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Category Archives: Biocontrol

The Persistence of Abrus

One of FIDO’s many inspiring volunteers has been Peter Dorney, a nurseryman from Boreen Point.  Pete was appalled by the extent and aggressiveness of the rampant Abrus he encountered during a Happy Valley working bee in March 2016.  He wondered how persistent the seed might be because this is critical to how long the vigilant treatment of Abrus needs to be maintained once no more seeds are set.  (more…)

Fraser Island Pandanus Rescue

Joel Fostin has launched Fraser Island’s first ever crowd-sourcing campaign. Can you help?

Fraser Island (K’Gari) has suffered catastrophic losses. Up to 50% of the east coast’s Pandanus have perished (approximately 50,000 plants).  A further 20% are likely perish without intervention within the next two months. Preserving the remaining Pandanus is crucial for successful natural regeneration, and vital for the many species of wildlife that rely on them for food and habitat.  The Pandanus on Fraser Island (K’Gari) need help right now.   (more…)

New Biosecurity Act

As of 1 July, a new Biosecurity Act now encompasses the previous Land Protection Act. Focused on risk-based management and on the likelihood and consequences of the risk of spread, this broader Act will continue the management of invasive plants and animals throughout Queensland.  All Queenslanders, individuals and organisations have a general biosecurity obligation to take reasonable steps to report and ensure they do not spread a pest, disease or contaminants. (more…)

A Little More about Pandanus Dieback

By now I’m sure the vast majority of the readers of the FINIA newsletter are aware of the Pandanus dieback occurring in Pandanus populations in South East Queensland and Northern New South Wales, and the severe dieback currently occurring on Fraser Island. Many will also be aware of the leafhopper primarily responsible for the dieback (Jamella australiae).

When a new Jamella outbreak occurs in the absence of the parasitoid wasp (Aphanomerus nr. pusillus), the leafhoppers breed to immensely high infestation levels and spread rapidly. The ensuing fungal pathogens and secondary detrimental insects decrease plant health, resulting in rapid and high mortality rates. Recent observations on the Sunshine Coast and at Agnes Water have uncovered over five non-native secondary insects (garden and agriculture escapees) greatly contributing to plant mortality.

While many predatory insects prey on Jamella adults and nymphs, only the parasitoid wasp has proven effective in mitigating the dieback. The wasp’s high predation rates on the leafhopper’s eggs (often upwards of 80%) lowers leafhopper numbers, greatly reducing the rate at which the outbreak spreads, and prevents the decline in plant health. In this way, the wasps act as prevention, rather than as a cure.

IMG_3639

Infected Pandanus leaf – note the egg rafts of 60-80 eggs and newly emerged leaf hoppers (white dots)

Environmental factors such as prolonged periods of drought or wet weather and cold winter temperatures also influence the predator/prey balance and subsequently the health of Pandanus populations. For Pandanus that are under severe stress, like the many thousands on Fraser Island, direct intervention in the form of leaf stripping or pesticide control is at present the only tested method to assist in their survival. Sadly, it is likely that more Pandanus will succumb until the wasp has been released and become naturalised throughout all parts of Fraser Island.

In recent years, there has been limited state-wide awareness raising, monitoring, research and action carried out to protect these iconic, culturally significant, and arguably the most important coastal ecosystem keystone species. Coastal beaches and coral islands from Gladstone north to Townsville are at risk of new outbreaks. With early detection of new Jamella australiae outbreaks and prompt release of Aphanomerus nr. pusillus, Pandanus dieback can be greatly mitigated.

To manage these outbreaks successfully, collaboration between local councils, parks, indigenous groups and environmental groups is required. Annual monitoring, localised wasp translocation, physical intervention and research into co-contributing insects are also essential. The challenge is coordinating all of these responses across multiple land tenures in an increasingly resource limited environment. Who are you going to call?

Joel Fostin, Student, University of the Sunshine Coast

Tiny Wasp Released to Save Fraser Island’s Pandanus

In an effort to rescue Fraser Island’s pandanus trees from the devastating effects of infestation by Jamella leaf-hopper (Jamella australiae), 26 October saw the long-awaited release around Eurong of a tiny sandfly-sized predatory wasp (Aphanomerus sp.) that is expected to help to check Jamella numbers.

Queensland Parks and Wildlife Service (QPWS) Principal Ranger Ross Belcher reported that University of the Sunshine Coast environmental science student Joel Fostin, with QPWS, released ~500 captive-bred wasps onto Jamella egg clusters at Eurong, One Tree Rocks and Lake Wabby. Subsequent releases are planned for Dundubara, Waddy Point and Dilli Village. Funding for this project comes from QPWS, with support from the Fraser Coast Regional Council, Fraser Island Defenders Organisation (FIDO), the Fraser Island Alliance and other stakeholders. All areas will be monitored for rate of spread and the effectiveness of the control.

The Jamella leaf-hopper, native to north Queensland, was accidentally transported to southern Queensland in the 1990s on infected plant material. In the north of the state, leaf-hopper numbers are controlled by the Aphanomerus wasp, which exclusively lays its eggs in leaf-hopper egg rafts, where immature wasps eat the developing Jamella. Released from predation, Jamella numbers skyrocketed, with devastating results for the pandanus populations of southern Queensland, including Fraser Island.

A dead pandanus tree, with a healthier plant behind it. It is these healthier plants that the biocontrol method aims to save

A dead pandanus tree, with a healthier plant behind it. It is these healthier plants that the biocontrol method aims to save

Biocontrol of Jamella by introduction of the wasp has been effective in other parts of SE Queensland and northern NSW, and QPWS has been applying to release the biocontrol wasp since 2011. The biocontrol responds to the Jamella outbreak by slowing down in cooler months and increasing numbers in warmer active months. The wasp has only 7–9 days to find a Jamella egg raft in which to lay its eggs.

The wasps released on Fraser Island were bred in sterile conditions by Joel Fostin from wasps collected from the Sunshine Coast and were fed on Jamella egg rafts, collected from Fraser Island. Once established at the release sites, the wasps can be relocated across the island. In combination with continued stem injection pesticide treatment, it is strongly anticipated that this step could spell a return of the iconic Fraser Island pandanus community to its former glory.

Adapted from Media Release from QPWS