Biocontrol Success in Peppers

Posted: December 14, 2011

Growers are reporting success with biological control of insect pests in peppers, and research data backs them up. Is this a good option for you? Which pests are controlled, and what are the risks?
Parasitic wasp attacks corn borers.

Parasitic wasp attacks corn borers.

In Pennsylvania, the important insect pests have been worms and aphids.  With rare exception, the worm is the larva of European corn borer (ECB).  If that matches your situation, then biocontrol has an excellent chance of working well.

European Corn Borer populations. First, consider how strong is the European Corn Borer pressure in peppers in your area today? If you don’t have a history of high rates of ECB damage (by high, I mean 30% or greater) in peppers, inundative release of Trichogramma ostiniae can be an effective biocontrol in high-value peppers.

Biocontrol of European Corn Borer. There are many naturally occurring predators of European Corn Borer. Releasing additional parasitoids can help bring down pest levels even further.

One very effective biocontrol is a tiny wasp, Trichogramma ostriniae. A native of China, this tiny wasp lays her eggs inside the eggs of the borer. The wasp develops inside the egg, killing it.

This wasp is reared commercially and can be ordered from multiple biocontrol producers including IPM labs. Call your producer well in advance, and schedule shipments during the time frame that you want Trichogramma emerging in your fields. For example, you might arrange for weekly shipments throughout the time that your peppers will have flower buds or young fruit (~6 to 8 shipments).

A fun part of innundative biocontrol is the field release. One way the biocontrol arrives is as parasitized alternate host eggs glued onto a paper substrate, such as the inside of a paper cup. You walk the field and attach cups to something to hold it off the ground – tie it to a plant stem, or staple it to a wooden stake. Keep the cup closed, to avoid predatory insects feasting on a gift of concentration of eggs, but have very small escape holes or crevices for the tiny Trichogramma to leave the cup.

Results from EPA-sponsored research led by Tom Kuhar at Virginia Tech in peppers in Virginia, Pennsylvania, and Massachusetts, and in potato in Virginia and Maine have been very good (Kuhar et al. 2004). More tests in peppers in Virginia, Pennsylvania, Delaware and Maryland documented how this approach also achieved biocontrol of aphids (Chapman et al. 2009). Growers in northeastern Pennsylvania were satisfied with the results. The replicated field trials do indeed show that the wasps, when released at high rates in small plots, increased the rate of parasitization of European Corn Borer eggs, and reduced the rate of borer damage. The grower trials did not have a control, so we cannot rule out the possibility that the European Corn Borer damage would have been low anyway, perhaps due to low pressure.

From a grower’s perspective, innundative release of T. ostriniae is not an unreasonable cost for a high-value pepper crop, and it not labor-intensive to release the Trichogramma.