Scientists urge transition to pollinator-friendly agriculture
Utrecht & Tokyo, 7 June 2013
Honeybee disorders and high colony losses have become global phenomena. An international team of scientist led by Utrecht University synthesized recent findings on the effects of neonicotinoid pesticides on bees. Scientists conclude that owing to their large scale prophylaxic use in agriculture, their high persistence in soil and water, and their uptake by plants and translocation to flowers, neonicotinoids put pollinator services at risk.
Press release Utrecht University - May 2, 2013
Insect numbers have been declining in recent years. Research by Utrecht University has found a link between the super insecticide imidacloprid and a decline in abundance of insects and other invertebrates in surface-water. Scientists are ringing international alarm bells. “Stricter standards alone are not enough. This insecticide is so harmful and remains in the environment for so long that an international ban is definitely warranted.”
EFSA scientists have identified a number of risks posed to bees by three neonicotinoid insecticides. The Authority was asked by the European Commission to assess the risks associated with the use of clothianidin, imidacloprid and thiamethoxam as seed treatment or as granules, with particular regard to: their acute and chronic effects on bee colony survival and development; their effects on bee larvae and bee behaviour; and the risks posed by sub-lethal doses of the three substances. In some cases EFSA was unable to finalise the assessments due to shortcomings in the available data.
Triodos Foundation requests your support for research
• Everywhere in the world a strong decline is observed in the presence of (wild) bees and other insects, playing a major role in pollination and reproduction of 80 % of wild plants and cultivated crops.
• Systemic pesticides are unprecedentedly poisonous for bees and other pollinating insects and are disastrous to the richness of insects in soil and water. Worldwide its use has increased in a period of 10 years to become the most widely used and strongest growing type of insecticide. Its application in ever increasing larger scale will not remain without consequences, not only for the insect richness of the planet, insect eating birds but eventually for humans as well. Insiders are extremely worried about this.
• On many places (partial) research is being done. However, there is a need for a coordinated and widely independent research by an international multidisciplinary team of honest scientists.
A 72-page 2010 publication raises new and troubling questions about a widely used insecticide's potential for harm to bees, beneficial insects, and bird populations. Using imidacloprid as an example, Dutch toxicologist Dr. Henk Tennekes reports on the hazards of imidacloprid to insects and birds. Imidacloprid is a neonicotinoid chemical, and has systemic action in plants. Other European researchers have linked this insecticide to significant risks for honey bee populations, including possible links to Colony Collapse Disorder.
[Summery story by Dr. Henk Tennekes on the background for starting this Dutch website]
Bees are dying at an alarming rate. Mortality doubled in Holland over the last six years. Elsewhere in Europe and in the US the situation is similar. In parts of China farmers are even forced to pollinate by hand. This ecological crisis threatens to bring global agriculture to a standstill. What are the reasons behind the decline of bee colonies across the globe? Some scientists believe pests, such as the varroa mite or Nosema ceranae, are at the root of this devastation. Recent French studies, however, suggest that these pests struck particularly hard in areas where a new class of insecticides, the so-called neonicotinoids, were being used. Neonicotinoids are insecticides which act on the central nervous system of insects with lower toxicity to mammals. The insecticides are water soluble and thus readily translocated in plant tissue and particularly effective against sucking insects. The application rates for neonicotinoids are much lower than older, traditionally used insecticides. They appear to be ideal insecticides, but unfortunately there are major disadvantages as well.
The European Commission has decided to ban three neonicotinoid insecticides. These chemicals can harm honeybees, according to a large body of scientific evidence, so the European Environment Agency (EEA) commends the precautionary decision to ban them.
Read full EEA highlight:
The American Bird Conservancy (ABC) says preliminary results of a study it is conducting show that EPA is underestimating the aquatic toxicity to birds and other wildlife of the controversial neonicotinoid class of insecticides, adding pressure to the agency to more strictly regulate those products amid concerns over their pollinator risks.
"Based on . . . preliminary results, we have reason to believe that EPA has underestimated the aquatic toxicity of the entire class of neonicotinoid insecticides," Cynthia Palmer, pesticide programs manager at ABC, says in Nov. 14 comments to EPA regarding the agency's registration review dockets for two of the neonicotinoids -- acetamiprid and thiacloprid.
