Management of water hyacinth (Eichhornia crassipes [Mart.] Solms) using bioagents in the Rift Valley of Ethiopia

Firehun Yirefu Gebregiorgis

Research output: Thesisinternal PhD, WU

Abstract

This thesis presents a study on management of water hyacinth (Eichhornia crassipes [Mart.] Solms) using insects and fungal pathogens as bioagents. The main goal was to develop an effective biocontrol strategy for water hyacinth in the Rift Valley of Ethiopia. To this end, a field survey was conducted to assess the agro-ecological distribution of water hyacinth and of native fungal pathogens found in association with water hyacinth. We also performed laboratory and lath house experiments on (i) pathogenicity and host specificity of the fungal pathogens; (ii) adaptability, life table, efficacy and host specificity of the two Neochetina weevils; and (iii) the synergetic effects of integrated use of Neochetina weevils and fungal pathogen as bioagents. Survey results indicated that the weed is distributed in the Rift Valley water bodies located in low, mid and high altitude. The survey results also identified 25 fungal species found in association with water hyacinth that belonged to nine genera. Among the isolates, Alternaria alternata, A. tenuissima, and Alternaria spp. hold promise as possible bioagents of water hyacinth.

Laboratory study on life cycle and development of Neochetina weevils indicated the two weevils took shorter generation time in Ethiopia than in Argentina but relatively similar to Kenya and Uganda. In Ethiopia, the two weevils produced four generations per year indicating their successful establishment. Feeding by adult weevils and tunneling by larvae significantly impacted the vigour and reproduction of water hyacinth plants. A herbivory loads of three pairs of N. bruchi and two pairs of N. eichhorniae showed the highest level of leaf damage and defoliated petioles. The study also reinforced that the two weevils are sufficiently host-specific. Finally, a study on integrated use of Neochetina weevils and an indigenous plant pathogen revealed that the two Neochetina weevils and the fungus A. alternata were together able to reduce the vegetative growth and fresh weight of water hyacinth plants considerably.

This study recommends integrated use of fungal species and the two weevils to control water hyacinth. Implications of the findings are also discussed in the context of integrated water hyacinth management using the native fungal pathogens and the two weevils.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Struik, Paul, Promotor
  • Lantinga, Egbert, Co-promotor
  • Tessema, Taye, Co-promotor, External person
Award date31 Mar 2017
Place of PublicationWageningen
Publisher
Print ISBNs9789463430562
DOIs
Publication statusPublished - 2017

Fingerprint

Eichhornia crassipes
Ethiopia
Curculionidae
Neochetina
valleys
pathogens
Alternaria alternata
host specificity
Alternaria tenuissima
life tables
Alternaria
Uganda
petioles
plant pathogens
Kenya
body water
vegetative growth
vigor
life cycle (organisms)
biological control

Keywords

  • eichhornia crassipes
  • biological control agents
  • biological control
  • neochetina
  • curculionidae
  • mycoherbicides
  • ethiopia

Cite this

Gebregiorgis, Firehun Yirefu. / Management of water hyacinth (Eichhornia crassipes [Mart.] Solms) using bioagents in the Rift Valley of Ethiopia. Wageningen : Wageningen University, 2017. 174 p.
@phdthesis{32a5cc26db8c4ebdb83f9d8b32d7ccff,
title = "Management of water hyacinth (Eichhornia crassipes [Mart.] Solms) using bioagents in the Rift Valley of Ethiopia",
abstract = "This thesis presents a study on management of water hyacinth (Eichhornia crassipes [Mart.] Solms) using insects and fungal pathogens as bioagents. The main goal was to develop an effective biocontrol strategy for water hyacinth in the Rift Valley of Ethiopia. To this end, a field survey was conducted to assess the agro-ecological distribution of water hyacinth and of native fungal pathogens found in association with water hyacinth. We also performed laboratory and lath house experiments on (i) pathogenicity and host specificity of the fungal pathogens; (ii) adaptability, life table, efficacy and host specificity of the two Neochetina weevils; and (iii) the synergetic effects of integrated use of Neochetina weevils and fungal pathogen as bioagents. Survey results indicated that the weed is distributed in the Rift Valley water bodies located in low, mid and high altitude. The survey results also identified 25 fungal species found in association with water hyacinth that belonged to nine genera. Among the isolates, Alternaria alternata, A. tenuissima, and Alternaria spp. hold promise as possible bioagents of water hyacinth. Laboratory study on life cycle and development of Neochetina weevils indicated the two weevils took shorter generation time in Ethiopia than in Argentina but relatively similar to Kenya and Uganda. In Ethiopia, the two weevils produced four generations per year indicating their successful establishment. Feeding by adult weevils and tunneling by larvae significantly impacted the vigour and reproduction of water hyacinth plants. A herbivory loads of three pairs of N. bruchi and two pairs of N. eichhorniae showed the highest level of leaf damage and defoliated petioles. The study also reinforced that the two weevils are sufficiently host-specific. Finally, a study on integrated use of Neochetina weevils and an indigenous plant pathogen revealed that the two Neochetina weevils and the fungus A. alternata were together able to reduce the vegetative growth and fresh weight of water hyacinth plants considerably. This study recommends integrated use of fungal species and the two weevils to control water hyacinth. Implications of the findings are also discussed in the context of integrated water hyacinth management using the native fungal pathogens and the two weevils.",
keywords = "eichhornia crassipes, biological control agents, biological control, neochetina, curculionidae, mycoherbicides, ethiopia, eichhornia crassipes, organismen ingezet bij biologische bestrijding, biologische bestrijding, neochetina, curculionidae, mycoherbiciden, ethiopi{\"e}",
author = "Gebregiorgis, {Firehun Yirefu}",
note = "WU thesis 6609 Includes bibliographic references. - With summary in English",
year = "2017",
doi = "10.18174/401611",
language = "English",
isbn = "9789463430562",
publisher = "Wageningen University",
school = "Wageningen University",

}

Management of water hyacinth (Eichhornia crassipes [Mart.] Solms) using bioagents in the Rift Valley of Ethiopia. / Gebregiorgis, Firehun Yirefu.

