Reducing disease and producing food: Effects of 13 agrochemicals on
snail biomass and human schistosomes
Abstract
Agrochemical use is predicted to increase 2-5 fold by 2050 to meet food
demand. Evidence suggests that agrochemical pollution could increase
snails that transmit the disease schistosomiasis to 250 million people,
but most agrochemicals remain unexamined. Here we quantify the relative
effects of fertilizer, six insecticides, and six herbicides on snail
genera responsible for 90% of global schistosomiasis cases. We
identified fertilizers and 4 of 6 insecticides as high risk for
increasing snail biomass by increasing snail habitat (aquatic
vegetation) or food (periphyton) and reducing snail predators,
respectively. Herbicides generally had negative effects on snails by
reducing habitat, with two herbicides increasing snails in the absence
of aquatic vegetation. Parasite production, which reflects human
infection risk, scaled positively to snail biomass. Our findings suggest
that fertilizers and insecticides present higher chances of increasing
human schistosomiasis than herbicides, and revealed several low risk
agrochemicals might help increase crop production without increasing
schistosomiasis.