. 16th WAS). The predominant coccinellid predator, Coccinella septempunctata Linnaeus (Grub and Adult) was active between 3rd week of January (3rd SMW i.e. 11th WAS) and last week of February (8th SMW i.e. 16th WAS). The syrphid fly, Xanthogramma scutellarae Fabricious was found active between 1st week of January (1st SMW i.e. 9th WAS) and 2nd week of February (6th SMW i.e. 14th WAS) in mustard ecosystem. Thereafter, larval population decreased gradually and reached up to 0.20 larva per plant during 3rd week of February (7th SMW i.e. 15th WAS). Among various weather parameters, wind velocity showed significantly positive correlation with mustard aphid population, whereas, morning relative humidity and evening relative humidity showed significant negative correlation. Weather parameters viz., evening relative humidity which had highly significant and negative association with the activity of grub of coccinellid as well on adult. Among various abiotic factors, evening relative humidity had highly significant and negative correlation with D. rapae activity. There was highly significant positive correlation between the activity of aphid and its natural enemies viz., coccinellids Grub, coccinellids adult and D. rapae.