Bees are the chief pollinators. They are flying insects and are quite closely related to wasps and ants. In a colony of honey bees, there could be nearly 50,000 to 60,000 workers. Wild bees are as important as bumblebees and solitary bees. They prefer to nest underground or sometimes they nest in stems, wood or even in stone. Like honeybees, wild bees are also crucial as there care certain crops which can be pollinated only by wild bees.
They are all found in rural as well as in urban regions. Previously, according to a report it stated that the use of toxic pesticides and disease outbreaks are the main reason for the constant decline in the bee population, but quite recently a new study from North Carolina State University unveiled that the increasing urban temperatures can also contribute to the decreasing bee population.
In the journal “Biology Letters,” it states that nearly 15 of the most typical wild bee species in the southeastern cities can be badly affected by the increasing temperatures in urban heat islands. Elsa Youngsteadt, a research confederate at NC State and a co-lead author of the study, in a press release stated that “species that have a lower CTmax (Critical thermal maximum) are most sensitive to urban warming.” For this particular study, the researches first specified that the so-called CTmax or the Critical thermal maximum of the different bee species.
In a tube, the bees were put, and the temperature was increased slowly until each bee became weakened. Then the CTmax was noted for each bee, as it is the temperature at which the bees started falling apart in the laboratory settings. Thus, these insects could be fatally affected by higher temperatures prompting them to leave their habitat or reproduce less. Finally, after much study, they concluded that the bee population decreases as the temperature in the urban area increases, and the bumblebee (Bombus bimaculatus) are among the least heat tolerant species since their CTmax value is even below 113-degrees Fahrenheit.
Multiple causes are responsible for such an unprecedented rise in temperature. The buildings and roads that replace the forests and gardens cause the alteration in thermal, moisture and aerodynamic properties of the surface and the atmosphere.
It is mainly due to the fact that urban construction materials have different thermal properties compared to the neighboring areas, which are rural. Hence, it results in more of the sun’s energy being absorbed and reserved in urban areas as compared to rustic surfaces.
Also, the height and alignment of the buildings are such that it affects the rate of escape of energy at night which is supposed to get absorbed during the day time. Owing to this fact urban areas cool at a much slower pace as compared to the rural area at night and thus, they have higher temperatures. In addition to that, much of the sun’s energy that is absorbed by the surface gets used to heat the atmosphere and causes an increase in the air temperature than into evapotranspiration (which is a process of water uptake and loss by plants), and that is a cooling process.
Other factors which contribute towards the rise in urban temperatures include the production of heat from the air conditioning and the refrigeration systems, industrial methods, motorized vehicular traffic and the hindrance of rural air flows by the windward side of the built-up surfaces. Also, many heat-related illnesses like thermal discomfort affect the human cardiovascular and respiratory system. Thus, hot cities are not suitable for the wild bee population in urban areas.
The pathogen pressure on bees also has increased significantly due to urbanization. Although there are initiatives like Insect Pollination Initiative (IPI), Urban Pollinators Project (UPP) prevalent abroad, which explore the lives of bees and other pollinators, yet the growing population requires more houses, bigger cities, and indirectly more farming to provide them with more food which progressively will force out bees and other pollinators from their natural homes thus has a adverse effects on the bee population.
The ultimate goal right now would be to incorporate the spirit of bee friendliness into the very framework of urban planning, and by making space in which we humans live along with comfort and nutrient offered to our winged counterparts.