Field tests of hexabutyldistannoxane (TBTO) in slow-release formulations against Biomphalaria spp.

Hexabutyldistannoxane (TBTO) in an asphalt base was found to retain molluscicidal activity for more than a year in the field. It was not deactivated by immersion in mud or by drying and exposure to the sun. Complete elimination of planorbid snails was achieved and maintained when repopulation pressure was sporadic, but control of a continuously entering population was not practicable. Fixing the product at the site is important, and a formulation in fragments of rubber that floated failed after 1-2 months. TBTO apparently acts cumulatively in snails, but is only initially toxic to aquatic insects and fish, which return to repopulate treated areas that remain snail-free.