*5.1.1.2 Effect of CO2 on pollen gathering ability of the forager*

The drastic effect of different chemicals used in the apiaries has been shown to decrease the pollen gathering ability of the forager bees. This decrease in the pollen supply during the blooming seasons can cause a severe threat to the reserves of the colony during winter season, where most of the pollen is consumed for the survival of the colony. This decrease in pollen gathering ability in the worker bees have been observed by different workers and such chemicals like, carbon dioxide, nitrous oxide and ammonium nitrate have been found to be decreasing the pollen gathering capacity of as many as 40 treated worker bees with a threatening outcome of no bee being able to gather pollen after the exposure to abovementioned chemicals, which are widely used in apiaries for different purposes [22].

#### *5.1.2 Metal toxicity*

Continued anthropogenic pressure due to the ever-highest human population, which has no signs to slow down in near future have put an alarming metal and metalloid pollutants pressure over the past century because of anthropogenic emissions into the environment. These pollutants may have negatively impacted the pollinators that reside in the soul of machinery responsible for the food production that sustains this human population. Metal pollutants are discharged into the air, water, and soil through different human activities including mining, agriculture, coal burning, hydraulic fracturing to extract gas and oil, and industrial and municipal waste production. Of all the toxic metals collected cadmium, copper and lead have been proved to be the most toxic to bees [23]. These three metals (Cd, Cu and Pb) have also been reported to change the feeding behavior in bees with increased sensitivity towards sucrose.

Once in soil, Cd and Cu is actively absorbed by plant roots, transferred via vascular bundles into the nectar and pollen, and subsequently accumulates in the pollinators and bee products since the pollinators collect the contaminated pollen and nectar. Copper is an essential trace element in plants and is able to accumulate in different plant tissues. Cu co-acts with several essential proteins to enhance growth and development of honey bees but it is toxic when it exceeds the cellular needs.

As lead is not easily trans-located within plants, thus, is also shown to be having a residual effect on forager honey bee. Lead gets trans-located within bees due to transfer through air and dislodgeable residues, resulting from deposition on surface contacted by bees [23].

#### **5.2 Toxins used in bee keeping**

A proper maintenance of an apiary depends upon the sanitation aspect of beekeeping but a proper and timely application of different synthetically formulated chemicals is also important for avoidance or management of severe health

**19**

*Detailed Review on Pesticidal Toxicity to Honey Bees and Its Management*

problems. Different health problems like infestation of *Varroa destructor*, wax moth (*Galleria mellonella*), tracheal mite and other pathogenic diseases along with the long debated CCD of U.S. apiaries exerts a severe pressure and a serious threat of total loss of millions of honey bee colonies throughout the world and have been successfully managed by the use of various chemical treatments known to be less harmful to the honey bees. These chemicals have been shown to be far more successful than the other treatments, but at the same time, their toxicity towards bees has been highly neglected or has been less explored. One of the best examples for this has been the introduction of formic acid and oxalic acid, for the better management of honey bee parasitic mite, *Varroa destructor*. Medicated strips impregnated with synthetic acaricides such as, fluvalinate-tau and coumaphos have been used for many years for the management of this pest but both the coumaphos and fluvalinate are known to be highly toxic to older bees then young bees [24–26]. Workers that were subjected to less stress appear to be more resistant to fluvalinate and coumaphos poisoning [27, 28]. However, the appearance of resistant mite populations has resulted into a sharp rise in the practice to use formic acid (FA) and oxalic acid (OA). Both of the two organic acids, are varroacides in nature and serve as an attractive natural options for chemicals like coumaphos and fluvalinate as both of them have been reported to be naturally present in *A. mellifera* honey [29, 30]. These pesticides have lower efficacy against the *Varroa* mite but when used in an integrated pest management strategy, they have known to provide an efficient way to control *Varroa* populations. FA is most effective by evaporation of an impregnated substrate with 65% FA inside the hive and OA is most effective when applied in honey bee colonies either by dripping or spraying or through fumigation [9]. Both FA and OA have been proved to be effective to control *Varroa* mite but very less work has been done to establish its negative effect on honey bees. Schneider et al. [31] highlighted the detrimental effects of FA and OA on honey bees which include:

