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In agriculture honey bees may be exposed to multiple pesticides. In contrast to single applications of plant protection products (PPP), the effects of tank mixtures of two or more PPP on honey bees are not routinely assessed in the risk assessment of plant protection products. However, tank mixes are often common practice by farmers. Mixtures of practically non-toxic substances can lead to synergistic increase of toxic effects on honey bees, observed for the first time in 19921 in combinations of pyrethroids and azole fungicides. 2004 Iwasa et al. already reported that ergosterol-biosynthesis-inhibiting (EBI) fungicides strongly increase the toxicity of neonicotinoids in laboratory for the contact exposure route. Furthermore, in agricultural practice additives, adjuvants and fertilizers may be added to the spray solution. For these additives usually no informations on potential side effects on bees are available when mixed with plant protection products. Therefore, it is considered necessary to investigate possible additive or synergistic impacts and evaluate potentially critical combinations to ensure protection of bees. Here, we investigated the effects on bees of combinations of insecticides, fungicides and fertilizers under controlled laboratory conditions. A spray chamber was used to evaluate effects following contact exposure by typical field application rates. Subsequently, mortality and behaviour of bees were monitored for at least 48 h following the OECD acute contact toxicity test 2143. Dependencies of synergistic effects and the time intervals between the applications of the mixing partners were evaluated.

Residues of plant protection products (PPPs) are frequently detected in bee matrices 1,2,3,4,5,6 due to foraging bees collecting contaminated nectar and pollen, which they bring back to their hive. The collected material is further used by nurse bees to produce glandular secretions for feeding their larvae. 7 Potential exposure to PPPs occurs through direct oral ingestion, contact during foraging, or interaction with contaminated hive material. 8,9 Contaminants can pose health risks to adult worker bees, 10,11 queens, 12,13 drones (males), 14 or larvae, 15,16 potentially impacting colony health and productivity. However, residue concentrations can vary significantly between analyzed matrices, and potential accumulation or dilution steps have not been widely investigated. Although research has provided valuable insights into contamination risks, there remain gaps in our understanding of the entire pathway from field, via foragers, stored products, nurse bees, and finally to food jelly, i.e., royal, worker, and drone jelly, and the larvae, including all possible processing steps. 17 We collected samples of bee-relevant matrices following the in-field spray application of the product Pictor Active, containing the fungicides boscalid and pyraclostrobin. The samples were analyzed for residues along this entire pathway. Fungicide residues were reduced by a factor of 8–80 from stored product to nurse bees' heads, suggesting a filtering function of nurse bees. Furthermore, detected residues in larval food jelly resulted from added pollen and not from nurse bee secretions. Calculated risk quotients were at least twice as low as the threshold values, suggesting a low risk to honey bee colonies from these fungicides at the tested application rate. [Display omitted] • Residues were analyzed along the entire transfer pathway from field to larvae • Residue concentrations decrease along the transfer pathway • Risk quotients for adult bees and larvae were below threshold values • Nurse honey bees act as a filter in the transfer of contaminants to larvae Wueppenhorst et al. investigate the full transfer pathway of two fungicides, from in-field application to honey bee larval food jelly and the larvae. Residues were diluted along the pathway and, based on residue levels, low risks are suggested for adult bees and larvae, indicating a filtering function of the honey bee colony. [ABSTRACT FROM AUTHOR]

Microbial pest control products are commonly applied worldwide as alternatives to avoid potential adverse effects of chemical plant protection products. Here, we aimed to evaluate the biosafety of a commercial product containing Bacillus thuringiensis ssp. aizawai (strain ABTS-1857) using four different approaches: 1) laboratory chronic exposure to evaluate the survival of adult and larval bee, 2) in-hive feeding under field conditions to examine the effect of B. t. on brood development and the core gut microbiome of adult bees, 3) semi-field colony-feeding to determine contamination levels of B. t. spores in various matrices, and 4) a field trial with spray application in a bee-attractive crop to estimate potential environmental accumulation and exposure of honey bee colonies. Adult bee and larval survival were negatively affected after chronic exposure depending on the tested concentrations; however, pollen feeding to adults promote survival of treated bees and delay the effects. Under colony conditions, treated colonies showed a higher brood termination rate and a significantly lower normalized abundance of the core gut microbiome in worker bees. B. t. spores were detectable in all matrices at different concentrations, decreasing over time under semi-field conditions. High spore levels were present in honey sacs and pollen pellets immediately after application. No spore reduction was seen in stored matrices like nectar and bee bread. In conclusion, the pest control product containing B. t. strain ABTS-1857 showed a negative effect on exposed bees under laboratory as well as field conditions, for instance on colony development and caused dysbiosis of the gut microbiome. However, further field-realistic exposure studies in bee attractive crops are needed to evaluate the potential risk of such products on honey bees. [ABSTRACT FROM AUTHOR]

