For many years, pastoralists in Northern Kenya have been affected by Opuntia stricta, an invasive type of cactus that has blanketed their land and killed many of their animals. The fruits produced by the cacti attract livestock and humans alike with their sweet flesh and this is part of the reason why the plant has spread like wildfire in such a short period of time.
Tales are told about how and when the invasive cactus was introduced in the area. Some like the current area chief Mr. Sepeika Milton of Makurian Location in Laikipia North attribute it to a white colonial District Officer in the 1950s. Others say it was introduced by a white colonial farmer in the 1940s. Yet others say it was brought into Kenya’s Northern Laikipia territory over 40 years ago to be used as a live fence on ranches and the prickly pear has kept out trespassers and indicated land boundaries. It is clear that no one knows exactly when the Opuntia stricta, an attractive prickly plant with yellow flowers and edible purple-reddish fruits was introduced in Kenya.
Mr. Sepeika, himself a livestock farmer in Laikipia North, a constituency in Kenya’s Rift Valley says the plant is so invasive that the cactus has literally taken over the area. He adds that domestic animals and wild animals suffer the same fate as none is spared by the wild fruit.
“The cactus has small spines on the surface of its fruits that can lodge in the throat, stomach or intestines of any animal that eats it.” He explains and adds, “This tool you have developed is assisting us in discovering new places where this opuntia weed is developing.”
Porson Liongo Lepose from Mukogodo, Laikipia, another farmer, says he too has been affected and lost his whole herd. “Those spines cause abscesses which often lead to secondary infections and death. There are other spines on the stems which can also pierce the eyes of livestock trying to access grass underneath the cactus, causing blindness. This Opuntia has invaded huge tracts of our grazing lands and thrives during dry spells.
For Lepose and his fellow pastoralists, livestock is everything to them because it provides food, income, as well as status.
Peter Hetz the Executive Director of the Laikipia Wildlife Forum (LWF) and Margaret Wambua the Head of Monitoring and Evaluation (M&E) said there had been efforts to curb spread and attempts to eradicate it. Peter said there had been attempts using biological controls, manual or mechanical controls. He said “We have tried removing the plant manually by clearing the bushes, we have combated the invasive cacti without success.” Only Impala conservancy seems to have used the super bug – which is a host specific parasite that heavily infests the prickly pear leaves, destroying the plant gradually until it finally dies. It has not worked in the other areas.
Margaret said methods that have been used to try and eradicate the Opuntia include, “chemical control by using herbicides and mechanical control by cutting down and burning individual cactus plants.”
Peter said LWF in conjunction with Centre for Agriculture Biosciences International (CABI) Regional Coordinator for Invasive Species Dr Arne Witt had compiled a Guide to the Naturalized and Invasive Plants of Laikipia. He also said CABI had introduced a sap-sucking bug (Dactylopius opuntiae) that feeds on Opuntia stricta. However this was on a pilot basis and though it has worked in some areas, it was yet to be used in the entire County.
He lauded the Invasive Species Mapper app and recommended that the application be utilised by policy makers as they devise policies. The tool focuses on mapping and modelling current and future distribution of Acacia reficiens and Prickly Pear (Opuntia stricta) within the larger Samburu - Laikipia region. It works by identifying areas of invasion – hotspots; and is extremely useful in prioritizing and planning of the conservation areas. Such information is central in controlling the spread and mitigating the impact of biological invasions. The data collected and maps developed will help the stakeholders in allocating both financial and human resources in invasive plant species eradication plans.
The mapper highlights the use of an android based application “Invasive Species App” in crowdsourcing training and validation data in mapping and modelling invasive species through involvement of the local communities. Correlative Species Distribution Models (SDMs - Maxent) are used to estimate the current potential distributions of invasive species using occurrence records from native range, with a projection of the models into new regions to assess susceptibility to invasion.
Edward Ouko, the ecosystems and landscapes service area lead with SERVIR Eastern and Southern Africa at the Regional Centre for Mapping of Resources for Development (RCMRD), explains that the RCMRD through the SERVIR-E&SA project developed the Invasive Species Mapper to ease the data collection. Edward says they have built the capacities of various RCMRD partners in collecting data using the app.
Edward explains that the Invasive Species Mapper was built by SERVIR Eastern and Southern Africa for the collection of invasive species data for analysis and deeper understanding of their spread. “This data enables rangeland conservation organisations in collaboration with Regional Center of Mapping of Resources for Development/SERVIR, a joint initiative between NASA and USAID, to monitor and engage in research to mitigate their spread.”
He says the data is viewed/downloaded through http://mobiledata.rcmrd.org/invspec and that reporting is done offline and can be sent in batches afterwards. “Data is directly fed to RCMRD invasive species mapping servers for processing and analysis. Authenticated automatic location loads from server on subsequent re-installations.”
John Letai the Deputy Director environment and natural resources of the Laikipia County Government welcomed the mapping tool saying the County had estimated they require 200 million to eradicate the species in Laikipia alone. He said Opuntia spreads remarkably fast especially when baboons and elephants move across the landscape. Livestock are affected if they eat the fruit of the Opuntia. Eating the prickly pear can destroy their digestive systems.
The negative impact to our lands from the cactus is undeniable. “We are looking at additional ways to reduce the effects of the plant on our grasslands, our livestock and our livelihoods. It is for this reason that additional solutions must be implemented to increase the rate at which the plant is destroyed.
He also said the Laikipia Permaculture Centre (LPC) was eradicating the weed through processing it into foodstuff like fruit jams, wine and oil. We spoke to Florence Laipei during our visit to the LPC. She said there are groups of women earn a living from it. “They harvest the fruits and wash them then they deliver here. We boil them, then blend the mixture to make juice, wine, jam and oil. In making juice, one litre of the pulp is diluted with two litres of water then sugar is added to sweeten it. To make wine, a litre of the pulp is diluted with three litres of water then cooled to lower the temperature to 40 degrees. Sugar and yeast is added to the mixture for fermentation. The low temperatures are maintained to activate the functioning of the enzymes in the yeast. After the one-hour process, the wine is then put in jerrycans for 14 days for fermentation before it is packed for consumption.
Florence expounds, “Opuntia stricta has small spines which lodge in the animals mouths, throats, stomachs and intestines often causing infection and death. But the women groups take their time to carefully separate the fruit from the spines, clean it thoroughly before they deliver to us.”
The County Government of Laikipia has requested a partnership for Capacity Building of its staff on application of invasive species mapper system (ISMS) tool and application of GIS & RS in county spatial planning. At the same time. The County is organizing a county wide stakeholder’s forum in May to chart a way forward on eradication of Opuntia stricta. At this forum, RCMRD (SERVIR will showcase the tool and how it works).