Field evaluations of the phytotoxic effects of Arosurf MSF on selected species of aquatic vegetation.

The use of the monomolecular film Arosurf@ MSF as a mosquito larvicide was first reported by Ganett and White (1977). Since then, the efficacy of this larvicide on many mosquito species has been demonstrated in a wide variety of aquatic habitats (Levy et al. 1981, 1982; Mulla et al. 1983, Takahashi et al. 1984). Aquatic plants which occur in fresh and salt water habitats are an important source of nutrient recycling in the aquatic food chain (Odum and de la Cruz 1967, Odum et al. 1984). Quantitative studies have demonstrated the effects of oil (petroleum hydrocarbons) surface films used as mosquito larvicides on some vegetation t1pes. Slavin et al. (1975) showed that 6 applications of oils at the rate of 20 gal/acte did affect the standing crop of Spartina patens Muhl. but not S. alterniflora Lbisel, while lower application rates (5 gal/acre) had no affect on either vegetation. Bearden and Steelman (1971) indicated that Flit@ MLO applied at the rate of.2 gal/acre did not affect rice yield, although formulations used previously had been detrimental to this crop. Qualitative observations have not shown any adverse effects upon aquatic plants prevailing in larval mosquito habitats (Levy et al. 1981, 1982); however, no quantitative studies of the phytotoxicity of Arosurf MSF have been reported. Therefore, this paper reports the results of a quantitative study designed to assess the phytotoxicity of Arosurf MSF on 5 species of aquatic vegetation. Phytotoxic effects of Arosurf MSF on 5 species of plants were studied in various aquatic habitats typical of those treated with larvicides for mosquito control. Effects on black mangrove lAuicenna germinan (Linn.)l and saltwort (Botrs maritima Linn.) were studied in a supratidal marsh located on Sanibel Island, Lee County, Florida. Effects on cordgrass (Spartina alternifloraLoisel) and arrowhead, (Sagittaria sp.) were studied in salt and freshwater marsh habitats, respectively, located on West Bay Point, Bay