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Classical BC: Weeds Pages 142148


We had the same situation with yellow starthistle in Idaho. Classical BC: Weeds (Pages 142-148) ... arvense (Linnaeus) Scopoli, Canada thistle. vulgare (Savi) ... – PowerPoint PPT presentation

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Title: Classical BC: Weeds Pages 142148

Classical BC Weeds (Pages 142-148)
  • The first effort at BC of weeds was the
    movement of a mealybug within India to control
  • However, the BC of weeds really entered the
  • consciousness about 50 years later
  • Prickly pear cacti, Opuntia spp., were widely
    planted as
  • living fences in semi-arid regions of the
  • Cacti spread widely in some areas.
  • The worst situation was in Australia
  • 30,000,000 hectares infested with O. inermis
    and O. stricta
  • Many ranches simply abandoned.

Classical BC Weeds (Pages 142-148)
  • Queensland Prickly Pear Traveling Commission
    Sought agents that might control cacti
  • Cactoblastis cactorum (Lepidoptera
    Pyralidae) Found in Argentina
    Imported to Australia Could not be reared
    to maturity
  • Commonwealth Prickly Pear Board Resumed
    search for agents in South America 150
    species of cactus-feeding insects found
  • 50 species were shipped to
    Australia 12 established and contribute to
    cactus control
  • Cactoblastis cactorum is the dominant

Classical BC Weeds (Pages 142-148)
The history of the C. cactorum introduction is
enlightening. January 1925 Alan Dodd found C.
cactorum in Argentina, on other Opuntia
spp. Larvae transferred to O. inermis and
O. stricta February 1925 Adult moths emerged
and oviposited March 1925 3000 eggs put on
Opuntia pads, shipped May 1925 Larvae
arrived in Australia Aug./Sept. 1925 1137 larvae
pupated Sept./Oct. 1925 1070 adult moths
Classical BC Weeds (Pages 142-148)
October 1925 100,605 eggs deposited Nov.
1925-Jan. 1926 Another generation
reared Feb./March 1926 2,263,150 eggs
released/distributed Apr.1926-March 1927
10,196,150 eggs released/distributed March
1927-Nov. 1929 389,225,520 C. cactorum
redistributed 1932 99 control 1933 Some
cactus regrowth Substantial
anxiety Moths re-established control
Classical BC Weeds (Pages 142-148)
Female Cactoblastis ovipositingon Opuntia,
linear egg mass attached to a cactus spine
Damage to Opuntia by Cactoblastis larvae,pad
destroyed, plant open to infection
Classical BC Weeds (Pages 142-148)
Following this stunning success, C. cactorum has
been widely used to control Opuntia spp. around
the world. Before Cactoblastis
After Cactoblastis This lodged the idea of
biological control of weeds in the minds of
scientists and launched succeeding programs.
Classical BC Weeds (Pages 142-148)
Goatweed/Klamath weed/St. Johnswort (Pages
143-145) All three names refer to Hypericum
perforatum Linnaeus,a European plant introduced
to semi-arid areas of the western US and
Australia. Unpalatable, livestock
selectivelyremove grasses, damaging
range. Toxic, irritates mouth tissues,so the
animal cant eat or drink. Photosensitization,
damaging the hide. In short, it is a serious
rangeland problem.
Classical BC Weeds (Pages 142-148)
  • Goatweed/Klamath weed/St. Johnswort
  • Australia
  • 100,000 hectares in Victoria alone
  • Explorers to Europe to seek agents
  • 1932 37 Hypericum-feeding insect species
    imported Starvation tests conducted to ensure
    insects did not consume desirable plants. The
    forerunner of modern host specificity testing.

