Threats affecting pollinators
The biggest threats to pollinators globally are chemicals (such as commercial pesticides), introduced pests, extreme weather and habitat destruction and/or fragmentation. The latter is particularly important as it diminishes genetic diversity.
In 2006 researched showed that the UK and the Netherlands had a 70% drop in wild flowers that need pollination and their were a shift in pollinator community structure since the 1980s. Stuart Roberts found that rare pollinator species tend to become rarer and the commoner becomes even more widespread. J. A. Thomas et al. (2004) have found that their were a a 71% decrease in butterfly species and 3.4% became extinct over the past 20 years.
In 2006 researched showed that the UK and the Netherlands had a 70% drop in wild flowers that need pollination and their were a shift in pollinator community structure since the 1980s. Stuart Roberts found that rare pollinator species tend to become rarer and the commoner becomes even more widespread. J. A. Thomas et al. (2004) have found that their were a a 71% decrease in butterfly species and 3.4% became extinct over the past 20 years.
Colony Collapse Disorder (CCD)
During the winter and spring of 2006-2007 North America experienced CCD. It is the lost of honeybee colonies with loses as high as 80% - 100%. It have the potential to cause $15 billion loss of crop reproduction and $75 billion in indirect losses.
CCD has been leading to low number of adult bees in the hives. Large numbers of adult workers had early and sudden death in the field. This lead to insufficient workforce that consists mostly out of young adult bees.
The exact causes are still not certain but there are a few potential causes.
Other causes that were not investigated by the CCD:
CCD has been leading to low number of adult bees in the hives. Large numbers of adult workers had early and sudden death in the field. This lead to insufficient workforce that consists mostly out of young adult bees.
The exact causes are still not certain but there are a few potential causes.
- Pathogens that are found in the brood and bees. European foul brood ( Mellisococcus pluton) and American Foul Brood ( Paenibacillus larvae) that is found on larvae and pupae.
- Chemical residue or contamination that is found in the wax, food stores and bees. Beekeepers may increase the dose of chemicals to kill mite because they develop resistance and this exposes honeybees to levels that influence longevity.
- Parasite load from Vorroa destructor on adult bees.
- Stress induced protein increase the stress level in adult bees.
- The lack of genetic diversity and lineage of bees makes them vulnerable for the development of epidemics.
Other causes that were not investigated by the CCD:
- The use of pesticides in an agriculture area , the lost of honeybees are a common sight.
- The change of agriculture practices calls for long distances to be traveled with the colonies and CCD is more common in these practices.
- GMO maybe a cause but the evidence does not match what would be expected of GMO effects.
Factors that contribute
It is not just the use of chemicals and pesticides that influence pollinators. Other factors that interferes with movement, habitat transformation and agriculture practices can all contribute to the decline.
Habitat transformation
- Fragmentation and degradation is the main habitat changes that effects the populations the most. When the habitat degrades so does the population structure. If the population can move from the area they will migrate to another one that is sufficient in resources. When they can not move, their numbers will decline to a point that the ecological services for plants is no longer effective.
- Fragmentation and destruction of habitat can add to genetic erosion. The pollinators movement is limited between populations and this reduce gene flow from different populations. The result is locally inbreeding and this increase the chances that populations will become extinct.
- For some wild pollinators nesting, roosting and foraging can only be done in undisturbed habitat and they are very susceptible to habitat degradation and fragmentation.
- Urbanisation does more than removing habitat directly. It also isolates and fragments the surrounding land that is not degraded.
- Food source reduction
- Migration, mating and nesting sites decline.
Agriculture practices
The improper use of pesticides, insecticides and herbicides in agriculture poses a threat to pollinators. Especially the use of systematic insecticide that is taken up by the roots and moves throughout the plant and ends up in the pollen and nectar. It is used to get rid of insects that is harmful for the crops but it also affects the useful ones like bees. There are cases of bees losing there sense of direction as a result of pesticides.
It is not just the use of pesticides that effects pollinators but also the replacement of natural vegetation wit a monoculture one. Many monoculture landscapes do not provide nectar or pollen and therefore it cant sustain pollinators.
Insecticides is not only applied to agriculture fields but also to parks, backyards, forests and mosquito-ridden marshes and swamps. Often broad-spectrum insecticides are used and they are as toxic to beneficial species as they are to the target species.
Other chemical can eliminate nectar from the plants, destroy the larval host plant of butterflies and moths and deplete the bees nesting material.
It is not just the use of pesticides that effects pollinators but also the replacement of natural vegetation wit a monoculture one. Many monoculture landscapes do not provide nectar or pollen and therefore it cant sustain pollinators.
Insecticides is not only applied to agriculture fields but also to parks, backyards, forests and mosquito-ridden marshes and swamps. Often broad-spectrum insecticides are used and they are as toxic to beneficial species as they are to the target species.
Other chemical can eliminate nectar from the plants, destroy the larval host plant of butterflies and moths and deplete the bees nesting material.
Other factors that can cause harm.
- Bees can get disease from Varroa mites which is a virus transmitter in the hives.
- Competition from invader species.
- Predator increase.
- Climate change on a global and local scale. The land-cover changes affects the regional climate through change in surface energy and water balance.
- Decrease in larval host plants.