Elucidating effect of different photosynthetic pigments on Lipaphis erysimi preference and population build-up on diverse Brassica juncea genotypes

Brassica juncea is the most important oilseed crop in India, and Lipaphis erysimi is a major pest of this crop. The study aimed at knowing the role of photosynthetic pigments in host preference and population build-up by L. erysimi on diverse B. juncea genotypes. We found significant differences among test genotypes for aphid preference, multiplication rate and population build-up, and chlorophyll A, chlorophyll B, total chlorophyll, total carotenoids and Soil Plant Analysis Development (SPAD) chlorophyll and Normalised Difference Vegetation Index (NDVI) values in healthy and aphid damaged flowers, immature siliquae and grain filled siliquae. The L. erysimi damage reduced all the photosynthetic pigments across plant parts of test B. juncea genotypes. The aphid damage resulted in change in chlorophyll B in flowers and total chlorophyll in immature siliquae showed positive association with leaf preference, while total carotenoids in flowers and grain filled siliquae had negative association with leaf and bud preference by L. erysimi. Chlorophylls A and B in the siliquae showed significant and positive association with multiplication rate and population build-up of L. erysimi on B. juncea. Change in chlorophyll A, total chlorophyll and total carotenoids because of aphid damage contributed to 38.6% variation in host preference and 21.9% variation in multiplication rate and population build-up of L. erysimi on different B. juncea genotypes. Genotypes PM 30, RH 749, PDZ 6, Pusa 119-1-3, Pusa 119-1-1 and Kranti were found with least leaf and bud preference, lower aphid multiplication rate and population build-up, and higher amounts of different chlorophylls and total carotenoids, suggesting their use in aphid resistance breeding programme.