biological agents for pest control

Biological Agents For Pest Control: Crop Pest Control With Insects


Biological pest control, or biopesticides, uses living organisms or natural substances to control pests. These agents are an alternative to traditional chemical pesticides, which can harm the environment and non-target species. Biological pest control agents originate from plants, microbes, or animals. They operate by disrupting pests’ reproductive or digestive systems, serving as predators or parasites, or utilizing other methods to manage them. They are often preferable to chemical pesticides due to their environmentally friendly nature and safety for humans and animals. This blog will delve into the diverse array of biological agents employed for pest control and their applications in managing pests within agriculture, forestry, and urban environments.

What is The Biological Agent?

Some pests feed on the eggs and larvae of other insects. And these insects are not harmful to regular crops. Instead, harmful insects that live by eating the leaves and stems of crops act as biological control agents by consuming the eggs and larvae. Many species of insects lay their eggs in the eggs or larvae of harmful insects. After the eggs hatch, the chicks grow by eating the eggs or larvae. Such insects are called bioagents.

Trichogramma Wasp: biological agents for pest control

Trichogramma Wasp.

You should know the appropriate timing and routine of the field release of biological agents for pest control beforehand. Otherwise, You will not achieve the desired pest control. It would help if you released biological agents immediately after the first sighting of harmful insects in the crop field. You must remember that it is wrong to expect immediate results in pest control with biological agents like pesticides. Moreover, biological agents will not work if the pest infestation is widespread. Furthermore, knowing the number of biological agents released per acre of land is essential.

Below, we’ll be discussing two biological agents.

Trichogramma Wasp: Biological Agents For Pest Control

The Trichogramma wasp is a tiny insect with small fringed wings belonging to the family Trichogrammatidae. A wasp that belongs to the Lepidoptera family (butterflies and moths) eats the eggs of enemy insects. Some species of these insects are parasites of water beetles, water bugs, and other insect eggs. Insects of this species can swim with their fins to find the eggs of host insects. In certain instances, a specific species of Trichogramma wasp reproduces on various host species. Depending on hormones and other substances, their body color can change, and they can develop or alter other characteristics.

The Trichogramma wasp lives inlays and grows within host insect eggs, preventing the host insect from hatching into larvae. Wasps hatch after 7 to 10 days in the host insect’s eggs. They are tiny insects, usually less than 1 millimeter long.

About 50 thousand Trichogramma parasites can be utilized on 1 hectare of land using one gram of host insect eggs.

The eggs of brinjal tip and fruit borers are uncoated, allowing Trichogramma wasps to parasitize them easily. From the beginning of the attack to the last harvest, You should remove this bolt after 10 to 15 days.

Chilonis of Trichogramma Wasp: biological agents for pest control

Chilonis of Trichogramma Wasp. Image: Collected

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Methods of Trichogramma Abolition: 

Things to pay special attention to for Trichogramma eradication:

    • Monitoring crop fields for any signs of pest activity is essential.
    • Trichogramma parasite control should begin upon egg detection on plant foliage. 
    • In the case of Brinjal, it is important to continue removing parasitic worms according to the rules during the season of tip and fruit borer attacks.
    • It is recommended to deworm between 8–10 am or 4:30–6 pm in autumn. Vials are used to transport parasitized eggs or newly hatched Trichogramma to the field.
    • Typically, old newspapers and other papers are cut into 6-7 cm squares and then folded in half, similar to how chocolate or candy wrappers are folded. A 22 cm long beam can typically hold around 120 to 130 pieces of paper.
    • After placing 120 to 130 folded pieces of paper in a vessel that is 22 cm high or can hold 3 liters of water, release 1 gram of Trichogramma, once the mature Trichogramma enters the paper fold, you should position it on the crop plant.
    • When planting Brinjal, leave two rows of space from the aisle and enter through a corner of the field. After walking 5-6 steps, place a folded piece of paper in the fold of a tree branch. Before reaching the end of the row, take a turn, skip two rows, and continue walking along the row again.
    • Trichogramma should be released throughout the area using a consistent method to ensure equal distribution. When placing Trichogramma on a strip or card, each one should be placed in a groove on a leaf or branch of a tree or hung in a jungle loft. This will allow for more Trichogramma to emerge and increase parasitism rates.

