Long-Term Effect of CMO Corn on Insecticide Use

Bt corn and Bt soybeans are two common genetically modified organisms (GMO) in the U.S that are engineered to be more resistant to pests. These crops are inserted with genetical materials of Bacillus thuringiensis (Bt)-- a soil bacteria that produces proteins poisonous to some insects. Agricultural census data indicates that the total insecticide usage in the U.S has been decreased since the 1980s, along with the expansion of GMO crops.

The benefits of reducing insecticide use has been emphasized by the GMO supports for decades. However, pest species in the field could develop resistant to the Bt toxins produced by the crops, and diminish/eliminate the effect.

Crop Diversity
Prop. Corn
Degree Day
Market Price

(Please click the buttons to view the spatial-temproal variation of different variables)

The maps above represent the percentage of farmland treated with insecticde use in each county, percentage of corn acerage in the county's agircultural area, and ecolgical/environmental factors that might affect pesticide use. The data were derived from the U.S. census of agricutlure database*, and NOAA's climate dataset. I used a regression model* to exmaine the relationship between pesticide use and all other factors listed above. My analysis negates pervious reserach that stated the increase of insectciide use was due to "monoculture" (single crop that spread out a large area). Furthermore, the result indicates that corn acerage is positively realted to insecticide use.

*U.S. census of agricutlure is conducted by USGS every four years, and is considered the most accurate data source for agricultural analysis. The released data were aggregated to county level.

**please check out this link if you are interested in the technical details: splm:spatial panel model in R