Bijensterfte, oorzaken en gevolgen

Report finds systemic pesticides not as effective as once thought, cites pest resistance as key reason to end mass uses of the harmful substances.

Overview
A new study published in the academic journal Environmental Science and Pollution Research calls into question the value of neonicotinoid insecticides (“neonics”) in agriculture. The research, conducted by the international Task Force on Systemic Pesticides, reviews more than 200 studies on the performance of neonics in controlling a wide range of insect pests on agricultural crops worldwide, including corn, wheat and many types of fruits and vegetables, as well as the available alternatives.

Teken nu de petitie Red de bij, Nederland gifvrij
In de derde week van maart 2018 stemt de EU opnieuw over een definitief verbod voor buitenteelten voor de neonicoitinoïden: clothianidin, imidacloprid, thiamethoxam. Initiatiefnemers en ondertekenaars willen dat Nederland stemt voor dit verbod. Hiermee beschermen we niet alleen de bijen, maar ook onze eigen gezondheid en de vitaliteit van onze leefomgeving.
Petitie: "Beste minister Schouten, bescherm onze bijen en stem voor een verbod op neonicotinoiden binnen de EU. U heeft de Nationale Bijenstrategie getekend, u noemt uzelf de bijenkoningin van Nederland. U bent een doortastende politica, die niet met zich laat sollen. Bijen en burgers rekenen op u! Wij roepen u op te stemmen voor een totaalverbod op de neonicotinoïden: clothianidin, imidacloprid en thiamethoxam voor buitenteelten om onze wilde bijen te beschermen. U bent niet alleen: Recentelijk benoemden de VN het gebruik van pesticiden als schending van het mensenrecht op gezondheid. Bovendien zullen Verenigd Koninkrijk, Frankrijk, Luxemburg, Estland, Malta, Slovenië, Ierland, Kroatië ook voor een totaalverbod stemmen en zo hun burgers en hun bijen beschermen."
https://secure.avaaz.org/nl/petition/Minister_Schouten_Bescherm_onze_bijen_en_stem_voor_een_totaalverbod_op_neo/

Wetenschappers dringen aan op transitie naar bijvriendelijke landbouw
Utrecht & Tokyo, 7 juni 2013
Wereldwijd kampen imkers met abnormaal hoge volksterfte en verzwakte bijen. Een internationaal team van wetenschappers geleid door Universiteit Utrecht bracht de recente wetenschappelijke stand van kennis in kaart over de effecten van neonicotinoïde insecticiden op bijen. Grootschalig preventief gebruik in de landbouw, in combinatie met hoge persistentie in bodem en water en opname door planten die het gif doorgeven aan hun stuifmeel en nectar, leiden tot substantiële risico’s. De wetenschappers concluderen dat de bestuiving van bloeiende planten en landbouwgewassen op het spel staat.

In een ingezonden brief in NRC van 11 mei 2013 geven Henk Vijverberg en voormalig Ctgb college lid Bas Blaauboer vier argumenten waarom ze vraagtekens plaatsen bij de betrouwbaarheid van onze studie in PLOS ONE naar de effecten van imidaclopridvervuiling van oppervlaktewater op de insectenrijkdom in en om het water. In het onderstaande weerleg ik deze argumenten/kritiekpunten een voor een.

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:
http://www.eea.europa.eu/highlights/neonicotinoid-pesticides-are-a-huge

Vrijdag 5 april 2013 verscheen het rapport van de Britse parlementaire enquette naar de misstanden bij de toelating van neonicotinoide insecticiden. Het parlementaire onderzoek waarin in uren lange zittingen gericht op waarheidsvinding tal van wetenschappers en industriemensen stevig aan de tand gevoeld zijn komt tot heldere conclusies. Er zijn grote redenen tot zorg dat het grootschalig gebruik van neonicotinoiden bijdraagt aan de sterke achteruitgang van wilde bestuivende insecten en bijdraagt aan de toegenomen problemen in de hongingbijenhouderij. Met de toelating is veel mis en de recente veldstudie waarmee Dr. Helen Thompson van Food and Environment Research Agency de eerdere veldstudie van Whitehorn ea (2012) (naar de lange termijn effecten van imidacloprid op het aantal koninginnen per hommelvolk) onderuit dacht te halen, is wetenschappelijk ver beneden de maat. De bevindingen van Whitehorn dat imidacloprid bij normaal toegelaten gebruik zeer schadelijk is voor hommels, blijven overeind.

Belangrijkste aanbeveling, unaniem gedragen door alle partijen in het lagerhuis :
Per 1 januari 2014 moeten imidacloprid, clothianidine en thiamethoxam in Engeland voorlopig worden verboden in voor bijen aantrekkelijke gewassen. Alle toelatingen voor particulier gebruik moeten per direct ingetrokken. De Britse regering moet zich daarnaast inzetten voor een Europees verbod.

[PERSBERICHT partij voor de dieren]
Neonicotinoïden brengen bijen in gevaar
Partij voor de Dieren wil onmiddellijk verbod op gevaarlijke bestrijdingsmiddelen

Den Haag, 16 januari 2012 - Na een jarenlange discussie over de oorzaken van bijensterfte concludeert ook de Europese Voedsel- en Warenautoriteit dat neonicotinoïden, een zeer giftig landbouwgif, een acuut en ernstig gevaar zijn voor de gezondheid van bijen. De Partij voor de Dieren wil dat deze middelen per direct van de markt worden gehaald.

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.

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.

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.

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."

Abstract
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

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.