It’s no wonder why our mailboxes and emails are filled with seed catalogs and special offers - winter is a great time to research and plan this year’s garden, especially when plans include food for pollinators.
Before making any purchases from seed catalogs with glossy photos of flowers, fruits, and vegetables promising similar growing perfection in our own yards, do your research on the company’s neonicotinoid use. And when spring arrives, be wary of neonicotinoid use in garden centers. Ask questions but do your own research – you may be surprised at what’s included with a beautiful pot of petunias.
To control insect pests, nitroguanidine neonicotinoid insecticides (NNIs or neonics) are used to treat seeds and plants in both commercial and residential applications. All parts of the treated plants can contain the synthetic insecticides – from root to fruit, including nectar and pollen, and researchers believe neonicotinoids may significantly contribute to bee decline. By the end of 2018, the European Union banned the use of neonics in all fields. There is no current ban of neonicotinoid use in the US.
To understand the effects of neonicotinoids on bees, below is the scientific research from xerces.org:
Effects on Honey Bees (Apis mellifera)
• Clothianidin, dinotefuran, imidacloprid, and thiamethoxam are highly toxic to honey bees by contact and ingestion.
• Thiacloprid and acetamiprid are moderately toxic to honey bees. (To understand how the EPA defines the levels of toxicity, see EPA Toxicity Classification Scale for Bees)
• Neonicotinoids absorbed by plants are metabolized over time. Some of the resulting breakdown products are also toxic to honey bees, and sometimes even more toxic than the original compound.
• Honey bees exposed to sublethal levels of neonicotinoids can experience problems with flight and navigation, reduced taste sensitivity, and slower learning of new tasks, all of which impact foraging ability and hive productivity.
• Larvae exposed to sublethal doses of imidacloprid in brood food had reduced survival and pupation, altered metabolism, and reduced olfactory response as adults.
• Contaminated talc, abraded seed coating, or dust that becomes airborne during planting of neonicotinoid-coated seed is acutely toxic on contact to honey bees.
Effects on Bumble Bees (Bombus spp.)
• Imidacloprid, clothianidin, dinotefuran, and thiamethoxam are highly toxic to bumble bees.
• Exposure to sublethal amounts of neonicotinoids can result in reductions in food consumption, reproduction, worker survival rates, colony survival, and foraging activity.
• Queen production is significantly reduced by sublethal amounts of neonicotinoids, which may lower bumble bee populations because fewer colonies are established the following year.
Effects on Solitary Bees
• Clothianidin and imidacloprid are highly toxic to blue orchard bees (Osmia lignaria) and alfalfa leafcutter bees (Megachile rotundata).
• Imidacloprid residues on alfalfa foliage increase rates of mortality of alfalfa leafcutter bees and alkali bees (Nomia melanderi).
• Blue orchard bee larvae required more time to mature after consuming sublethal levels of imidacloprid in pollen.
• Sublethal amounts of neonicotinoids can have harmful effects on the reproduction of red mason bees (Osmia bicornis).
One way to avoid neonicotinoid exposure in seeds and plants is to purchase from trusted sources. Talk to the owners of your favorite greenhouse and ask if they sell seeds treated with neonicotinoids or employ their use on the plants they offer. Be curious and ask why, then find the certified organically grown section. In 2017, only 5 to 10 percent of Michigan’s greenhouses used biocontrols – natural predators to control insects. Neonicotinoid use is a question worth asking to avoid bringing affected plants home for pollinators.
There are many online and catalog companies offering certified organic seeds, and the Michigan Pollinator Initiative (pollinators.msu.edu) has extensive information on planning a pollinator garden with flowering plants native to Michigan. Gardening plans can also include trees that offer a large volume of food for pollinators and often last for years. The American basswood with its heart shaped leaves and fragrant flowers is a prolific nectar producer. Lindens, dogwood, and fruit trees are also pollinator-friendly and arborday.org offers a list for more ideas.
Looking outside, it’s hard to believe spring is just weeks away but the memories of watching bees and butterflies lap up food from flowering trees and plants are close at hand. Now is a great time to plan a new pollinator paradise, re-work an existing one, or design this year’s vegetable garden, and sourcing seeds and plants - free of neonicotinoids is an important step to protect and assist our pollinators.