RESPONSE OF ADULTS OF BIOTYPE A SWEET POTATO WHITEFLY, BEMISIA TABACI (GENNADIUS) (HOMOPTERA; ALEYRODIDAE) TO THREE CLASSES OF INSECTICIDES

摘要

Historical data from 1993 indicated that whitefly adults of biotype A were resistant to organophosphorus insecticides acephate, azinphosmethyl, methyl parathion and profenofos. LC50s were >20 mu g/vial or mortalities did not exceed 50%. An LC50 of >20mu g/vial, after 3 h, is proposed as a resistance threshold for all insecticides tested against this biotype. Biotype A was resistant to amitraz which killed <50% of the adults at >20 mu g/vial. The biotype was susceptible to the cyclopropane pyrethroidbifenthrin; LC50.s of dead + moribund ranged from 0.0027 to 0.15 mu g/vial. LC50s of bifenthrin in the dead category ranged from 0.057 to 95.15 mu g/vial; 17% of LC50s for bifenthrin indicated resistance. LC50s of the cyclodiene endosulfan and the organophosphorus methamidophos were about equal and indicated susceptibility. LC50s of both insecticides for dead + moribund ranged from 0.06 to 18.14 mu g/vial, while the LC50s for dead ranged from 9.2 to 56.5 mu g/vial. LC50s for dead + moribund were susceptible. LC50s for dead indicated that 50% were resistant and 50% were susceptible. The biotype was identified by nonspecific esterase activity.