ESTERASE VARIATION AND SQUASH INDUCTION IN B-TYPE BEMISIA-TABACI (HOMOPTERA, ALEYRODIDAE)

Polyacrylamide gel electrophoresis was used to study esterase variation in a population of B-type Bemisia tabaci (Gennadius). A total of six esterases was identified within an overall B-type pattern. However, both qualitative and quantitative variation in some of these esterases gave three clearly defined phenotypes. One of these lacked esterase E(0.14) which until now has been the key band used to classify B-type strains electrophoretically. A strain homozygous for the E(0.14) null allele (B-Null) retained the ability to induce squash silverleaf, a plant physiological disorder which hitherto has only ever been associated with whitefly strains possessing this band.