The Impact of Selected Pesticides on Honey Bees

Beekeeping and Bee Conservation - Advances in Research, 2016

This chapter focuses on the detrimental effects that pesticides have on managed honey bee colonies and their productivity. We examine first the routes of exposure of bees to agrochemicals used for crop protection and their application to crops, fate and contamination of water and plants around the fields. Most of the time, the exposure of bees to pesticides is through ingestion of residues found in the pollen and nectar of plants and in water. Honey bees are also exposed to pesticides used for the treatment of Varroa and other parasites. The basic concepts about the toxicity of the different kinds of pesticides are explained next. Various degrees of toxicity are found among agrochemicals, and emphasis is given to the classic tenet of toxicology, "the dose makes the poison," and its modern version "the dose and the time of exposure makes the poison." These two factors, dose and time, help us understand the severity of the impacts that pesticides may have on bees and their risk, which are analysed in the third section. Sublethal effects are also considered. The final section is devoted to some practical advice for avoiding adverse impacts of pesticides in beekeeping.

Pesticides in the Modern World - Risks and Benefits, 2011

Pesticides in the Modern World-Risks and Benefits 90 system of plants (Knutson et al., 1990). In contrast to the above, there are few cases of pesticides proved dangerous to public health. A typical example is the chlorinated hydrocarbon DDT, which was previously used against mosquitoes. The active substance DDT contributed greatly to reduce the spread of diseases like malaria, but was withdrawn in 1970 as it was considered dangerous for human and environment safety. Active substances are classified into five groups according to their toxicity. The first group (Ia) includes the extremely toxic agricultural plant protection agents, while the four other groups of substances are listed in order of decreasing toxicity (Ib, II, III). The fifth group (U) includes substances that are unlikely to become toxic to humans (International Programme on Chemical Safety, 2004). The adverse effects of these compounds may be observed in a short period (acute toxicity) or after a long time (chronic toxicity). In any case, it should be noted that, although the annual reported number of deaths by poisoning is 355.000, only a part of these poisonings, which is not specified in the World Health Report, are due to pesticides (WHO The World Health Report, 2003). Moreover, all cases of poisoning are due to accidents, like accidental ingestion or inhalation of chemicals, and not by food intake. However, the possibility of indication of various effects in consumer health through chronic toxicity cannot be ignored. Toxicity of a plant protection product depends on various factors, including chemical structure, temperature and humidity conditions, dose, duration of exposure, mode of action and the kind of exposure, like ingestion, inhalation, dermal etc. Different groups of pesticides and veterinary drugs are likely to be responsible for causing malaise, sore eyes, abnormalities to skin and respiratory system. Moreover, some pesticides and veterinary drugs are suspected of causing certain types of cancer, teratogenicity, chromosomal abnormalities and the weakening of the immune system of humans (Banerjee, 1999). The toxicity of various active substances, which can be detected in bee products, varies according to their chemical synthesis. In any case, poisoning or deaths due to the presence of toxic substances exclusively to bee products have not been reported. An exception is the death of infants, which was caused by Clostridium botulinum (Arnon, 1980). Even in these cases, however, the responsibility of honey has not been proven clearly, as this clostridium appears in the environment widely (Midura, 1996). In addition, 65% of infants that became ill had not eaten honey at all (Arnon et al., 1979). In any case, appropriate infant feeding prohibits the consumption of honey until the age of one year to eliminate possible poisoning from toxins of this microorganism. Another way of classification of active substances, relates to the subject of this investigation, and is based on bee toxicity. In general, active substances are classified as very toxic, moderately toxic and non-toxic to bees. The most significant impact on bee colonies has been observed after treatments with plant protection products during the blooming. Most deaths occurred during the stage of forager worker bee that collects nectar and pollen. Moreover, larvae and domestic bees die because of pesticide residues detected in pollen. Although in many cases the concentration of pesticide found in pollen is not lethal, it is however likely to cause paralysis of bees, irritability, killing and replacing of the queen bee and generally abnormal behavior. This behavior can also be caused by substances that do not kill bees directly (e.g. carbaryl as active ingredient of Sevin®) but are transferred into the hive by foragers and affect the entire population (Sanford, 1993). The long-term persistence of many pesticides in stored pollen has also serious impact of bees' survival. Arsenic from paris green and calcium arsenate was present in pollen stored in comb analyzed six months after application. Methomyl residues persisted in honeybee combs for eight months. Methyl parathion from Penncap M, persisted in combs samples of stored pollen for 7 to 14 months after use and carbaryl similarly persisted over winter for 7-9 months (Erickson et al., 1983) www.intechopen.com

