Farmers, grab it! Parasitic wasps are easy to use, but the supply is unstable. Taiwan Sugar recently mass-produced Trichogramma eggs, limiting the purchase of 200 tablets per person.

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In nature, when a creature preys on or harms another creature, we call the latter its natural enemy. Tom cat catches Jerry mouse in cartoon is an example; so is mantis catching cicada in idiom. This natural law of one thing conquering another can also be applied to agriculture.

Biological control by natural enemies can be divided into two types: predatory type and parasitic type. Predatory species, such as chrysophora, eat pests, while parasitic species are most commonly used as parasitoids. Domestic experiments have found that red eye egg wasp is very effective in controlling corn borer, sugarcane borer and other lepidopteran pests. For autumn army worm, it needs to be combined with pesticides, which can also achieve the purpose of pesticide reduction.

The red-eyed egg wasp lays its eggs in the eggs of the outer rice moth. There are three types of parasitic wasps: egg-eating, puppy-eating, and larva-eating.

Hsieh Chia-hung, an associate professor in the Department of Forestry and Nature Conservation at the Chinese Culture University, is an expert on parasitic wasps in Taiwan. He says that under the national policy of halving pesticides, biological control is indeed worth promoting vigorously. It not only reduces pesticide use and environmental pollution, but also does not sacrifice the quality and quantity of agricultural products. It is a win-win method for farmers, consumers and the environment.

According to Hsieh Chia-hung, parasitic wasps can be divided into three categories: egg wasps, pupa wasps, and larva wasps. Red eye egg wasp is a kind of egg parasitic wasp, its host is lepidopteran pests such as rice moth. After mating, the red-eyed female will lay eggs in the eggs of the outer rice moth. After the eggs hatch into young bees, they will eat the substances in the eggs of the outer rice moth, and the outer rice moth will not hatch larvae.

The female lays eggs in the pupae of rice bollflies and moths. The larvae hatch and feed on pupae, thus avoiding the pupae from becoming adults.

Larval parasitoids such as the small cocoon bee lay eggs in the larvae of the diamondback moth or the litura moth, and the larvae eat the organs of the larvae after hatching. Although larvae are not killed immediately after parasitism, they may still be harmful for a while, but they are still helpful in reducing field hazards.

Xie Jiahong is an expert on parasitic wasps in Taiwan (Photo/Yang Yuyun). The effect of red-eyed egg parasitic wasps is comparable to chemical pesticides, but farmers report that they cannot buy bee tablets.

Xie Jiahong will enter the field of parasitic wasp research because of the invitation of Feng Haidong, former director of the Bureau of Prevention and Inspection. Feng Haidong, who was born in the insect department, wanted to foster the biological control industry. At that time, Taiwan Sugar, which specialized in raising parasitic bees, reported that their bee species had been domesticated, and the result of the weakening of their provenance caused them to lose their ability to search and parasitize in the wild. He hoped that researchers could help. Xie Jiahong also came from the insect family, so he joined the research field of parasitic bees at this time.

Hsieh Chia-hung and other researchers first found many varieties in the field, mixed them with Taiwan sugar parasitoid varieties for improvement, and released the improved varieties in Yunlin and Hualien simultaneous experiments. In Yunlin County, the effect of using red eye wasps to control corn borers was very good, and the effect of using parasitic wasps alone was not significant, but the effect of using red eye wasps with half of pesticides was comparable to that of using chemical pesticides alone. It is obvious that the egg wasp is effective in the integrated control of corn borer, sugarcane borer and other lepidopteran pests.

Unfortunately, such an effective method cannot be used by farmers. Chiayi and Yunlin are the main planting areas of corn in Taiwan. Corn borer is the most important pest of corn. When the damage is serious, it will cause the plant to collapse and cause serious yield loss. Although farmers are willing to try parasitic bees, bee tablets have been out of stock for at least two years. Farmer Kuo Ming-hsien questioned whether the government was promoting biological control in rural areas, but Taiwan sugar, the only one that produces parasitic bees, was not supplied."Is it treating farmers as idiots?" he asked.