Classical BC Weeds (Pages 142-148)
Goatweed/Klamath weed/St. Johnswort Australia
Three agents established Chrysolina quadrigemina
and C. hyperici (Coleoptera Chrysomelidae),
leaf-feeding beetles and Agrilus
hyperici (Coleoptera Buprestidae), a root-boring
beetle Gave good control
Chrysolina quadrigemina
Classical BC Weeds (Pages 142-148)
  • Goatweed/Klamath weed/St. Johnswort
  • 1,000,000 hectares infested in northern
  • Importations from Europe impossible because of WW
  • H. S. Smith corresponded with A. J. Nicholson
    about the
  • biological control program in Australia.
  • US Army transported beetles to California in Oct.
  • C. B. Huffaker and J. K. Holloway received the

Classical BC Weeds (Pages 142-148)
Goatweed/Klamath weed/St. Johnswort October is
late spring in Australia, so first challenge was
to break the beetles diapause. Misting with
water was adequate for Chrysolina spp., but
Agrilus would not break diapause. Chrysolina
were subjected to the first mandated host
specificity testing sugar cane, beets, flax,
hemp, sweet potato, tobacco and cotton. Both
passed the tests.
Classical BC Weeds (Pages 142-148)
Goatweed/Klamath weed/St. Johnswort Chrysolina
hyperici was released in spring 1945. Chrysolina
quadrigemina was released in February 1946,
reproduced rapidly and became the dominant
agent. Agrilus hyperici was introduced in
1950. It established, but seemed to offer
little control. Zeuxidiplosis giardi
(DipteraCecidomyiidae) was released In 1950.
It established in some moister, usually
forested sites.
Classical BC Weeds (Pages 142-148)
Goatweed/Klamath weed/St. Johnswort Chrysolina
spp. dispersed slowly, so redistribution was
done. Within a decade Hypericum infestations
were reduced by 99.
Hypericum infestation (foreground)after
Chrysolina release
Hypericum infestation (foreground)before
Chrysolina release
Classical BC Weeds (Pages 142-148)
Goatweed/Klamath weed/St. Johnswort Similar
impacts were seen in Oregon, Washington and
Idaho. This where things stood for 40
years. Chrysolina quadrigemina was seen as the
single critical agent. Until Campbell and
McCaffrey found that Agrilus hyperici had an
important role in Hypericum control. Agrilus
larvae feed in the roots of older, larger plants
often killing them. These are the plants that
are least susceptible to Chrysolina damage.
Classical BC Weeds (Pages 142-148)
The Opuntia and Hypericum programs formed the
foundation for biological control of weeds,
establishing the nine-step concept.
  • 1. Planning
  • 2. Exploration
  • 3. Shipment
  • Quarantine
  • Host specificity testing
  • 6. Rearing
  • 7. Colonization
  • 8. Establishment
  • 9. Evaluation

