Plant Doctor Archive

 SINCE the early seventies there’s been a move away from pesticides into biological control.

Biological control means reducing your pest population by employing their natural predators, and these days you can buy some of these great little insects off the shelf.

Most people don’t like spraying noxious chemicals, and people certainly don’t like eating them. So putting a good bug into an environment to kill the bad bugs is a simple solution to a long-standing problem.

Bioforce, in Karaka, breeds predators and parasites in glasshouses to sell to commercial growers and the public. Their biggest seller is the encarsia, a parasitoid that kills whitefly.

The encarsia parasitises the juveniles. They lay their eggs into the juveniles, and the juveniles turn black with a wasp in it.

Bioforce harvests the wasps, sticks them on a tag and sells them. The tags can then be planted on tomatoes or other plants to kill the whitefly.

This is just one of a number of parasites and predators that are commercially available.

Another small wasp lays its egg inside a live host, in this case an aphid. The parasitic wasp curls the egg-laying tube under her body to deposit an egg inside the aphid.

Also available is the reddish mite — a very active predator mite which just loves to eat the two-spotted spider mite.

Home gardeners with a pest problem must first identify their culprit before they can employ a biological enemy for control. Your beneficials need really good conditions in order to thrive — Bioforce has that information available.

The problem is, when people use pesticides to kill the bugs, they kill the beneficials, which are twice as susceptible to the poison.

For more information, contact:

Bioforce Ltd: www.bioforce.co.nz