Environmental Risk Assessment of the Insecticide Metamidophos in Bioassays with Four Non-Target Aquatic Organisms

José Iannacone O.1, 2 *, Roxana Onofre C.2, Olga Huanqui S.2, Jorge Giraldo A.2, Nancy Mamani P.3, Maria C. Miglio T.3 y Lorena Alvariño F.2

The aim of this research was to evaluate the ecotoxicological effect of methamidophos using two formulations of different toxicological class [Monofos®, class Ia (extremely dangerous) and Tamaron®, class Ib (highly dangerous)] on four non-target aquatic organisms: bloodworm Chironomus calligraphus (Goeldi, 1905) (Diptera: Chironomidae), black sea urchin Tetrapygus niger Molina, 1782 (Echinodermata: Arbaciidae), neon tetra Paracheirodon innesi (Rabout, 1940) (Osteichthyes: Characidae); and rainbow trout Oncorhynchus mykiss (Walbaum, 1792) (Osteichthyes: Salmonidae). Both methamidophos formulations evidenced a high risk effect on the aquatic environment, finding effects on larvae of C. calligraphus (Class Ia, LC50 at 48 h = 1.32 mg a.i. L-1 and Class Ib, LC50 at 48 h = 4.5 mg a.i. L-1), on fertilization of T. niger (Class Ia, IC50 at 1 h = 1423 mg a.i. L-1 and Class Ib, IC50 at 1 h = 608 mg a.i. L-1), on P. innesi (Class Ia, LC50 at 96 h = 20.56 mg a.i. L-1 and Class Ib, LC50 at 96 h = 10.13 mg a.i. L-1) and O. mykiss (Class Ib, LC50 at 96 h = 19.12 mg a.i. L-1). The sequence of sensibility to methamidophos in both formulations was: C. calligraphus > O. mykiss ≈ P. innesi > T. niger. In addition, two sublethal effects were evaluated on P. innesi, immobilization and strange swimming, and finally an increment of opercular movement in O. mykiss. Risk quotients (RQ) indicated in all cases a high risk of methamidophos towards the aquatic environments.

Keywords: Chironomus calligraphus, Oncorhynchus mykiss, Paracheirodon innesi, Tetrapygus niger, ecotoxicology, methamidophos.
1 Universidad Ricardo Palma (URP), Facultad de Ciencias Biológicas, Av. Benavides 5440, Santiago de Surco, Lima 33, Perú. E-mail: joseiannacone@yahoo.es *Autor para correspondencia.
2 Universidad Nacional Federico Villarreal (UNFV), Facultad de Ciencias Naturales y Matemática, Calle San Marcos 351, Pueblo Libre, Perú.
3 Universidad Nacional Agraria La Molina (UNALM), Facultad de Pesquería, Av. La Molina s/n, Apartado 12-056, Lima 12, Perú.