Genetical relationships between malathion-resistance and fenthion-resistance in larvae of Culex pipiens pallens Coquillett

1. Monofactorial inheritance of resistance to malathion and fenthion was proved in the colony of Culex p. pallens which showed 13-fold resistance to malathion and 50-fold resistance to fenthion after 10 generations of the larval selection with malathion and 5 further generations with fenthion; the factors for malathion- and fenthion-resistance were incompletely dominant. 2. Genetical linkage relationships were investigated between malathion-resistance and fenthion-resistance in this colony; the results show that a malathion-resistance factor is located at crossover distances of 48-50% from ru on chromosome 2, though of 40-43% from ru in the previous study, and of 12-15% from the fenthion-resistance factor linked to ru with a 48% crossover unit.