Usually you can recognize that a particular insect is a bee. They differ from closely related groups such as wasps having branched or plume-like setae (bristles or combs) on their forelimbs for cleaning their antennae. Also, small anatomical differences in the limb structure and the venation of the hind wings and by having the seventh dorsal abdominal plate divided into two half-plates with females.
Behaviorally, one of the most obvious characteristics of bees is they collect pollen to provide provisions (food) for their young and have the necessary adaptive nature to do this. However, certain wasp species such as pollen wasps have similar behaviors and a few species of bees scavenge from carcasses to feed their offspring. The world's largest species of bees is thought to be the Indonesian Resin bee, Megachile Pluto, whose females can attain a length of 1.54" (39 mm) . The smallest species may be the dwarf sting-less bee in the tribe, Meliponini, whose workers are less than 0.08" (2 mm) in length.
A bee has a pair of large compound eyes which cover much of the surface of their heads. Between and above these are three small simple eyes which provide information for the bee on light intensity. The antennae usually have 13 segments in males and 12 in females and are bent at an angle, having an elbow joint part way along. They house large numbers of sense organs that can detect touch, smell and taste and small hairlike mechanoreceptors (organ that responds to vibration, stretching or pressure) that can detect air movement, enabling them to hear sounds. The mouth parts are adapted for both chewing and sucking.
The thorax has three segments, each with a pair of robust legs and a pair of membranous (membranes) wings on the hind two segments. The front legs have a cavity in which they collect pollen. In many species, the hind legs bear pollen baskets, (flattened sections with in-curving hairs to secure the collected pollen). The wings are synchronized in flight, the somewhat smaller hind wings connect to the forewings by a row of hooks along their margin which connect to a groove in the forewing. The abdomen has nine segments, the hinder most three being modified into the sting.
With bumblebees, the queen initiates a nest on her own. Colonies typically have from 50 to 200 bees at peak population, which occurs in mid to late summer. Nest architecture is simple and limited by the size of the pre-existing nest cavity with colonies rarely lasting more than a year. In 2011, the International Union for Conservation of Nature, set up the Bumblebee Specialist Group to review the threat status of all bumblebee species worldwide.
Sting-less bees are highly eusocial (advanced level of social organization). They practice mass provisioning, (When a parent stocks all the food for each of her offspring in a small chamber (cell) before she lays the egg). They have complex nest architecture and perennial colonies.
The true honey bees are also highly eusocial and are among the best known of all insects. There are 29 sub-species of honey bees native to Europe, the Middle east, and Africa. Africanized bees are a hybrid strain of A. Mellifera that escaped from experiments involving crossing European and African subspecies, making them unusually defensive.
Co-evolution
The novelty is that bees are specialized as pollination agents with behavioral and physical modifications that specifically enhance pollination and are the most efficient pollinating insects. In a process of co-evolution, flowers developed longer tubes and bees developed longer tongues to extract the nectar.
Solitary And Communal Bees
Most other bees, including familiar insects such as carpenter bees, leaf cutter bees and mason bees are solitary in the sense that every female is fertile and typically inhabits a nest she constructs herself. There are no worker bees for these species. Solitary bees typically produce neither honey or beeswax. Solitary bees are important pollinators, they gather pollen to provision their nests with food for their brood. Often it is mixed with nectar to form a paste-like consistency. Some solitary bees have advanced types of pollen-carrying structures on their bodies. A few species are being cultured for commercial pollination. Most of these species belong to a distinct set of genera, namely: carpenter bees, sweat bees, mason bees, polyester bees, squash bees, dwarf carpenter bees, leaf cutter bees, alkali bees and digger bees.
While solitary females each make individual nests, some species are sociable, preferring to make nests near others of the same species. Large groups of solitary bee nests are called aggregations, to distinguish them from colonies. In some species, multiple females share a common nest but each makes and provisions her own cells independently. This type of group is called "communal" and is not uncommon. The primary advantage appears to be that a nest entrance is easier to defend from predators and parasites when there are multiple females using that same entrance on a regular basis.
Honey Bee Life Cycle
The life cycle of a bee, be it a solitary or social species, involves the laying of an egg, the development through several molts of a legless larva, a pupation stage during which the insect undergoes complete metamorphosis, followed by the emergence of a winged adult. Most solitary bees and bumble bees in temperate climates overwinter as adults or pupae and emerge in spring when increasing numbers of flowering plants come into bloom. The males usually emerge first and search for females to mate with. The sex of a bee is determined by whether or not the egg is fertilized. After mating, a female stores the sperm and determines which sex is required at the time each individual egg is laid. Fertilized eggs produce female offspring and unfertilized eggs produce males. Tropical bees may have several generations in a year with no diapause stage.
