author(s)
SK Mishra and PM Kanwat

abstract
Field experiment was conducted during Rabi 2000-2001 and 2001-2002 at Agronomy Farm of S.K.N. College of Agriculture, Jobner (Rajasthan) to ascertain the pest incidence in mustard variety ‘Varuna’. The incidence of aphid started in the last week of December (31.75 aphids/5 plants). The aphid population reached to its peak (404.25 aphids/5 plants) in the last week of January. Thereafter, the population declined abruptly. Negative significant correlation was found between aphid population and maximum temperature (r = -0.4576, -0.7692 and -0.6094) for the years of 2000-2001, 2001-2002 and pooled data, respectively and minimum temperature (r = -0.6047, -0.4944 and -0.5491) for the years of 2000-2001, 2001-2002 and pooled data, respectively. Positive significant correlation was found between aphid population and relative humidity (r = 0.4196, 0.5059 and -0.4616) for the years of 2000-2001, 2001-2002 and pooled data, respectively. Five species of predator were found predating on mustard aphid. C. septempunctata and M. sexmaculatus appeared in the first week of January and population reached to its peak in the last week of January and coincided with the peak of aphid population. C. transversalis and A. variegata were noticed during second and third week of February, respectively and remained in the field for a short period of time. The maggot of syrphid fly, X scutellarae appeared in the second week of January and its population reached to peak (13 larvae/ 5 plants) during fourth week of January.