Biological control introduces insects and plant diseases that target specific weed or other pest populations. Thistles are tough weeds to control, and the weevil appears promising in controlling pest populations.
Insect control is best suited for pasture land rather than crop land Cultivation tends to disrupt the life cycle of the insects.
Researchers are also developing microbial controls. These microbes are essentially plant diseases that occur naturally. The microbes are cultured in labs and sprayed on fields where they select the weeds but not the crops.
One major advantage of biological control is that the diseases can adapt to changing weeds so they can’t build up resistance or tolerances, which has occurred with herbicides and insects.
Musk thistle weevils are used as a biological control on thistles.