Life table for establishment of potato tubermoth Phthorimaea operculella

Life table studies of the potato tubermoth, Phthorimaea operculella (Zeller) (Lepidop-tera: Gelechiidae) for six generations (July 1988 to May 1989) in storage conditions revealed that the maximum mortality was observed in younger larval stages. The mortality ranged from 9.0 to 20.0, 36.0 to 86.66, 0 to 23.07, 0 to 36.84% in egg, younger larval, older larval and pupal stages, respectively. The predatory mite, Blattisocius keegani Fox on eggs, a Nosema sp., lizards, spiders and ants on larvae and pupae were identified as critical mortality factors. Among these, the predatory mite (B. keegani and the microsporidium (Nosema sp.) were recorded for the first time on PTM from India. Generation trend index (GTI) showed 2.66 to 17.55 times multiplication rate. The survivorship curve followed Slobodkin type IV curve. The population growth parameters revealed that the net reproductive rate (R_o) varied from 1.36 to 7.9, the mean of 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 six generations.