Bees and toxic chemicals

Natural processes can also introduce toxic substances into nontoxic honey produced from nontoxic nectar. Microorganisms in honey can convert some of the sugars in honey to ethanol. This process of ethanol fermentation is intentionally harnessed to produce the alcoholic beverage called mead from fermented honey.

Ethanol

Effects of intoxication

The introduction of certain chemical substances—such as ethanol or pesticides or defensive toxic biochemicals produced by plants—to a bee's environment can cause the bee to display abnormal or unusual behavior and disorientation. In sufficient quantities, such chemicals can poison and even kill the bee. The effects of alcohol on bees have long been recognized. For example, John Cumming described the effect in an 1864 publication on beekeeping.^[5]

When bees become intoxicated from ethanol consumption or poisoned with other chemicals, their balance is affected, and they are wobbly when they walk. Charles Abramson's group at

A temulent bee is more likely to stick out its tongue, or proboscis. Inebriated bees spend more time flying. If a bee is sufficiently intoxicated, it will just lie on its back and wiggle its legs. Inebriated bees typically have many more flying accidents as well. Some bees that consume ethanol become too inebriated to find their way back to the hive, and will die as a result.^[6] Bozic et al. (2006) found that alcohol consumption by honeybees disrupts foraging and social behaviors, and has some similar effects to poisoning with insecticides.^[7] Some bees become more aggressive after consuming alcohol.^[8]

Exposure to alcohol can have a prolonged effect on bees, lasting as long as 48 hours.^[9] This phenomenon is also observed in fruit flies^[10] and is connected to the neurotransmitter octopamine in fruit flies, which is also present in bees.^[11]

Bees as ethanol inebriation models

In 1999, research by David Sandeman led to the realization that bee inebriation models are potentially valuable for understanding vertebrate and even human ethanol intoxication:

"Advances over the past three decades in our understanding of nervous systems are impressive and come from a multifaceted approach to the study of both vertebrate and invertebrate animals. An almost unexpected by-product of the parallel investigation of vertebrate and invertebrate nervous systems that is explored in this article is the emergent view of an intricate web of evolutionary homology and convergence exhibited in the structure and function of the nervous systems of these two large, paraphyletic groups of animals."^[12]

The behavior of honey bees intoxicated by ethanol is being studied by scientists at

"The purpose of this experiment was to test the feasibility of creating an animal model of ethanol consumption using social insects.... The experiments on consumption, locomotion, and learning suggest that exposure to ethanol influences behavior of honey bees similarly to that observed in experiments with analogous vertebrates."[6]

It has thus been found that "the honey bee nervous system is similar to that of vertebrates".^[13][14] These similarities are pronounced enough to even make it possible to derive information on the functioning of human brains from how bees react to certain chemicals. Julie Mustard, a researcher at Ohio State, explained that:

"On the molecular level, the brains of honey bees and humans work the same. Knowing how chronic alcohol use affects genes and proteins in the honey bee brain may help us eventually understand how alcoholism affects memory and behavior in humans, as well as the molecular basis of addiction."^[13][15]

The evaluation of a bee model for ethanol inebriation of vertebrates has just begun, but appears to be promising. The bees are fed ethanol solutions and their behavior observed.

Bees^[17][18] can be severely and even fatally affected by pesticides,^[19][20] fertilizers,^[21][22][23] copper sulfate (more lethal than spinosad),^[24][22] and other chemicals that man has introduced into the environment.^[1] They can appear inebriated and dizzy, and even die. This is serious because it has substantial economic consequences for agriculture.

This problem has been the object of growing concern. For example, researchers at the University of Hohenheim are studying how bees can be poisoned by exposure to seed disinfectants.^[25] In France, the Ministry of Agriculture commissioned an expert group, the Scientific and Technical Committee for the Multifactorial Study on Bees (CST), to study the intoxicating and sometimes fatal effects of chemicals used in agriculture on bees.^[26] Researchers at the Bee Research Institute and the Department of Food Chemistry and Analysis in the Czech Republic have pondered the intoxicating effects of various chemicals used to treat winter rapeseed crops.^[27] Romania suffered a severe case of widespread bee intoxication and extensive bee mortality from deltamethrin in 2002.^[28] The United States Environmental Protection Agency (EPA) even has published standards for testing chemicals for bee intoxication.^[29]

Natural compounds

Bees and other

The flower is constructed in such a way as to make the surface almost impossible to cling to, with smooth, downward-pointing hairs; the bees commonly slip and fall into the fluid in the bucket, and the only navigable route out is a narrow, constricting passage that either glues a "pollinium" (a pollen sack) on their body (if the flower has not yet been visited) or removes any pollinium that is there (if the flower has already been visited). The passageway constricts after a bee has entered, and holds it there for a few minutes, allowing the glue to dry and securing the pollinium. It has been suggested that this process involves "inebriation" of the bees,^{[33][34][35][36]} but this effect has never been confirmed.

In this way, the bucket orchid passes its pollen from flower to flower. This mechanism is almost but not quite species specific, as it is possible for a few closely related bees to pollinate any given species of orchid, as long as the bees are similar in size and are attracted by the same compounds.^[37]

Van der Pijl and Dodson (1966) observed that bees of the genera

"A hapless male bee, blind drunk with the flower's overpowering pheromones, might well mistake a toadstool for a suitable mate, but the flower has made at least a modest attempt at recreating a beelike gestalt."[41]

This seems unlikely, given that no one has ever documented that female euglossines produce pheromones; male euglossines produce pheromones using the chemicals they collect from orchids, and these pheromones attract females, rather than the converse, as Cullina (2004) suggests.^[41]

Toxic plant honey

A number of plants produce alkaloids which can taint honey made from their flowers.

Grayanotoxin

Some substances which are toxic to humans have no effect on bees. If bees obtain their nectar from certain flowers, the resulting honey can be psychoactive, or even toxic to humans, but innocuous to bees and their larvae.^[42][43] Poisoning from this honey is called mad honey disease.

Accidental intoxication of humans by

The New Zealand native plant Tutu produces poisonous honey, due to the toxin tutin.^{[citation needed]}

Tecoma stans

The Tecoma stans plant is unique because although it is nontoxic itself, its honey from its flowers is poisonous nonetheless.^[45][46]

Opium

• Colony collapse disorder
• Honey bee starvation
• Pesticide toxicity to bees
• Diseases of the honey bee
• Pollinator decline
• List of honey plants

Notes and references