Mosquitoes of British Honduras, with some comments on malaria, and on arbovirus antibodies in man and equines

Abstract

A survey in 1967 of mosquitoes taken by human bait and trap catches in British Honduras along a transect from the coast near Belize City to riverine terrain and upland forest 45 miles inland yielded 65 species— Chagasia (1), Anopheles (8), Trichoprosopon (2), Wyeomyia (5), Limatus (2), Sabethes (2), Mansonia (2), Coquillettidia (2), Uranotaenia (5), Aedomyia (1), Psorophora (8), Aedes (9), Haemagogus (2), Culex (15), Deinocerites (1). Mosquito densities are very low in the dry season (April–May), rapidly increasing with the main rains which begin about late May–June, and continuing probably considerable until the following April–May dry season. Diurnal, crepuscular and nocturnal activity, and vertical distribution in forest, resembled findings from elsewhere in Middle America. The coastal pest, Aedes taeniorhynchus, occurred in small numbers as far inland as 45 miles. The Aedes terrens group includes a new species, Ae. bertrami Schick 1970. Mansonia dyari and Ae. cozumelensis first described, respectively, from Jamaica in 1970 and from the Yucatan in Mexico in 1966, were taken, and also Ae. vexans, common in North America. Differentiation within C. (Mel.) opisthopus/taeniopus is still inconclusive, available larvae and ♂ genitalia being assigned to C. (Mel.) n. sp. near paracrybda. Ae. aegypti was not found, following an eradication programme. The anopheline and culicine species include, respectively, vectors of malaria and of arboviruses. As a result of a malaria eradication campaign, few cases of malaria occur. In 1967, equines had VEE antibodies and VEE virus was isolated, by other workers, in sentinel hamsters near Belize City but the human population which showed NT-antibodies to VEE, SLE and Ilheus appears on the whole to have escaped any major infections, in recent years. There was no conclusive evidence for arbovirus infections of British garrison troops. Up to early October 1971, British Honduras escaped, although several competent vectors occur, the severe wave of epizootic VEE in equines, with also human cases, which occurred in other Central American countries from 1969 to September 1971. In 1969 and, particularly in 1971, precautions were taken by vaccination of horses in a buffer zone along the borders of the adjacent, and severely affected, territories of Mexico and Guatemala.