Researchers Call In Overseas Agent

An overseas agent of the insect variety has been assisting researchers in attacking New Zealand’s wasp problem.

Researcher Barry Donovan is studying the impact of a parasitic insect that eats developing wasps in their cells, the research is an investment of the Public Good Science Fund.

During the last half-century, New Zealand has been invaded by two species of wasps, the German wasp and the common Wasp.“These wasps are subjecting our small forms of native wildlife to enormously devastating predatory pressures against which they have no defences at all” says Dr Donovan.

“People are also suffering from stings and the fear of stings, and honey beehives and fruits such as peaches, plums and particularly winegrapes are being spoiled” he said.

“A dozen enemies of wasps are known from different areas of the home range of wasps in the Northern Hemisphere. The philosophy behind my approach is that if most of these enemies could be introduced, our wasps could be subjected to a much greater biological control pressure than they experience anywhere in their home range”

New insects must be quarantined before they can be released into the field. This ensures that they are free not only of all enemies and diseases that might harm them, but also that they are free of organisms that might harm other beneficial organism already in New Zealand.

Three parasitic insects have been introduced from Europe, North America and Israel since 1979.

One of these three has been released in the field with promising results. “Studies at Perlorus Bridge in Marlborough indicate that the number of parasitoids is tripling annually, therefore the number of wasps killed annually is tripling,” said Dr Donovan.

“The establishment and continuing spread of this first parasitoid shows that this research is paying off. It is the only wasp control research that is promising to permanently reduce the number of wasps here to a level below which they no longer cause problems”.

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