*DOI: http://dx.doi.org/10.5772/intechopen.91196*

1.Increased mortality

*5.2.1 Formic acid toxicity*

*5.2.2 Oxalic acid (OA) toxicity*

2.Negative effects on brood development

5.Reduced hive cleaning and increased self-grooming

The mode of action of FA against *Varroa* is by inhibition of electron transport into the mitochondria via binding to the last enzyme of electron transport chain, cytochrome c oxidase [32]. Formic acid may produce different toxicity symptoms in honey bees, including reduced longevity of the worker bees [33] and reduced rate of brood survival [34]. Other negative effects of formic acid treatments to honey bee colony mainly includes, increased number of dead bees in front of colonies during the FA treatment period, rejection of queen, worker bees may repel from the colony

As OA is generally provided to the honey bee colony in sugar syrup, in order to increase its efficacy against the *Varroa* mite by increasing its stickiness on to the

and a comparatively lower honey yield from the FA treated colony [9].

3.Reduced fitness of treated colony

4.Decreased division of labour

#### *Detailed Review on Pesticidal Toxicity to Honey Bees and Its Management DOI: http://dx.doi.org/10.5772/intechopen.91196*

problems. Different health problems like infestation of *Varroa destructor*, wax moth (*Galleria mellonella*), tracheal mite and other pathogenic diseases along with the long debated CCD of U.S. apiaries exerts a severe pressure and a serious threat of total loss of millions of honey bee colonies throughout the world and have been successfully managed by the use of various chemical treatments known to be less harmful to the honey bees. These chemicals have been shown to be far more successful than the other treatments, but at the same time, their toxicity towards bees has been highly neglected or has been less explored. One of the best examples for this has been the introduction of formic acid and oxalic acid, for the better management of honey bee parasitic mite, *Varroa destructor*. Medicated strips impregnated with synthetic acaricides such as, fluvalinate-tau and coumaphos have been used for many years for the management of this pest but both the coumaphos and fluvalinate are known to be highly toxic to older bees then young bees [24–26]. Workers that were subjected to less stress appear to be more resistant to fluvalinate and coumaphos poisoning [27, 28]. However, the appearance of resistant mite populations has resulted into a sharp rise in the practice to use formic acid (FA) and oxalic acid (OA). Both of the two organic acids, are varroacides in nature and serve as an attractive natural options for chemicals like coumaphos and fluvalinate as both of them have been reported to be naturally present in *A. mellifera* honey [29, 30]. These pesticides have lower efficacy against the *Varroa* mite but when used in an integrated pest management strategy, they have known to provide an efficient way to control *Varroa* populations. FA is most effective by evaporation of an impregnated substrate with 65% FA inside the hive and OA is most effective when applied in honey bee colonies either by dripping or spraying or through fumigation [9].

Both FA and OA have been proved to be effective to control *Varroa* mite but very less work has been done to establish its negative effect on honey bees. Schneider et al. [31] highlighted the detrimental effects of FA and OA on honey bees which include:

### 1.Increased mortality

*Modern Beekeeping - Bases for Sustainable Production*

*5.1.1.2 Effect of CO2 on pollen gathering ability of the forager*

are widely used in apiaries for different purposes [22].

