A network that helps people worldwide obtain rapid advice and information on crop protection, including the identification and management of plant pests.
PestNet is a network that helps people worldwide obtain rapid advice and information on crop protection, including the identification and management of plant pests. It started in 1999. Anyone with an interest in plant protection is welcome to join. PestNet is free and is moderated, ensuring that messages are confined to plant protection.
February 2016. A report from Landcare Research on the potential biocontrol of vespid wasps – European and common wasps – brought a number of posts about these wasps. A mite has been recognised as a potential biocontrol agent, a new species named Pneumolaelaps niutirani. In response a member asked about the specificity of the mite and also about the target of the research.
Several scientist responded and mentioned that these are vespid wasps, German wasp and common wasp, Vespula germanica and V. vulgaris. They build up to high numbers in New Zealand bush and impact general biodiversity both directly, by preying on insects and indirectly by roving food species for native birds. Information on them is here:
One of the wasps is also reported from French Polynesia.
Some general comments on wasps as predators, from recent observations in Cambodia were provided:
Predatory wasps can be quite important and common in vegetable crops. They are NOT the same species as discussed for NZ (Vespula). Their real impact is probably unknown but certainly interesting in agricultural and horticultural crops grown in the tropics. They predate on many insects, but they are real generalists, taking beneficial insects as well as pests. They predate on mainly larger insects, such as caterpillar, but will happily take a natural enemy such as a lacewing or hoverfly larva.
Their impact will depend on the dynamics of crop infestations. For example, if a crop is infested with mainly caterpillars, they will certainly be beneficial. But where there is a dynamic interaction between pests such as, for example, aphids and caterpillars and their foliage-dwelling predators (such as lacewings and hoverfly larvae), and the parasitiods of the pests (developing inside their pest hosts). Predatory wasps may well be disruptive to biological control in that situation.
The original article from the Landcare site is here:
Rigorous tests for potential wasp biocontrol
Monday 01 Feb 2016
Tests will soon begin to ensure a mite, that looks a promising biocontrol agent against wasps, isn’t a threat to bees.
The mite, discovered by Landcare Research scientist Dr Bob Brown on wasp nests in 2012, has just recently been recognised as a new species and been named – Pneumolaelaps niutirani.
It was identified and named by fellow Landcare Research scientist Dr Zhi-Qiang Zhang and Ministry for Primary Industries scientist Dr Qing-Hai Fan.
Dr Brown has been researching the mites’ potential as a biocontrol agent against wasps, which cost the country’s primary industries around $130 million a year and cause biodiversity loses.
He has found wasp nests where the mites are present are 50 to 70 per cent smaller than uninfested nests. Immature mites have also been found in nests indicating wasps could be a host.
However, other species in the genus of the mites are often found in association with bees. As a result, the next step is to conduct safety trials to make sure the mite does not pose a risk to honeybees or bumblebees.
In order to do this, bee larvae would be fed stable isotopes and the mites later inspected to see if it was in their system, Dr Brown said.
“Stable isotopes are molecules that act like a chemical marker that we can track. If the stable isotopes are found in the mites this will conclusively tell us they are feeding on the bees because there is no other way for them to acquire these molecules,” he said.
“We found the mites in low numbers in quite a few honeybee hives so we need to check out what their association is. It’s not uncommon for organisms to have a different association with other species and feed on different things. It is possible the mites are there because they hitched a ride on wasps that were robbing honey from the hive.”
The tests would begin as soon as Dr Brown had excavated wasp nests over the coming months and had access to the mites. Once complete, attention would turn to checking the mites were not harmful to native bees.
Dr Brown will also investigate the associations between the mites and wasps. In particular, if and how the mites are responsible for decreased aggression levels in the wasps and how they are managing to enter the nests.
“Wasps don’t like anything in their nest but somehow these mites are tricking them into letting them be there.”
He wanted to thank the public for their support after an appeal for wasp queens to assist his research saw him sent 436 from around the country. An analysis of the wasps found 35 per cent had a least one mite.
The Vespula Biocontrol Action Group contracted Landcare Research to investigate the mite’s potential as a biocontrol agent against wasps.
The research is funded by the Ministry of Primary Industries’ Sustainable Farming Fund.