Indoor-resting blood-fed Anopheles gambicie s.l. were collected from selected localities in Ethiopia. Anopheles arabiensis was the only sibling species identified. Paracentric chromosomal inversion polymorphisms were observed on the 2R and 3R arms. A significant excess of heterozygotes was obtained in samples from Siile carrying the 3Ra inversion. Similarly, significant variation was seen in the frequencies of the 3Ra inversion between the study localities. The observed intraspecific inversion polymorphisms relative to indoor resting behaviour are discussed.

Cytogenetic studies in indoor resting An. gambiae s.l. complex in five selected localities from east, south, and southwestern parts of Ethiopia were conducted. An. arabiensis was the only cyto-species found. Close examination of the inversion polymorphisms revealed the existence of two more polymorphisms in the 2Ra and 2Rd inversions, in addition to those previously reported viz. 2Rb and 3Ra, by Mekuria et al. (1982) and White (1974). The study covered wide ecological and altitudinal ranges and the karyotype frequencies were in agreement with the Hardy-Weinberg expectations. However, it was not possible to correlate the relationship between the 2Rb inversion and altitude as has previously been reported by Mekuria et al. (1982). The adaptive value of the 2Rb to increase in altitude (Mekuria et al., 1982), in view of diverse ecological and climatic conditions in An. arabiensis in Ethiopia is open to question.