Rubber Vine, the Rubbish

Photo by Colin G Wilson. Rubber vine smothering vegetation.
Viewed 30.03.2014

Rubber Vine, Cryptostegia grandiflora, endemic to the Island of Madagascar, was introduced to Northern Australia in 1917 in the hope of becoming a rubber source ( Huwer, McFadyen, 1999).  The shrub has since become a serious problem in the areas that it inhabits.

 Rubber vine generally invades waterways first where the seeds germinate in moist silt layers after rain fall. From there it expands outward invading hillsides and pastures forming dense and often inpenetratable thickets resulting in not only a decrease in biodiversity but a loss of grazing land and can make it difficult to muster stock.  In addition rubber vine creates habitat for feral animals, which poses further threat to native species.  Once the thickets are established the plant can cover trees up to 30m tall which choke out native vegetation (McFadyen, Harvey, 1990). The weed is poisonous to stock however it is rarely consumed, only when other feed is scarce.

There have been several mechanisms to conquer this weed. Chemical control is effective as rubber vine is susceptible to many herbicides however this method has proven to be uneconomical due to the vast areas of infestation.  In 1988, Euclasta whalleyi , a leaf feeding moth, also endemic to Madagascar was released as a potential biocontrol agent. It has been effective to a degree, increasing leaf litter which promotes grass growth amongst rubber vine which intern increases fuel loads for fire management. This creates opportunities to use fire as a part of the approach to manage this damaging weed (Tomly, Evans, 2004).

 

 In 1995 a rust fungus, Maravalia cryptostegiae, also from Madagascar was released to areas of the weed’s range in Queensland.  The results showed a rust-induced defoliation, producing an overall reduction in fecundity and biomass of the plant. Particularly in areas with low water tables weed growth decreased noticeably. At some sites both drought and rust induced stressed caused up to 75% plant mortality. This resulted in improved growth of indigenous grasses amongst thickets which creates ideal conditions in order to burn off and control the weed further. In order to gain full restraint over this economically and ecologically damaging weed would require the assistance of the landholders in which the rubber vine occupies.

 

 

Refereneces:

 

Huwer RK, McFadyen R.E, 1999, 'Biology and the host range of the hawk moth Nephele densoi Keferstein (Lep.: Sphingidaw) a potential agent for the biological control of rubber vine Cryptosteyia grandflora', Biocontrol Science Technology, Vol.9, no. 1, p.10.

 

McFadyden R.E, Harvey G.J, 1990, 'Distribution and control of rubber vine Cryptosteyia grandflora weed in North Queensland, Plant Protection Quarterly, Vol.5 no. 4, pp. 152-155.

 

Tomley A.J, Evans H.C, 2004, 'Establishment of and preliminary impact studies on, the rust, Maravalia Cryptopstegiae, of invasive alien weed, Cryptosteyia grandflora in Queensland, Australia, Plant Pathology, Vol.53, no. 4, pp. 475-484.

 

 

 

 

 

The Indian Myna Bird (blog #3 for 24.03.14)

Source: Andrew Tatnell. viewed 21.03.2014

The  Common Indian Myna bird (Acridotheres tristis) has been declared by the Worlds Conservation Union as only one of three birds among the 'Worlds 100 worst  invasive species' (Peacock et al 2007).  They are becoming an increasing environmental nuisance for more than one reason. They rob endemic and native birds and possums of their nests by aggressively chasing them out of their natural habitat and eating their eggs, as well as compete with other omnivores for food resources (Canning 2011). They  also eat native fruits and insects that are important for pollination.  It has also been suggested that they pose a threat to human well-being through the spread of parasites and diseases and agricultural crop damages.

The Indian myna bird is native to southeast Asia occurring from Afghanistan through the Indian subcontinent and Burma to Indochina. They have been deliberately introduced to many parts of the world and now occur on all continents except South America and Antarctica. They were originally introduced into many areas as a potential biological control agent of insects, in particular grasshoppers and locusts.  The generic name Acridotheres means 'grasshopper-hunter'! However as they spread rapidly they are increasingly causing more negative impacts on biodiversity 
(Baker et al. 1987).

 In addition to deliberate introductions by humans, the Indian mynah has been undergoing a natural range expansion . This is thought to be a result of extensive clearing of natural vegetation for agriculture and increasing population densities. A study was done to establishish if there was a relationship between the human population size, land-transformation and mynah bird distribution. The results showed a strong possitive correlation. It showed that most highly successful allien bird species are closely accociated with human habitation and modified habitats, one of which being the Indian Myna bird. The study was conducted over the highly transformed parts of South Africa which represent urban areas and perminent cultivated lands which are both suitable habitats. 

The eradication program to reduce the damage caused by these pests is ongoing through  live trapping devises followed by the birds being humanely enuthanized.


