30 Jun 2017

Neonicotinoids linked to bee harm by two studies

11:43 am on 30 June 2017

New links between certain insecticides and a decline in bee populations have surfaced, but an entomologist says more data is needed before a ban is considered in New Zealand.


Victoria University's Phil Lester wants more data collected to determine how neonicotinoids affect bees in New Zealand. Photo: 123RF

Two studies out of Canada and Europe, published today in Science, show increased mortality in exposed populations and negative effects on bee reproduction.

In Canada, worker bees had shorter lifespans and colonies were more likely to lose queens after being exposed to neonicotinoids.

In the other study, there were lower reproduction rates in bees from Germany, Hungary and the UK where the insecticide residue was found in nests.

While bees in the UK and Hungary did have reduced survival rates during winter, bees in Germany were unaffected.

Victoria University professor of ecology and entomology Phil Lester said there was almost no question neonicotinoids could reduce bee lifespan and foraging.

But he said while there was a strong push around the world to ban neonicotinoids, there wasn't enough conclusive research here to suggest it was needed.

"The effects of these pesticides are quite variable between different countries and we should be cautious about taking a blanket ban of these sorts of chemicals or imposing regulation of these chemicals without really understanding country-specific factors and things going on," he said.

"Within New Zealand there is some neonicotinoid use. We don't see the bee collapse in most areas around New Zealand that we have in North America and parts of Europe so there's no colony collapse disorder over here.

"Should we go about banning neonicotinoids just yet? Probably not is my impression."

Prof Lester said he would want more data collected in New Zealand before a ban was considered.

"There's a little bit of work, there's not a huge amount.

"We've looked at it in some beehives in Gisborne and not found a huge number of beehives that have any evidence of neonicotinoid residues in them.

"But those are pretty limited studies... what we need is much more information."

Latest research 'very interesting' - EPA

The Environmental Protection Authority (EPA) enforces rules forbidding spraying insecticides near hives or on crops likely to be visited by bees.

Spraying is also not allowed on budding or flowering plants.

EPA chief scientist Jacqueline Rowarth said the new research was interesting and it would be considered by the authority.

"We are working with the industry - both the chemical industry and the apiculturists - to develop strategies that allow both protection of crops and protection of these pollinators, the important bees and other insects that do a good job. "

The current restrictions on insecticides were likely to be good enough for now, she said.

"Always we are concerned about chemicals and them affecting organisms that weren't being targeted.

"Any interesting research that comes out as this has done, we look at it very carefully to see how applicable it is for New Zealand," Dr Rowarth said.

"At the moment we're saying this is very interesting research, we'll keep an eye on it.

"But for New Zealand we don't need to change anything because we've got very strict regulations."

'Wake-up call'

However, an anti-pesticide advocacy group says the pesticides have been in the firing line for a long time and action is well overdue.

Pesticide Action Network co-ordinator Meriel Watts said the results were a wake-up call for New Zealand.

She was particularly alarmed at evidence from colonies near cornfields.

"They found ... an increase in the mortality of the workers, reduced queens in the late part of the season, meaning hives would go into winter with no queen and of course they wouldn't survive like that."

She said neonicotinoid seed treatments were absorbed by all parts of plants as they grew and were passed on to bees.

Though the bees might not go to the pollen, they might still be exposed to neonicotinoid insecticides in tiny droplets of water expressed by the plant in the early hours of the morning.

"They are very clearly able to be affected by these residues in corn plants."

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