Beekeepers in New Zealand are eagerly awaiting the arrival of a tiny insect called Pauesia nigrovaria. This parasitoid insect is being imported from California for a very specific reason: it preys on giant willow aphids.
Giant willow aphids are a devastating exotic species that negatively affect the health of willow trees around the country. The aphids reduce the vigor and strength of willows, in some cases leading to the death of the tree. Willows are an essential source of pollen and nectar for bees in the spring, so getting the green light to release the parasitoid is an important step to control this nasty pest.
Experts believe the introduction of the parasitoid will prove to be an efficient control factor and benefit the health of willow trees and in extension make the life of bees a lot easier. On top of its disastrous effect on the trees themselves, the aphids secretion would also attract wasps, which would multiply and attack the bees.
The giant willow aphids were first discovered in New Zealand in 2013. They primarily breed on willow trees, but winged adults can be found elsewhere too, even on buildings.
Being a parasitoid, the insect deals with the aphids by laying an egg inside of it. That egg hatches inside the aphid and becomes a pupae at which point the aphid dies. The parasitoid then chews its way out of the aphid, only to find a mate and repeat the process with another aphid.
The impending arrival of the parasitoid insect was welcomed by the chairperson of the Apiculture New Zealand Science and Research Focus Group, Barry Foster. The process is due to start by next autumn.
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