References:
 Baker, A.j 1987, 'Rapid Genetic Differentiation and Founder effect in Colonizing Populations of Common Mynas (Acridotheres tristis) Society for the study of Evolution, Vol.41, no.3 p.526
viewd 21 March 2014 
URL <http://www.jstor.org/stable/2409254?seq=2>

Canning, G 2011, 'Eradication of the Invasive Common Myna, (Acridotheres tristis) from Fregate Island, Seychelles'  Phelsuma p.43 Viewd 21 March 2014
URL <http://islandbiodiversity.com/Phelsuma%2019d.pdf>

Peacock, D.S, Van Rensburg, J.B, Robertson M.P 2007, 'The distribution and spread of the Invasive alien common myna, Acridotheres tristis L. (Aves: Sturnidae), In Southern Africa', South African Journal of Science, vol.103 no. 11-12
view on 21 March 2014
URL <http://www.scielo.org.za/scielo.php?pid=S0038-23532007000600008&script=sci_arttext&tlng=es>
 

The Invasion of the Electric Fire Ant (Wasmannia Auropunctata)

Australia has a dozen invasive species of ants, in fact of the most invasive species in the word we have them all, according to Dr Alan Anderson, chief research scientist at CSIRO. The Electric fire ant (Wasmannia Auropunctata) is considered one of the worlds worst alien species.

The Electric ant is named as such for their painful sting. Originating in South America they have since invaded areas of Africa, North America, several Pacific Islands and Far north Queensland causing problems for residents, pets and native wildlife. In 2006 infestations were discovered in Smithfield, Cairns and have since spread 260 Hectares around Far Northern Queensland, including 106km further south to Bingle Bay.

The cause of the spread in the far north region, particulary to the areas south of Cairns is thought to have occurred in the years following cyclone Larry in 2006. During the rehabilitation where soils, mulch, plants and equipment were moved to the cyclone zones is believed to be the reason behind new ant colony discoveries.

They pose a threat because where electric ants are present they have displaced 95% of native ants. Native ants play an important role in the ecosystem, without them local plants, crops and tress may suffer, says Gary Morton, coordinator for the eradication program at Biosecurity Queensland.

Biosecurity Queensland eradication program is based on three fundamental activities:
1.Surveillance to locate the ants which they are currently trailing a new method using sniffer dogs.
2.Treatment to kill the ants
3. Containment to stop them spreading.

References:

Brennan 2011, Australian Geographic, 16 March 2014 http://www.australiangeographic.com.au/news/2011/05/electric-ants-invade-northern-australia-/

Department of Agriculture, Fisheries and Forestry 2013, Queensland Government, 16th March 2014 http://www.daff.qld.gov.au/plants/weeds-pest-animals-ants/invasive-ants/electric-ants/eradication-program

Mulherin, T, 2010, "Detection of Electric Ants at Bingil Bay', Washington DC, 18 August 2010

Invasive species

Hi and welcome to my page! The purpose of this blog is to look at invasive species and the effects they have on communities and ecosystems. An invasive species is defined as an introduced organism (plant, animal, fungus or bacterium) that exceeds its normal distribution which threatens valued environmental resources. This can include diseases, fungi, parasites weeds, feral animals and insects. While some invasive species can be beneficial to the environment the more harmful varieties can devastate agriculture, cost the world economy millions of dollars and spread painful and even lethal diseases (Simberloff, 2013).

A recent example of an invasive species are  the Burmese Pythons that have overtaken Florida's Everglades. The pythons originated in south east Asia and have been imported to Florida, USA and bred as pets. Pythons show indeterminate growth and when people no longer know how to care for the ever growing snake they have simply been set free in the wild and have multiplied by the thousand.  The area has become so over populated by this alien species that it is now throwing out the ecological balance of the relationships between existing organisms and their environment. For millions of years the Alligator has been the top predator, but the rapidly multiplying pythons are taking over and are making many species at risk of being wiped out. Since the pythons have become more common in the everglades over the last 20 years there has been a dramatic decrease in many species, more notably deer, racoons and opoosums. There hasn't been a land predator in the Everglades big enough to swallow a deer or a full-grown raccoon in a million years, as a result the animals haven't learned to be wary of the giant snakes (Reed, p.254) Without control of this species the affects are going to be irreversible for much of the native wildlife.

For more on this subject refer to the reference list below:

References:
Reed, RN, Willson, JD, Rodda, GH, Dorcas, ME 2012 Ecological correlates of invasion impact for Burmese Pythons in Florida, Integative Ecology, Vol.7 issue 3. p.254.

http://www.env.gov.yk.ca/animals-habitat/invasivespecies.php

http://www.environment.gov.au/topics/biodiversity/invasive-species