• Jessica Evans

A bug can do WHAT?!


This is going to be a longer read than usual - my mom said it's interesting enough to keep the reader attentive so that should be reason enough for you to have a look (I'm joking - I hope that it's that interesting though!). It's so long because it's so packed with goodness that I simply can't (don't want to) separate it. So grab some tea and get cosy and let's learn about biocontrol...

Ever since humans have been able to travel far they have been introducing new plants and animals to regions where they had never previously occurred. South Africa was particularly prone to these introductions because of its mid-way location between the west and the east. As a result, South Africa loses nine percent of its mean annual run-off (rain water that should end up in catchment areas) to alien invasive plants like Eucalyptus trees and Australian Acacias, which could contribute to drought. That may not sound like a lot of water but it translates into 3300 MILLION cubic metres of water! It’s easy to get upset at alien invasions when, now, we can see the damage they do. But these introductions often had a purpose at one point – whether that be aesthetic, horticulture, or food. The problem arises when all these new plants don’t have any natural enemies or competition in this new environment.


A water fern (Azolla filiculoides) invasion in the Albany District. (Photo provided by Prof Martin Hill)

Biological control, or biocontrol, is one method conservationists are using to combat the damage already done. I spoke to Prof Martin Hill, Head of Entomology at Rhodes University and Director at the Centre for Biological Control (CBC), and Kim Weaver, Community Engagement Officer for the CBC, who are doing loads of projects to tackle invasive species all over Africa, with a complementary community aspect.

Hill’s speciality is water weeds. They were introduced in the early 1900s because they are beautiful and people wanted them in their ponds. Soon they got into local ecosystems and they wreaked havoc. They starve local underwater plants of light, and fish of oxygen, causing the whole food web to become distorted, and natural waterways to become polluted. Not only that, but they cost the government millions by reducing the quality and quantity of potable water and affecting people whose livelihoods depend on fishing. Working for Water is a governmental programme in the Department of Environmental Affairs. It is part of the Expanded Public Works Programme and it funds the CBC because of its capability to reduce the dire water situation South Africa is experiencing by reducing the populations of alien invasive plants.


This is a frog, just chillin' amongst some water hyacinth, just one of the problematic aquatic weeds the CBC is working on. The bottle it is on is used to slowly release fertiliser to keep the plants with good nutrition (I'll explain why later). (Photo: Jessica Evans)

Biocontrol is the solution to weeds like water hyacinth. "We go to the country of origin of these [invasive plants] and that sounds very simple but it’s not, because there’s all sorts of hybridisation and genetic mixing going on,” explained Hill. After the plant has been identified and genetically verified to confirm that it is in fact the problem plant, scientists look for the insects in the region that eat that plant and keep its population controlled. Thereafter, the insect is kept in quarantine and tested extensively “for years, sometimes,” Weaver emphasised. It’s important that the insect damages the problem plant, but also that it doesn’t harm any indigenous plants. So the insect needs to be studied in depth before being released into a new country.

The quarantine facilities at the Entomology Department are something to be revered – an ominous yellow sign reading “QUARANTINE FACILITY. NO UNAUTHORISED ENTRANCE” hangs on the thick, heavy door. Behind the door is a pitch dark corridor that ends in yet another door. Then there’s the changing room so that the insects can't even hitch a ride out on anybody's clothes. Then finally there’s the room where the insects are kept and studied until it is confirmed that they are safe to use as biocontrol agents.

Next, if the insect is in fact suitable it is put into a mass-rearing programme so it can be farmed in large numbers to tackle the huge number of plants it needs to eat. That’s where community involvement comes in. The mass-rearing programme based in Makhanda (Grahamstown) was first founded in 2009 with a total of three employees. Presently, the Waainek mass-rearing facilities employ 12 people, of whom eight have disabilities (more on this in the next blog post ).

Hill explained the necessity for mass-rearing programmes: “It’s like developing a new type of car. You go through the whole research and development process and you’ve got this really lekker car that’s going to work really well and then you don’t mass produce it, market it and sell it.” The CBC's mass-rearing takes place in multiple large 'tunnels'. The tunnels maintain the right conditions for the plants to grow so that healthy populations of insects are maintained. As Lulama Poni, an employee at Waainek, put it: "Happy plants make for happy insects".


Inside on of the CBC's tunnels at Waainek. (Photo: Jessica Evans)

Weaver works on making biocontrol a common concept in schools and local communities and runs several programmes in partnership with schools in Makhanda. She explained that the community engagement aspect of the CBC’s work is vital in the large scale change they want to see. The goal is “trying to get everyone to know what biocontrol is and what invasive alien plants are and the different ways of controlling them, and just setting that ethos within people in South Africa.”

The CBC runs a science internship programme where grade ten and eleven school learners spend mornings of their holidays shadowing the people in the centre. Ekhona Zozo joined the internship programme in 2012. “I remember our first day of the programme – Martin asked us what career path we wanted to take. I told him I wasn't sure, but the internship programme introduced me to biological control (which I love!), some field work and a few project research principles as I helped around,” explained Zozo. He expressed his gratitude, saying that today he is studying Entomology because the programme inspired him to take science subjects at university. Ntsikelelo Charles was also part of the programme and is now studying Physics at Rhodes. He is grateful for the experience, saying that it trained him to be scientifically minded and environmentally cautious. He added that “till this day I still apply the very same principles to problem solving that I gained from the internship programme.”

Rosali Smith is doing her PhD in Entomology, focussing on biocontrol, more specifically a fly that kills an underwater invasive plant, Brazilian water weed (Egeria densa). On the 12th of October in East London, the fly (Hydrellia egeriae) will be released for the first time. It’s a big deal because it will be the first biocontrol agent to be released in South Africa for a submerged aquatic invasive plant. “Biocontrol is finding a more environmentally safer way of getting rid of invasive plants or at least managing them,” said Smith. “It’s working around the Enemy Release Hypothesis, which is introducing the plant’s natural enemies.”


Smith and her PhD project in quarantine. (Photo provided by Rosali Smith)

Smith explained why biocontrol is the best option to manage invasive species: “When you use chemical control, many of the herbicides are non-specific,” meaning that indigenous plants are also killed. “With mechanical control you need to repeat the treatments a lot,” she said. Mechanical control involves chopping down or manually removing invasive plants and/or burning them, but it is very labour intensive and expensive. “We try to rehabilitate these systems. If you reduce the competitive ability of these plants by stressing them with biological agents, the anticipation is that those resources will then be used by the native species to grow back,” said Smith.


Brazilian water weed and it's enemy - Hydrellia egeriae (Photo provided by Rosali Smith)

After mass-rearing and releasing the insect, the CBC follows up on the site to determine if the insect population is sustaining itself and if it is effectively reducing the impacts of the alien.


Here is the same place in the Albany District that had the water fern invasion after weevils (Stenopelmus rufinasis) were introduced (Photo provided by Prof Martin Hill)

The CBC has ex-students based in Kenya, Uganda, Senegal, Côte d’Ivoire, Ghana, Benin, Cameroon, Nigeria, Zambia, Malawi, Mozambique, Zimbabwe and in Europe, Australia and New Zealand. This vast reach is a promising sign that correction of the past, at least in terms of conserving indigenous plants and water ways, is underway.

The CBC represents the perfect culmination of science, conservation and community and it is a model every scientist and conservationist should strive to adopt at some point in their work. It touches so many lives and it touches them very deeply. And that’s what science and conservation is about.

You can find more about the CBC's employment of people with disabilities here.

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©2018 by Bite-sized Sci | Jessica Evans