DETERMINANTS OF THE COLOR OF HOST EGGS PA RASITIZED BY TRICHOGRAMMA-FUENTESI

In Cuba, during its larval development inside its host egg, Trichogram ma fuentesi turns its host egg either black or brown. Crossings carrie d out between the two forms of T.fuentesi allowed to show that this ch aracter is determined by one locus with two alleles: Bh, dominant, col ours the host black; and bh, recessive, colours the host brown. The bh allele is more frequent in the eastern region of Cuba which is also t he warmest, than in the western region. We studied the evolution of fr equencies of the two alleles in different experimental polymorphic pop ulations at 23 degrees C and at 30 degrees C. In all tested conditions , bh was at a disadvantage by comparison with Bh, except at 30 degrees C when its initial frequency was high (90%). Thus, temperature alone should certainly not explain the maintenance of the observed polymorph ism in Cuba.