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Asian Journal of Plant Sciences

Year: 2003  |  Volume: 2  |  Issue: 17  |  Page No.: 1170 - 1174

Relative Fitness of Pyrethroid Selected Populations of Helicoverpa armigera Hub.

T. Ramasubramanian and A. Regupathy


The relative fitness of pyrethroid selected populations of Helicoverpa armigera was studied by construction of age specific fecundity tables for F2,F7 and F14 generations of unselected, fenvalerate and cypermethrin selected populations. The net reproductive rate computed from the life table statistics indicated that the fitness of the pyrethroid selected populations decreased drastically as the population advanced to fourteenth generation. In F2 the net reproductive rate was 237.437, 231.359 and 228.24 for the unselected, fenvalerate and cypermethrin selected populations respectively. It came down to 123.677 and 121.432 for fenvalerate and cypermethrin selections respectively and only a marginal decline to 197.962 in unselected population. The decrease in fitness was greatly manifested through reproductive behaviour but not by the developmental traits. The variation in generation time was insignificant between the selected and unselected populations irrespective of the generations.

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