Farmers, grab it! Parasitic wasps are easy to use, but the supply is unstable. Taiwan Sugar recently delivered Trichogramma slices with a purchase limit of 200 tablets per person.

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In nature, when one creature specially preys on or endangers another, we call the latter the natural enemy of the former. Tom's cat in the cartoon catches Jerry mice, and so is the idiom "mantis catches cicadas". This natural law of one thing and one thing can also be applied to agriculture.

Biological control with natural enemies can be divided into two types: predator and parasite. Predators, such as lacewings, feed on pests, while parasitic wasps are the most common application. Domestic experiments have found that Trichogramma is very effective in controlling Lepidoptera pests such as corn borer and sugarcane borer, and it is necessary to use pesticides for autumn army insects, which can also achieve the purpose of pesticide reduction.

Trichogramma lays eggs in the eggs of the moth. (courtesy of Xie Jiahong) there are three kinds of parasitic bees: eating eggs, pupae and larvae

Xie Jiahong, an associate professor in the Department of Forest and Nature Conservation at China Culture University, is a domestic expert on parasitoids. He says that under the national policy of "halving pesticides," biological control is indeed worth vigorously promoting. It can not only reduce the amount of pesticides and environmental pollution, but also do not sacrifice the quality and quantity of agricultural products. It is a win-win approach for farmers, consumers and the environment.

Xie Jiahong pointed out that according to the growth stage of insects, parasitic wasps can be divided into three types: egg parasitoids, pupa parasites and larval parasitoids. Trichogramma is a kind of egg parasitoid, and its host is Lepidoptera such as Spodoptera litura. After mating, the Trichogramma female will lay the eggs inside the eggs of the rice moth, and after the eggs are hatched into young bees, they will eat the substances in the eggs, and the moths will not be able to hatch their larvae.

On the other hand, the wasp is a kind of pupa parasitic wasp, the main hosts are rice borer and nocturnal moth, the female will lay the eggs in the pupae of the fly or moth, and the young wasp will take the tissue of the pupa as food after hatching, so as to prevent the pupa from becoming an adult.

As for larval parasitic wasps such as small cocoon wasps, the eggs are laid into the larvae of Plutella xylostella or Plutella xylostella, and the larvae will eat the larval organs after hatching. Although the larvae will not die immediately after being parasitized, and may still be harmful for a period of time, it is still helpful to reduce the damage in the field.

Xie Jiahong is an expert on parasitic wasps in Taiwan (Photo / Yang Yuyun) Trichogramma parasitic wasps are as effective as chemical pesticides, but farmers report that they can't buy bee tablets.

Xie Jiahong stepped into the field of parasitoid research because of the invitation of Feng Haidong, former director of the Prevention and Inspection Bureau. Feng Haidong, who came from an insect family, wanted to support the biological control industry. at that time, Taiwan Sugar, which specializes in parasitoids, reflected that their bee species had been domesticated, and as a result of the weakening of their provenance, they lost their ability to search for and parasitize in the field. I hope there are researchers who can help. Also from the insect family, Xie Jiahong joined the research field of parasitic wasps at this time.

Xie Jiahong and several other researchers first found many varieties in the field, mixed them with Taiwan Sugar's parasitoid species to improve them, and put the improved varieties into simultaneous experiments in Yunlin and Hualien. The effect of controlling corn borer with Trichogramma in Yunlin is very good, which is not inferior to the effect of conventional pesticides. The effect of parasitic wasps in Hualien is not significant, but when pesticides are halved, the effect of Trichogramma is comparable to that of chemical pesticides. It can be seen that Trichogramma is indeed effective in the comprehensive control of Lepidoptera pests such as corn borer and sugarcane borer.

Unfortunately, such an effective method cannot be used by farmers. Chiayi and Yunlin are the main corn planting areas in Taiwan, and corn borer is the main pest of corn. When the damage is serious, it will lead to plant collapse and serious loss of yield. Although farmers are willing to try parasitic wasps, bee slices have been out of stock for at least two years. Kuo Ming-hsien, a farmer, questioned that the government went to the countryside to promote biological control, but Taiwan Sugar, the only producer of parasitic wasps, did not supply it. "are you treating farmers like idiots?" He asked.