Butachlor at environmentally relevant concentrations induces partial feminization in male Luzon wart frog Fejervarya vittigera Wiegmann, 1834

Abstract

Exposure to herbicides and pesticides is linked to adverse effects on amphibian populations. Butachlor (C17H26ClNO2) is one of the common herbicides used in rice fields in the Philippines and Southeast Asia. The Luzon wart frog Fejervarya vittigera is abundant at high densities in rice fields in the Philippines. Adult F. vittigera are exposed to agriculturally relevant concentrations of butachlor for seven days under laboratory conditions to assess the effect of exposure on the histology of the testis and ovaries. Six groups: dechlorinated water (control), 0.4 mg/L, 0.8 mg/L, 1.6 mg/L, 3.2 mg/L, and 4.8 mg/L butachlor were used as test treatments, and morphology of the oocytes and seminiferous tubules and spermatogenic cells in adult F. vittigera. Partial feminization, as seen by the appearance of testicular (perinucleolar) oocytes, was observed in the testis of frogs exposed to realistic concentrations of butachlor. Overall results suggest that butachlor may interfere with normal reproductive conditions and may cause irregularities in the male reproductive tissues and the hormonal milieu.