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| Environmental Stress
It should come as no surprise that the ever-increasing stress placed upon the environment through human interaction has had an impact on the stability of the honeybee population. However, so as not to place all the blame upon aspects of human society, Nature, itself, provides its own stress inducers, sometimes in the form of predatory species, or natural diseases. As such, the following information will cover aspects of environmental stress both existing naturally and unnaturally. The topics will focus on overheating, genetic lethality, plant poisoning, and pesticide poisoning.
Overheating can be a common, natural occurrence within the honeybee hive. Overheating is often a secondary affect to a sudden loss of worker bees to disease or otherwise. Worker honeybees control the temperature of the hive through the vibration of their wings, utilizing them in a similar fashion as fan. If there were to be a sudden decrease in the amount of worker honeybees during hot weather, the lack of cool air provided to the larvae could cause them to die, often turning black. It is sometimes observed that newly emerged adult, having suffered overheating problems while a pupa, will be wingless, and therefore useless to the hive. On a more macroscopic scale, “adult bees dying from overheating crawl about rapidly while fanning their wings. They are often wet, and their wings appear hazy. In some cases, an abnormally large accumulation of dead bees may be seen at the hive entrance” (Shimanuki, Hachiro & Knox 2000:38).
Genetic lethality is a common occurrence that transcends all families of the animal kingdom. Honeybees may die from lethal gene or chromosome mutations at any stage of their development. While the likelihood of mutation can be increased through exposure to certain chemicals or radiation, the collapse of a colony consistently exhibiting such undesirable traits is less of a concern to honeybee breeders concerned with ensuring a healthy, genetically robust population.
Plant poisoning occurs when local, poisonous species of plants are producing pollen. Small amounts of poison are taken back to the hive and stored in the honeycomb, later becoming a source of food for all members of the hive. Certain plant poisons yield different affects in the honeybee population, “Aesculus californica (California buckeye)... probably [being] the best known of the poisonous plants in the United States... exhibiting symptoms similar to those of chronic bee paralysis” (Shimanuki, Hachiro & Knox 2000:39). While plant poisoning and pesticide poisoning are two different environmental stress inducers, “there is no clear-cut method for differentiating between [them]. The effects of plant poisoning are usually more gradual, and last longer than the effects of pesticide poisoning. Plant poisoning [also] occurs in the same geographical area at the same time each year, whereas pesticide poisoning is indiscriminate” (Shimanuki, Hachiro & Knox 2000:39-40).
Lastly, pesticide poisoning has become a major issue especially in populations contracted for pollination means. The changing agricultural trend towards the use of bee pollinations for mass field propagation has in turn exposed the honeybee population to a wider array of chemical agents such as pesticides. In smaller, better-controlled honey producing fields, care is taken to ensure organic products only be used within the vicinity of the hives. However, in fields of produce, farmers are more apt to use such pesticides not for a means of protection against the honeybees, but for parasitic insects specific to their crop.
Since all arthropods are similar in nature, pesticides, being non-discriminate chemical agents, will often harm insects considered to be beneficial. Transmission and symptoms of pesticide poisoning are similar to plant poisoning in that, contaminated pollen is brought back to the hive to be fed out too all divisions of labor. However, pesticide poisoning often yields a higher overall death rate within a given amount of time, affecting adult bees more often than larvae, and causing some to expire before returning to the hive. In most cases, “the loss is characterized by the appearance of many dead and dying adult bees... at the colony entrances” (Shimanuki, Hachiro & Knox 2000:40-41).
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