Differential sensitivity of mosquito taxa to vegetable tannins

The sensitivity of larval Culicidae to vegetable tannins was investigated i n different taxa representative of the fauna from alpine hydrosystems (Aede s rusticus, Culex pipiens) and foreign noxious fauna (Aeries aegypti, A. al bopictus). Bioassays reveal that tannic acid at concentrations of 0.1-6 mM is significantly more toxic for C. pipiens than for Aedes taxa, and A. aegy pti is more sensitive than A. albopictus and A. rusticus. Comparison of the rank order of sensitivity among taxa with the associated levels of cytochr ome P-450, esterase, and glutathione-S-transferase activities suggests that cytochrome P-450 and esterases may be involved in the detoxification of ta nnins. A possible involvement of these detoxifying enzymes is also revealed in vivo by the synergistic effects of S,S,S-tributyl phosphorotrithioate ( esterase inhibitor) and piperonyl butoxide (P-450 inhibitor). The different ial sensitivity to tannins among taxa is discussed in terms of ecological i mplications within mosquito communities from alpine hydrosystems, where the acquisition of tannins-detoxifying enzymatic systems may be considered as a key innovation.