Tip Top Bio-Control Technical Bulletin

Trichogramma minutum
Minute Parasitic Wasp

Target Pests:
Over 200 pest moth species (armyworms, borers, cutworms, fruit worms, leaf worms, leaf worms, leaf rollers, loopers etc.) eggs can be destroyed by Trichogramma. Trichogramma prevents ravenous worms (caterpillars) from hatching out and devouring crops. Recommended for ornamentals, orchards, and grapes.

Description:
Trichogramma are pale-yellow micro-wasps, 1/100 inch long, smaller than a pinhead. They drill through moth eggs to deposit 1 to 3 of their own eggs depending on moth egg size.

Product information:
Trichogramma is a very minute wasp that lays its egg in the eggs of moths. The wasps are shipped as immatures inside moth eggs glued to small cards that can be attached by hand to infested plants. Aerial application is possible for large acreage's. Keep the cards in a warm, humid place out of direct sunlight until the emerging adults can be seen as small dots moving around in the closed container. A few tiny caterpillars may also be found in the container because it is very difficult to obtain 100% parasitization of the moth eggs, but these are harmless in most crops.

Trichogramma are shipped as pupae ready to emerge as adults, usually glued to perforated cards. Each card can then be broken into thirty 1-inch squares to permit even distribution in fields and orchards. Loose eggs are also available on request for aerial release in addition to cards. There can be between 100,000 to 150,000 host eggs per card. Parasitism rate can be monitored by comparing the ratio of black (contains pupating Trichogramma) to white (unparasitized) eggs. Parasitism can range from 70% to 95%. The sex ratio may range between 50% and 75% female. A more uniform measure of yield is the number of females.

Cut the Trichogramma Card into 30 hangable tabs, and hang tabs on or near the plants to be protected. Each unit or tab has a built-in hook that fits over a 1/4 inch stem. Card stock is black to optimize emergence. Keep cards out of direct sunlight.

Release Rates:
For 12,000/500 sq. ft. - 40,000-200,000/acre weekly for 2-6 weeks. Trichogramma are shipped on cards that look like sandpaper. Each square on the card contains 3,000-5,000 Trichogramma eggs, depending on the species ordered.

Put out the Trichogramma when you see the first flight of moths whose caterpillars cause damage to plants and every 7-10 days thereafter until infestation subsides. The County Ag Commission or University extension agent can tell you the usual time of moth flight. Monitor during that time period with simple light traps, pheromone traps, or other methods to detect when moths are flying before they start laying eggs.

When most of the adults have emerged, place the cards in a shaded spot upwind of the areas where moths are suspected or egg laying is occurring. The adult wasps will fly onto the plants in search of new host eggs to attack. Do not put the cards out before the wasps have emerged because ants and other predators may eat them. The emerging wasps will have the best chance of finding and parasitizing eggs when the weather is moderate.

Good timing and higher frequency during moth flight are more important factors than wasp numbers. Use generally 1/4 card to 2 cards per acre weekly during moth flights, increasing with moth trap counts.

For corn and tomatoes, use 1/10 card per acre per week. Part of your Trichogramma order can be packed cold so you can store for release every 3 or 4 days over a 2 week period.

For treating the codling moth, Trichogramma should be released in the morning hours in the lower tiers of the crown of each fruitbearing tree. Therefore it is important to start early with good distribution to achieve 70% to 90% parasitism from the progeny of the releases.

Life Cycle:
As the parasite develops within the egg, it turns black, and after about 10 days, an adult Trichogramma emerges. Adult Trichogramma can live up to 14 days after emergence.

Strategic Considerations:
The best time to release is early morning or evening when direct sunlight will not hit the cards. Avoid making releases under extremely hot, cold, rainy, or windy conditions.