Life table for establishment of potato tubermoth Phthorimaea operculella.
Life table studies of Phthorimaea operculella conducted under storage conditions for 6 generations (July 1988 to May 1989) revealed that the maximum mortality was observed in early-instar larvae. The mortality ranged from 9.0 to 20.0, 36.0 to 86.66, 0 to 23.07, 0 to 36.84% in eggs, early-instar larvae, late-instar larvae and pupal stages, resp. The predatory mite, Blattisocius keegani (which fed on eggs), the pathogen Nosema sp. and lizards, spiders [Araneae] and ants [Formicidae] (which fed on larvae and pupae) were identified as critical mortality factors. Among these, B. keegani and the microsporidium Nosema sp. were recorded for the first time as natural enemies of P. operculella in India. The generation trend index of P. operculella showed a 2.66 to 17.55 increase and survivorship followed a Slobodkin type IV curve. The net reproductive rate varied from 1.36 to 7.9, the mean generation length from 20.94 to 28.81 days, the innate capacity of natural increase from 0.0142 to 0.0790 and the finite rate of increase from 1.012 to 1.08 in 6 generations.