RESUMEN
Slugs have been known worldwide as important pests of agricultural and horticultural production. They also play a role as intermediate or definitive hosts of helminths parasite. In this purpose, current study was carried out to examine slug radular teeth structure and slug infection with helminths larvae in north of Iran. A total number of 114 slugs were collected from center and east parts of Mazandaran province from May 2011 to June 2012. The specimens were rinsed, measured, and identified. The radula of all collected slugs was extracted and stained by using Mallory II. For detecting the helminths parasite infection, foot- head and viscera of examined slugs were removed, minced, and digested with 4.5% acid pepsin. Two species of Limax [Caspilimax] keyserlingi [Martens 1880] [11.4%, 13/114] and Parmacella ibera [Eichwald 1841] [88.6%, 101/114] were prevalent in the region. There was significant difference between body length and shell size. P. ibera had the highest number of teeth rows [145 +/- 5]. The radu-lar teeth formula was approximately similar in both identified slugs. In P. ibera, there was no significant difference in the average length and width of radula. The radular teeth in L. keyserlingi were larger and thicker than P. ibera. In all examined slugs for helminths larvae infection, P. ibera [7.69%, 1/13] was infected with Strongyloid larvae from Fereidonkenar area. Two prevalent species of slugs exist in the same region of which P. ibera has capability to play a role as intermediate host of nematode helminths. Radular morphology within the slug species may be also systemically informative.