“…Freshwater aquatic insects have been used as indicators of water quality since the Berlin botanists Kolkwitz and Marsson described tolerance values in the Saprobien system over 100 years ago [90]. They are well catalogued internationally, and while rooted in the defence, mating Parfitt [30], Reeker [31], Sopp [32], Clainpanain [33], Arrow [29], Mukerji [34], Marku [35], Balfour-Browne [36], Leston et al [37], Smith [38] mating, defence Balfour-Browne [44], Buhk [45], Procher [46], White [47], Allen [48], Spangler [49], van Tassel, [50], Maillard [51], Britton [52], Maillard & Sellier [53], Meyer-Rochow [54], Ryker [55], Ryker [56], Hammond [42] air expulsion from spiracles mating Butler [59], Poisson [60], Moore [61], Finke [62], Jansson [63], Jansson [64], Jansson [65], Jansson [66], Aiken [67], Theiss [68] last century [91][92][93], many of these have recently been updated or adapted to different stressors [94]. While all of these assign tolerance values-measures of the sensitivity to various aspects of water pollution-to species, genera or sometimes higher taxonomic levels, extra research will be needed to overcome a key problem with the distribution of indicator values concerning aquatic insects.…”