Eight decades of invasion by Chromolaena odorata (Asteraceae) and its biological control in West Africa: the story so far
- Authors: Aigbedion-Atalor, Pascal O , Adom, Medetissi , Day, Michael D , Uyi, Osariyekemwen O , Egbon, Ikponmwosa N , Idemudia, I , Igbinosa, Igho B , Paterson, Iain D , Braimah, Haruna , Wilson, David D , Zachariades, Costas
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417450 , vital:71454 , xlink:href="https://doi.org/10.1080/09583157.2019.1670782"
- Description: 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.
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The South America tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae), spreads its wings in Eastern Africa: distribution and socioeconomic impacts
- Authors: Aigbedion-Atalor, Pascal O , Hill, Martin P , Zalucki, Myron P , Obala, Francis , Idriss, Gamal E , Midingoyi, Soul-Kifouly G , Chidege, Maneno , Ekesi, Sunday , Mohamed, Samira Abuelgasim
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423859 , vital:72099 , xlink:href="https://doi.org/10.1093/jee/toz220"
- Description: Following the arrival of Tuta absoluta Meyrick in the eastern African subregion in 2012, several studies have shown numerous ecological aspects of its invasion. We investigated the impact of T. absoluta on people’s livelihoods across four counties of Kenya. Here, 200 farmers in the country were interviewed in person using semistructured questionnaires. In addition to livelihood surveys, T. absoluta distribution was mapped between 2016 and 2018 to determine its current distribution across four countries (Kenya, Sudan, Tanzania, and Uganda) in the subregion. Albeit a recent invader, T. absoluta is abundant and distributed throughout the subregion and is viewed as the worst invasive alien species of agriculturally sustainable livelihoods by tomato farmers. The arrival of T. absoluta in the subregion has resulted in livelihood losses and increased both the cost of tomato production and frequency of pesticide application. We recommend the implementation of biological control along, with other control measures in an integrated approach, against T. absoluta in the subregion, where its impact on sustainable livelihoods is serious and long-term control strategies are required to curb its detrimental effects.
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With or without you: stem-galling of a tephritid fly reduces the vegetative and reproductive performance of the invasive plant Chromolaena odorata (Asteraceae) both alone and in combination with another agent
- Authors: Aigbedion-Atalor, Pascal O , Day, Michael D , Itohan Idemudia , Wilson, David D , Paterson, Iain D
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/418093 , vital:71508 , xlink:href="https://doi.org/10.1007/s10526-018-09917-x"
- Description: With or without another biological control agent, the specialist folivore Pareuchaetes pseudoinsulata, the stem-galling fly Cecidochares connexa reduced the performance of the invasive alien plant, Chromolaena odorata in Ghana. There was a strong significant negative relationship between gall densities of the gall fly and stem height, and the number of stems and flower heads of C. odorata. Pareuchaetes pseudoinsulata had very little impact on any C. odorata parameters. However, at sites where both C. connexa and P. pseudoinsulata occurred simultaneously, the performance of C. odorata was significantly reduced when compared with control plants. Increasing densities of both agents had a strong significant negative correlative effect on C. odorata plant parameters. Cecidochares connexa was recorded in all five regions of the country sampled, while P. pseudoinsulata was recorded in four regions. Densities of both agents declined in the dry season, but galls were persistent throughout the study period. This is the first report of the impact of C. connexa on C. odorata in the West African sub-region since its introduction to Cote d’Ivoire in 2003 and it is clear that the agent has a significant impact on C. odorata in Ghana. Further surveys are required to determine the impact of both biological control agents in other parts of the sub-region where they have established.
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