OBSERVATIONS ON FEEDING AND POPULATION-STRUCTURE OF 5 NEW-ZEALAND TERRESTRIAL PLANARIANS WHICH PREY ON LUMBRICID EARTHWORMS

The feeding of five terrestrial planarians found in New Zealand on Eur opean lumbricid earthworms was studied. Under laboratory conditions be tween 60-83% of Artioposthia spp. fed in the first 24 h compared with 21-40% of Australoplana spp. The mean percentage weight gain varied fr om 31% for Australoplana sanguinea var. alba to 113% for Artioposthia sp. 1. Analysis of the weights of the planarian species showed a mean 11-fold difference between Australoplana sanguinea and Artioposthia tr iangulata and that these body weights were not related to mean percent age weight gains after feeding. The relationship between the weights o f egg capsules and pregnant female planarians was similar for Australo plana sanguinea var. alba (11%), Artioposthia triangulata (12%) and Ar tioposthia testacea (13%). This study confirms that there are terrestr ial planarians in New Zealand which have the potential to prey upon Eu ropean lumbricid earthworms but which have not been detected in Europe . Greater knowledge of their biology is necessary to control the sprea d and impact of these organisms around the world.