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• Weed of international significance – introduced to 30

countries throughout the world (Shabbir 2012)

Parthenium hysterophorus

• Current global control strategies:– Chemical– Mechanical – Other (containment, competitive species, etc.)– Biological

• Strategies in SA:– Chemical – Biological

Zygogramma bicolorata

Listronotus setosipennis

Smicronyx lutulentus

Epiblema strenuanaPuccinia abrupta var. partheniicola (Winter rust)

Carmenta sp. nr ithacae

Puccinia xanthii var. parthenii-hysterophorae (Summer rust)

Epiblema strenuana (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

Epiblema strenuana• 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., Bidens pilosa– Australia: P. hysterophorus, Ambrosia artemisifolia, X.strumarium– India: P. hysterophorus, Guizotia abyssinica

Guizotia abyssinica (noog, niger seed, blackseed)

The “dilemma”• Epiblema is very damaging & widespread in Australia• Epiblema will rapidly disperse northwards in Africa

based on Australian evidence• Guizotia not an issue for SA, but of important

consideration for Ethiopia• SA legally obliged to only inform SADC members of

releases• Polyphagous in native range• Future pressure from SA roleplayers to further test and

consider Epiblema

Epiblema strenuana• 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., Bidens pilosa– Australia: P. hysterophorus, Ambrosia artemisifolia, X.strumarium– India: P. hysterophorus, Guizotia abyssinica

• Imported to SA (2010)• Initial strategy: Test host range of agent on the main varieties of G. abyssinica grown in East Africa

Guizotia abyssinica• Five main varieties of G. abyssinica grown in Ethiopia

(Kuyu, Shambu, Ginchi-1, Fogera & Esete)

SNNP

Amhara

Tigray

Parthenium hysterophorus

Noog growing areas (mid- to high altitude)

No-choice trials

SubfamilyTribe

Species (cultivar) n Mean tunnelling score (± SE)a, b

Mean number of galls (± SE)b

Mean number oflarvae (± SE)b

Mean number of adults (± SE)b

Asteroideae

Heliantheae Parthenium hysterophorous 3 2.67 (±0.33) 8.33 (±4.06) 2.33 (±1.86) 5.00 (±2.52)

Heliantheae Guizotia abyssinica (Ginchi-1) 3 3.00 (±0.00) 7.67 (±2.03) 1.67 (±0.88) 1.00 (±1.00)

Heliantheae G. abyssinica (Esete) 3 2.67 (±0.33) 5.33 (±2.03) 1.50 (±0.50) 0*

Heliantheae G. abyssinica (Fogera) 3 2.67 (±0.33) 5.00 (±2.52) 0.67 (±0.67) 0*

Heliantheae G. abyssinica (Shambu) 3 3.00 (±0.00) 5.67 (±1.67) 0.67 (±0.67) 0*

Heliantheae G. abyssinica (Kuyu) 3 3.00 (±0.00) 3.67 (±1.86) 0.67 (±0.33) 0*

a Tunnelling scores 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.

• 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

Epiblema damage

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

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

SubfamilyTribe

Test plant species n Mean tunnelling score (± SE)a,b

Mean number of galls (± SE)b

Mean number oflarvae (± SE)b

Mean number of adults (± SE)b

Asteroideae

Heliantheae Parthenium hysterophorous 9 2.56 (±0.33) 6.33 (±4.33) 13.33 (±5.49) 2.44 (1.45)

Heliantheae Guizotia abyssinica ( (Ginchi-1) 6 0.17 (±0.33)* 0* 0.17 (±0.33)* 0*

Heliantheae G. abyssinica (Esete) 6 0.33 (±0.333)* 0.17 (±0.33)* 0.67 (0.67)* 0*

Heliantheae G. abyssinica (Fogera) 6 0* 0* 0* 0*

Heliantheae G. abyssinica (Shambu) 9 0.5 (±0.33)* 0.33 (±0.33)* 0.5 (±0.33)* 0*

Heliantheae G. abyssinica (Kuyu) 9 0.11 (±0.00)* 0.11 (±0.00)* 0* 0*

Heliantheae Xanthium strumarium 3 1.50 (±0.50) 4.50 (±2.50) 5.50 (±4.50) 2.50 (±0.50)

a Tunnelling scores 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.

Larval development trials

SubfamilyTribe

Species (cultivar) n Feeding damage (frass)

Gall formation Eclosion Total developmental time (days ± SE)

Asteroideae

Heliantheae Parthenium hysterophorous 6 Yes Yes (6/6) Yes (4/4) 40.8 (2.1)

Heliantheae Guizotia abyssinica (Ginchi-1) 6 Yes Yes (3/6) Yes (1/6) 47*

Heliantheae G. abyssinica (Esete) 6 Yes Yes (2/6) Yes (3/6) 46.7 (1.5)*

Heliantheae G. abyssinica (Fogera) 6 Yes Yes (3/6) Yes (2/6) 48.5 (1.5)*

Heliantheae G. abyssinica (Shambu) 6 Yes Yes (2/6) Yes (1/6) 49*

Heliantheae G. abyssinica (Kuyu) 6 Yes Yes (3/6) Yes (4/6) 53 (3.4)*

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.

• Tests conducted in gauze covered cages• Eggs incubated & placed singly on plants• Plants held separately in cages until adults eclosed

Summary• No-choice:

– E. strenuana feeding damage (larval tunnelling & galling) & larval counts on G. abyssinica not significantly different to P. hysterophorus

– No adults eclosed from 4 cultivars of G. abyssinica, possibly due to insufficient stem tissue to complete development

• Multiple choice:– Significantly less E.strenuana feeding damage & larval counts on G.

abyssinica cultivars– Lack of adult eclosion on G. abyssinica again possibly due to insufficient stem

tissue to complete development• Larval development:

– Variable gall formation and eclosion of E. strenuana on G. abyssinica cultivars– Significantly longer developmental times on G. abyssinica cultivars

Conclusions• Decision at SA national weed biocontrol workshop

(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?

Acknowledgements

• Staff: Sakhi Sambo, Milly Gareeb, Derrick Nkala, Samora Mqolombeni, Lynette Khumalo

• Funders: DEA (Natural Resource Management Programmes), KZN DAEA