Effect of strain and selection line on the fecundity of the cyclopoid copepod Paracyclopina nana Smirnov, 1935

Abstract

We studied the effect of strain and selection lines on the fecundity of the cyclopoid copepod Paracyclopina nana. We used six strains (HL, YL, BS, SL, TH, TS) and six isofemale lines (including three higher and three lower fecundity lines). As for the selection of strain, total nauplii production per female of SL strain was the highest in the individual culture (231 nauplii per female) and population growth rate in HL and SL strains showed higher values than the others in combined culture. For the selection of line, the total nauplii production per female of HF2-2 (high fecundity and second generation) line was the highest (302 nauplii per female) but those of LF2-1 (low fecundity) (80 nauplii per female), and LF2-3 (46 nauplii per female) lines were lower than the others. In F4 generation, three selected HF2-2 line showed that the total nauplii production were higher than those of three selected LF2-3 lines. In the combined culture on the different selection lines (F8), population growth rate of two selected high fecundity lines showed higher values than that of the non-selection group and selected low fecundity line. Our results demonstrate that the production of P. nana can be improved by selection of the line with high fecundity.