2012

Pesticides in the Modern World-Risks and Benefits 90 system of plants (Knutson et al., 1990). In contrast to the above, there are few cases of pesticides proved dangerous to public health. A typical example is the chlorinated hydrocarbon DDT, which was previously used against mosquitoes. The active substance DDT contributed greatly to reduce the spread of diseases like malaria, but was withdrawn in 1970 as it was considered dangerous for human and environment safety. Active substances are classified into five groups according to their toxicity. The first group (Ia) includes the extremely toxic agricultural plant protection agents, while the four other groups of substances are listed in order of decreasing toxicity (Ib, II, III). The fifth group (U) includes substances that are unlikely to become toxic to humans (International Programme on Chemical Safety, 2004). The adverse effects of these compounds may be observed in a short period (acute toxicity) or after a long time (chronic toxicity). In any case, it should be noted that, although the annual reported number of deaths by poisoning is 355.000, only a part of these poisonings, which is not specified in the World Health Report, are due to pesticides (WHO The World Health Report, 2003). Moreover, all cases of poisoning are due to accidents, like accidental ingestion or inhalation of chemicals, and not by food intake. However, the possibility of indication of various effects in consumer health through chronic toxicity cannot be ignored. Toxicity of a plant protection product depends on various factors, including chemical structure, temperature and humidity conditions, dose, duration of exposure, mode of action and the kind of exposure, like ingestion, inhalation, dermal etc. Different groups of pesticides and veterinary drugs are likely to be responsible for causing malaise, sore eyes, abnormalities to skin and respiratory system. Moreover, some pesticides and veterinary drugs are suspected of causing certain types of cancer, teratogenicity, chromosomal abnormalities and the weakening of the immune system of humans (Banerjee, 1999). The toxicity of various active substances, which can be detected in bee products, varies according to their chemical synthesis. In any case, poisoning or deaths due to the presence of toxic substances exclusively to bee products have not been reported. An exception is the death of infants, which was caused by Clostridium botulinum (Arnon, 1980). Even in these cases, however, the responsibility of honey has not been proven clearly, as this clostridium appears in the environment widely (Midura, 1996). In addition, 65% of infants that became ill had not eaten honey at all (Arnon et al., 1979). In any case, appropriate infant feeding prohibits the consumption of honey until the age of one year to eliminate possible poisoning from toxins of this microorganism. Another way of classification of active substances, relates to the subject of this investigation, and is based on bee toxicity. In general, active substances are classified as very toxic, moderately toxic and non-toxic to bees. The most significant impact on bee colonies has been observed after treatments with plant protection products during the blooming. Most deaths occurred during the stage of forager worker bee that collects nectar and pollen. Moreover, larvae and domestic bees die because of pesticide residues detected in pollen. Although in many cases the concentration of pesticide found in pollen is not lethal, it is however likely to cause paralysis of bees, irritability, killing and replacing of the queen bee and generally abnormal behavior. This behavior can also be caused by substances that do not kill bees directly (e.g. carbaryl as active ingredient of Sevin®) but are transferred into the hive by foragers and affect the entire population (Sanford, 1993). The long-term persistence of many pesticides in stored pollen has also serious impact of bees' survival. Arsenic from paris green and calcium arsenate was present in pollen stored in comb analyzed six months after application. Methomyl residues persisted in honeybee combs for eight months. Methyl parathion from Penncap M, persisted in combs samples of stored pollen for 7 to 14 months after use and carbaryl similarly persisted over winter for 7-9 months (Erickson et al., 1983) www.intechopen.com

Modern Beekeeping [Working Title]

This chapter deals with the effects of different pesticides used in agro-ecosystem on honey bees and other pollinators and probable measures to manage this escalating problem of global decline of managed as well as the wild insect pollinators. This chapter describes different routes from which pollinators, especially honey bees get exposed to the different toxicants, followed by poisoning symptoms in honey bees. Further, this chapter focuses on the classification of different toxicants in different classes as per their nature. Finally, the management of these different toxicants and their toxicity to avoid bee poisoning has been considered in the later portion of the chapter.

