Bernice Sainepo1, Martin Tabe2, Samuel Kiboi3, Itambo Malombe4, Mathias Becker1, Thomas Heckelei2 and Miguel Alvarez1
1INRES-Plant Nutrition, University of Bonn, Karlrobert-Kreiten-Straße 13, 53115 Bonn, Germany
2Economic and Agricultural Policy, University of Bonn, Germany
3School of Biological Sciences, University of Nairobi, Kenya
4East African Herbarium, National Museums of Kenya, Nairobi, Kenya
Invasive species are considered one of the greatest threats to biodiversity, second only to habitat destruction. These invader species alter the ecosystem balance whereby they reduce species diversity and population. Consequently, there is a ripple effect on the ecological nexus which affects the ability of an environment to provide ecosystem services. Research in sub-Saharan Africa on Parthenium hysterophorus has become inclined to understanding the allelopathic nature of plant alien species, their distribution range, ways of control and management, competition with native species and their toxicology to the human health component among other numerous studies. Although, there are many papers released, evidence of duplicated work and ideas is still a prominent issue among the African research space, while some pertinent issues are still untouched or researched only on the surface in invasion ecology. This paper seeks to review studies over the last decade on parthenium hysterophorus, regions in which they have been conducted, their focus topic and consequently to identify the gaps in research of this alien species.
Published works (60) were collected, by running specific keywords independently or in combination (i.e. alien, invasive, parthenium hysterophorus). Key topics of the papers were identified based on their geographical focus. These topics include: allelopathy, distribution, competition, toxicology, management and control. While some compounds of Parthenium have been proven to cause dermatitis, there are also several medicinal applications for this plant species. Most of the consulted publications demonstrated a high competition ability, including allelopathic effects of Parthenium on crops and fodder plants.
The most important research gaps detected in this work are related to the lack of research on dispersal mechanisms, the effects of consumption by livestock and seasonal dynamics on Parthenium populations, degrees of invasion and biosecurity, and risk assessment of the weed. Moreover, none of the studies dealing with allelopathy considered possible auto-allelopathic effects.