The principle and methods of using Trichogramma wasps to control the Asian corn borer

There are many species of Trichogramma wasps in nature. The Trichogramma species currently used to control the Asian corn borer is Trichogramma dendrolimi. Generally, at the beginning of the egg-laying period of adult Asian corn borers, Trichogramma wasps are artificially released into the field so that they lay their eggs inside the eggs of the Asian corn borer, preventing the pest eggs from hatching into larvae and thereby achieving control of the Asian corn borer. Let us take a look below at how to use Trichogramma wasps to control the Asian corn borer!

Release timing

To control the Asian corn borer with Trichogramma wasps, the wasps are released twice in total. The first release is at the beginning of the egg-laying period of the Asian corn borer, which generally refers to when the pupation rate of the overwintering generation of the Asian corn borer reaches 20% or when the egg mass count per 100 corn plants in the field is 1-1.5 (fish-scale-like egg masses deposited on corn leaves); then 10 days later, the first release is made. After an interval of 5-7 days, the second release is made, with 10,000 wasps released each time.

Release method

Using Trichogramma wasps to control the Asian corn borer is one of the biological control methods for the Asian corn borer. When using this technique, the plots must be contiguous. Release should begin at the early stage of Asian corn borer egg laying. The total number of wasps released per mu is 20,000, with 10,000 per mu for the first release and 10,000 per mu for the second release.

How to pin the wasp cards

Separate the wasp cards evenly (generally each wasp card contains about 70 tussah silkworm eggs, and each tussah silkworm egg can produce 70-80 Trichogramma wasps; generally 2 wasp cards are pinned per mu), and fix them in the middle of the underside of the middle leaves of corn plants in a shaded spot. The method is to select a middle leaf of a corn plant, roll the leaf downward into a tube shape, and then pin it inside the tube with a toothpick or needle and thread.

Set release points

Set 2 release points per mu. Starting from the edge row of the release field, count to the 15th row as the first release row. From the first release row, walk 15 steps inward as the first release point, then walk 30 steps forward along the row as the second release point. From the second release row, walk 30 steps inward as the second release point. Continue by the same method.

Precautions

1. When releasing wasps, choose a sunny morning and avoid noon or windy weather. If there is heavy rain, release the wasps after the rain; light rain does not affect it.

2. After receiving the wasp cards, pin them onto corn leaves immediately, no later than 1.5 days.

3. The hatching time of the Asian corn borer must coincide with the emergence time of the Trichogramma wasps.

4. Trichogramma wasp cards are distributed free of charge.

5. Generally, Trichogramma wasp cards should be pinned by a professional wasp release team organized uniformly by the township-level department. If there is any violation of regulations locally, you may complain to the local government.