Surviving a Municipal Cosmetic Pesticide Ban: Controlling pests with nematodes

Two Galleria melonella insect larva. The red one has been infected by the nematode Heterorhabditis bacteriophora, and infection caused the larva to turn this characteristic red colour. The white larva is uninfected. This insect is not a pest of turf, but a lab-reared insect commonly used to study insect pathogens. Photo courtesy Deborah Henderson

By Deborah Henderson, PhD

Nematodes are microscopic ‘worms’ that do not require registration in Canada as a pesticide, and control soil-dwelling insects. There are two groups (i.e. genera) available commercially that can be quite useful. Numerous suppliers provide nematodes of various species and some have pest specificity, so one should check the labels.

One genus, Heterorhabditis (i.e. H. bacteriophora, H. megidis, and H. marelatus), finds its prey in the soil by using a ‘seeking’ predator strategy, actively moving about in the soil searching out prey. The other genus, Steinernema, is a smaller nematode (i.e. S. carpocapsae, S. krausii, and S. feltiae) that uses an ‘ambush’ strategy, waiting for hosts to come along then latching on.

Nematodes find natural host orifices and burrow inside to grow, mate, release insect toxins and produce young. The host insect turns a characteristic colour and dies. The juvenile nematodes burst out of the dead insect and start their search in the soil to find another host. While an application of nematodes will result in some being present in the following year, the concentration is not usually high enough to provide a second year of control for a pest that annually invades turf or ornamentals.

Read the full article: Surviving a Municipal Cosmetic Pesticide Ban

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