Intra-population variation in reproductive potential offers scope for enhancing the parental stock in mass-reared insect bio control agents. Laboratory cultures of two cold adapted strains of Trichogramma chilonis, along with a local strain and T. pretiosum were studied for such variation in fecundity by evaluating randomly chosen iso-female lines. The indicative fecundity (in first 3 days of adult life) was compared among 10 iso-female lines each among the strains/species. The results showed considerable variation in fecundity among the iso-female lines in Nilgiris, Kodaikanal and local strain of T. chilonis, besides T. pretiosum, from such selective pooling as parental stock, there was enhancement in overall progeny production capacity by 37.3, 19.7, 28.0 and 21.0, (for five pairs of adults) in Nilgiris, Kodaikanal and local strains of T. chilonis and T. pretiosum, respectively.
The progeny from the top 3 lines for fecundity were selected for pooling as parental stock leading to enhancing the progeny production capacity by 26 and 15 per cent in the two cold adapted strains, besides 17 per cent for the local strain while for T. pretiosum such enhancement was 19 per cent. The utility of selecting among iso-female line within Trichogramma species/strains for parental stock improvement in commercial mass production is indicated. This initiative enabled the culturing of strains/ species with more robust genetic base for pursuing future studies on diapause induction in these strains/species.
Trichogramma strains, fecundity enhancement, iso-female lines, parental stock
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