Pyrethroids in Agriculture
Economists generally agree that insects consume or destroy around 10% of gross national production in large, industrialized nations and up to 25% of gross national production in some developing countries.
Insects directly impact the agricultural food production of over 120 crops by chewing leaves, sucking out plant juices, boring within the roots, stems or leaves, and spreading plant pathogens. Pyrethroids are one of the most effective and widely used tools for controlling insect damage in agriculture.
Pyrethroids can be applied by hand, by machine, via aerial application, or as soil granules or drenches depending upon the life-cycles and behaviors of the target pests. Pyrethroid residues dissipate relatively quickly on crops and therefore, for some pests which breed rapidly, pyrethroids may be applied multiple times in a growing season.
Nowadays, it is typical for pyrethroid use to be alternated with other chemical classes to minimize the risk of resistance developing to any of the commonly-used classes of insecticide. The battle against pest resistance is an endless struggle but, thankfully, most growers have become much more aware of the need for judicious IPM (Integrated pest management) solutions.
Growers are highly cost conscious and therefore, contrary to some media comments, do not apply pesticides (including pyrethroids) and fertilizers indiscriminately. Costs dictate that they use the minimum necessary treatments to ensure a profitable harvest.
To put a U.S. perspective on the importance of pyrethroids to agriculture, data was collected for 14 major crops: alfalfa, citrus, corn, cotton, potato, rice, sorghum, soybean, spring wheat, sugar beet, sunflower, sweet corn, tomato and winter wheat across the USA between 2012 and 2014. The annual average acreage treated with pyrethroids for for these 14 crops was almost 50 million acres or 53% of the more than 93 million acres treated with any foliar- or soil-applied insecticide.
Four crops had pyrethroids used on more than 70% of their insecticide treated acres: rice, sunflower, corn and winter wheat, while sweet corn, soybean, sorghum, and spring wheat used pyrethroids across 50 to 70% of their treated acres. Crops using pyrethroids on 30% or less of their insecticide treated acres included cotton, tomato, potato and citrus, with sugar beet an intermediate case with 43% of treated acres using pyrethroids.
Across all 14 crops, pyrethroids represented just under half (49%) of all foliar insecticides and just under three-quarters (72%) of all soil-applied insecticides. Corn and soybean are the most extensively treated crops – in each case, over 14 million acres are treated with pyrethroids. Cotton was third with 5.5 million pyrethroid-treated acres. In summary, pyrethroids are a critical element in US crop production because they provide safe, cost-effective strategies for ensuring that farmers can meet the increasing needs for feeding US citizens and ensuring that other countries which depend in part on US exports have increased food security. Similar benefits are seen in countries around the World.
