RESISTANCE OF BRASSICA, ESPECIALLY BRASSICA-JUNCEA (L) CZERN, GENOTYPES TO THE DIAMONDBACK MOTH, PLUTELLA-XYLOSTELLA (L)

Resistance of Brassica, especially B. juncea (L.) Czern, genotypes to the diamondback moth (DBM), Plutella xylostella (L.), was evaluated in growth room studies in Saskatoon, Canada, and in field studies at Ang unakolapelessa, Sri Lanka. Growth room studies of DBM oviposition pref erence on 33 genotypes of Brassica showed that Cutlass, Rahangala Sp-2 , MI Sp-3 and Kudaoya Sp-ll (B. juncea), Echo [B. rapa (L.)], S-67 [B. carinata (Braun)], Vates [B. oleracea (L.)] and Nilla [B. napus (L.)] were the least preferred hosts. These genotypes were field-tested in two cropping seasons under insecticide-treated and untreated condition s. Counts of DBM eggs and larvae showed that Rahangala Sp-2 and Vates were most resistant to DBM, whereas Cutlass was moderately resistant. Further, these three genotypes were the least damaged by DBM larvae. R ahangala Sp-2 and Cutlass represent the first sources of resistance to DBM identified in B. juncea. It is suggested that Rahangala Sp-2, Vat es and Cutlass may serve as sources of resistance to DEM and prove use ful in genetic improvement programs for resistance to this major pest of brassicaceous crops. (C) 1998 Elsevier Science Ltd. All rights rese rved.