After learning that hungry chimpanzees feeding on maize fields bordering forests in Uganda benefit from the nutrition of the crops, the same study also points to exposure from pesticides as a drawback. Exposure to pesticides in crops and water can threaten chimp health with deformities and fertility problems. Previous studies in the study’s region link organophosphate, pyrethroid and other pesticide use like carbofuran, an insecticide that was canceled for use by the U.S. EPA in 2009, with negative health effects on the chimps.  

At first, the researchers assumed that the chimps look for food in croplands when fruit-bearing trees and other sources of forest food are in low supply but couldn’t confirm this in their findings, published in PLOS One this month. Instead, they think the chimps may prefer the maize crops for their high nutrients and easier access over wild foods. For over a year, the researchers monitored with cameras a forest-maize interface of eight square miles to observe the primates in the Sebitoli region of Kibale National Park, known for its biodiversity and chimpanzee population. 

The study suggests that farmers could increase their vigilance in monitoring the fields at night when the chimps visit and consider other 24-hour methods for deterrence. Farmers guard their fields during the day from other visitors like elephants to prevent extensive damage to their crops, prompting the chimps to forage the fields at night in smaller groups. Chimps are diurnal and likely choose to disrupt their sleep for easier calories from maize crops. Rarely do they search for wild foods from the forest at night, a sign of human encroachment. The researchers also propose palatable crops relocate away from reserve boundaries or nonfood crops grown near forest edges to prevent unnecessary harm to the endangered chimps.  

Tea, banana, eucalyptus and maize crops are grown in the area and the researchers recommend that pesticide exposure on chimps in the Sebitoli area also be investigated further. While the researchers do not suggest changes to farming practices as a way to manage the adverse effects of pesticides, organic agriculture is known to reduce pesticide use in the U.S. (including corn crops) as it relies on lower-impact practices without synthetic chemical interventions.