Classical BC Weeds (Pages 142-148)
Host specificity testing (Page 145) The
procedures have developed over time. Crops remain
on the test plant list. Species related to the
target weed were added about 1960. This created
the idea of concentric rings of plants to be
tested, members of the same genus, members of the
same family, etc. With the Endangered Species
Act, rare native taxa have received attention in
the host testing process since 1972. Preliminary
host specificity testing is conducted overseas,
but a complete series of tests is usually
conducted in quarantine.
Classical BC Weeds (Pages 142-148)
Conflicts of interest (Page 145) During this era
another reality emerged. Weeds are not defined
solely by society(anthropocentrically), they
are also defined by individuals
(egocentrically). This can yield strongly
differing views of a plant species. Echium
plantagineum Linnaeus was simultaneously known to
Australian ranchers as Pattersons curse and to
their bee-keeping neighbors as Salvation Jane
because it was a good source of pollen and nectar
during the late summer when other flowers were
scarce. We had the same situation with yellow
starthistle in Idaho.
Classical BC Weeds (Pages 142-148)
Conflicts of interest This reality requires that
an evaluation of potential conflicts of interest
be part of the planning process for a biological
control of weeds program. As with anything that
involves peoples personal and economic
interests, the debate can become heated. Now I
would like to look at a few recent programs that
illustrate additional points.
Classical BC Weeds (Pages 142-148)
Tansy ragwort (pages 145 146) Senecio jacobaea
Linnaeus (Asteraceae) is a European species. It
is established in moister areas of the Pacific
Northwest,entering California in 1912 and Oregon
in 1922. By 1976 it occupied 1,500,000 hectares
in Oregon alone. It contains pyrrolizidine
alkaloids,it is distasteful and toxic,causing
liver damage. Cattle and horses are most
susceptible to the alkaloids. BC efforts began
in the 1950s.
Tansy ragwort
Classical BC Weeds (Pages 142-148)
Tansy ragwort (pages 145 146) Three agents
were established on tansy ragwort Cinnabar
mothTyrea jacobaea (Linnaeus) (Lepidoptera
Arctiidae) Imported from France 1959 Released in
California 1959, Oregon and Washington
1960 Larvae are gregarious and defoliate the
Cinnabar mothlarva and adult
Both are beautiful,brightly colored and
Classical BC Weeds (Pages 142-148)
Tansy ragwort (pages 145 146) Botanophila
seneciella (Meade) (Diptera Anthomyiidae) Importe
d 1966, released in California and Oregon Larvae
feed in seedheads, destroying seeds
Adult Botanophila
Classical BC Weeds (Pages 142-148)
Tansy ragwort (pages 145 146) Longitarsus
jacobaeae (Waterhouse) (Coleoptera
Chrysomelidae) Imported 1969 Released in
California 1969, Oregon and Washington
1970 Larvae feed on roots, major impact Adults
defoliate plant, minor impact
Adult Longitarsus jacobaeaeon tansy ragwort
Classical BC Weeds (Pages 142-148)
Tansy ragwort (pages 145 146) Together the
agents gave good control, reducing tansy ragwort
abundance by about 99. Cinnabar moth, large,
brightly colored, conspicuous was given most of
the credit. Peter McEvoy of Oregon State
University initiated a nine-yearevaluation and
ecological study. Multiple sitesNumerous
micro-plotsInclusion cages, multiple densities
Exclusion cages
Classical BC Weeds (Pages 142-148)
Tansy ragwort (pages 145 146) He
found Botanophila was insignificant Cinnabar
moth, univoltine, larvae depleted metabolic
reserves, but rarely killed the plant. Flea
beetle, univoltine, adult defoliation a minor
supplement to cinnabar moth damage larval damage
to roots could kill plants Overall
impactgreatest when root damage was combined
with defoliation This is the classic ecological
study of BC of weeds.
Classical BC Weeds (Pages 142-148)
Thistles (Pages 146-148) Numerous weedy European
species, e. g. Carduus nutans Linnaeus, musk or
nodding thistle acanthoides Linnaeus,
plumeless thistleCirsium arvense (Linnaeus)
Scopoli, Canada thistle vulgare (Savi)
Airy-Shaw, bull thistle All can form dense,
impenetrable stands that devalue rangeland.
Carduus nutans Cirsium vulgare
Classical BC Weeds (Pages 142-148)
Thistles (Pages 146-148) Agents imported for
Carduus control included Rhinocyllus conicus
Froelich (Coleoptera Curculionidae)Trichosirocal
us horridus Panzer (Coleoptera
Curculionidae) Rhinocyllus conicus Trichosiro
calus horridus
Rhinocyllus conicus larval damage to a plumeless
thistle seedhead, about 12 occupying a cavity
having destroyed many seeds
Classical BC Weeds (Pages 142-148)
Thistles (Pages 146-148) Agents imported for
Cirsium control included Urophora stylata
(Linnaeus) (Diptera Tephritidae)Urophora cardui
(Linnaeus) (Diptera Tephritidae)
Urophora stylata adult and larvae forming galls
in a thistle seedhead
Urophora cardui adult, larvae form stem galls
in thistles
Classical BC Weeds (Pages 142-148)
Thistles (Pages 146-148) Agents imported for
Cirsium control included Ceutorhynchus litura
Fabricius (Coleoptera Curculionidae)Altica
