AUGUST 2024 27 PESTICIDES Not your typical worm, nematodes— specifically beneficial nematodes— have long been known to kill harmful crop pests below the ground. But what about above-ground? The problem with nematodes is that they die when removed from their home beneath the ground. The trick is to find a way to keep the nematodes alive above the ground. Luckily, researchers have found a solution within a solution. Nematodes—roundworms usually no bigger than 2.5 mm—are usually found in the top several centimetres of soil and perform pest control by becoming parasites—entering and using the hoist insect as food, killing them from within. They do this by entering a larger insect, either through the host’s mouth, anus, or spiracles, and laying their eggs. One such beneficial species is the entomopathogenic nematode (EPN). As it lays its eggs, it releases the toxic Xenorhabdus spp. bacteria it carries from their gut into their new host pest insect. Soon enough, the bacteria break down the pest’s tissue from the inside out, killing the host after, at most, 48 hours. The nematode young are born within the host, and all the nematodes consume the bacteria-infected tissue. EXPANDING THE ROLE OF NEMATODES AS A PESTICIDE Because nematodes can’t live long above their subterranean home, placing them in a hydrogel allows them to be used as an effective above-ground pest control. Andrew Joseph, Editor A vial of parasitic nematode worms—with beneficial species targeting specific below-ground pests. wildpixel/iStock/Getty Images Plus photo
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