An invasive species in Kenya, Opuntia (Prickly Pear)

Photo credit: SciDevNet

Copyright: CABI

Sap-sucking insects may combat Kenyan cactus plague

“So when times are good it will continue to displace local plants and make more valuable pasture inaccessible.” – Arne Witt, CABI-Africa

Speed read

  • Prickly pear cactus is an invasive plant that threatens grazing areas in Kenya
  • A trial now shows that a species of bug can be used to control the cactus
  • But further safety testing and approvals are needed before rolling it out

An insect that sucks the sap out of cactus plants has been trialled in East Africa to contain the spread of an invasive cactus species that threatens local grazing areas.

The cochineal bug, known as dudu in Swahili, for biological control has been released on farmland in Kenya’s Laikipia region, which is used by Maasai for livestock herding. The trial showed that the bug feeds exclusively on the Opuntia stricta cactus, better known as prickly pear, which has invaded grasslands and drives out local plants used to feed cattle.

The Maasai community in Laikipia partnered with the Centre for Agriculture Biosciences International (CABI) to conduct the trial and halt the spread of the cactus. According to CABI, an non-profit science organisation from the United Kingdom, the trial, which concluded last month, has shown that the dudu bug will not be harmful to native and non-harmful imported plants in the region.

“The cochineal has not been found on other cactus species such as Austrocylindropuntia subulata and Cereus jamacaru that are growing in association with Opuntia stricta,” says Arne Witt, the coordinator of the invasive species programme at CABI-Africa. “In a nutshell, there is no risk.”

The prickly pear cactus was introduced in Kenya during colonial times as an ornamental plant capable of living in arid regions. Since then, the plant has colonised thousands of acres of fragile rangelands in northern Kenya, putting at risk the livelihood of animal herders.

According to CABI the cactus is also suspected to have caused the death of baby elephants after they consumed its fruit, meaning it poses a threat to local wildlife and related income from tourism.

Read the full article: SciDevNet

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COMMENT OF Willem Van Cotthem

The prickly pear (Opuntia ficus-indica) is an invasive species.  Due to its hard spines it has almost no predators and known methods to destroy it are expensive.

On the contrary, the spineless variety (Opuntia ficus-indica var.inermis) is a widely cultivated plant in Central and South America, edible for men and animals.

Therefore, describing the prickly pear (Opuntia ficus-indica) as a noxious invasive species is a generalisation that is far too negative for its edible and ornamental spineless variety.  Moreover, the prickly pear can also be used to produce an interesting biofuel.

Author: Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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