The egg is generally oblong, slightly curved and tapering at one end. In the case of solitary bees, each one is laid in a cell with a supply of mixed pollen and nectar next to it. This may be rolled into a pellet or placed in a pile and is known as mass provisioning. In social species of bees there is progressive provisioning with the larva being fed regularly while it grows. The nest varies from a hole in the ground or in wood, with solitary bees, to a substantial structure containing wax combs with bumblebees and honey bees.
The larvae are generally whitish grubs, roughly oval and bluntly-pointed at both ends. They have no legs but are able to move within the confines of the cell. They have short horns on the head and jaws for chewing their food on either side of the mouth. There is a gland under the mouth that secretes a viscous liquid which solidifies into the silk they use to produce their cocoons. The pupa can be seen through the semi-transparent cocoon and over the course of a few days, the insect undergoes metamorphosis into the form of the adult bee. When ready to emerge, it splits its skin and emerges out of the cell as a winged adult.
Flight
In 1996 it was shown that a vortex created by many insects' wings helped to provide lift. High-speed cinematography and robotic mock-up of a bee wing showed that lift was generated by "the unconventional combination of short, choppy wing strokes, a rapid rotation of the wing as it flops over and reverses direction and a very fast wing-beat frequency." Wing-beat frequency normally increases as size decreases but as the bee's wing-beat covers such a small arc, it flaps approximately 230 times per second, faster than a fruitfly's 200 times per second, which is 80 times smaller.
Navigation, Communication And Finding Food
Karl von Frisch (1953) discovered that honey bee workers can navigate, indicating the range and direction to food to other workers with a waggle dance. He studied navigation in the honey bees and showed that honey bees communicate by the waggle dance, in which a worker indicates the location of a food source to other workers in the hive. He demonstrated that bees can recognize a desired compass direction in three different ways. By the sun, the polarization pattern of the blue sky and the earth’s magnetic field. He showed that the sun is the preferred or main compass; the other mechanisms are used under cloudy skies or inside a dark beehive. Bees navigate using memory with a "rich, map-like organization."
Ecology
Many bees are aposematically (strategy used to alert others of their presence and promote avoidance) colored, typically orange and black, warning of their ability to defend themselves with a powerful sting. As such, they are models for mimicry by non-stinging insects such as bee flies, robber flies and hover flies, all of which gain a measure of protection by superficially looking and behaving like bees.
Bees are themselves mimics of other aposematic insects with the same color scheme, including wasps, lycid and other beetles. Many butterflies and moths which are themselves distasteful, often through acquiring bitter and poisonous chemicals from their plant food. All the mimics, including bees, benefit from the reduced risk of predation that results from their easily recognized warning coloration.
Bees are also mimicked by plants such as the bee orchid which imitates both the appearance and the scent of a female bee. Male bees attempt to mate with the furry lip of the flower, thus pollinating it.
Nocturnal Bees
Four bee families, Andrenidae, Colletidae, Halictidae and Apidae contain some species that are crepuscular, (dusk or dawn). Most are tropical or subtropical but there are some which live in arid regions at higher latitudes. These bees have greatly enlarged ocelli ( light detecting organs consisting of a single lens). They are extremely sensitive to light and dark, though incapable of forming images. Some have refracting superposition compound eyes: these combine the output of many elements to provide enough light for each retinal photoreceptor. Their ability to fly by night enables them to avoid many predators and to exploit flowers that produce nectar only at night.
Predators, Parasites And Pathogens
Vertebrate predators of bees include bee-eaters, shrikes and flycatchers, which make short trips to catch insects in flight. Swifts and swallows fly almost continually, catching insects as they go. The honey buzzard attacks bees' nests and eats the larvae. The greater honeyguide interacts with humans by guiding them to the nests of wild bees. The humans break open the nests and take the honey and the birds feed on the larvae and the wax. Among mammals, predators such as the badger, dig up bumblebee nests and eat both the larvae and any stored food.
The beewolf will paralyze a bee with its sting. Specialist ambush predators of visitors to flowers include crab spiders, which wait on flowering plants for pollinating insects; predatory bugs and praying mantises, some of which wait motionless, mimicking flowers. They are large wasps that habitually attack bees. The Ethologist Niko Tinbergen estimated that a single colony of the beewolf might kill several thousand honeybees in a day. All the prey he observed were honeybees. Other predatory insects that sometimes catch bees include robber flies and dragon flies. Honey bees are affected by parasites including acarine.
