Removal trapping to control Artioposthia triangulata

Removal trapping was used to try and reduce numbers of the predatory planarian Artioposthia triangulata in polythene tunnels on a nursery and a grass field. Ten months of trapping in the tunnels failed to have any impact upon flatworm numbers but weekly catches reduced over a period of 12 weeks' trapping in grassland. The calculated residual population in the grassland (40 ha(-1)) was small in comparison with that estimated from formalin sampling (940+/-1288 ha(-1)). A separate field study examined the effect of trap density on catch by spacing traps at 2.5, 5, 10 and 20 m intervals. This showed that the numbers of planarians caught was inversely related to the logarithm of trap spacing. It is concluded that removal trapping is too demanding of resources to be a viable control option for this pest in commercial and agricultural situations.