Variability of the respiratory surface area of pupae in Simulium monticola species group (Diptera, Simuliidae)

Abstract

The variability of the respiratory surface area of Simulium monticola Friederichs, 1920 and Simulium argyreatum Meigen, 1838 pupae was studied in detail. 333 pupae from Western Carpathian Mts. were investigated. According to the tubercles on thorax and head of the pupa of S. monticola, two morphological forms were distinguished ( S. monticola 1 and S. monticola 2). Both were studied separately. In any species or form respectively we measured the lengths of all respiratory filaments and basal trunks, the widths of the basal trunks, the widths of the filaments on their proximal and distal end and the widths 0.25 mm from the proximal end. In all species (forms) differences in the size of the respiratory surface area between the first (April – June) and the second generation (August – October) were found. In S. monticola 1 the mean real respiratory surface area was significantly (p < 0.001) larger in spring (3.67 mm 2) than in summer (2.19 mm 2). In S. monticola 2 the mean real respiratory surface area was 3.45 mm 2 in spring, and it was significantly larger in females than in males (p = 0.034). In S. argyreatum the mean real respiratory surface area was 2.80 mm 2 in spring 2001 while in different summer generations it was significantly smaller: 1.58 mm 2 in 1999, 1.84 mm 2 in 2000 and 2.12 mm 2 in 2001. All these groups differed significantly from each other. Regression models could explain 64.5% (power model) of the real respiratory surface area in S. monticola 1 and 19.9% (various models) of the real respiratory surface area in S. argyreatum due to the variability of the adult size.