Studies on the effects of intraspecific competition for food and space on biological indexes of Anopheles stephensi (Dip:Culicidae) in laboratory conditions

This study investigates the intraspecific competition, for food and density amongst larvae of Anopheles stephensi (main malaria vector in south Iran). The effects of 4 selected food quantities (1x,2x,4x,6x) and 5 larval densities (0.1 to 3 larva/cm2) were tested individually or in combination on 7 biological indexes of the vector and the results were statistically analyzed. The competition starts when the food quantity decreases from 6x to x and the larval density increases from 0.1 up to 3 larva/cm2. The biological indexes that showed significant alterations at competing conditions (reduced food quantity and increased larval density) were as follows. Increasing of the larval, pupal and total mortality, alteration of the sex ratio in favor of male production, and decrease of the speed of larval development and survival rate. However, body sizes did not show any significant difference among individuals of both sexes. So, reducing the food quantity and increasing the larval density make a decrease in abundance and activity of An. Stephensi and it may provide a useful method for control of this mosquito population.