How to Rear Nematodes

1. Inoculate the Host Insects: Prepare the infection chamber.

Line a petri dish with a piece of filter paper or a paper towel. Moisten the paper with distilled water containing your starter nematode culture. Place 10 to 20 healthy mealworms into the dish, pop the lid on, and store it in a dark drawer at room temperature for 2 to 3 days.

2. Confirm Successful Infection: Look for the color shift.

After a few days, check the larvae. If you are using Heterorhabditis, the infected mealworms will die and turn a distinct gummy, reddish-brown color due to the symbiotic bacteria the nematodes release. Crucial tip: If any larvae turn black or smell rotten, throw them away—they died from scavenger bacteria, not your biocontrol nematodes.

3. Set Up a ‘White Trap’: Build the escape route.

Once the larvae turn red, move them to a harvesting setup called a White Trap. Place a small petri dish lid upside down inside a slightly larger container. Lay a piece of damp filter paper over the small lid so the edges drape over the sides, and fill the outer container with a shallow layer of distilled water. Place the infected larvae on top of the draped paper.

4. Harvest the Emerged Nematodes: Watch for the swarm.

In 10 to 14 days, the next generation of juvenile nematodes will have completely consumed the inside of the host. They will naturally crawl out of the carcass, slide down the damp paper, and swarm into the surrounding water. The water will take on a slightly milky, swirling appearance-those are your millions of new biocontrol agents!