Four ways with pesticides

Pesticides, substances designed to prevent, destroy or mitigate any pest, are beneficial in many ways. They protect crops from infestation, allowing for higher and more stable yields, and they protect humans from insect attack, crucial in the fight against insect-transmitted diseases such as malaria. But they also pose serious threats to the environment and to human health. In response to the concerns over the impact of pesticides on bee populations, for example, the European Union, earlier this year, issued a partial ban on neonicotinoids.

A new special issue of Science, The Pesticide Paradox, through a series of papers, explores the benefits and impacts of pesticides and discusses what more can be done to track pesticide use, reduce our reliance and its impact, and find alternatives.

Track their use and evaluate their impacts

Understanding how and where pesticides are used and what hazards they pose is the first step to minimising their impact. For example, pesticide degradation and its effect on the landscape is little understood, as are the impacts of pesticides on non-target organisms and communities, and on human health and development. One paper shows the alarming impact exposure to pesticides in early life can have on brain development – reducing IQ and causing ADHD-like behavioural problems.

Verger and Boobis in their article, Reevaluate Pesticides for Food Security and Safety, discuss the use and sale of generic versions of pesticides, which account for some 30% of total pesticide sales. As the original producer has little impetus to assess the usage and hazards, these pesticides, despite being more affordable to farmers in developing countries, may not meet internationally accepted criteria. Authors describe how these generic pesticides can be monitored.

Reduce their use

The next obvious step is to minimise their use. For some farmers, prudent use of pesticides can boost crop production but for others, particularly under intensive farming, pesticides are over-used, sometimes creating new pest problems or pest resistance. For example, in Indonesia where the Brown Panthopper became a serious pest of rice, pesticides were found to be ineffective because they also killed parasites and wolf spiders, natural enemies of the Brown Planthopper. Use of Integrated Pest Management, a combination of pest control techniques, reduced the use of pesticides while at the same time raising rice yields. More holistic methods of pest control, however, can be knowledge-intensive. In Vietnam, large-scale experiments and use of radio have shown farmers how to use pesticides more judiciously to increase their profits.

New Research Shows the Damaging Impacts of Pesticides on Bees

While modern synthetic pesticides are developed to reduce impacts on non-target organisms, two recent papers published in Science have brought to light new evidence of the damaging effects of pesticides on bee colonies.

Both papers investigated the impact of the use of neonicotinoid pesticides on bees. When sprayed on crops such as oilseed rape, maize and sunflower, these pesticides spread throughout plant tissues including into nectar and pollen, and as such are directly available to bees, although in trace amounts.

The first paper published in March 2012, found that bumblebee colonies exposed to field-realistic levels of the neonicotinoid imidacloprid suffered reduced growth rates and an 85% reduction in the production of queen bees.