This article responds to a previous article proposing reforms to pesticide regulations to protect pollinators. The authors, who are part of a risk assessment authority, aim to provide clarifications about the regulatory framework in Europe. They emphasize that both the active substance and formulated products undergo thorough risk assessments to ensure their safety. They also mention efforts to include non-Apis bees in risk assessments and the development of test methods for bumble bees and solitary bees. The authors welcome enhancements to regulatory testing and invite stakeholders to participate in discussions to improve risk assessment and management. [Extracted from the article]

An inventory and review of current pesticide regulatory risk assessment procedures for bees and other pollinators is presented. For North America, the European Union, Brazil, China, and Australia, the work is based on a review of the published literature, covering pesticide regulatory risk assessment approaches of high-income countries. For low- and middle income countries in the African, Pacific and Caribbean region, the work is based on an online questionnaire, conducted during the summer of 2021, followed by ad-hoc questions for further details and clarifications. In hindsight, the focus on the above-mentioned high-income countries is justified, as the expectations were met that it is a widespread practice for low- and middle-income countries to consult assessments by APVMA (Australia), USEPA (USA) and EFSA (European Union). Protection goals in the published approaches focus on bees, especially the honey bee as a prevailing model organism. Approaches incorporating further taxa, in particular with regard to local pollination services, may be adopted in the future, but are currently prevented by knowledge gaps. All established risk assessment procedures follow a tiered approach, and establishing a lower-tier system in regions currently lacking risk assessment procedures is a much more important step toward improved pollinator protection compared to risk refinement at higher tiers. Several established risk assessment approaches include toxicity classification, which are similar to each other in general, offering an opportunity to assess risks at a screening level without data on exposure. However, basic toxicity data on pesticides are currently not required at all in many low- and middle-income countries. Thus, establishment of a general requirement of data on acute toxicity for honey bees would markedly improve risk assessment in these countries, given that obtaining and assessing such data is a comparatively standardized endeavour and not particular resource demanding. Exposure is handled in different ways by the established risk assessment procedures, with similarities in considered application methods, but marked differences between further parameters of exposure scenarios, e.g. regarding spatial and temporal relation between pesticide application and exposure event, contaminated matrices considered etc. There is a general consensus in the established risk assessment procedures with regard to adopted guidelines and guidance documents used for effect assessment. Approaches established by EPPO, EFSA and USEPA all compare exposure-toxicity quotients to predefined levels of concern for identification of unresolved unacceptable risks to bees, while the calculative basis for these quotients and/or threshold values differs between these approaches, reflecting particular application or situation specific factors or models, accounting inter alia for background mortality, interspecific extrapolation, uncertainty, measured residue data. The other established risk assessment procedures largely follow the approaches of EPPO, EFSA or USEPA. Risk enveloping might offer a resource saving strategy to assess risks of pesticides with similar use patterns in similar cropping systems, and adopting an approach similar to a working example set by IBAMA in Brazil might be feasible, at least for similar geographic regions, given that there are some commonalities in pollinator depend crops among the surveyed low- and middle-income countries. Risk management and uncertainty analysis should always be linked to the risk assessment at all stages, and resulting risk mitigation measures should be practicable in the local agricultural context and comprehensible, while not compromising product efficacy. [ABSTRACT FROM AUTHOR]

The importance of microbial plant protection products (PPPs) in agriculture is steadily increasing, especially since they are considered to substitute chemical PPPs. Tank mixes are often common practice by farmers to reduce costs and increase the effectivity by controlling a broader spectrum of pests. However, there is no available information on the possible interactions between microbial PPPs and bee ́s responses after exposure to such combinations. We studied several tank mixes of microbial PPPs depending on application of the products on the same crops. Five products with different microorganisms as active ingredients and their combination were tested, including Bacillus thuringiensis ssp. aizawai (strain: ABTS-1857), B. thuringiensis ssp. kurstaki (strain: EG 2348), B. amyloliquefacien (strain: QST 713), Beauveria bassiana (strain: ATCC 74040) and Cydia pomonella granulosis virus (GV0005). Caged winter honey bees were placed in an incubator at 26°C and 65% humidity and exposed orally either acute or chronic (over 10 d) to the maximum recommended application rate of solo-product or mixture of two products. Mortality and food uptake amount was recorded daily over 15 d. Our results show that mixture of products containing B. thuringiensis ssp. aizawai and B. amyloliquefacien caused higher mortality rate compared to the solo products, whereas the effects in other mixtures are mostly related to the solo products which have the strongest effects. On the other hand, mixtures containing C. pomonella granulosis virus and/ or B. thuringiensis ssp. kurstaki did not affect the beeʼs survival compared to the other microbial PPPs. In conclusion, further studies are necessary to assess the effects of such mixtures as the effects of tank mixtures of two or more PPPs on honey bees, as these are not routinely assessed in the risk assessment of plant protection products. [ABSTRACT FROM AUTHOR]

The article offers study on the assessment of the impacts of microbial plant protection products on the health and development of the gut microbiome of honeybee. It discusses the Microbial plant protection products as substitutes for chemical plant protection products enjoy an increasing popularity because of their compatibility with integrated pest management.