Morphological and chemical traits of host plants play a vital role in the abundance and infestation of herbivore insects. The study was carried out to know the abundance and infestation of aphid Lipaphis erysimi Kaltenbach (Hemiptera: Aphididae) on selected mustard varieties namely BARI-14, BARI-15 and Tori-7, and to find out the relationship of the abundance and infestation of aphids with plant morphological and chemical traits. The percent plant infestation was lowest on BARI-15 and highest on BARI-14. Similarly, leaf and pod infestations per affected plant were less on the BARI-15, followed by Tori-7 and BARI-14. Aphid abundance on the plants and pods was minimal on BARI-15, followed by the Tori-7 and BARI-14. Aphid infestations were positively correlated with the percent water content and diameter of stems and pods. Likewise, percent nitrogen and organic carbon in the stems and pods were influential in elevating aphid abundance. Therefore, BARI-15 was the least preferred variety to aphids than Tori-7 and BARI-14. The higher proportion of water, nitrogen and organic carbon in the plants, stems and pods and the larger diameter of stems had positively influenced aphid infestations.
Key words: Brassica spp.; Lipaphis erysimi; morphological features; water content; nitrogen content; organic carbon content