Bees treated with a mixture of air and CO2 for 5 min have shown to stop their movement and went motionless but regaining their activity, once it was left for 30 min. The same experiment when repeated with only air for comparative study showed that only air did not anesthetize the bee. Thus, it can be concluded that the CO2 at even low concentrations is detrimental to honey bees since they have a

The drastic effect of different chemicals used in the apiaries has been shown to decrease the pollen gathering ability of the forager bees. This decrease in the pollen supply during the blooming seasons can cause a severe threat to the reserves of the colony during winter season, where most of the pollen is consumed for the survival of the colony. This decrease in pollen gathering ability in the worker bees have been observed by different workers and such chemicals like, carbon dioxide, nitrous oxide and ammonium nitrate have been found to be decreasing the pollen gathering capacity of as many as 40 treated worker bees with a threatening outcome of no bee being able to gather pollen after the exposure to abovementioned chemicals, which

Continued anthropogenic pressure due to the ever-highest human population, which has no signs to slow down in near future have put an alarming metal and metalloid pollutants pressure over the past century because of anthropogenic emissions into the environment. These pollutants may have negatively impacted the pollinators that reside in the soul of machinery responsible for the food production that sustains this human population. Metal pollutants are discharged into the air, water, and soil through different human activities including mining, agriculture, coal burning, hydraulic fracturing to extract gas and oil, and industrial and municipal waste production. Of all the toxic metals collected cadmium, copper and lead have been proved to be the most toxic to bees [23]. These three metals (Cd, Cu and Pb) have also been reported to change the feeding behavior in bees with increased

Once in soil, Cd and Cu is actively absorbed by plant roots, transferred via vascular bundles into the nectar and pollen, and subsequently accumulates in the pollinators and bee products since the pollinators collect the contaminated pollen and nectar. Copper is an essential trace element in plants and is able to accumulate in different plant tissues. Cu co-acts with several essential proteins to enhance growth and development of honey bees but it is toxic when it exceeds the cellular needs.

As lead is not easily trans-located within plants, thus, is also shown to be having a residual effect on forager honey bee. Lead gets trans-located within bees due to transfer through air and dislodgeable residues, resulting from deposition on surface

A proper maintenance of an apiary depends upon the sanitation aspect of beekeeping but a proper and timely application of different synthetically formulated chemicals is also important for avoidance or management of severe health

*5.1.1.1 Narcotic effect of CO2*

narcotic effect [1].

*5.1.2 Metal toxicity*

sensitivity towards sucrose.

contacted by bees [23].

**5.2 Toxins used in bee keeping**

**18**


#### *5.2.1 Formic acid toxicity*

The mode of action of FA against *Varroa* is by inhibition of electron transport into the mitochondria via binding to the last enzyme of electron transport chain, cytochrome c oxidase [32]. Formic acid may produce different toxicity symptoms in honey bees, including reduced longevity of the worker bees [33] and reduced rate of brood survival [34]. Other negative effects of formic acid treatments to honey bee colony mainly includes, increased number of dead bees in front of colonies during the FA treatment period, rejection of queen, worker bees may repel from the colony and a comparatively lower honey yield from the FA treated colony [9].

#### *5.2.2 Oxalic acid (OA) toxicity*

As OA is generally provided to the honey bee colony in sugar syrup, in order to increase its efficacy against the *Varroa* mite by increasing its stickiness on to the

mite body, thus, its repeated application to a colony can be proved as lethal to the honey bees as well. A high queen mortality and reduced number of sealed brood have been reported in the colonies treated with OA [35]. The OA treatment has also been reported to be associated with an increased apoptosis in bee midgut [36]. Worker bees have been reported to be showing an abnormal age-related patterns problem while treated with oxalic acid during their early life stages. A dose of 3.5% oxalic acid dehydrates at after 24 h of emergence have been reported to have a disturbance in the normal age-related patterns of worker honey bees. All the agerelated patterns of the workers appear in the natural chronology: they shows first events of behavioral patterns for nursing, followed by, honey or pollen manipulation, wax manipulation and patrolling at the same time but in different intensity. The bees start showing all age-related patterns somewhat earlier than the normal. Treated bees show an increased self-grooming, a superior tendency to inactivity and decreased nursing behavior. For all other behavioral patterns, including trophallactic interactions, house-cleaning, honey manipulation and patrolling, bees show no significant changes than the normal chronology [27].
