RESISTANCE IN SOME CARIBBEAN POPULATIONS OF AEDES-AEGYPTI TO SEVERAL INSECTICIDES

Thirty-four strains of Aedes aegypti larvae from 17 Caribbean countrie s were bioassayed for sensitivity to temephos, malathion, fenitrothion , fenthion, and chlorpyrifos. There were fairly high levels of resista nce in Tortola (10-12-fold resistance) and Antigua (6-9-fold resistanc e) strains to temephos and to fenthion (Tortola, 7-10-fold; Antigua, 6 -10-fold resistance). Most other strains showed some resistance to mal athion, fenitrothion, and chlorpyrifos, but only moderate levels. Adul t populations of Ae. aegypti-Aruba, Jamaica, Trinidad, Puerto Rico, St . Lucia, and Antigua strains-also showed moderate resistance to malath ion. Mosquito control field data supported the laboratory findings. Do ubling the diagnostic dosage of temephos for larval Ae. aegypti was on ly partially effective against a more resistant strain, and even so, t he chemical lost its limited efficacy over a short period of time. Int egrated strategies for Ae, aegypti control to mitigate the negative ef fects of insecticide resistance in the Caribbean strains are suggested .