INSECTICIDE SUSCEPTIBILITY IN MOSQUITOS (DIPTERA, CULICIDAE) FROM FRENCH-POLYNESIA

Susceptibility to six organophosphate (OP), two pyrethroid (PY), and o ne carbamate (C) insecticides was investigated in Culex pipiens quinqu efasciatus Say, Aedes aegypti (L.), and Aedes polynesiensis Marks larv ae from the island of Tahiti. Cx. p. quinquefasciatus and Ae. aegypti were compared with susceptible reference strains treated simultaneousl y. A low, but significant, resistance to bromophos (4.6x), chlorpyrifo s (5.7x), fenthion (2.4x), fenitrothion (5.0x), temephos (4.3x) and pe rmethrin (2.1x) was found in Cx. p. quinquefasciatus, and to malathion (1.5x), temephos (2.3x), permethrin (1.8x) and propoxur (1.7x) in Ae. aegypti. Cx. p. quinquefasciatus was shown to possess over-produced e sterases A2 and B2, which are known to be involved in resistance to OP s in other countries. Ae. polynesiensis was less resistant than the Ae . aegypti reference strain to all insecticides except temephos (1.8x) and permethrin (6.7x). To determine whether Ae. polynesiensis had deve loped resistance to these insecticides in Tahiti, a geographical surve y covering 12 islands of the Society, Tuamotu, Tubuai, Marquesas, and Gambier archipelagoes was undertaken with three insecticides (temephos , deltamethrin, and permethrin). Two- to threefold variations in LC50s were observed among collections. Results are discussed in relationshi p to the level of insecticide exposure on the different islands.