Carbamate resistance in Anopheles albimanus. Cross resistance spectrum and stability of resistance.

Carbamate resistance induced in a field strain of A. albimanus from El Salvador by laboratory selection with propoxur remained fairly stable on relaxation of selection pressure for 12 generations. Studies on cross and multiple resistance showed that this strain was not resistant to the pyrethroids bioresmethrin, bioallethrin, and CRC 11451, although resistance to cismethrin was 2.3-fold. Resistance to 10 carbamates of various structural configurations covered a broad spectrum, being for example >100x to Bay 38799, Ciba 17474, and Ciba 18107, 74.8x to carbaryl, 20.57x to carbanolate, and 2.27x to Stauffer R 15396. The possible causes of the presence or absence of cross resistance and the implications of stability of resistance and cross resistance are discussed.