Eight decades of invasion by Chromolaena odorata (Asteraceae) and its biological control in West Africa: the story so far
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Date
2019-09-24
Journal Title
Journal ISSN
Volume Title
Publisher
Biocontrol Science and Technology
Abstract
Chromolaena odorata (L.) R.M. King and H. Robinson (Asteraceae) is a
perennial weedy shrub of neotropical origin and a serious biotic
threat in its invasive range. The Asian-West Africa (AWA) biotype
of C. odorata present in West Africa is both morphologically and
genetically different from the southern African (SA) biotype. The
AWA biotype was first introduced into Nigeria in the late 1930s
and rapidly spread across West Africa. Currently, 12 of the 16
countries in West Africa have been invaded, with significant
negative effects on indigenous flora and fauna. However, locals in
West Africa have found several uses for the weed. As chemical,
physical and other conventional methods were unsustainable,
costly and largely ineffective, three biological control agents,
Apion brunneonigrum (Coleoptera: Brentidae), Pareuchaetes
pseudoinsulata (Lepidoptera: Erebidae) and Cecidochares connexa
(Diptera: Tephritidae), have been released in West Africa between
the 1970s and the early 2000s. However, only C. connexa and
P. pseudoinsulata established, contributing to the control of the
weed, in six and four countries in West Africa respectively. Limited
research funding, the absence of post-release evaluations of the
established agents, and the ‘conflict of interest’ status of
C. odorata (i.e. being beneficial for local use but damaging to
ecosystem services and agriculture), are serious factors deterring
the overall biological control effort. Here, using historical records
and field surveys, we examine the invasion history, spread,
impacts, and management of C. odorata in West Africa and make
recommendations for the sustainable management of C. odorata
in the region.
Description
Research Article
Keywords
Invasive alien plant, weed, biocontrol, introduction and impact, management strategies, Pareuchaetes pseudoinsulata, Cecidochares connexa