LIFE-HISTORY AND LIFE-TABLES OF WESTERN FLOWER THRIPS, FRANKLINIELLA-OCCIDENTALIS (THYSANOPTERA, THRIPIDAE), ON ENGLISH CUCUMBERS

The life history of Frankliniella occidentalis (Pergande) was studied at six different temperatures on English cucumbers, cv. Pepinex. Life tables constructed indicate that the highest population growth rate (r (m)) and net reproduction rate (R0) occur at 30-degrees-C and the lowe st at 15-degrees-C, where the population remains nearly stable. Genera tion time (T) was the shortest at 30-degrees-C and increased as temper ature decreased. At 30-degrees-C oviposition increased, females mature d and reproduced earlier and the time specific fecundity (m(x)) was hi gher than at lower temperatures. Adult longevity was shortest at 30-de grees-C and longest at 15-degrees-C. The threshold value for developme nt was determined as 9.4-degrees-C. Average duration of each developme ntal stage and the sex ratio at six different temperatures are given.