The irritant and repellent effects of organophosphates on the Tasmanian lacewing, Micromus tasmaniae (Neuroptera : Hemerobiidae)

The irritant and repellent effects of two organophosphate insecticides, dia zinon and chlorpyrifos, were examined on adults of the Tasmanian lacewing, Micromus tasmaniae, in the laboratory. Two household pyrethroid sprays were used as positive controls. The organophosphates did not induce a more rapi d onset of preening, a more rapid flight from contaminated filter papers or an avoidance response in Petri dishes. A small but statistically significa nt avoidance of diazinon, but not chlorpyrifos, occurred when M tasmaniae w ere introduced onto sprayed potted bean plants. It is concluded that these two organophosphates are not intrinsically irritating or repellent to M tas maniae and any avoidance reaction would not prevent a lethal dose from bein g obtained. Therefore, a decline in natural populations of M tasmaniae afte r application of these chemicals is Likely to be due to mortality, rather t han dispersal. The implications of these results with regard to using this species as a bioindicator are discussed. (C) 2000 Society of Chemical Indus try.