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Biological controls are working

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Unfortunately, there are an increasing number of injurious agencies finding their way to or threatening the natural integrity of K’gari (Fraser Island).  Recent records include myrtle rust and feral fauna including foxes and pigs as well as new weeds and the jamella leaf-hopper.  Fortunately, some of these and other adverse impacts are being in part countered by biological controls.

The discovery of the Boronia moth as part of the 2018 Cooloola BioBlitz opened the eyes of many botanists established and aspiring to the importance that sometimes the most minuscule organisms can have on environmental health.

The loss of Pandanus has been arrested by the release of a parasitic wasp not much larger than a grain of sand.  A more significant and less noticed biological control has been the slow but progressive demise of lantana on K’gari.

PricklyPear_BioThere have rarely been silver bullet biological controls such as the parasitic wasp on the Jamella leaf-hopper that is saving K’gari’s pandanus.  Another silver bullet was dealing with the cactus invasion particularly of Queensland’ Brigalow and mulga lands where it was invading at the rate of acres per minute.

Prickly pears (mostly Opuntia stricta) were imported into Australia in the 19th century and progressively became a widespread invasive species, rendering 40,000 km2 (15,000 sq mi) of farming land unproductive. The moth, Cactoblastis cactorum whose larvae eat prickly pear, was introduced in 1925 and almost wiped out the population.  The few surviving cacti became the host for the moth and their larvae so that whenever the prickly pear population builds up the biological control kicks in.

Given the horrific history of Prickly Pear, there is a human compulsion to eradicate the very last Cactus.  This is notable on K’gari (Fraser Island) because it leads to needless pain and difficulty when it is only a matter of time before the Cactoblastis will get around to dealing with it.

Article contributed by John Sinclair, FIDO


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