Insecticide resistance in Bemisia tabaci (Homoptera: Aleyrodidae) populations from Crete

The resistance levels to α‐cypermethrin, bifenthrin, pirimiphos‐methyl, endosulfan and imidacloprid were determined in Bemisia tabaci (Gennadius) from Crete. Five B tabaci populations collected from greenhouse and outdoor crops were bioassayed and compared with a reference susceptible strain. Bemisia tabaci collected in a floriculture greenhouse exhibited the highest resistance against all insecticides: at LC 50 , resistance factors were 23‐fold for bifenthrin, 80‐fold for α‐cypermethrin, 18‐fold for pirimiphos‐methyl, 58‐fold for endosulfan and 730‐fold for imidacloprid. A population collected on outdoor melons was more susceptible than the reference strain against all insecticides tested, suggesting the occurrence of local highly susceptible B tabaci populations in ‘refugia’. In pairwise comparisons of resistance levels, correlation was observed between the LC 50 values of the pyrethroid insecticides bifenthrin and α‐cypermethrin. Copyright © 2005 Society of Chemical Industry