\" \" Imagine a pesticide made of fungi that could fend off unwanted insects, while leaving other living organisms unharmed. But let's face it: We wouldn't have a robust agricultural system we have if it weren't for pesticides killing unwanted critters. Imagine a pesticide that could fend off unwanted insects while leaving everybody else alone. The reason for this is that, while some biopesticides fend off pests or screw up their mating cycles, these mushroom-based pesticides take no prisoners. Some downsides of mushroom-based pesticides are price and finickiness: They could easily cost farmers 20 times more than they're used to paying for pesticides, and like other living things, they're sensitive to environmental conditions like temperature and humidity.