Peter Neuenschwander: How Africa can control invasive pests

P Neuenschwander
P Neuenschwander
The “father of biocontrol”, Peter Neuenschwander, joined IITA’s biocontrol project against the cassava mealybug in 1983. The project was later expanded to include biological control and integrated pest management of mango mealybug, spiraling whitefly, and floating water weeds. He retired in 2003. Last year, the International Organization for Biological Control recognized his life-long contributions to biological control by giving him Honorary Membership. In this interview with Godwin Atser, he bares his mind on the contribution of biocontrol and strategies on how Africa can check invasive pests.

Please explain the concept of biocontrol.
Biological control is a technique whereby we use natural enemies to combat pests. The pests can be insects, mites, pathogens, or even plants. Most times we apply biocontrol against invading pests. The beauty is that once something works, it spreads on its own and it carries on its business without difficulties.

Please give an overview of your work on biocontrol in Africa.
The cassava mealybug was actually one of the things that brought me to Africa. The mealybug was introduced in Africa in the 1970s. Eventually parasitoids were found in South America and transported here. With national partners, we made about 150 releases in most sub-Saharan African countries. From there we went on to other projects such as the mango mealybug, and water hyacinth control.

How can biocontrol check the spread of invasive pests in Africa?
Biocontrol is good; it slows the pests but it would have been best not to have introduced those exotic organisms in the first place. So, we need to strengthen and train the quarantine people.

We also need to tighten quarantine services in all African countries, not just on land borders but also the seaports and the airports so such invasions which cost so much can be reduced.

What has been the impact of biocontrol?
For the cassava mealybug alone, the project resulted in money directly going to the farmers with the entire cassava improvement project in Africa.

What are the challenges you faced in the biocontrol projects?
Our main challenge is the uptake or adoption by the countries. Countries are autonomous in their decisions to import or not to import.

So, we have to convince some 30 quarantine authorities that they should give us quarantine permits, that they should help us, and that they should allow the insect to come in, and so on.

The challenges also include unsatisfied expectations from colleagues from different disciplines who expect us to extinguish the pest. We don’t really extinguish anything.

What is the perception of people towards biocontrol?
The public in most cases is more afraid of biocontrol (insects) than the invasion itself. This is because they don’t understand how it works.

Does biocontrol break down?
In technical terms, yes, it can break down—when biocontrol is working and you forget about it and suddenly start spraying the field with pesticides. That is, you kill the natural enemies and the pest.

What is the future of biocontrol?
The demand for biocontrol is already there and there will always be invasive pests. We also have to maintain the human capital in biocontrol. Unfortunately, the capacity in biocontrol worldwide is declining, not only in IITA.

Your colleague referred to you as the father of biocontrol. Can you comment on this.
I am the last surviving biocontrol specialist at IITA. That was what was written about me when I retired 6 years ago. I am still helping out.

What were the most exciting moments in your work on biocontrol?
The excitement was going out in the field and also the fact that I had a “privileged” job. It also includes getting recognition. In the scientific world, the cassava mealybug project was seen as a success.

You have been retired for several years now. What’s next?
I have a request to go to Asia, because after 20–30 years, the cassava mealy bug turned up in Asia, and it is spreading. They want us to introduce biocontrol to curtail the spread.

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.

Unraveling the diversity of African insects

“A problem identified is half-solved.” — Anonymous

The IITA insect center in Bénin houses one of the largest reference collections of arthropods and microorganisms in West Africa. An insect identification hub, it plays the role of a “gatekeeper” by facilitating the discovery and monitoring of invasive pests in the region. The resulting information helps to locate the probable area of origin where promising natural antagonists may be found.

Entomologist Georg Goergen, IITA-Benin
Entomologist Georg Goergen, IITA-Bénin. Photo by IITA

Several invasive insect pests have recently been identified by the center, among which are fruit flies, whiteflies, and moths. An example was when a myriad of caterpillars and moths invaded Liberian farms early this year, providing entomologists a puzzle. The identity of this pest that devastated crops and contaminated water supply in northern Liberia had been established through the joint efforts of FAO, IITA, and CABI. It was later identified as Achaea catocaloides by Georg Goergen, IITA entomologist and biosystematist. The insect is a member of the Lepidoptera group and known as a fruit-sucking moth.

Goergen says that proper identification is a starting point for any basic or applied research and a prerequisite for any successful biocontrol program. “Any biocontrol approach without proper identification of the insect pests will fail,” he says.

Rapidly accelerating human trade, transport, travel, tourism, and porous borders have dramatically contributed to the introduction, ease of movement, and spread of invasive pests thereby overwhelming the capacities of quarantine services in West Africa.

IITA works with national and international partners to control the spread of these invasive species. In addition to its role of identifying insects, the center is also helping scientists to unravel and conserve the rich diversity of African insects.

Through the identification of insect specimens, scientists get more insight on the species richness of the African insect diversity in various ecosystems, the structure of their populations, their interrelationships, and interactions with their habitats.

Insect collection, IITA Benin
Insect collection, IITA Bénin. Photo by IITA

Insects represent the majority of living organisms, accounting for about two-thirds of all living animals on earth and filling many niches in both terrestrial and aquatic ecosystems. They thus play an important regulatory role in all ecosystems including agricultural environments. Many of them can become notorious pests of agricultural, medical, and veterinary importance.

However, existing knowledge on insect diversity is still inadequate for large parts of the globe and no one knows exactly how many species of insects exist. The situation is worse in Africa where much of the planet’s biodiversity occurs, but where traditionally the scarcity of biosystematists is the strongest.

Goergen says, “Biosystematics is important in all phases of a control program starting from a reliable pest identification, assessment of native antagonists, monitoring faunal changes following the use of exotic beneficials, and detection of eventual nontarget effects. To do that, you need to have a reference collection such as the one we have here in Cotonou.”

IITA has developed a strong regional capacity in biosystematics through the West African Network for Taxonomy, BioNET-INTERNATIONAL.

The center continues to attract students from different parts of the world while offering capacity building and ensuring a requisite contribution to countries seeking to comply with the sanitary and phytosanitary agreement of the World Trade Organization and to fulfill the objectives anchored in the Convention on Biological Diversity.