Braconid Wasp: Biological Agents For Pest Control

Braconid is a parasitic insect belonging to the Braconidae family. This medium-sized wasp can parasitize many insect pests. Both males and females can be winged or wingless. Their abdomen is hairless or sparsely hairy. Pests A single worm caterpillar (caterpillar) can have many caterpillars. The pupa grows in the white, yellow-colored silk cocoon of the worm’s body. Some species of enemy insects live within the caterpillars and pupae.

Bracken worm is a very invasive ectoparasite. The female braconid first injects poison into the body of the host insect worm, paralyzing the worm. A female Braconid can parasitize 500 to 1,000 host insect worms. Parasitized worms become weak and can no longer survive. The female bracken lays eggs on the parasitized worm and then feeds and grows inside the worm’s body. As a result, the insect is destroyed.

Braconid wasp

Braconid wasp.

Keep adults of this species in glass or plastic containers and provide them to the field using these containers. This process is referred to as “Banker” Baiyam. A bunker can hold 800 to 1,000 live adult bracken. Release male and female insects in a 60:40 ratio in the bunker or field. Release full-grown bracken 5-6 times at 10-15 day intervals during the cropping season.

biological agents for pest control

Attack of Braconid Wasp on Harmful Insect Larvae

Braconid Release Method in The Field: 

When handling Brinjal plants, it’s crucial to eliminate grown insects of tip and fruit borers starting from the onset of infestation until the last harvest. This practice should be carried out within 10 to 15 days. When weaning adult bracken, paying attention to certain things is crucial.

    1. You should regularly confirm the presence of brinjal tip and fruit borer or national crop fly through surveys.
    2. When you observe host insect larvae on the foliage or fruit, promptly eliminate the parasitic braconids. Then, consistently follow the prescribed procedure for applying parasitic braconids throughout the infestation season.
    3.  Generally, it is best to exterminate the parasite between 8 a.m. and 10 a.m. or 4:30 p.m. and 6 p.m. in the fall. Parasitized eggs or newly hatched broilers are transported to the field in crates or bankers. 
    4.  Typically, a 22cm tank or bunker holds 800 to 1,000 full-grown bracken. At the beginning of the release of this insect, after leaving two lines from the side of the aisle and going in through one of the fields, after going 5-6 steps, open the lid of the mouth of the bunker a little and take out a few brackets. In this way, if you finish in one line, skip two lines or 6-7 steps, walk straight again in the next line, and leave the insect after 5-6 steps. 
    5. In this manner, once the braconid population has been eradicated, you should vacate the entire area of the Banker. The following day, upon the emergence of adult braconids, release them once more and repeat this process until the full emergence of the braconids.
    6. Ultimately, fasten the strips/cards onto the branches of trees or bushes to facilitate the subsequent emergence and parasitization by additional braconids.

Artificial Feeding of Trichogramma And Braconid: 

If it is impossible to release Trichogramma and Braconid in the field due to strong sun or heavy rain, honey or sugar syrup should be provided. You should place a small piece of clean cotton soaked in honey or sweet syrup on the mouthcloth of the vial or bunker. Ensure that honey or syrup does not drip or flow into the vials or bunkers, and take measures to prevent any interference with ant infestation.
Once the cotton piece dries, soak it again with honey or syrup. Do not release Trichogramma and braconid wasps during hot sun or rain; if you cannot remove them, keep them out of the reach of ants. For this purpose, you can place a water container under the table or the foot of the stool—store vials in a well-ventilated area.


Biological agents are a great option for pest management that can help you control the pests that damage your crops. They are environmentally friendly, cost-effective, sustainable, and selective. They work by different mechanisms, such as competition, antibiosis, predation, parasitism, pathogenesis, or behavior modification. You can utilize them through various methods, including foliar application, soil application, seed treatment, or trap cropping. Using biological agents can reduce your reliance on chemical pesticides and improve your crop quality and yield.


I am Gaushoul Agam

𝐂𝐨-𝐅𝐨𝐮𝐧𝐝𝐞𝐫 & 𝐂𝐄𝐎

I am an experienced Horticulture Officer in the Department of Agricultural Extension in Bangladesh. I am committed to improving agriculture and farming.

I created ToAgriculture to address global food safety concerns. These concerns are caused by a growing population, diminishing farmland, and the impact of climate change on agriculture. I assist readers in learning modern farming techniques.

I also help them control pests and diseases. Additionally, I guide managing agriculture sustainably. All of this is aimed at creating a better and more successful future in farming.

I have experience in field crops and horticulture crops. I know about fruit and vegetable farming, managing pests and diseases, irrigation, and grafting. Come with me as I share my knowledge and experiences to help you create a better future.

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