Andy Sheppard & Rachel McFadyen

Fireweed Workshop Bega May 08

Andy Sheppard & Rachel McFadyen

Research into the biological Research into the biological control ofcontrol of

FireweedFireweed

Brian Sindel, Louise Morin, Royce Holtkamp, Kathyn Edmonson & Dept Ag Hawaii


Outline

• Know your target• Biocontrol history• Biocontrol future?• Biocontrol as a part of integrated management

• Recommendations


Know the target: Taxonomy

Senecio inaequidens4N

Lesotho

Senecio madagascariensis 2N

Kwazulu-Natal

xS. harveianus

2N ?

Weed in EuropeWeed in Australia, South America, Hawaii & Japan

• Fireweed part of a complex of probably 3-6 species in South Africa

S. burchelliS. skirrhodonS. pellucidus

(Hilliard 1977)

(Lafuma et al. 2003)

All species hybridise and produce viable seed


Phylogeny of Senecio(Pelser et al. 2002)

Fireweed groupFireweed group

Australian native Australian native groupgroup


Know your target: Origin and Distribution

∆ S. madagascariensis

▲S. harveianus

S. inequidens

KWZULU-NATAL

Lafuma et al. 2003


Natural enemies on Fireweed in Australia

• Survey by Hosking & Holtcamp and in late 1990’s all the common insects attacking S. pinnatifolis group in E Australia also attacked fireweed

- further evidence of close taxonomic

• Fireweed in Australia systematically attacked by the Australian rust (Puccinia lagenophorae)

- also recorded from S. pinnatifolius group.


Know the Target : Variation in Australia

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

S. jacobae S. inaequidens S.madagascariensis

Con

cent

ratio

n de

PA

en

µg/m

g de

PA

Native

Invasive

• Still spreading - covering only small part of potential distribution (Sindel & Michael 1996, Sindel 2008) and becoming more sympatric with related native species in S. pinnatifolius group.

• S. pinnatifolius group spp. also invade pasture systems (e.g. S. brigalowensis in central QLD)

• Sterile hybrids with most closely related S. pinnatifolius group• Toxic alkaloids low but variable


Outline


• Recommendations


Biocontrol history : Australia

• Declared target for biological control in 1991

• Surveys for agents in Madagascar prior to fireweed evolutionary origins knowledge led to testing pyralid (Phycitodes sp.) and a tortricid (Lobesia sp.). Both failed to be fireweed specific (McFayden and Sparks 1996)

• PPRI scientists in South Africa found a rust fungus on S. madagascariensis.

• MLA funded project initiated to assess this fungus in 2002-2003

Dried specimen


Biocontrol history: Search for rust fungi (Morin 2003)

▲ S. madagascariensis populations located without rust fungus

S. madagascariensis populations located without rust fungus

Morin 2003


Biocontrol history: Assessment of SAf rust in Quarantine (Morin 2003)

• Isolates shipped to Quarantine in Canberra

• Taxonomic evidence suggested newrust was also P. lagenophorae

• could not be confirmed

• SAf rust isolates• attacked AU fireweed

• failed to penetrate S. lautus subsp. lanceolatus in trials

• SAf rust isolates comparable, but sometimes less virulent than AustralianP. lagenophorae rust isolates

• 18 records of P. lagenophorae on S. lautus in Australia suggest at least different pathotypes exist.


Biocontrol history: Overseas activities (Hawaii)

• Host specificity testing complete for an Arctiid moth (Secusio extensa) collected from “fireweed” in Madagascar

• Development completed on 5 plant genera (Senecio, Emilia, Erechtites, Delairea & Crassocephalum) in the tribe Senecioneae Not nearly specific enough for release in

Australia with many native Senecio’s


Other potential agents • Nyctemera apicalis (Arctiid tiger moth) appears restricted to

tribe Senecioneae

• Hawaii planning further agent selection activities in Africa in June-August 2008

Biocontrol history: Overseas activities (Hawaii)


Outline


• Recommendations


Biocontrol future : For v against

For• Biocontrol only continent-

wide control option• Fireweed still spreading• Existing grazing management

options have not provided a widespread solution

• Weed is exotic• Biocontrol of other Senecio

sp. has been successful in Australia

• Weed biocontrol historically good investment B/C 23:1

• Weed of international relevance

Against• Fireweed hybridises with

native Senecio’s – minimal taxonomic isolation

• Mono-specific biocontrol agents hard to find?

