A natural virus could control devastating pest outbreaks and improve food security for thousands of farmers. In a special video diary, Ken Wilson reports on a long weekend in Zambia.

Ken Wilson

“We have arranged for you to meet the Vice President at 10am on Sunday. Is this OK?”. That was it, my trip to Zambia was definitely on and I had just a few hours to prepare for my field visit and meet one of the country’s top politicians who was leading their efforts to manage a food security crisis.

But as you can see in the video below (which you can also watch on YouTube, or in a shorter 03:50 video feature), this visit turned out to be rather different from the rest.

Hunting the African armyworm

Video transcriptVideo and audio helpWatch video on YouTube

For nearly twenty years now, I have been working on an infamous crop pest called the African armyworm. This small 3-4cm long caterpillar feeds on all of the major cereal crops, including maize, rice, sorghum and millet, as well as on pasture grasses where densities typically reach hundreds of insects per square metre.

Together with David Grzywacz at the University of Greenwich and Wilfred Mushobozi at Crop Bioscience Solutions (CBS) Ltd in Tanzania, I have been trying to develop a local natural baculovirus called SpexNPV as a biological pesticide against this serious pest. As part of our research, we have visited more than 60 armyworm outbreaks across Africa in the last four years and clocked up thousands of miles in doing so.

Our research has both applied and fundamental aspects to it. The applied work has recently culminated in the construction of a UK Government-funded biopesticides facility in northern Tanzania, run by CBS.  Through this route, production of the SpexNPV biopesticide should start very soon. And once we have a formulated product, this will be registered first in Tanzania and then hopefully throughout Africa.

Devil in the details

The basic science that underpins this applied work has largely been funded by the Sustainable Agriculture Research for International Development (SARID) programme, jointly supported by BBSRC and the UK Government’s Department for International Development (DFID).

There are a number of important questions that we wanted to address during this project: why is the prevalence of natural virus disease so variable and are there any predictable patterns? How much genetic variation is there in the SpexNPV virus and could this stop the build-up of resistance to the biopesticide in armyworms? How does the virus persist during the harsh dry season when there are so few armyworms? And how can we utilise this information to use SpexNPV more intelligently for Africa-wide control of armyworms?

To tackle these questions, we visited lots of armyworm outbreaks in Tanzania to assess the natural prevalence of viral disease, collected caterpillars that had died of the virus, and live caterpillars that appeared healthy. We also set up a network of pheromone traps to collect adult male moths – the males are attracted to the trap by the artificial scent of sexy females. We then took all these back to the laboratory in Lancaster and did lots of genetic analyses and bioassays, and found out some really interesting stuff – ecological details that could help us control armyworm. For instance, the presence of a bacterium, Wolbachia, increases their susceptibility to the virus. (See my publications page for more).

On the road again

As part of the SARID project, we also established a website called ArmyWeb, which acts as a ‘one-stop shop’ for lay people, scientists and other stakeholders to access information about the African armyworm and its control.

It was through this website that I was contacted in mid-December by Brother Paul Desmarais, Director of the Kasisi Agricultural Training Centre in Lusaka, Zambia. His email said that they had been “hit by armyworms” and that they had large commercial fields of organic maize that they wanted to protect without using chemicals. He had read about SpexNPV on our website and wanted to know where they could purchase some.

Although I had been to Zambia several times, I had never collected armyworms from there. So I replied to Br. Paul that although SpexNPV was not yet commercially available, I would like to visit him to discuss various options, collect some armyworm samples, and visit some other local farmers in the district who had been hit by armyworms. He put me in touch with his colleague Donald Zulu, who agreed to host my visit.

Unfortunately, I was committed to speaking at the British Ecological Society (BES) meeting in Birmingham on December 20th, so I booked a flight to Zambia for the following day. As I was anxious to get back to the UK before Christmas, this also meant that I could only stay in the country for 32 hours if I was to get back in time. Together with the five flights, nearly 40 hours of flying, and around 10,000 air miles, it promised to be a rather hectic and long weekend!

Whilst at the BES meeting, I received an email from Donald, who said that they had arranged for me to meet the Vice-President of Zambia, Dr Guy Scott, who also chairs the Zambian Government’s Disasters and Mitigation Committee, on the morning I was due to leave the country “to explore different armyworm mitigation options”.

I also met Mrs Annie Matutu, an inspirational farmer who managed to save half her maize crop from armyworms by using conventional chemical pesticide, but lost overnight the other (unsprayed) half to a voracious hoard of caterpillars. Both Dr Scott and Mrs Matutu were keen to learn more about SpexNPV and I promised them that one day I would return with some for them.

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About Ken Wilson

Professor Ken Wilson is an evolutionary ecologist based at Lancaster University and is interested in the interactions between insects and their pathogens, especially baculoviruses. He has been obsessed with the African armyworm ever since his first field visit to Kenya in 1989, and has been ‘armyworm chasing’ ever since.

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