Relative Abundance of Turnip Aphid and the Associated Natural Enemies on Oilseed Brassica Genotypes

A two-year field study was conducted at Punjab Agricultural University, Ludhiana, India, to study the relative abundance of mustard/turnip aphid, Lipaphis erysimi (Kaltenbach) (Hemiptera: Aphididae) and the associated resident natural enemies on ۱۰ different rapeseed-mustard genotypes which included: Brassica juncea: RH ۷۸۴۶, RH ۹۵۰۱, RK ۹۵۰۱, JMM ۹۲۷, Purple Mutant; B. napus: Hyola PAC ۴۰۱ (Hybrid); B. rapa ecotype yellow sarson cv. YST ۱۵۱; B. rapa ecotype brown sarson cv. BSH ۱; B. carinata: DLSC ۲ and Eruca sativa: T ۲۷. The objective was to study whether indigenous natural enemies can be used for biological control of mustard aphid. Population of turnip aphid and different natural enemies was recorded at weekly intervals. There was lack of synchronization in the peak activity of natural enemies with that of the aphids with a time lag of one to two weeks depending upon the genotype. For example, on B. juncea cv. RH ۷۸۴۶, the peak aphids’ population was recorded during the ۱۰th Standard Meteorological Week (SMW) while that of predators’ was recorded during the ۱۲th SMW in ۲۰۰۷-۲۰۰۸ crop season. Among the different natural enemies, coccinellids were the most abundant with grubs being dominant in the initial phase of population development and adults in the later one. There is a need to conserve the resident natural enemies in mustard ecosystem for effective early season suppression of the aphid population or release them early in the season to suppress aphid population in lag phase of its development.