Mexican squadron lines up to sting sharpshooter

Mexican squadron lines up to sting sharpshooter News Wine News
  • Thursday 12 April 2001

The University of California is planning to release an army of wasps to seek and destroy the vine-threatening glassy-winged sharpshooter.

The sharpshooter (pictured) carries Pierce's Disease, which has devastated vineyards in Southern California. So far it has cost the state and the US government around US$36 million (£22.5m) in agricultural aid and funding.

The parasitic wasp Gonatacerus triguttatus originates from Mexico and is related to a native wasp (Gonatacerus ashmeadi) already being deployed in California.

By laying its own eggs in the sharpshooter's, the native wasp presently kills more than 90 per cent of the insects that would potentially hatch in the summer. But the wasp is not considered as effective as its Mexican cousin, which kills eggs in the spring.

Mark Hoddle, a biological control specialist at UC Riverside, wants to control the insect's spread as soon as possible. 'We are looking to specifically attack the spring infestation and knock numbers back by up to 80 per cent,' he says.

Squads of between 150 and 300 wasps will be released into critically-hit Californian areas such as Temecula, and will be expected to advance north into Napa and Sonoma. The university is currently holding the Mexican wasps in quarantine. According to research so far, the wasps do not sting humans, damage insects or eat plants.

Hoddle says, 'The safety testing has been good. But, we can only control a certain number of sharpshooters using biological techniques so we also hope to add pesticide treatment and vacuuming to the eradication process.'

The Californian Department of Food and Agriculture has already approved the move. The University is now awaiting US Department of Agriculture approval. The wasps could be released by the end of August (2000) although the project's real aim is to be prepared for spring 2001 when they will be released in 'huge numbers', according to Hoddle.

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