A new technique of mass-screening rice seedlings for resistance to the crab, Sesarma huzardi, developed by the West Africa Rice Development Association (WARDA) at Rokupr is described.
About 500 mangrove swamp local collections and a few exotic varieties have been screened for resistance to crab damage. Only 2% of the varieties have been identified as highly tolerant. Generally, the local collections were tolerant, while none of the foreign introductions have been tolerant.
The basis of resistance appears to be morphological, which physically affects feeding mechanism; thus, some varieties were more susceptible to crab damage than others.
Degree of the heritability (hb2 = 61%) estimate indicated that there is genetic variability for tolerance. In a team-oriented research, some of the varieties are being used in the WARDA breeding programme at Rokupr.