Abstract: Reported widespread declines of wild and managed insect pollinators have serious consequences for global ecosystem services and agricultural production1, 2, 3. Bees contribute approximately 80% of insect pollination, so it is important to understand and mitigate the causes of current declines in bee populations 4, 5, 6. Recent studies have implicated the role of pesticides in these declines, as exposure to these chemicals has been associated with changes in bee behaviour7, 8, 9, 10, 11 and reductions in colony queen production12. However, the key link between changes in individual behaviour and the consequent impact at the colony level has not been shown. Social bee colonies depend on the collective performance of many individual workers. Thus, although field-level pesticide concentrations can have subtle or sublethal effects at the individual level8, it is not known whether bee societies can buffer such effects or whether it results in a severe cumulative effect at the colony level. Furthermore, widespread agricultural intensification means that bees are exposed to numerous pesticides when foraging13, 14, 15, yet the possible combinatorial effects of pesticide exposure have rarely been investigated16, 17. Here we show that chronic exposure of bumblebees to two pesticides (neonicotinoid and pyrethroid) at concentrations that could approximate field-level exposure impairs natural foraging behaviour and increases worker mortality leading to significant reductions in brood development and colony success. We found that worker foraging performance, particularly pollen collecting efficiency, was significantly reduced with observed knock-on effects for forager recruitment, worker losses and overall worker productivity. Moreover, we provide evidence that combinatorial exposure to pesticides increases the propensity of colonies to fail.
By Toshiro Yamada, Kazuko Yamada and Naoki Wada, Jpn. J. Clin. Ecol. （Vol.21 No.1 2012)
Abstract Recently it has become a serious problem that honeybees suddenly vanish in their colony, which is referred to as a colony collapse disorder（ CCD）. We have made it clear by the field experiments for about four months what effect neonicotinoid pesticides such as dinotefuran and clothianidin have on the occurrence of CCD. Eight colonies consisting of about ten-thousand honeybees in each colony were investigated under the practical beekeeping conditions in our apiary. In this study foods containing dinotefuran of 1 ppm to 10 ppm or clothianidin of 0.4 ppm to 4 ppm were fed into a beehive. Three levels of concentration were 10（ high-conc.）, 50（ middle-conc.） and 100 low-conc.） times lower than that in practical use. The changes of adult bees, brood and the pesticide intake in each colony were directly examined. They suggest that each colony with the pesticide administered collapses to nothing after passing through a state of CCD, the high-concentration pesticides seem to work as an acute toxicity and the low- and middle-concentration ones do as a chronic toxicity. CCD looks mysterious, but it is just one of situations where a colony dwindles to nothing. We have proposed a CCD occurrence mechanism based on our results.
The NMR spectral analyses of dinotefuran and clothianidin in aqueous solution give the speculations that both are thermally stable under the heating condition of 50 ℃ ×24 hours and dinotefuran is radiationally stable under the ultraviolet-irradiation condition of 310 nm×50 W/m2 but clothianidin is unstable.
Abstract: There has been recent interest in the threat to bees posed by the use of systemic insecticides. One concern is that systemic insecticides may translocate from the soil into pollen and nectar of plants, where they would be ingested by pollinators. This paper reports on the movement of two such systemic neonicotinoid insecticides, imidacloprid and thiamethoxam, into the pollen and nectar of flowers of squash (Cucurbita pepo cultivars “Multipik,” “Sunray” and “Bush Delicata”) when applied to soil by two methods: (1) sprayed into soil before seeding, or (2) applied through drip irrigation in a single treatment after transplant. All insecticide treatments were within labeled rates for these compounds. Pollen and nectar samples were analyzed using a standard extraction method widely used for pesticides (QuEChERS) and liquid chromatography mass spectrometric analysis. The concentrations found in nectar, 10±3 ppb (mean ± s.d) for imidacloprid and 11±6 ppb for thiamethoxam, are higher than concentrations of neonicotinoid insecticides in nectar of canola and sunflower grown from treated seed, and similar to those found in a recent study of neonicotinoids applied to pumpkins at transplant and through drip irrigation. The concentrations in pollen, 14±8 ppb for imidacloprid and 12±9 ppb for thiamethoxam, are higher than those found for seed treatments in most studies, but at the low end of the range found in the pumpkin study. Our concentrations fall into the range being investigated for sublethal effects on honey bees and bumble bees.
