Vegetos

Abstract

Aphids are important pests of crop plants and to maintain their regular supply for laboratory experiments, the insects are usually reared on their respective host plants. During present study, authors evaluated the performance of Lipaphis erysimi (mustard aphid) on two in vitro rearing methods: (i) aseptic cultures of Brassica juncea plants and (ii) detached leaves of B. oleracea (cauliflower). Apterous L. erysimi showed similar reproductive rates on both the systems, producing an average of 31 nymphs in nine days. Longevity of the adults and duration of prereproductive growth of nymphs were also comparable in both methods. However, with increasing population, nymphal mortality was significantly higher in B. juncea leading to contamination of the culture media at later stages due to contact with dead aphids. Therefore, use of aseptic B. juncea cultures was preferred for aphid rearing. This method was used to phenotype six lectinoverexpressing transgenic lines of B. juncea, which had been tested earlier for aphid resistance/sensitivity under natural infestation conditions during the growing season. No significant difference was observed in aphid mortality among the selected transgenic plants vis-à-vis the untransformed control plants. However, five lines showed significant reduction in fecundity. These results were in consonance with natural infestation data thus confirming the suitability of using in vitro cultures for rearing and assays. This is the first study to demonstrate use of aseptic B. juncea cultures as an efficient method for season-independent rearing of L. erysimi and its use for rapid in vitro screening of transgenic plants for aphid resistance. This approach could be used with other aphid-host plant systems.