Natives provide food and shelter for beneficials

Almost 3000 insects, spiders and mites have been found in native planting at a Pukekohe demonstration vegetable farm, designed to provide food and habitat to maintain beneficial species populations over winter.

Hoverflies were among beneficial species identified in the biodiverse planting.

From June to October, Plant and Food Research (PFR) carried out fortnightly monitoring of the native plant species in the non-cropping areas of the farm to increase understanding of the role the plants play in supporting key beneficial invertebrate populations from winter into spring.

The biodiversity project is a partnership between A Lighter Touch, Vegetables New Zealand and Onions NZ.

PFR entomologist Asha Chhagan says using sweep netting, nearly 3000 individual invertebrates were identified from the first seven of 10 monitoring visits and were categorised as natural enemy, pest, pollinator or other.

“We monitored at least 30 flowering native plants during each visit in order to gather data based on as many different flowering species as possible.”

Chhagan says the most abundant beneficial group of invertebrates found in the monitoring were spiders, which are known to attack a variety of vegetable pests, including mites, aphids and caterpillars.

“Three different hoverfly species were identified. Their larvae are voracious generalist predators and feed on a range of soft-bodied pests, including aphids, caterpillars, psyllids and mealybugs.”

Also found were various parasitoid wasps, including species which attack scale insects and the eggs of stink bugs such as green vegetable bugs.

Other beneficial species included predatory mites, beetles and ladybirds. A range of pollinating fly species were identified, as well as a few pest species.

The permanent native planting on the demonstration farm is made up of a mix

of ground covers and shrubs, and is one component of the biodiversity project, which also includes cover crops, annual flower strips and mobile insectaries.

Planted in non-cropping areas such as beside fence lines and waterways, the plant species selected were chosen to provide year round food sources, and shelter for the beneficial invertebrate species over winter.

They were also selected based on full growth size in order to avoid impeding machinery and minimise the need for maintenance such as trimming.

Ground cover species included carex, muehlenbekia and pratia, with shrubs such as coprosma, olearia and pittosporum.