Abstract: Declines in pollinator colonies represent a worldwide concern. The widespread use of agricultural pesticides is recognized as a potential cause of these declines. Previous studies have examined the effects of neonicotinoid insecticides such as imidacloprid on pollinator colonies, but these investigations have mainly focused on adult honey bees. Native stingless bees (Hymenoptera: Apidae: Meliponinae) are key pollinators in neotropical areas and are threatened with extinction due to deforestation and pesticide use. Few studies have directly investigated the effects of pesticides on these pollinators. Furthermore, the existing impact studies did not address the issue of larval ingestion of contaminated pollen and nectar, which could potentially have dire consequences for the colony. Here, we assessed the effects of imidacloprid ingestion by stingless bee larvae on their survival, development, neuromorphology and adult walking behavior. Increasing doses of imidacloprid were added to the diet provided to individual worker larvae of the stingless bee Melipona quadrifasciata anthidioides throughout their development. Survival rates above 50% were only observed at insecticide doses lower than 0.0056 µg active ingredient (a.i.)/bee. No sublethal effect on body mass or developmental time was observed in the surviving insects, but the pesticide treatment negatively affected the development of mushroom bodies in the brain and impaired the walking behavior of newly emerged adult workers. Therefore, stingless bee larvae are particularly susceptible to imidacloprid, as it caused both high mortality and sublethal effects that impaired brain development and compromised mobility at the young adult stage. These findings demonstrate the lethal effects of imidacloprid on native stingless bees and provide evidence of novel serious sublethal effects that may compromise colony survival. The ecological and economic importance of neotropical stingless bees as pollinators, their susceptibility to insecticides and the vulnerability of their larvae to insecticide exposure emphasize the importance of studying these species.
Abstract: Bumble bees are important pollinators whose populations have declined over recent years, raising widespread concern. One conspicuous threat to bumble bees is their unintended exposure to trace residues of systemic neonicotinoid pesticides, such as imidacloprid, which are ingested when bees forage on the nectar and pollen of treated crops. However, the demographic consequences for bumble bees of exposure to dietary neonicotinoids have yet to be fully established. To determine whether environmentally realistic levels of imidacloprid are capable of making a demographic impact on bumble bees, we exposed queenless microcolonies of worker bumble bees, Bombus terrestris, to a range of dosages of dietary imidacloprid between zero and 125 μg/L and examined the effects on ovary development and fecundity. Microcolonies showed a dose-dependent decline in fecundity, with environmentally realistic dosages in the range of 1 μg/L capable of reducing brood production by one third. In contrast, ovary development was unimpaired by dietary imidacloprid except at the highest dosage. Imidacloprid reduced feeding on both syrup and pollen but, after controlling statistically for dosage, microcolonies that consumed more syrup and pollen produced more brood. We therefore speculate that the detrimental effects of imidacloprid on fecundity emerge principally from nutrient limitation imposed by the failure of individuals to feed. Our findings raise concern about the impact of neonicotinoids on wild bumble bee populations. However, we recognize that to fully evaluate impacts on wild colonies it will be necessary to establish the effect of dietary neonicotinoids on the fecundity of bumble bee queens.
EFSA has published a state-of-the-art scientific review of the risks posed by pesticides to honey bees, bumble bees and solitary bees. This major piece of work will support the development of specific guidance for the assessment of possible risks to bees from the use of plant protection products. The guidance will provide up-to-date advice to those involved in the evaluation of plant protection products and their active substances, including industry and public authorities.
Abstract - Concern about the role of pesticides in honey bee decline has highlighted the need to examine the effects of sublethal exposure on bee behaviors. The video-tracking system EthoVisionXT (Noldus Information Technologies) was used to measure the effects of sublethal exposure to tau-fluvalinate and imidacloprid on honey bee locomotion, interactions, and time spent near a food source over a 24-h observation period. Bees were either treated topically with 0.3, 1.5, and 3 mg tau-fluvalinate or exposed to 0.05, 0.5, 5.0, 50, and 500 ppb imidacloprid in a sugar agar cube. Tau-fluvalinate caused a significant reduction in distance moved at all dose levels (p<0.05), as did 50 and 500 ppb imidacloprid (p<0.001). Bees exposed to 50 and 500 ppb spent significantly more time near the food source than control bees ( p<0.05). Interaction time decreased as time in the food zone increased for both chemicals. This study documents that video-tracking of bee behavior can enhance current protocols for measuring the effects of pesticides on honey bees at sublethal levels. It may provide a means of identifying problematic compounds for further testing.
