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    Osservazioni citogenetiche e biometriche sui membri del complesso Anopheles gambiae in Mozambico.

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    Four species of the Anopheles gambiae complex were identified in Mozambique (East Africa) by chromosomal analysis. They were An. merus, An. gambiae s.s., An. arabiensis and An. quadriannulatus. An. merus was observed in coastal zones as well as in inner areas where the rivers are tidal and brackish and/or the soil is salty. An. gambiae s.s. is present in the central-northern regions (north of Save river) from the coast to the western mountains. On the coast it is often sympatric with An. merus. It is apparently absent south of Save river. An. arabiensis was observed in samples from the north-western hilly and mountainous areas, sympatrically with An. gambiae s.s., as well as south of Save river where often it is sympatric with An. merus. Only one specimen of An. quadriannulatus was observed. It was from a small sample collected feeding on bovid in a southern locality (Bela Vista-Maputo area). No inversion polymorphism was observed in the 446 An. merus identified. A quite low degree of inversion polymorphism was shown by both An. gambiae s.s. and An. arabiensis, involving 2Rb, 2La and 2Rb inversion systems respectively. By morphological analysis of cytogenetically identified samples of three species of the complex, number of sensilla coeloconica and palpal ratio were confirmed to be useful to distinguish An. merus from An. gambiae s.s./An. arabiensis. The overlapping areas between brackish and freshwater species become smaller when both characters are considered together, 1.5% and 3.5% being the probabilities of confusing An. merus with An. gambiae s.s. and An. arabiensis respectively

    Propensione al pasto di sangue in condizioni di laboratorio e polimorfismo cromosomico in Anopheles stephensi.

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    Propensity to blood feeding under laboratory conditions was studied in females of A. stephensi carriers of different arrangements of a polymorphic paracentric inversion of chromosome 2R (+/+, +/b, b/b). One hour experiments were performed at various hours of the day, in continuous light, with temperature between 26 and 28 degrees C and relative humidity between 65 and 75%, using unfed mosquitoes 4-5 days old and guinea pigs as hosts. The frequency of blood fed females was found to be constantly much lower in the +/+ homokaryotypes, than in the other two karyotypes. Smaller differences in biting activity were observed between the heterokaryotypes and the b/b homokaryotypes, the latter appearing significantly more active at least during the scotophase hours. The evidence of a lower activity of the +/+ homokaryotypes was confirmed when the mosquitoes were stimulated by a human arm. Such marked and constant behavioural difference is tentatively considered as the expression of a diversified response to the environmental conditions whose deterrent effect on biting activity would be more pronounced on the +/+ homokaryotypes than on the carriers of the 2Rb arrangement
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