Manuele Tamò: Biocontrol should be the first option

Manuele Tamo inspects plant
Manuele Tamo inspects plant. Photo by IITA

Dr Manuele Tamò is the Officer-in-Charge of IITA-Bénin. In this interview, he talks about the outlook regarding invasive pests in Africa and the role of biocontrol.

Africa seems to be witnessing a lot of invasive pests. What are the factors responsible for this?
That observation may be a bit of an exaggeration at the moment. However, we have been experiencing some invasive species in the past years and, unfortunately, that might increase in the future. This is mainly due to the increase in people’s travels—people travel but do not know that they are carrying pests in their suitcases. Trade is also another contributing factor to the spread of invasive pest species in Africa.

What control measures have governments put in place to check this trend?
We have Plant Quarantine officers all over Africa. They are doing their best but, unfortunately, in West Africa, for instance, the borders are porous so people can pass through from one country to the other without much control. Also some of the invasive species spread freely and once they land on the continent the quarantine officers have no control over them.

How does biocontrol help in this instance?
Biocontrol is a natural response to controlling invasive pest species. It simply means reuniting the invasive species and its natural enemies found it its area of origin. This is what is called classical biological control.

How has your work on biocontrol helped in the control of, for instance, cowpea pests?
Let me start with the project on flower thrips (Megalurothrips sjostedti) that may be the oldest one—we have found a new natural enemy and we are spreading it all over West Africa. We are monitoring the situation in Bénin, Ghana, and also in Nigeria where we made the releases.

For the cowpea pod borer (Maruca vitrata), we have just introduced a new natural enemy from Asia. Our aim is to release it and establish it on wild occurring host plants so that the M. vitrata population that is able to invade cowpea farms will be much reduced.

What is the damage caused by these pests on cowpea?
The damage can be devastating. If you take a susceptible variety in an uncontrolled situation, you might get about 80% yield loss, at least.

Some people worry that results from biocontrol never come early. What is your reaction to this statement?
Biocontrol is both a science and an art. As scientists, we know that experiments can take several years before results are achievable and thus conclusions are made. Just as it takes several years to develop a new crop variety, so it is for biocontrol.

The cassava mealybug biocontrol project gave results already after 2 to 3 years. This has raised stakeholders’ expectations. Now, every time we embark on a biocontrol project, farmers and also politicians expect us to have the same level of success within 2 to 3 years.

In certain cases, results are obtained quite rapidly, but at other times, it might take 5 to 10 years. Results vary because we work on various types of insects that live in different environments.

On the other hand, biocontrol is an art because sometimes you need luck to get quick results.

Why biocontrol and not pesticides?
I am not against pesticides if they are used correctly to save crops from pest attacks. But biocontrol is an option that controls pests by reestablishing the natural balance (in nature) and should be considered first, particularly in the case of alien invasive species.

What are your future plans?
Continue the work on flower thrips and Maruca vitrata and measure the impact. I am also working on a feasibility study on cotton. Cotton is the biggest consumer of insecticides in the whole of West Africa, and a source of concern with regard to environmental and human health.

We also want to start a new project investigating insects attacking cashew. The project is important because cashew nuts exported to Europe and the United States must be pesticide free.

How do you work with the government in achieving your results?
We collaborate with the government, starting with the Plant Protection Services. For instance, we need to comply with country quarantine regulations for the introduction of new biocontrol agents. Plant protection officers are with us in the field—from experimental releases of natural enemies to measuring establishment and impact. We also work with the NARS, which include research institutes and universities, by offering training to students and collaborators.