Nicotine-based pesticides currently under review in New Zealand have been linked to declining bird populations in the US.
The rules around using neonicotinoid pesticides are being reviewed in New Zealand after they were linked to declines in honeybee populations.
A new study released today found it's also impacting bird populations and biodiversity in the US.
Lead author Dr Madhu Khanna, from the University of Illinois, says it shows a "significant detrimental impact" to grassland and insect-eating birds.
"These impacts could grow over time. Because as these decimated bird populations, they reduce their capacity to reproduce," she says.
"And so these impacts would grow over time because they are gradually reducing the amount of birds that are available to bring the population numbers back up."
After controlling for other influences, the study found the nicotine-based pesticides were linked to a four per cent annual decline in the bird populations.
It's a "substantially greater" impact than conventional pesticides, despite other pesticides being used more widely, according to the study.
Dr Khanna says it's not clear what the best solution is.
"I think we need to find other alternative, either to the pesticides or to the way that these pesticides are used if we want to continue to use them."
Neonicotinoid pesticides have been used in New Zealand for more than 20 years, according to the Environmental Protection Agency.
Rules around their use are attempted to help protect bees, including no spraying near hives and not spraying crops likely to be visited by bees, while the bees are foraging, or while plants are budding or flowering.
In Europe, outdoor use is banned - they're only allowed to be used for crops within permanent greenhouses.