Decline In Honey Bee Population
As most of us know, honey bees are essential for the pollination of flowers, fruits and vegetables but what most people don't know is they support about $20 billion worth of crop production in the U.S. annually and worldwide, honey bees and other pollinators help to produce about $170 million in crops, according to Scott McArt, assistant professor of pollinator health at Cornell University.
Over the past 15 years, bee colonies have been disappearing in what is known as "colony collapse disorder," according to National Geographic. Some regions have seen losses of up to 90%, the publication reported.
"Honey bees are one of the most important agricultural commodities in the country," stated Geoff Williams, an assistant professor of entomology at Auburn University who also serves on the board of directors for the Bee Informed Partnership.
Between Oct. 1, 2018, and April 1, 2019, 37.7% of the managed honey bee population, (colonies kept by commercial beekeepers) declined seven percentage points lower than the same time frame during the 2017-2018 winter, according to preliminary data from the Bee Informed Partnership, a nonprofit associated with the University of Maryland.
The number of hives that survive the winter months is an overall indicator of bee health, according to the U.S. Environmental Protection Agency.
Worker bees tend to live longest during the winter; up to six months and just four weeks in the spring and summer, according to the American Bee Journal.
Managed colonies are shipped around the country to pollinate our food. Much of the produce seen in grocery stores like watermelon, apples, peppers, cucumbers and nuts are pollinated by millions of European honey bees that travel across the country and are managed by commercial beekeepers.
These U.S. crops are produced with the help of 2.6 million colonies transported by semi-trucks from place to place during peak flowering, McArt said. Of the $20 billion worth of U.S. crop production supported by pollinators, commercial honey bees are responsible for about half. Wild bees and other pollinators take care of the rest.
In February, about 60% of managed colonies head to California to begin almond production, the bees then travel to Florida to pollinate citrus crops before making their way up through the Southeast for the production of blueberries, cherries and other specialty fruits and vegetables, McArt said.
Apple pollination begins on the Northeast in June and the last pollination event typically occurs in Maine in late June and early July for lowbush blueberries, McArt said. The bees then go to a set location for several months, where they gather nectar and produce honey.
The largest contributor to the decline of bee health is the varroa mite, a parasite that invades hives and attaches itself to the bee and consumes it's fat body, also spreading diseases.
Other reasons for the loss in population are loss of habitat and poor management practices, such as moving bees through the frigid Rocky Mountains during their winter journey to California, McArt said.
Incidental exposure to pesticides, pest and other diseases within the hive are also affecting the decrease of the population.
The populations of wild bees and other pollinators are suffering too, McArt stated.
While most experts do not believe honey bees are under threat of extinction, if their numbers continue to dwindle they could become a much more costly commodity for farmers, he said.
High bee losses year after year could lead to fewer beekeepers and rental prices per bee colony could increase dramatically, possibly leading to rising food prices. The cost for renting bee colonies has risen in recent years. The per-hive prices range from $80 to 300 per hive.
All of the reasons for the loss of the honey bee population derive from human error, McArt said.
"Every single one of these stresses that we put on pollinators is man-made.”
To save the bee population, researchers are looking into better management practices for beekeepers, such as how to treat hives for varroa mite.
They are also trying to figure out which pesticides could potentially be replaced with chemicals that are more bee-friendly and what changes can be made to habitats to help increase the bee population, such as planting wildflowers instead of green grass in the front yard and encouraging home owners to mow their lawns less often, McArt said.
The U.S. Department of Agriculture announced that it has suspended data collection for its Honey Bee Colonies survey due to budgetary reasons, just weeks after researchers reported that nearly 40% of managed honey bee colonies in the country were lost over the past winter.
"The decision to suspend data collection was not made lightly but was necessary given available fiscal and program resources," a July 1, 2019 statement from the USDA read.
The USDA's National Agricultural Statistics Service report is only one of three major bee surveys published each year. The Bee Informed Partnership and the USDA's Animal and Plant Health Inspection Service also file reports that are widely used in the industry.
The experts in this industry are quite surprised that the USDA made the decision to stop tracking the honey bee population and adds to the importance for independent studies to continue so scientists can understand the long-term trends of honey bees so policy makers can make sound, well informed decisions in the future.