Reduce pesticide, herbicide or fertilizer use
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Agricultural land often receives high chemical inputs to control pests, weeds and fungal infections. These chemicals also enter water bodies through spray drift or run-off. With both aquatic and terrestrial life stages, amphibians can be exposed to toxicants in two environments. These pollutants can have significant effects on populations. For example, atrazine is one of the most commonly used herbicides in the world. One study found that atrazine caused 10–92% of wild male leopard frogs Rana pipiens tested across the USA to have abnormal reproductive organs including slowed development and development of egg cells within their testes (Hayes et al. 2002).
Hayes T., Haston K., Tsui M., Hoang A., Haeffele C. & Vonk A. (2002) Herbicides: feminization of male frogs in the wild. Nature, 419, 895–896.
Supporting evidence from individual studies
A study in 1999–2006 of a water lily paddy field in Taipei County, Taiwan (Lin et al. 2008) found that stopping using pesticides along with habitat-improvement work doubled a population of Taipei frogs Rana taipehensis. In 2002, a farmer stopped using herbicides and pesticides on his field, which was at the centre of the frogs’ breeding habitat. By August 2003, the Taipei frog population in the field had more than doubled (from 28 to 85) and the farmer fully adopted organic-farming practices. Pollution from river construction work resulted in a drastic decline in the population in 2004–2005 (20 to 4), but by 2006 the population appeared to be recovering (19). Habitat-improvement work included cutting weeds in the field.Study and other actions tested