Pesticide misuseIt is a label violation to apply most insecticides on crops during bloom, or to allow the pesticide to drift to blooming weeds that bees are visiting. Yet such applications are frequently done, with little enforcement of the bee protection directions.[citation needed] Pesticide misuse has driven beekeepers out of business, but can affect native wild bees even more, because they have no human to move or protect them.[citation needed]
Bumblebee populations are in jeopardy in cotton-growing areas, since they are dosed repeatedly when pesticide applicators apply insecticides on blooming cotton fields while the bees are foraging.[citation needed]
Widespread aerial applications for mosquitoes, med-flies, grasshoppers, gypsy moths and other insects leave no islands of safety where wild insect pollinators can reproduce and repopulate. One such program can reduce or endanger pollinator populations for several years.[citation needed]
Many homeowners feel that dandelions and clover are weeds, that lawns should only be grass, and that they should be highly treated with pesticides.[citation needed] This makes a hostile environment for bees, butterflies and other pollinators
Rapid transfer of parasites and diseases of pollinator species around the worldIncreased international commerce within modern times has moved diseases such as American foulbrood and chalkbrood, and parasites such as varroa mites, acarina mites, and the small African hive beetle to new areas of the world, causing much loss of bees in the areas where they do not have much resistance to these pests. Imported fire ants have decimated ground nesting bees in wide areas of the southern US.
Loss of habitat and forage
The push to remove hedgerows and other "unproductive" land in some farm areas removes habitat and homes for wild bees. Large tractor mounted rotary mowers may make farms and roadsides look neater, but they remove bee habitat at the same time. Old crops such as sweet clover and buckwheat, which were very good for bees have been disappearing. Urban and suburban development pave or build over former areas of pollinator habitat.
Clearcut logging, especially when mixed forests are replaced by uniform age pine planting, causes serious loss of pollinators, by removing hardwood bloom that feeds bees early in the season, and by removing hollow trees used by feral honey bees, and dead stubs used by many solitary bees.
Nectar corridors
Migratory pollinators require a continuous supply of nectar sources to gain their energy requirements for the migration. In some areas development or agriculture has disrupted and broken up these traditional corridors, and the pollinators have to find alternative routes or discontinue migration. A good example is the endangered lesser long-nosed bat (Leptonycteris curasoae) which was formerly the main pollinator of a number of cactus species in southwestern United States. Its numbers have severely declined, in part due to disruption of the nectar corridors that it formerly followed. Other migratory pollinators include monarch butterflies and some hummingbirds.
Hive destruction
Bees are often viewed negatively by homeowners and other property owners. A search for "carpenter bees" on the Internet primarily yields information on removal rather than information regarding bees in a positive light. Recent hysteria regarding killer bees has contributed to these views. Beekeepers find increased vandalism of their hives, more difficulty in finding locations for bee yards, and more people inclined to sue the local beekeeper if they are stung, even if it is by a yellow jacket.[citation needed]
Light pollution
Increasing use of outside artificial lights, which interfere with the navigational ability of many moth species, and is suspected of interference with migratory birds may also impact pollination. Moths are important pollinators of night blooming flowers and moth disorientation may reduce or eliminate the plants ability to reproduce, thus leading to long term ecological effects.[citation needed] This is a new field and this environmental issue needs further study.
Threat by invasive honey bees
Many native pollinators decline in population when faced with competition from invasive honey bees. For example, the western honey bee is invasive in the United States, the wild population consisting entirely of feral bees escaped from European bee colonies imported to fertilize non-native, old-world crops. Where colony collapse disorder reduced invasive honey bee populations in the US, native pollinators sometimes have made recoveries[citation needed], restored to their natural niche by the loss.
Air pollution
Researchers at the University of Virginia have discovered that air pollution from automobiles and power plants has been inhibiting the ability of pollinators such as bees and butterflies to find the fragrances of flowers. Pollutants such as ozone, hydroxyl, and nitrate radicals bond quickly with volatile scent molecules of flowers, which consequently travel shorter distances intact. There results a vicious cycle in which pollinators travel increasingly longer distances to find flowers providing them nectar, and flowers receive inadequate pollination to reproduce and diversify. [2]
Solutions
The decline of pollinators is compensated to some extent by beekeepers becoming migratory, following the bloom northward in the spring from southern wintering locations. Migration may be for traditional honey crops, but increasingly is for contract pollination to supply the needs for growers of crops that require it.
Conservation and restoration efforts
Efforts are being made to sustain pollinator diversity in agro- and natural eco-systems by some environmental groups. Prairie restoration, establishment of wildlife preserves, and encouragement of diverse wildlife landscaping rather than monoculture lawns, are examples of ways to help pollinators.
Use of alternative pollinators
Honey bees are usually the most widely chosen insects in most managed pollination situations. However they are not the most efficient pollinators of some flowers. Alternative pollinators, such as for example, leafcutter and alkali bees in alfalfa pollination and bumblebees in greenhouses for tomatoes are used to augment and in some cases replace honey bees. A wide variety of other bees can be found in the environment that are specialist pollinators (some only using one plant species). However, most of these alternative insects' value as pollinators and their relationships with plants are as yet little known.
In the US, some think that other pollinators will in time replace the lost honey bees, blamed on introduced acarine and varroa mites, but general pollinator decline was already happening before these entered the picture. Only in a few areas are wild populations of pollinators building up; in most areas they are declining as quickly as honey bees.[citation needed]
Furthermore pollinators cannot be exchanged on a one-for-one basis. They are not all equal. Some are generalists, some are specialists. Some are brawny; some are feeble. Some have long tongues; some short. Some work at colder temperatures than others. Bees may deliberately collect pollen, but have different collection techniques, which can greatly affect their efficiency as pollinators.
Flowers are frequently specifically adapted to one pollinator, or a small group of pollinators because of floral structure, color, odor, nectar guides, etc. Proposed alternative pollinators may not be physically capable of accomplishing pollination, or they may not be attracted to the flower of that plant species, or they may rob nectar by cutting sepals, thus avoiding pollination. Understanding the pollination needs of a species is vital to understanding of a plant species, yet this is often poorly understood. In horticulture it is critical to the economic success of the grower, and crops have sometimes been abandoned from general use in an area because of lack of understanding of pollinator needs