• No specific/effective agents have yet been found

• Even with specific agents 1 in 3 Biocontrol programs fail

• Biocontrol will require nearer a $3-5M budget ($300K < 10% required)

• Long time frames (next generation benefits)


Biocontrol future : Analysing “Against”

• Fireweed hybridises with native Senecio’s – minimal taxonomic isolation

• Targets with congeneric natives are the focus of other programs in Australia - Senecio’s, Acacia’s, Sporobolus’s, Nasella’s, Rubus’s, Rumex’s etc.

McFadyen IOBC conference paper Feb 2008 – “Classical Biocontrol: possible even for weeds with

congeneric native species”



• Mono-specific biocontrol agents hard to find?

• Availability of monospecific agents – not as hard as expected

- species specific agents - most widespread targets have a few.

- biotype specific arthropods (e.g. Chromolaena)

- biotype specific pathogens (pathotypes) the norm for obligate pathogenic fungi used as biocontrol agents





• No specific/effective agents have yet been found

• Past surveys have focussed outside the native range of S. madagascariensis

• Surveys in native range focussed on one rust pathogen – although no others were clearly obvious

• Additional searching and screening may reveal more virulent rust pathotypes – no guarantee of success

• Manipulating target densities in native range might “trap” effective agents not found by observation



• Even with specific agents 1 in 3 Biocontrol programs fail

• Successful programs exist so such agents can be effective (e.g. Senecio jacobaea, Rumex pulcher)





• Biocontrol will require nearer a $3-5M budget ($300K < 10% required)

• Long time frames (next generation benefits)

• Generic issues for all biocontrol programs… history has shown they are usually worth the investment


Outline


• Recommendations


Biocontrol as a part of IWM

• Practitioners consistently argue biocontrol provides a basis for integrated weed management particularly in grazing systems – key focus of CRC Weed Management Systems

• Defeating the Weed Menace proposal ($800K) in 2005 included biocontrol as a component of developing a larger IWM package built around the Fireweed Regional Weed Management Plan – not funded.

• Project activities in South Africa can also explore the ecology and status of the plant there and the ecological basis for its lower abundance or how it is managed in the native range.

– strategic directions for both agent selection and IWM.


Outline


• Recommendations


Recommendations : past and present

• Detailed surveys of potential biocontrol agents… should …be carried out in…the country identified as the origin of fireweed (McFadyen & Sparks 1996)

• DNA sequencing to [understand] whether or not the SAf rust fungus is P. lagenophorae [and] Additional screening of rust isolates from SAf .. in the hope of finding isolates that are more virulent to those in Australia (no guarantee of success) (Morin 2003).

• • There is a sound case for further investigation of the

potential for biological control of fireweed in Australia (Sindel 2008)


Recommendations : Agent specificity and IWM

• If no fireweed-specific agents are found a test case could be initiated for release of an agent known to attack a native plant species or group of species (McFadyen & Sparks 1996).

• economic study of the impact of fireweed on grazing [and]

• environmental impact study on the impacts of fireweed and any biocontrol agents on native Senecios

• For biological control agents that are not absolutely specific to fireweed a cost benefit analysis is required to weigh up the case for release of such organisms (Sindel 2008)

• Search for biocontrol based integrated weed management

systems to tackle the increasing fireweed problem in eastern Australia (Morin 2002)


Not much has changed

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Andy Sheppard & Rachel McFadyen