The United Nations Environment Programme (UNEP) has recently released a report called Global Honey Bee Colony Disorders and other Threats to Insect Pollinators
For the 100-some crops that provide 90% of the world’s food, 71 rely on bee pollinators, a figure highlighting the importance of insect pollinators in a recent report by the United Nations Environment Programme. The report addresses the question of whether the crisis of pollinator decline is occurring independently or is just another sign of the global decline of biodiversity. More importantly, it summarizes our current understanding of the threats to insect pollinators and measures that we can take to slow their decline.
To understand why the decline of pollinators is important to people around the world, think about the important role of pollinators to the reproduction of plants. In this mutually beneficial relationship, both the pollinators and the plants have developed adaptations, either in anatomy or behavior, that ensure that insects are attracted to the plant and that plant reproduction is successfully carried out. This co-adaptation is what “raises troubling questions about the potential consequences of declining diversity in pollination networks.” (UNEP report 2011)
The honey bee (Apis mellifera), the most commonly known pollinator, remains the most economically valuable pollinator for agriculture. In Europe and North America, numbers of honey bee colonies have been in decline for decades. Recently colony collapse disorder, reports of honey bees disappearing suddenly from colonies, has captivated the public’s attention, but other problems also plague beekeepers, like parasites and viruses. These problems are generally shared by beekeepers in Europe, North America and Asia, while Africa has reported no large scale losses of honey bees.
But crops do not depend entirely on the honey bee for pollination, wild bees also provide pollination services to agriculture, although less data is available on their numbers worldwide. A 30 year study in the UK and the Netherlands report a 70% drop in insect-pollinated wild flowers along with a change in the species of pollinators that are found. Rare species have become rarer while common species have increased their expanse. This type of shift in species composition means that biodiversity in the landscape is decreasing.
Natural habitat degradation is considered the key factor that is adversely affected insect pollinators. Human-caused degradation leads to diminishing food resources but also an increase in transmitted diseases, as insects become weakened, and the influx of invasive species, including parasites, that are transported around the world by humans. Insecticide use in agriculture also threatens insect pollinators, while honey bee colony health may be adversely affected by beekeeping practices (see this post).
So what can be done to stop the decline of insect pollinators? Firstly, as a response to the key factor threatening pollinator species, support habitat conservation. For example, farmers who provide habitats for insect pollinators on their land should be rewarded (see recent action by the Pollinator Partnership). Investment in alternative agriculture that limit pesticides and in alternative pollinators for agriculture is also recommended. In addition, developing our understanding of insect pollinator taxonomy and biology is vital for their preservation.
The report concludes that current available data are not sufficient to say that there is a worldwide decline in pollinators but human activity seems to be detrimental to the biodiversity of species. Overall the report stresses that pollination by insects should not be taken for granted. We must be gracious stewards of our natural and agricultural ecosystems.
The Science of Pollinators 