PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
CONTROL
METHODS
(contd)
.BIOLOGICAL CONTROL. (contd)
Disease organisms
– Rabbits. Myxomatosis, caused by the myxoma virus of the South American
forest rabbit is spread from rabbit to rabbit by mosquitoes and rabbit fleas. It
was introduced into Australia in the early 1950s and was spectacularly
successful in controlling rabbits, but over many years the rabbit has developed
resistance to the virus. Rabbit Calicivirus Disease (RCD) was accidentally
released in 1997. At least 10 species of insects are vectors including 5 species of
blowflies, a carrion fly, 2 species of mosquitoes and the European rabbit flea.
Myxamatosis and RCD occur seasonally throughout southern Australia.
Genetic changes in the RCD virus are already apparent. New strains of the
calicivirus are to be introduced to Australia in a bid to halt rapidly spiraling
rabbit numbers. Domestic rabbits can be vaccinated against the virus.
– Pigs. Overseas, there have been many unofficial attempts to control wildlife
populations with diseases, eg the 100% successful project to eliminate wild pig
populations on an island off California by introducing the hog cholera virus.
– Birds. There is much published data on the occurrence of potential diseasecausing
organisms in wild birds but as yet no practical application has been
made of them, possibly because few, if any, are host specific.
– Cats. In Australia, it has been suggested that feral cats could be controlled by a
virus disease, registered domestic cats could be immunized against the disease.
Controlled breeding Many techniques are still experimental.
Invasive Animals CRC www.invasiveanimals.com/
– Genetic engineering
Virally-vectored immune contraception. In the future rabbits could be
vaccinated with a myxoma virus which has been genetically engineered to
carry a gene which would make rabbits infertile. This technique could also be
used to control breeding of mice, foxes and other vertebrates.
Mice. Focus is on using either a mouse-specific virus or bait as a vehicle to
vaccinate mice and induce infertility which would be long enough to prevent
mouse populations building up into plagues.
Cane toads. Attempts to use a viral vector to transfer a gene which would
prevent tadpoles of the cane toad metamorphosing into adults.
– Chemosterilants
Regulating birth rates. Chemosterilants, eg birth control, spermatocidal and
immunological drugs, artificially regulate the birth rate of populations of wild
vertebrates that live in semi-naturalistic situations and are troublesome to
humans and the environment.
FeralMone Spray Attractant ('Synthetic Fermented Egg' ('SFE')) is an
aerosol spray used to attract foxes and wild dogs to bait stations.
Animal Control Technologies www.animalcontrol.com.au
– Desexing
More and more local councils are moving towards the compulsory de-sexing
and chipping of domestic dogs and cats in urban areas.
.RESISTANT, TOLERANT VARIETIES.
Overseas, the search for bird-resistant varieties of cereal grains continues and aims
to yield long lasting results; however, early results have been disappointing.
.ANIMAL QUARANTINE.
AQIS (Australian Quarantine Service). Like many plant pests, vertebrate
pests have been introduced from abroad, eg cane toads, rabbits, starlings, sparrows.
Many still occur overseas that would be unwelcome in Australia, eg certain species
of rats.
Commonwealth quarantine www.daff.gov.au/aqis
State/Regional Quarantine. Within Australia, both introduced and native
vertebrate pests may occur in certain areas and not in others, eg starlings which do
not occur in WA, are trapped on the Nullarbor Plain.
Local Quarantine. Indian mynahs are inadvertently encouraged into gardens by
plantings of dense conifers which provide ideal nesting sites. Some new suburbs
adjacent to bushland have been designated ‘no free-roaming cats’. Night curfews
have been suggested for cats.
.PEST-DAMAGED PLANTING MATERIAL.
Seed, grain, bulbs, tubers and other vegetative propagation material may be eaten and
contaminated with faeces. Damaged seed may not germinate, or may geminate but
seedling may not develop normally, eg French bean seedlings with no growing tips, the
stem above the cotyledons is a bare stump, seedlings may die or shoots develop in the
axils of the cotyledons.
Vertebrate pests 245