2021

The spread of disease and pests in bee colonies, habitat loss, reduced access to or quality of food resources, climate change, queen bee deterioration, changing trade practises, and exposure to apicultural and agricultural pesticides both in and out of beehives are all factors contributing to bee population decline. Pesticide exposure is a significant factor in this. A better awareness of the problems with bee pesticides should motivate all parties involved to take the necessary efforts to limit chemical impacts on bees and apiarist productivity. Pollinator species other than honey bees may be damaged if farmers contaminate the surrounding landscapes, particularly water bodies, with pesticides.

PLoS ONE, 2014

Bees are essential pollinators of many plants in natural ecosystems and agricultural crops alike. In recent years the decline and disappearance of bee species in the wild and the collapse of honey bee colonies have concerned ecologists and apiculturalists, who search for causes and solutions to this problem. Whilst biological factors such as viral diseases, mite and parasite infections are undoubtedly involved, it is also evident that pesticides applied to agricultural crops have a negative impact on bees. Most risk assessments have focused on direct acute exposure of bees to agrochemicals from spray drift. However, the large number of pesticide residues found in pollen and honey demand a thorough evaluation of all residual compounds so as to identify those of highest risk to bees. Using data from recent residue surveys and toxicity of pesticides to honey and bumble bees, a comprehensive evaluation of risks under current exposure conditions is presented here. Standard risk assessments are complemented with new approaches that take into account time-cumulative effects over time, especially with dietary exposures. Whilst overall risks appear to be low, our analysis indicates that residues of pyrethroid and neonicotinoid insecticides pose the highest risk by contact exposure of bees with contaminated pollen. However, the synergism of ergosterol inhibiting fungicides with those two classes of insecticides results in much higher risks in spite of the low prevalence of their combined residues. Risks by ingestion of contaminated pollen and honey are of some concern for systemic insecticides, particularly imidacloprid and thiamethoxam, chlorpyrifos and the mixtures of cyhalothrin and ergosterol inhibiting fungicides. More attention should be paid to specific residue mixtures that may result in synergistic toxicity to bees.

PLOS ONE, 2014

Recently, the widespread distribution of pesticides detected in the hive has raised serious concerns about pesticide exposure on honey bee (Apis mellifera L.) health. A larval rearing method was adapted to assess the chronic oral toxicity to honey bee larvae of the four most common pesticides detected in pollen and wax -fluvalinate, coumaphos, chlorothalonil, and chloropyrifos -tested alone and in all combinations. All pesticides at hive-residue levels triggered a significant increase in larval mortality compared to untreated larvae by over two fold, with a strong increase after 3 days of exposure. Among these four pesticides, honey bee larvae were most sensitive to chlorothalonil compared to adults. Synergistic toxicity was observed in the binary mixture of chlorothalonil with fluvalinate at the concentrations of 34 mg/L and 3 mg/L, respectively; whereas, when diluted by 10 fold, the interaction switched to antagonism. Chlorothalonil at 34 mg/L was also found to synergize the miticide coumaphos at 8 mg/L. The addition of coumaphos significantly reduced the toxicity of the fluvalinate and chlorothalonil mixture, the only significant non-additive effect in all tested ternary mixtures. We also tested the common 'inert' ingredient N-methyl-2-pyrrolidone at seven concentrations, and documented its high toxicity to larval bees. We have shown that chronic dietary exposure to a fungicide, pesticide mixtures, and a formulation solvent have the potential to impact honey bee populations, and warrants further investigation. We suggest that pesticide mixtures in pollen be evaluated by adding their toxicities together, until complete data on interactions can be accumulated.

