Cytogenetic study of the Anopheles maculatus complex

Abstract

An. maculatus Theobald is recognized as an important vector of malaria in Thailand and its neighbouring countries such as malaysia. Results of inter-specific hybridizations among the An. sawadwongporni, An. maculatus, An. dravidicus and An. notanandai are F1 male sterile and F1 female fertile. Percentages of the eggs hatch anbd percentages of the pupae develop into adults are lower than that of the intra-specific hybridization. These clearly indicate that reproductive isolation exists among these species of the An. maculatus complex and the lack of gene flow between them. These data of hybridizations correspond with cytological evidence i.e. The pairing of chromosome in F1 hybrids showed the parts of the asynapsis in various chromosomal arms. This suggest that there are genetic incompatibility within these species of An. maculatus. The data from both hybridizations and cytological evidence seem to suggest that An. sawadwongporni and An. notanandai are most closely related. Next distant are An. maculatus and An. dravidicus, An. sawadwongporni and An. maculatus, with An. sawadwongporni and An. dravidicus mostly distantly. The crossing between An. maculatus form B and form E produced F1 fertile of both sexes as F1 females showed the typical loop arrangement of inversion heterozygotes. This might be a preliminary evidence of the speciation process within the taxon An. maculatus. The hybridization results support the current classification and species divergence within taxon An. maculatus.