Naibunga Community Conservancy have partnered with plant specialists (and insects!) to control the spread of an invasive cactus that is engulfing the land and threatening livelihoods in Laikipia.
The Opuntia stricta cactus is native to the Americas, but over the last 50 years it has made the Laikipia rangelands a ‘home away from home’. This prickly alien is most definitely not welcome here. As well as displacing native plant species, it prevents any rehabilitation of degraded land — a devastating effect in a region where overgrazing has already taken its toll on grasslands. Livestock frequently feed on the plant too, sustaining injuries from ingesting the spines that often result in death. Furthermore, elephants are now venturing in to settlement areas to feed on the cactus’ sweet fruit, increasing incidents of human-wildlife conflict.
It’s not hard to see why the Opuntia stricta has been nominated by the IUCN’s Invasive Species Specialist Group as one of the world's top 100 worst invasive alien species.
Naibunga have been seeking solutions to this challenge. To date, over 500 community members from Naibunga have been trained to remove and destroy Opuntia stricta plants by hand, this created short-term employment and can work well in small areas. However, this is an expensive and short-term solution, and one that cannot have an impact on a large-enough scale to deal with the massive area of land invaded by this species.
That is why in 2009, Ol Jogi Conservancy partnered with the Centre for Agriculture and Biosciences International (CABI) to explore an alternative. The Dactylopius opuntiae insect feeds and develops solely on Opuntia stricta, offering a low-cost, long-term solution to controlling it’s spread. Five years of monitoring and trials were carried out to ensure the insect would not itself become a destructive alien species. In 2014 it was formally released into the Laikipia ecosystem.
The insects are now reared in greenhouses managed by the community. Nine greenhouses are now operational and Greenhouse managers have been employed by Naibunga to look after and mobilise community members to release the insects.
“There is definitely a sense that the community see biological control as having the potential to really make a difference” says Juliet King, technical advisor to NRT.
In Ol Jogi Conservancy where the insect was released almost 5 years ago, it is showing good success, particularly in areas where infestation rates of the cactus were high. But there is still a long way to go, biological control is a slow process and visible impact may take several years. However, this is the only cost-effective and sustainable solution that can deal with the scale of the Opuntia invasion. Critically, restoration of degraded rangelands must go hand-in-hand with the control of Opuntia to ensure bare ground is quickly covered in the areas where the cactus is removed.
“Complete eradication of invasive species such as Opuntia will be impossible to achieve,” says Juliet, “but the aim of an invasive species control program should be to contain and control the spread of invasive species and restore healthy and productive ecosystems”.