LIFE-HISTORY PARAMETERS OF WESTERN FLOWER THRIPS ON SUSCEPTIBLE AND RESISTANT CUCUMBER GENOTYPES

The life-history parameters reproduction rate, developmental time and age specific survival of the western flower thrips, Frankliniella occi dentalis (Pergande) [Thysanoptera:Thripidae], were determined on susce ptible and resistant cucumber (Cucumis sativus L.) genotypes. Both new ly emerged and F. occidentalis females of mixed ages showed a substant ial reduction (36 to 50%) of the reproduction rate on all resistant ge notypes, in particular after the second day. On the resistant genotype s 9127 and 9140, F. occidentalis had a prolonged developmental period. This was primarily due to a prolongation of the second larval stage. On all resistant genotypes, F. occidentalis suffered from high (82 to 97%) preadult mortality, predominantly at the second larval stage. It is concluded that the resistant genotypes do not cause an immediate in toxication of adult nor preadult thrips stages.