The Nano Technology Department of the Wayamba University and the Horizon Campus have identified a self-limiting gene to destroy the eggs of the Fall Armyworm (FAW) (Spodoptera frugiperda).

They are working together to develop this gene in their own labs to find a permanent solution for the crisis. According to them, this can be applied to a large area like 10,000 -15,000 acres within one day using drones. They have already tested this gene on affected-fields in Ukraine as well and the cost of applying this to a one-acre plot of land is estimated around Rs. 200 – Rs. 300.null

Spread of FAW

The Fall Armyworm is a pest which can destroy more than 80 kinds of plants, including maize, rice, sugarcane and cotton. It has spread throughout North, South and Central America, where it has caused significant crop damage for decades. The FAW has developed resistance to insecticides in a number of regions and growers are in need of new solutions to control this pest.
According to an Agriculture and Biosciences International Centre report, the FAW has caused an estimated US dollars 13.8 billion loss to maize, sorghum, rice and sugarcane cultivations in Africa.

Since 2016, the Fall Armyworm has been spreading throughout Africa and is now found in at least 28 countries. Native to America, the FAW was identified in Sri Lanka last year and has rapidly spread over the entire country. It has infected nearly 50 percent of the maize cultivation in the country, extending to 82,000 hectares. If it infects the export-oriented crops, we may face some problems in exporting as well.

Efforts to control FAW

Considering the damage caused by the FAW to the country, the Wayamba University and the Horizon campus dedicated their efforts to identifying and providing a rapid solution to the issue. According to them, this self-limiting gene is the heart of this method of insect control. When male insects with the self-limiting gene are released to reproduce with wild females, all of their offspring receive a copy of this gene. The self-limiting gene disrupts the proper functioning of their cells by flooding the insect’s cells with a protein to stop them from properly expressing other essential genes needed for development and preventing the offspring from surviving until adulthood.

Since the self-limiting gene functions by using the insect’s own biology against itself, this method of control provides a solution that only affects the particular species of pest without introducing harmful toxins.

Fluorescent marker

They have also designed insects that can turn-off the self-limiting gene with an antidote called tetracycline. This allows breeding insects on a large scale without the need for any additional genetic engineering.

They are aiming to introduce a marker gene into insects, which expresses a protein called ‘DsRed2’. Like the self-limiting gene, it will also be inherited by all offspring. This protein is found in the body of the larvae and pupae and glows red under a special light. As a result, these insects can be easily identified apart from the wild ones.

The marker gene is vital for a control programme as it allows scientists to easily identify the offspring of target insects while enabling their tracking-and-tracing in the wild. The number of offspring of the self-limiting insects and wild ones can be calculated through the examination of larvae in the field. This makes it a highly useful tool for quality control in production and effective monitoring in the field. They use that data to tailor the releases and ensure high levels of pest suppression.

As the marker is integrated into the insect’s DNA, this method provides a better monitoring tool compared to fluorescent dust or food dyes used in other insect control programmes.

About the self-limiting gene

1. The self-limiting gene produces a tetracycline-controlled trans-activator protein.

The self-limiting gene creates a protein called tetracycline-controlled trans-activator (tTAV protein). One section of the self-limiting gene contains a binding site called tetO.

2. tTAV protein binds to tetO, producing positive feedback.

The tTAV protein binds to the tetO site on the self-limiting gene. This works as positive feedback, informing the gene to produce more tTAV. As the amount of tTAV protein is increased, there is more positive feedback, and even more protein is created.

3. High levels of tTAV prevent cells from working properly.

Once there is enough tTAV protein, it interferes with the machinery which cells use to control the expression of genes. Essential genes are not expressed, and the insects die while they are still pupae or larvae.

In some research, both male and female insects die, while in others the gene only affects female insects.

4. The self-limiting gene can be turned off with an antidote.

When the pests are reared with an antidote called tetracycline, the tTAV protein binds to the antidote instead of tetO. There is no positive feedback, so levels of tTAV remain low and the insect survives.

They said they can breed these self-limiting insects by adding tetracycline to their food. However, in the wild their offspring do not have access to tetracycline and so they die.

According to their statement, if government authorities can test this gene on affected grounds, the waste of public money can be stopped. Further, this team is willing to extend their support to the government to develop this kind of technology in the country without depending on imported pesticides.

Even the use of some natural extractions like neem oil may kill other environmental-friendly species that are important to agriculture. It is hard to control the FAW even after applying natural or artificial pest control techniques.

Usually, one single egg will lead to 2,000 eggs, but the technique they proposed will destroy each and every egg that remains in the field, without allowing the pest to regenerate.

Academicians involved  in this project:

* Prof. C.A.N Fernando, Nano Science Technology Department, Technology Faculty, Wayamba University of Sri Lanka, Kuliyapitiya

* Prof. Ajith C. Herath, Applied Science Faculty, Rajarata University of Sri Lanka, Mihintale.

* Prof. L. Obeysekara, Technology Faculty, Horizon Campus, Malabe

* Prof. P Samarasekera, Physics Department, University of Peradeniya

* Prof. D.P.S.T.G Attanayake, Biotechnology Department, Wayamba University, Makandura

*Prof. R.C.W.M.R.A Nugawela, Biotechnology Department, Wayamba University, Makadura

* Prof. Aruni Weerasinghe, Plant Science Department, Agriculture Faculty, Rajarata University of Sri Lanka, Anuradhapura.

* Prof. D.P.S.T.G Attanayake, Biotechnology Department, Wayamba University, Makadura

* Prof. Sanath Rajapakse, Molecular Biology and Biotechnology Department, Science Faculty, University of Peradeniya

* Prof. Sanath Hettiaracchi, Applied Sciences Faculty, Rajarata University of Sri Lanka, Mihintale

* Prof. Rohan Weerasooriya, National Institute of Fundamental Studies, Kandy

* Prof. B. Obeysekara, Australia

* Prof. Ronald Hummel, Germany

* Dr. PSB Wanduragala (Coordinator) – Secretary, National Institute of Fundamental Studies, Kandy

* Dr. K.H Sarananda, Bio Systems Engineering Department, Wayamba University, Makadura

* Dr. Upaneth Liyanarchchi (Coordinator), Nano Science Technology Department, Technology Faculty, Wayamba University of Sri Lanka, Kuliyapitiya

* Dr. Pradeep Perera, Nano Science Technology Department, Technology Faculty, Wayamba University of Sri Lanka, Kuliyapitiya

* Dr. Nimali Tharangani De Silva (Coordinator)- Nano Science Technology Department, Technology Faculty, Wayamba University of Sri Lanka, Kuliyapitiya

* Dr. Asanka Rajapakse, Nano Science Technology Department, Technology Faculty, Wayamba University of Sri Lanka, Kuliyapitiya

* Dr. Malita Abeykoon, Bells Lab Communication PLC , Sri Lanka

Reference : Daily News – 06th February 2019