Why is there so much Opuntia cactus at Loisaba Conservancy?

Opuntia engelmannii – commonly known as prickly pear – was first introduced to the conservancy by the previous owner in the 1970’s as ornamentals or ‘living fences’, when the negative impacts were unknown. The cactus, originally from Texas, thrives in harsh conditions, meaning it has evolved to become durable and resilient, and therefore difficult to remove. Removing the cactus and controlling the spread is currently Loisaba’s number one conservation priority.

 

Is it harmful to the wildlife?

Although some wildlife species (baboons, elephants, birds, squirrels and more!) have been observed feeding on introduced cacti species in Africa, there have been no definite studies to determine impacts, other than the fact they contribute to the dispersal of cacti. However, it is assumed that the spines penetrate their skin and feet and can cause injuries, and the barbed hairs on the fruit could lodge in their mouths which could lead to feeding issues. 

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What is Loisaba doing about it?

Thanks to generous support from The Nature Conservancy, funding was raised to tackle removal of the cactus. We currently have three teams across the conservancy, who manually remove the cactus with the help of two JCB back-hoes. Some of the cactus is used in our BioDigester (which generates fuel for cooking on one of our staff canteens), and the rest buried deep in the ground in holes dug by the JCBs. 

 

In addition to the mechanical removal, Loisaba partnered with invasive species specialists at CABI (Centre for Agriculture and Bioscience) to identify the most effective biological control – a species of sap-sicking insect known as cochineal (Dactylopius opuntiae). You may be able to spot these insects on the cactus plants – they look like small white clusters on the cladodes. We are already seeing positive results, with the plants producing far fewer flowers and fruit than before.

 

Loisaba is also working with surrounding communities on landscape level control and removal.

 

What is the current rate of eradication?

We are currently clearing on average 19,000 plants per month. This is a considerable improvement from 2022’s monthly average of 5,100 plants per month, largely thanks to a generous donation from The Nature Conservancy, which enabled us to increase the number of teams in the field working on the removal. 

 

How much land has been cleared to date?

Since mechanical removal started, over 4,300 acres have been cleared.

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How far to go?

We estimate that we will have the majority of the cactus cleared by 2028. This is tricky to estimate, as there are many factors to consider such as the effect of the biological control, regrowth, weather and terrain.  

 

How much does it cost?

Our annual cost for of our mechanical removal is around US$ 220,000 per year (subject to inflation). With the teams getting more efficient and starting to clear 100 acres per month, this works out to around US$ 180 per acre (or $1-2 per plant).

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Have you thought about using the cactus to make leather, alcohol or selling the fruit?

You may have seen articles about entrepreneurs turning opuntia cactus into biodegradable plastic like material, or ‘vegan leather’ for sale. While we are always looking for additional ways to fund our conservation efforts, we are wary of adding value to the cactus which could encourage people to plant more to fuel businesses. We have instead invested in a BioDigester, which can turn any biological waste into cooking gas. The Opuntia is used, and when it has finally all been removed, anything can be used in its place – from kitchen waste to cattle manure! 

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