Wasps’ sex life under microscope

Kiwi scientists have studied the bedroom behaviour of a parasitoid wasp to reveal its mating habits.

Cotesia urabae is a natural enemy of the eucalypt feeding pest Uraba lugens, an Australian moth whose larvae can cause severe damage to a range of eucalyptus tree species.

Severe outbreaks of U. lugens have been reported in Western Australia, affecting more than 250,000ha.

Scientists say a similar outbreak in New Zealand could potentially devastate commercial plantations of eucalyptus and cost the industry many millions of dollars.

Using a special Y-shaped olfactory tube, scientists from Plant and Food Research, B3 (Better Border Biosecurity), Scion and the University of Auckland investigated how odours emitted by both male and female wasps influenced attraction.

The tube presented the target wasp with a choice of odours emitted down the arms of the tube.

The researchers found that male wasps were overwhelmingly drawn to the odour of virgin females and not previously mated ones.

They also explored how male competition and body size affect results.

Success was more likely when two males were competing, Plant and Food Research entomologist Dr Gonzalo Avila said.

The results also revealed that larger males had more success.

By understanding the conditions leading to successful reproduction of C. urabae, scientists hope to advance the capability of rearing the wasp for use as a biocontrol agent against U. lugens. The research has been published in the scientific journal Bulletin of Entomological Research.