ABSTRACT: Pollination is a well-studied and at the same time a threatened ecosystem service. A significant part of global crop production depends on or profits from pollination by animals. Using detailed information on global crop yields of 60 pollination dependent or profiting crops, we provide a map of global pollination benefits on a 5′ by 5′ latitude-longitude grid. The current spatial pattern of pollination benefits is only partly correlated with climate variables and the distribution of cropland. The resulting map of pollination benefits identifies hot spots of pollination benefits at sufficient detail to guide political decisions on where to protect pollination services by investing in structural diversity of land use. Additionally, we investigated the vulnerability of the national economies with respect to potential decline of pollination services as the portion of the (agricultural) economy depending on pollination benefits. While the general dependency of the agricultural economy on pollination seems to be stable from 1993 until 2009, we see increases in producer prices for pollination dependent crops, which we interpret as an early warning signal for a conflict between pollination service and other land uses at the global scale. Our spatially explicit analysis of global pollination benefit points to hot spots for the generation of pollination benefits and can serve as a base for further planning of land use, protection sites and agricultural policies for maintaining pollination services.
The European Ombudsman, P. Nikiforos Diamandouros, has opened an investigation into whether the European Commission has taken appropriate measures to combat increased bee mortality in the EU, which is potentially linked to certain insecticides. This follows a complaint from the Austrian Ombudsman Board, alleging that the Commission has failed to take into account new scientific evidence arguing in favour of restricting the use of these insecticides. The Ombudsman has asked the Commission to submit an opinion by 30 June 2012.
Abstract – During their foraging activity, honey bees are often exposed to direct and residual contacts with pesticides, especially insecticides, all substances specifically designed to kill, repel, attract or perturb the vital functions of insects. Insecticides may elicit lethal and sublethal effects of different natures that may affect various biological systems of the honey bee. The first step in the induction of toxicity by a chemical is the interaction between the toxic compound and its molecular target. The action on the molecular target can lead to the induction of observable or non-visible effects. The toxic substance may impair important processes involved in cognitive functions, behaviour or integrity of physiological functions. This review is focused on the neural effects of insecticides that have repercussions on (a) cognitive functions, including learning and memory, habituation, olfaction and gustation, navigation and orientation; (b) behaviour, including foraging and (c) physiological functions, including thermoregulation and muscle activity.
Re this study, at first glance it appears to support the hypothesis that chronic exposure to field realistic doses of imidacloprid during summer and fall can lead to late winter collapse of the treated colonies.
[Press release Harvard School of Public Health] Imidacloprid, one of the most widely used neonicotinoid pesticides, has been named as the likely culprit in the sharp worldwide decline in honey bee colonies since 2006. Researchers at the Harvard School of Public Health say their new research provides "convincing evidence" of the link between imidacloprid and colony collapse disorder. "It apparently doesn't take much of the pesticide to affect the bees," says Alex Lu, associate professor of environmental exposure biology at Harvard's Department of Environmental Health, "Our experiment included pesticide amounts below what is normally present in the environment."
Sudden losses of bees have been observed in spring during maize sowing. The death of bees has been correlated with the use of neonicotinoid-coated seed and the toxic particulates emitted by pneumatic drilling machines. The contamination of foragers in flight over the ploughed fields has been hypothesized. The airborne contamination has been proven, both with bees inside fixed cages around the field and in free flight near the driller. A new trial involving mobile cages has been established and consists of making rapid passes with single bees inside cages fixed to an aluminium bar. The bar was moved by two operators at different distances from the working drilling machine. A single pass was shown as sufficient to kill all the bees exposed to exhaust air on the emission side of the drill, when bees were subsequently held in high relative humidity. The extent of toxic cloud around driller was evaluated at the height of 0.5, 1.8 and 3.5 m and proved to be about 20 m in diameter, with an ellipsoidal shape. The shape may be influenced by working speed of the drill and environmental parameters, and is easily shown by adding talc powder to the seed in the machine hopper. A new driller equipment was evaluated consisting of two tubes inclined towards the soil that direct the exhaust air towards the ground. The survival rate of the bees was not substantially increased using the modified drill and was lower than 50%. Chemical analyses show up to 4000 ng of insecticide in single bees with an average content around 300 ng. Similar quantities were observed at increased distances from the modified or unmodified drillers. This new evaluation of bee mortality in the field is an innovative biological test to verify the hypothetical efficiency (or not) of driller modifications.
