Independent scientists now largely concur that the dramatic declines in bee populations over the past decade are caused by a combination of several factors, including: increased overall pathogen loads, poor nutrition, habitat loss and pesticide exposure.
Neonicotinoid pesticides — both alone and in combination with other pesticides — have emerged as a key catalyst behind this disturbing phenomenon, both because of their direct toxicity to bees and their indirect and cascading effects.
Scientists know that individual bees and other pollinating insects can be acutely poisoned while flying through pesticide-contaminated dust in recently planted fields. However more commonly, they are chronically poisoned at sublethal levels by eating and drinking contaminated pollen, nectar and water over time.
Even at low doses, neonics can cause harm to honey bee health. Impacts include:
- Compromised immune response
- Shortened adult life cycles
- Impaired memory and learning
- Reduced social communication, which in turn reduces foraging efficacy
- Disorientation, which also impairs foraging
- Delayed larval development and disrupted brood cycle
- “Gut” microbe disruption, leading to malnutrition
In the U.S., pollinators and other insects are increasingly at risk from pesticide exposure. One 2019 study found that U.S. farmland is 48 times more toxic to pollinators and other insects than it was 20 years ago.
Value of pollination
The economic benefits of pollinators are also clear. According to a recent UN report, more than 70 of the 100 crops that provide the majority of the world’s food rely on bees for pollination. Managed honey bees remain the most economically important pollinator, contributing an estimated $50 billion annually to the U.S. economy, according to a recent study from Rutgers University.
The same study found that wild pollinators, also at risk from pesticides, contribute an estimated 1.5 billion in just seven crops studied.
Farmers and beekeepers are on the frontlines of the economic impacts of bee decline. Beekeepers routinely lose significant portions of their hives annually, and the cost of almond pollination in the U.S. has nearly tripled since colonies began collapsing in 2004. According to analysts, in 2020 an estimated 1.2 million acres of almond orchards will require 2.4 million colonies for pollination, and the costs continue to rise.
Keystone species
In addition to their agricultural value, pollinators are keystone, indicator species. Their decline points to (and will likely accelerate) broader environmental degradation.
Researchers point to pesticides as a key driver of a broader decline of insect populations across the globe, with pollinator population declines as a disproportionately important piece of the current collapse in biodiversity.
Resources
EU resource page: Pesticides and bees