Archives of Biological Sciences, 2017

Bees are potential pollinators of wide variety of crops. The European dark bee, Apis mellifera mellifera (L.) is widely used for crop pollination. However, pesticide usage in modern agriculture has threatened the plant-bee pollinator interaction. There is lack of data regarding lethal time, insecticide concentration and poisoning symptoms, especially for formulated insecticides that are widely used in insect management. This study shows that the intrinsic toxicity of insecticides (LC 50) to A. mellifera mellifera (L.) was in the following order: imidacloprid (0.0070) > fipronil (0.0125) > indoxacarb (0.0266)> cypermethrin (0.0370) > dimethoate (0.0385). The lethal time (LT 50) values (h) in the ascending order of toxicity of insecticides were as follows: fipronil (6.56), cypermethrin (6.69), dimethoate (8.00), imidacloprid (9.85) and indoxacarb (13.45). Distinct poisoning symptoms observed in A. mellifera mellifera were extended proboscis, expanded wings, unhooked wings, extended legs and twisted bodies, defecation on cage covers, sting in release-out position and anus with excreta. All the tested pesticides are harmful to the honey bee except azadirachtin. The tested pesticides exhibited different poisoning symptoms in bees, which could be useful for beekeepers in identifying the cause of colony mortality. In conclusion, the pesticide toxicological research on bees is an important safety aspect for beneficial organisms. This study reveals a realistic acute toxicity in the field of commonly used insecticides. The information is important for insecticide selection in order to minimize direct killing of foraging honey bees while maintaining effective management of crop pests.

Journal of Insect Science, 2015

Apis mellifera L. is the main pollinator of cultivated plants. With the increased emphasis on organic agriculture, the use of botanical insecticides has also increased. However, the effects of these products on bees remain to be determined. In this study, we aimed at assessing the acute toxicity and sublethal behavioral effects of botanical insecticides such as andiroba oil, citronella oil, eucalyptus oil, garlic extract, neem oil, and rotenone on honey bees, A. mellifera. Only andiroba oil demonstrated no lethality to A. mellifera adult workers. However, andiroba oil, garlic extract, and neem oil demonstrated an acute toxicity to bee larvae. Except for eucalyptus oil, larvae fed with syrup containing the other insecticides led to the development of lower body mass in adult workers. All these botanical insecticides were repellent to A. mellifera adult workers. In addition, the eucalyptus oil, garlic extract, neem oil, and rotenone decreased the rate of walking activity in adult workers. Our results demonstrate the potential acute toxicity and sublethal effects of botanical insecticides on honey bees and, thereby, provide evidence of the importance of assessing the risks of the side effects of biopesticides, often touted as environmentally friendly, to nontarget organisms such as pollinators.

Although the bee deaths that started in 2006 have passed for a long time, no solution has been found and even bee deaths have started to increase again in recent years. The end of winter and spring months are periods when bee deaths are seen intensely. When these periods are examined, it can be seen that many factors (disease-harmfulness, hunger, cold, etc.) cause bee deaths. One of these factors is the pesticides used in springtime in the wintering region. In this study, the effects of pesticides, which are commonly used against factors damaging agricultural crops grown in regions where bee deaths is high, on the body motor movements of the bees are investigated. The most commonly used product used for agricultural combat in pesticides used in our study and the label dose (recommended dose) used for this product was fed twice with the label dose and half by oral gavage, after 1, 4 and 24 hours, the bees were checked and some of the body parts (antenna, leg, abdomen and mouth parts) were rated according to motor movements. As a result of the study, pesticides affecting body motor movements of bees are listed as Chlorpyrifos-Ethyl, Imidacloprid, Deltamethrin, Thiacloprid, Acetamiprid, Abamectin and Tau-fluvalinate active substances from high to low. Spirodiclofen, Glyphosate Potassium Salt, and Penconazole active substance chemicals arranged in the same group with control and did not changed their body motor movements.