Scientists have produced the first evidence that the more farming intensifies in New Zealand, the less our native bees like it.
While ecologists worldwide are concerned about the decline of native bee populations, in New Zealand very little research has been done on the 27 endemic species, which play an important role in pollination not just of native plants but also agricultural crops.
In a new study from the University of Auckland’s School of Biological Sciences, researchers planted fields of flowering plants in areas with intensive and non-intensive agriculture in the surrounding landscape. They then collected and identified insects visiting the flowers at each site to measure the abundance of different pollinator species.
The study found that at plots surrounded by high-intensity agriculture, exotic pollinators such as the honeybee thrived, with populations increasing by 150 per cent.
Conversely, native bee numbers in those plots declined by 90 per cent.
Because native bees nest in natural, unmodified soil and only forage for food within a limited range from the nest, they are vulnerable to intensive farming, study author and doctoral candidate Jamie Stavert says.
“Native bees were very common at low-intensity sites but were mostly absent from high-intensity sites and this has important implications because native bees play a vital role as pollinators of many native plant species and crops in New Zealand.”
Mr Stavert says the study is the first indication that intensification of agriculture is having a strong negative impact on native bee populations and we are in danger of becoming too reliant on the ubiquitous honeybee.
“The exotic honeybee is an important crop pollinator and no-one disputes that,” Mr Stavert says. “But they are also vulnerable to disease and we cannot become too reliant on one species for pollination.
“The health and resilience of our native and agricultural ecosystems comes from biodiversity. We need a wide range of pollinators to do the job.”
Although the study was focused on agricultural areas, Mr Stavert says people can do practical and simple things in urban gardens to help native bees. This includes planting native species that flower at different times of the year, protecting areas of bare soil for nesting and reducing insecticide use.
The study is published in Proceedings of the Royal Society B: Biological Sciences.