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Andrew McConnachie* & Lorraine Strathie

The Epiblema “Dilemma” : Challenges for its use as a biological control agent for parthenium in Africa. Andrew McConnachie* & Lorraine Strathie (ARC-PPRI, Cedara , South Africa) *mcconnachiea@arc.agric.za. Parthenium hysterophorus.

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Andrew McConnachie* & Lorraine Strathie

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  1. The Epiblema“Dilemma”:Challenges for its use as a biological control agent for parthenium in Africa Andrew McConnachie* & Lorraine Strathie (ARC-PPRI, Cedara, South Africa) *mcconnachiea@arc.agric.za

  2. Parthenium hysterophorus • Weed of international significance – introduced to 30 countries throughout the world (Shabbir 2012)

  3. Parthenium hysterophorus • Current global control strategies: • Chemical • Mechanical • Other (containment, competitive species, etc.) • Biological • Strategies in SA: • Chemical • Biological Pucciniaxanthiivar. parthenii-hysterophorae (Summer rust) Pucciniaabruptavar. partheniicola (Winter rust) Epiblemastrenuana Listronotussetosipennis Carmenta sp. nr ithacae Zygogrammabicolorata Smicronyxlutulentus

  4. Epiblemastrenuana(Tortricidae) • Origin: Widely distributed over North & Central America (Canada in north to Mexico in the south; California in west to eastern seaboard of the USA) • Mode of action: Stem-galler (stems & growing points) • Impact: Significant - plant height and flowering (Dhileepan 2003) • Most damaging and widespread agent in Australia at present

  5. Epiblemastrenuana • Field host range (native range): • Canada: Xanthium commune • USA: P. hysterophorus, X. trifida, X. artemisiifolia, X. psilostachya • Mexico & Caribbean: P.hysterophorus • Laboratory host range: • Mexico: P. hysterophorus, P. confertum, Ambrosia psilostachya, Rudbeckia sp., Bidenspilosa • Australia: P. hysterophorus, Ambrosia artemisifolia, X.strumarium • India: P. hysterophorus, Guizotiaabyssinica

  6. Guizotiaabyssinica(noog, niger seed, blackseed)

  7. The “dilemma” • Epiblema is very damaging & widespread in Australia • Epiblema will rapidly disperse northwards in Africa based on Australian evidence • Guizotianot an issue for SA, but of important consideration for Ethiopia • SA legally obliged to only inform SADC members of releases • Polyphagousin native range • Future pressure from SA roleplayers to further test and consider Epiblema

  8. Epiblemastrenuana • Field host range (native range): • Canada: Xanthium commune • USA: P. hysterophorus, X. trifida, X. artemisiifolia, X. psilostachya • Mexico & Caribbean: P.hysterophorus • Laboratory host range: • Mexico: P. hysterophorus, P. confertum, Ambrosia psilostachya, Rudbeckia sp., Bidenspilosa • Australia: P. hysterophorus, Ambrosia artemisifolia, X.strumarium • India: P. hysterophorus, Guizotiaabyssinica • Imported to SA (2010) • Initial strategy: Test host range of agent on the main varieties of G. abyssinicagrown in East Africa

  9. Guizotiaabyssinica • Five main varieties of G. abyssinicagrown in Ethiopia (Kuyu, Shambu, Ginchi-1, Fogera & Esete) • Parthenium hysterophorus • Noog growing areas (mid- to • high altitude)

  10. No-choice trials • Tests conducted in gauze covered cages • 5 pairs of one-day old adults per cage • Duration: 15 days • Plants held in cages for 8 weeks (eclosion ceased) • Dissected & assessed a Tunnellingscores were assessed as follows: 0 – no tunnelling; 1 – 1-30% stem tunnelled; 2 – 31-60% stem tunnelled; 3 – 61-100% stem tunnelled. b Within the same column, asterisks following the mean (±SE) indicate a significant difference (p < 0.05) between the control and the test species; Mann-Whitney U test.

  11. Epiblema damage

  12. Multiple-choice trials • Tests conducted in walk-in cage (5x3x2m) • 10 pairs of one-day old adults • Duration: 15 days (5 day rotation to compensate for effect of light) • Plants held separately in cages for 8 weeks (eclosion ceased) • Dissected & assessed

  13. Multiple-choice trials • Tests conducted in walk-in cage (5x3x2m) • 10 pairs of one-day old adults • Duration: 15 days (5 day rotation to compensate for effect of light) • Plants held separately in cages for 8 weeks (eclosion ceased) • Dissected & assessed a Tunnellingscores were assessed as follows: 0 – no tunnelling; 1 – 1-30% stem tunnelled; 2 – 31-60% stem tunnelled; 3 – 61-100% stem tunnelled. b Within the same column, asterisks following the mean (±SE) indicate a significant difference (p < 0.05) between the control and the test species; Mann-Whitney U test.

  14. Larval development trials • Tests conducted in gauze covered cages • Eggs incubated & placed singly on plants • Plants held separately in cages until adults eclosed Within the same column, asterisks following the mean (±SE) indicate a significant difference (p < 0.05) between the control and the test species; Mann-Whitney U test.

  15. Summary • No-choice: • E. strenuanafeeding damage (larval tunnelling & galling) & larval counts on G. abyssinicanot significantly different to P. hysterophorus • No adults eclosedfrom 4 cultivars of G. abyssinica, possiblydue to insufficient stem tissue to complete development • Multiple choice: • Significantly less E.strenuana feeding damage & larval counts on G. abyssinicacultivars • Lack of adult eclosionon G. abyssinicaagain possibly due to insufficient stem tissue to complete development • Larval development: • Variable gall formation and eclosionof E. strenuanaon G. abyssinicacultivars • Significantly longer developmental times on G. abyssinicacultivars

  16. Conclusions • Decision at SA national weed biocontrolworkshop (2012): • Shelve agent • Compile a risk analysis & publish • Reassess after all other agents have established & been assessed • Further information: • Competitive interactions with other agents? • Conduct open field host range trials (Israel or Australia) • Acceptable levels of damage to noog in Ethiopia? Use of pesticides?

  17. Acknowledgements • Staff: SakhiSambo, MillyGareeb, Derrick Nkala, SamoraMqolombeni, Lynette Khumalo • Funders: DEA (Natural Resource Management Programmes), KZN DAEA

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