Native vegetation insectaries creating a big buzz

Karen Thomas, regional Landcare facilitator for the Port Phillip & Westernport Catchment Management Authority (PPWCMA), has been investigating ways that farmers could improve their farm biodiversity in combination with adopting sustainable land management principles.

The National Horticulture NRM Strategy, released in 2006, contained a small case study on Integrated Pest Management (IPM) and research which demonstrated the use of native vegetation as habitat for beneficial insects.

Karen found that a lot of work had already been done in South Australian vineyards, and a number of resources were already available. Other than a single vineyard in the Pyrenese, there didn’t seem to be much known about the practice in Victoria. So a few months later, Karen spoke with some of the researchers and found a local ‘you-pick’ berry farm in the Dandenong Ranges willing to set up a trial site.

The owners of the berry farm began preparing areas for planting by using a light herbicide spray, and a team planted the areas with native tubestock in August 2016. Indigenous plants that complied with the documented Ecological Vegetation Class were used, alongside some non-local Indigenous plants, to be used as bush foods.

A main insectary was planted along a fence line between two paddocks. This will become a multi-strata shelterbelt creating a corridor from the existing native vegetation on the property (63 acres) into the production area (containing Rubus sp and blueberries). Smaller plantings were scattered across the production area in pre-existing empty garden beds and surrounding the ‘you-pick’ gazebo.

The owners of the property gained local planning permits to construct a restaurant onsite, so the incorporation of bush foods and citrus not only provides nectar during flowering phases but can be freshly harvested to supply the restaurant, once operational.

Mary Retallack from Retallack Viticulture has been conducting PhD research into native vegetation which offers the greatest nectar and shelter for beneficial insects. The PPWCMA hosted three workshops with Mary last year, where Mary’s preliminary results were discussed. Mary has identified three ‘HERO’ native plants that provide excellent alternative habitat for beneficial insects.

To monitor insect diversity and abundance across the property, sticky traps and pit fall traps were installed, with monitoring being conducted monthly from October to January. Within ten weeks of planting, several native plants were already flowering and the new insectary had an abundance of Hover flies. A staggering 232 hover flies were counted in the ten week flowering insectary. Interestingly, these numbers were not found anywhere else across the property – only in the newly planted vegetation. Hover flies are highly beneficial and after feeding on nectar, the females seek out aphids in which to lay their eggs.

With re-vegetation a part of good farm practice, incorporating native plants that provide excellent habitat for beneficial insects into re-vegetation projects will vastly improve conservation biological control as a crucial mechanism for good integrated pest management.

Developing and introducing methods, such as native vegetation insectariums which allow growers to better understand the diversity of beneficial insects on their farm, the services these insects provide, the timing of their abundance or critical life stages for bio-control alongside softer pesticide options, will mean growers can vastly improve their IPM strategies and environmental assurance.

For more information on the trial, contact Karen Thomas on 0427 480 170 or email [email protected]. A copy of the presentations from the native vegetation insectarium workshops can be found here: http://www.ppwcma.vic.gov.au/news/publications/