Wageningen : Wageningen University, 2017. 174 p.

Research output: Thesisinternal PhD, WU

TY - THES

T1 - Management of water hyacinth (Eichhornia crassipes [Mart.] Solms) using bioagents in the Rift Valley of Ethiopia

AU - Gebregiorgis, Firehun Yirefu

N1 - WU thesis 6609 Includes bibliographic references. - With summary in English

PY - 2017

Y1 - 2017

N2 - This thesis presents a study on management of water hyacinth (Eichhornia crassipes [Mart.] Solms) using insects and fungal pathogens as bioagents. The main goal was to develop an effective biocontrol strategy for water hyacinth in the Rift Valley of Ethiopia. To this end, a field survey was conducted to assess the agro-ecological distribution of water hyacinth and of native fungal pathogens found in association with water hyacinth. We also performed laboratory and lath house experiments on (i) pathogenicity and host specificity of the fungal pathogens; (ii) adaptability, life table, efficacy and host specificity of the two Neochetina weevils; and (iii) the synergetic effects of integrated use of Neochetina weevils and fungal pathogen as bioagents. Survey results indicated that the weed is distributed in the Rift Valley water bodies located in low, mid and high altitude. The survey results also identified 25 fungal species found in association with water hyacinth that belonged to nine genera. Among the isolates, Alternaria alternata, A. tenuissima, and Alternaria spp. hold promise as possible bioagents of water hyacinth. Laboratory study on life cycle and development of Neochetina weevils indicated the two weevils took shorter generation time in Ethiopia than in Argentina but relatively similar to Kenya and Uganda. In Ethiopia, the two weevils produced four generations per year indicating their successful establishment. Feeding by adult weevils and tunneling by larvae significantly impacted the vigour and reproduction of water hyacinth plants. A herbivory loads of three pairs of N. bruchi and two pairs of N. eichhorniae showed the highest level of leaf damage and defoliated petioles. The study also reinforced that the two weevils are sufficiently host-specific. Finally, a study on integrated use of Neochetina weevils and an indigenous plant pathogen revealed that the two Neochetina weevils and the fungus A. alternata were together able to reduce the vegetative growth and fresh weight of water hyacinth plants considerably. This study recommends integrated use of fungal species and the two weevils to control water hyacinth. Implications of the findings are also discussed in the context of integrated water hyacinth management using the native fungal pathogens and the two weevils.

AB - This thesis presents a study on management of water hyacinth (Eichhornia crassipes [Mart.] Solms) using insects and fungal pathogens as bioagents. The main goal was to develop an effective biocontrol strategy for water hyacinth in the Rift Valley of Ethiopia. To this end, a field survey was conducted to assess the agro-ecological distribution of water hyacinth and of native fungal pathogens found in association with water hyacinth. We also performed laboratory and lath house experiments on (i) pathogenicity and host specificity of the fungal pathogens; (ii) adaptability, life table, efficacy and host specificity of the two Neochetina weevils; and (iii) the synergetic effects of integrated use of Neochetina weevils and fungal pathogen as bioagents. Survey results indicated that the weed is distributed in the Rift Valley water bodies located in low, mid and high altitude. The survey results also identified 25 fungal species found in association with water hyacinth that belonged to nine genera. Among the isolates, Alternaria alternata, A. tenuissima, and Alternaria spp. hold promise as possible bioagents of water hyacinth. Laboratory study on life cycle and development of Neochetina weevils indicated the two weevils took shorter generation time in Ethiopia than in Argentina but relatively similar to Kenya and Uganda. In Ethiopia, the two weevils produced four generations per year indicating their successful establishment. Feeding by adult weevils and tunneling by larvae significantly impacted the vigour and reproduction of water hyacinth plants. A herbivory loads of three pairs of N. bruchi and two pairs of N. eichhorniae showed the highest level of leaf damage and defoliated petioles. The study also reinforced that the two weevils are sufficiently host-specific. Finally, a study on integrated use of Neochetina weevils and an indigenous plant pathogen revealed that the two Neochetina weevils and the fungus A. alternata were together able to reduce the vegetative growth and fresh weight of water hyacinth plants considerably. This study recommends integrated use of fungal species and the two weevils to control water hyacinth. Implications of the findings are also discussed in the context of integrated water hyacinth management using the native fungal pathogens and the two weevils.

KW - eichhornia crassipes

KW - biological control agents

KW - biological control

KW - neochetina

KW - curculionidae

KW - mycoherbicides

KW - ethiopia

KW - eichhornia crassipes

KW - organismen ingezet bij biologische bestrijding

KW - biologische bestrijding

KW - neochetina

KW - curculionidae

KW - mycoherbiciden

KW - ethiopië

U2 - 10.18174/401611

DO - 10.18174/401611

M3 - internal PhD, WU

SN - 9789463430562

PB - Wageningen University

CY - Wageningen

ER -