Control of cytoplasmic incompatibility in the Aedes scutellaris complex

Abstract

Most of the interspecific crosses in the Aedes scutellaris complex result in unidirectional cytoplasmic incompatibility. The case of cytoplasmic incompatibility presented here involves Aedes polynesiensis and Ae. kesseli. While the cross Ae. kesseli♀ and Ae. polynesiensis ♂ is compatible, the reciprocal cross is not. By treating the larval stages of the parental stock with heat or the antibiotics tetracycline hydrochloride and chloramphenicol, the incompatible cross Ae. polynesiensis ♀ × Ae. kesseli ♂ is made compatible. Both sexes of the hybrid progeny were fertile and no hybrid breakdown occurred in any subsequent generation tested up to F₆. Presence of the rickettsia-type microorganisms (RMO) in the ovaries of both species and their absence from the treated parental strains and the hybrids may indicate that the RMO is responsible for this incompatibility. This is not proof of the cause of incompatibility, as the alteration of physiological functions and structure of the cytoplasmic organelles (mitochondria and ribosomes) of the mosquito (eukaryotic) cells by treatment with heat and antibiotics may be responsible for the alteration of incompatibility as well. Maintaining a temperature of 32.5°C, and treating larvae with tetracycline hydrochloride in a concentration of 0.1 g/l and chloramphenicol in a concentration of 2.0g/l was the most effective method for changing incompatible crosses into compatible ones in the Aedes scutellaris complex.