Studies on morphological variations of spiracles in three vector species of mosquitoes

Laboratory reared and wild populations of Anopheles stephensi, vector of malaria; Culex quinquefasciatus, vector of filaria and Aedes aegypti, vectors of dengue, were subjected to study the spiracular indices. The average length of anterior spiracle of An. stephensi, Cx. quinquefasciatus and Ae. aegypti ranged from 0.1 to 0.12, 0.11 to 0.14 and 0.14 to 0.15 mm respectively. Similarly the average length of posterior spiracle ranged from 0.1 to 0.12, 0.13 to 0.15 and 0.14 to 0.15 mm respectively. The average of spiracular indices of An. stephensi, Cx. quinquefasciatus and Ae. aegypti ranged from 7.07 to 8.13, 8.05 to 9.05 and 9.02 to 10.01 mm respectively. In wild populations, the average length of anterior spiracle of An. stephensi, Cx. quinquefasciatus and Ae. aegypti ranged from 0.07 to 0.11, 0.12 to 0.13 and 0.14 to 0.16 mm respectively. The average length of posterior spiracle ranged from 0.08 to 0.11, 0.13 to 0.14 and 0.14 to 0.17 mm respectively. The average of spiracular indices of An. stephensi, Cx. quinquefasciatus and Ae. aegypti ranged from 6.9 to 7.10, 8.05 to 9.6 and 11.01 to 11.7 mm respectively. These measures provide structurally differentiation of mosquito vectors.