Establishment and WSSV resistant characteristics of selective breeding families for resistance to the white spot syndrome virus of Litopenaeus vannamei

Abstract

Based on one generation of individual selective breeding and four generations of family selective breeding of Litopenaeus vannamei,120 selective breeding families of resistance to WSSV were produced from 2002 to 2007.Experimental WSSV challenging tests showed that the survival rates of generation 2(G2),G3,G4 and G5 were 5.57%±9.83%,8.66%±11.52%,9.52%±8.84% and 13.79%±12.86%0%,and the variation coefficient of survival rates were 1.77,1.40,0.97and 0.87,respectively.Each generation of selective breeding families of resistance to WSSV was divided into three groups:relatively high resistant families,mid-resistant families and susceptible families post WSSV infection.The proportions of susceptible families in G2 to G5 were 76.5%,55.2%,51.4% and 33.3%,and the survival rates were 0.44%±1.09%,0.78%±1.70%,2.27%±2.76% and 2.44%±3.09%,respectively,with an acute mortality peak occurring on 2nd-3rd day post infection.The proportions of mid-resistant families in G2 to G5 were 0,20.7%,31.1% and 38.5%,and the survival rates were 0,9.08%±1.46%,10.7%±1.41%and 11.36%±3.30%,respectively,with two mortality peaks at post WSSV infection,and the 1st peak value was greater than that of the 2nd peak.The proportions of relatively high resistant families in G2 to G5 were 23.5%,24.1%,17.1% and 28.2%,and the survival rates were 22.23%±5.21%,22.7%±12.30%,24.45%±6.56% and 28.98%±8.09%,respectively,with two mortality peaks at post WSSV infection,and the 1st peak value was less than that of the 2nd peak,which showed that these families in this group possessed strong resistance to WSSV infection.So the eruption time of WSSV was delayed and the valuable opportunity could be used to take effective measure to prevent and cure.However,the average of spawning quantity of each generation was declining(P0.05)year after year.