As the world’s population increases and agricultural frontiers expand into native tropical habitats, researchers are working furiously to understand the impacts on tropical forests and global biodiversity. But one obvious impact has been little studied in these agricultural frontiers: pesticides. However a new study in the journal Philosophical Transactions of The Royal Society B seeks to shine a light on the problem.
Intensive land modification in many parts of the Brazilian Amazon is exposing large numbers of species to pesticides with unknown impacts, according to Luis Schiesari of the University of São Paulo, Brazil and his team of researchers.
“Pesticides are products deliberately designed to reduce organismal growth, development, reproduction and survival and as such have a potentially broad range of lethal and sublethal effects of concern,” Schiesari told mongabay.com.
Tropical forests regions like the Amazon not only have more species to be lost in absolute terms, but also contain relatively more sensitive, vulnerable and endemic species that are likely threatened by both pesticide use and agricultural land expansion.
Patchwork of legal forest reserves, pasture, and soy farms in the Brazilian Amazon. Photo by Rhett A. Butler / mongabay.com.
The overuse of pesticides is predominately, but not solely, attributed to small produce farmers whose primary income is based on total production and quality of agricultural yields, according to the researchers. In contrast larger, corporate farms are under the public eye and more likely to obey regulations set by governmental organizations.
Overuse of pesticides could very well be a product of limited, or poor, levels of education in regard to the chemicals.
“I believe that any education, technical support, or transfer of technology that would help smallholders increase production, increase income, minimize losses, and protect health would be welcome,” Schiesari said. “Appropriate pesticide use could contribute to any of these topics, and is one of the most technically challenging land management practices: for example, soy beans alone are responsible for 400 pesticide formulations containing 137 active ingredients in Brazil. Deciding which of them to use, when, how, and how much is a considerable technical challenge.”
Schiesari and his team also argue that where governmental reach and control are limited, market pressure can be directly or indirectly important in biodiversity conservation. However, this can be deceiving. For instance, when analyzing a large-scale soya plantation where governmental regulations are high, there was a gradual decreasing trend in total toxicity of mammals and humans and an increasing trend of toxicity in freshwater aquatic species.
Selected pesticides designed specifically to protect mammals do not guarantee protection of aquatic organisms, according to Schiesari’s research. In addition, “one of the earliest and most pervasive changes in freshwater systems accompanying land conversion is damming. Producers construct small dams for granting access of cattle to water, to generate hydroelectric power, and stock reservoirs with fishes.”
As with the case of agricultural expansion into tropical forests where land is plentiful, readily appropriated, and cheap, it is common for economic incentives to outweigh conservation and the overall health of surrounding species.
Small produce farmers, for example, make their primary wage based on the quantity of their frontier land’s yield. This quantity over quality farm structure leads to the occasional overuse of pesticide to secure the integrity of their crop as well as the desire to expand property into undisturbed tropical forest.
The infiltration of tropical habitats for agricultural frontier land is detrimental to the biodiversity and integrity of the Brazilian Amazon, especially when pesticide usage is unregulated and land management is lacking.
“There is ample need for pesticide risk mitigation at all scales of production. This can only be achieved through responsibility-sharing by, and involvement of, a wide diversity of stakeholders,” Schiesari stated in his research paper.
Better land management practices and regulations are needed if we are to move towards more sustainable practices of agriculture that include protections for biodiversity, according to the study. But this isn’t just a job for governments.
“Consumers can have a significant effect on biodiversity conservation in agricultural landscapes by purchasing food from, and therefore rewarding, producers that manage land in environmentally responsible ways – from either conventional or organic production systems,” notes Schiesari.
Large-scale soy fields in the southern Brazilian Amazon. Photo by Rhett A. Butler / mongabay.com
CITATION: Schiesari L, Waichman A, Brock T, Adams C, Grillitsch B. 2013 Pesticide use and biodiversity conservation in the Amazonian agricultural frontier. PhilTrans R Soc B 368: 20120378.