On 30 March 2012 Science published 2 studies and a comment on neonicotinoid insecticides and pollinator decline:
- A Common Pesticide Decreases Foraging Success and Survival in Honey Bees
- Neonicotinoid Pesticide Reduces Bumble Bee Colony Growth and Queen Production
- Field Research on Bees Raises Concern About Low-Dose Pesticides
New study in Nature - Scientific Reports finds strong evidence for pesticide + pathogen hypothesis as key explanation for bee disorders.
ABSTRACT: In ecosystems, a variety of biological, chemical and physical stressors may act in combination to induce illness in populations of living organisms. While recent surveys reported that parasite-insecticide interactions can synergistically and negatively affect honeybee survival, the importance of sequence in exposure to stressors has hardly received any attention. In this work, Western honeybees (Apis mellifera) were sequentially or simultaneously infected by the microsporidian parasite Nosema ceranae and chronically exposed to a sublethal dose of the insecticide fipronil, respectively chosen as biological and chemical stressors. Interestingly, every combination tested led to a synergistic effect on honeybee survival, with the most significant impacts when stressors were applied at the emergence of honeybees. Our study presents significant outcomes on beekeeping management but also points out the potential risks incurred by any living organism frequently exposed to both pathogens and insecticides in their habitat.
ABSTRACT ELISA techniques were used to detect imidacloprid in guttation fluid of young cantaloupe plants in Arizona. Imidacloprid was detected at up to 4.1 micro g/ml (ppm) in a coincidental guttation collection 3 d after a top label rate soil application and at 37 micro g/ml one d after a separate top label rate soil application study. These imidacloprid titers exceed reported median oral toxicities for several insect species by factors of 10 or more. Pesticides in guttation fluid are a relatively unexplored route of exposure for both pest and beneficial insects, and could represent an important risk for both of these groups in guttation-prone environments.
Background: Honey bees are exposed to phytochemicals through the nectar, pollen and propolis consumed to sustain the colony. They may also encounter mycotoxins produced by Aspergillus fungi infesting pollen in beebread. Moreover, bees are exposed to agricultural pesticides, particularly in-hive acaricides used against the parasite Varroa destructor. They cope with these and other xenobiotics primarily through enzymatic detoxificative processes, but the regulation of detoxificative enzymes in honey bees remains largely unexplored.
Methodology/Principal Findings: We used several approaches to ascertain effects of dietary toxins on bee susceptibility to synthetic and natural xenobiotics, including the acaricide tau-fluvalinate, the agricultural pesticide imidacloprid, and the naturally occurring mycotoxin aflatoxin. We administered potential inducers of cytochrome P450 enzymes, the principal biochemical system for Phase 1 detoxification in insects, to investigate how detoxification is regulated. The drug phenobarbital induces P450s in many insects, yet feeding bees with phenobarbital had no effect on the toxicity of taufluvalinate, a pesticide known to be detoxified by bee P450s. Similarly, no P450 induction, as measured by tau-fluvalinate tolerance, occurred in bees fed xanthotoxin, salicylic acid, or indole-3-carbinol, all of which induce P450s in other insects.
Only quercetin, a common pollen and honey constituent, reduced tau-fluvalinate toxicity. In microarray comparisons no change in detoxificative gene expression was detected in phenobarbital-treated bees. However, northern blot analyses of guts of bees fed extracts of honey, pollen and propolis showed elevated expression of three CYP6AS P450 genes. Diet did not influence tau-fluvalinate or imidacloprid toxicity in bioassays; however, aflatoxin toxicity was higher in bees consuming sucrose or high-fructose corn syrup than in bees consuming honey.
Conclusions/Significance: These results suggest that regulation of honey bee P450s is tuned to chemicals occurring naturally in the hive environment and that, in terms of toxicological capacity, a diet of sugar is not equivalent to a diet of honey.