How do biological control nematodes work?
All biological control nematodes have an infective stage (called third-stage juvenile or daur larvae) that will enter into the insect host. The nematodes usually enter the insect through its breathing holes, mouth, or anus (Figure 1), but some species are capable of penetrating thin areas of the insect’s cuticle. After they enter the insect’s body the nematodes release special bacteria into the insect. These bacteria are only found associated with the biological control nematodes. The toxins produced by the bacteria kill the insect after a few days. The bacteria multiply inside the body of the insect and the nematodes eat the bacteria. The nematodes mature, mate, and multiply inside the insect. Eventually, the insect’s body becomes filled with nematodes (Figure 2). Infective stage nematodes then exit the insect body in search of other insects to infect (Figure 3). Figure 1. A biological control nematode entering the anus of an insect larvae. Figure 2. A beetle grub that is filled with
