Research Product

SevinŽ is the registered trademark of the synthetic carbamate insecticide, 1-naphthyl N-methylcarbamate. It is also known as carbaryl. This insecticide is toxic to a wide variety of insects as both a contact and a stomach poison. It is reported to be effective against many insects which have become resistant to chlorinated hydrocarbon and phosphate insecticides. SevinŽ is also toxic to crustaceans and has been used to a limited extent in marine environments to control burrowing shrimp, Callianassa californiensis and Upogebia pugettensis. The digging activities of these crustaceans make the substrate in some areas unsuitable for oyster production. SevinŽ has a relatively low degree of mammalian toxicity and is generally classified among the safer pesticides now in use. This comparatively low acute toxicity also applies to fish. The amount of SevinŽ required to produce a 48-hr. LC50 (concentration lethal to 50% of test population) in rainbow trout, Salmo gairdneri, and longnose killifish, Fundulus similis, is about 250 times greater than that of DDT. Katz tested 95% SevinŽ and reported the 48-hr. TLm (median tolerance limit) for coho salmon (Oncorhynchus kisutch), rainbow trout, bluegill, (Lepomis macrochirus), and threespine stickleback (Gasterosteus aculeatus) to be 0.99, 1.35, 5.30, and 10.45 p.p.m., respectively. Stewart, Millemann, and Breese reported 80% SevinŽ to give a 24-hr. TLm of 6.7 p.p.m., for the threespine stickleback. They also found 1-naphthol, a hydrolytic product of Sevin, to be more toxic than SevinŽ to fish. In the present study juvenile spot, Leiostomus xanthurus, survived 5 months of continuous exposure to 0.1 p.p.m. SevinŽ in flowing sea water. I am unaware of previous studies in which marine fish were chronically exposed to SevinŽ or other carbamate insecticides.