carduorum Guerin (Coleoptera Chrysomelidae)
Altica carduorum adults damage foliage, larvae
feed on roots
Ceutorhynchus lituraadult on foliage and larvae
mining in stem
Classical BC Weeds (Pages 142-148)
Thistles (Pages 146-148) All of these agents
passed host specificity testing Most are
established in North America and helping to
control their target weed(s). But, this is where
the story gets complicated.
Classical BC Weeds (Pages 142-148)
Thistles (Pages 146-148) During host specificity
testing it was noted that R. conicus fedon
several native thistles. This was deemed to be
acceptable in 1968. In the field, R. conicus
dispersed widely. Populations adapted to
additional thistle species, including Silybum and
Onopordum spp. 1972 the Endangered Species Act
was passed. This initiated a socio-political
Classical BC Weeds (Pages 142-148)
Thistles (Pages 146-148) These two trends
collided in Nebraska, where R. conicus
encountered the rare Platte thistle, Cirsium
canescens. Svata Louda studied the Platte thistle
and found seed production to be a limiting factor
in its abundance and R. conicus was the major
seed predator. Her publication unleashed a
backlash against BC of weeds. Donald Strong, UC
Davis wrote a biological control program gone
haywire and the dark side of biological
control in Science. San Francisco Chronicle
entitled a story Weevil That Kills Alien Thistle
Goes Bad.
Classical BC Weeds (Pages 142-148)
Thistles (Pages 146-148) The current science is
correct R. conicus did produce some undesirable
results. However, the implications that the
weevil went bad or that the scientific work in
the 1960s was poor are not correct Lloyd Andres
knew R. conicus would attack native thistles. He
told people it would do this. The 1968
socio-political evaluation was that the benefits
of controlling musk thistle outweighed the risks
to native spp. The socio-political climate
changed, altering our assessment of R. conicus,
but this does change the quality of the early
Classical BC Weeds (Pages 142-148)
Similar stories exist for other biological
control of weeds agents, but they are less widely
publicized, e. g. Cactoblastis cactorum has
damaged rare native cacti in Florida. Again,
this is not a surprise, C.cactorum was shown to
be able to shift hosts in the original Australian
work. Chrysolina quadrigemina eats some
ornamental St. johnsworts. This was known and
accepted in 1946. The science was not bad in any
of these projects. Our assessment of the
cost-benefit ratio changed. We need to re-examine
how we decide what taxa to release.
Classical BC Weeds (Pages 142-148)
The current situation US Fish and Wildlife
Service has primary responsibility for protecting
rare and endangered species They have tightened
regulation on importing potential agentsmore
work on host specificity testingmore emphasis on
rare and endangered species in testsmore
restrictions on species that can be
released This will make people more aware of the
benefits and risks. It will protect some rare
species. It will reduce the degree of biological
control of some weeds.
Classical BC Weeds (Pages 142-148)
The impacts of these shifts are already being
felt, but programs continue and new programs
begin. Meadow and orange hawkweed, Hieracium
spp., are from Europe and are weeds in the
Pacific Northwest. We have numerous native
Hieraciumgeneral form
Meadow hawkweeddetail of inflorescence
Orange hawkweedgrouped inflorescences
Classical BC Weeds (Pages 142-148)
A biological control program is beginning in this
country, building on efforts in New Zealand. We
know of several hawkweed-feeding insects from
Europe. Some look promising in terms of impact on
hawkweed, e. g. Cheilosia sp. (Diptera
Syrphidae) But, concerns about non-target impacts
are already focusingattention on stolon-feeding
gall formers, because only the European species
are stoloniferous.
Aulacidea sp.(Hymenoptera Cynipidae Mylabris
sp.(Diptera Cecidomyiidae
Classical BC Weeds (Pages 142-148)
A Hawkweed Consortium has been formed in the
US. They are organizing interested parties to
support funding requests and research. Pre-release
studies were done to assess likely impacts of
herbivores. A proposed test plant list has gone
to Fish and Wildlife. Material of most species on
the list has been sent to Europe for preliminary
testing at CABI. (Experience with NZ
program) Progress has been slower, but it is
Classical BC Weeds (Pages 142-148)
White top, Cardaria draba (Brassicaceae), is
another serious weed with a biological control
program in an even earlier stage. An added
challenge her is the fact that Cardaria is
closely related to rape and canola, Brassica
spp., and mustards, Sinapis spp. Cardaria
Classical BC Weeds (Pages 142-148)
A final concern The Biological Control
Treadmill Much of the land that was covered with
goatweed in 1945 now supports knapweed or yellow
starthistle. We traded one weed for another. How
long until we get a weed we cannot control? An
integrated effort is required, includinggrazing
managementrevegetation Acceptance is growing,
but it is expensive and the science needs work