Suchergebnisse

AbstractBiopesticides, having as active ingredients viruses, bacteria, or fungi, are developed to substitute or reduce the use of chemical plant protection products in different agrosystems. Though the application of mixtures containing several products is a common practice, interactions between microbial biopesticides and related effects on bees as non-target organisms have not been studied yet. In the current study, we exposed winter bees to five different microbial-based products and their combinations at the maximum recommended application rate to assess their responses. Laboratory oral exposure tests (acute/chronic) to single or binary products were conducted. Survival and food consumption of the tested bees were evaluated over the experimental duration. Our results show that some product combinations have potential additive or synergistic effects on bees, whereas others did not affect the bee's survival compared to the control. Exposure of tested bees to the most critical combination of products containing Bacillus thuringiensis aizawai ABTS-1857 and B. amyloliquefaciens QST 713 strongly resulted in a median lifespan of 4.5 days compared to 8.0 and 8.5 days after exposure to the solo products, respectively. The exposure to inactivated microorganisms by autoclaving them did not differ from their respective uncontaminated negative controls, indicating effects on bee mortality might originate in the treatment with the different microorganisms or their metabolites. Further investigations should be conducted under field conditions to prove the magnitude of observed effects on bee colonies and other bee species.

AbstractThe increasing use of Bacillus thuringiensis (Bt)–based plant protection products (PPPs) has recently raised some concerns regarding their environmental accumulation and possible chronic exposure of non-target species, including pollinators, to higher than expected doses. The exposure level of such microbial PPPs in bee's matrices under field conditions has not yet been described. Therefore, the current study aims at evaluating the realistic exposure level and comparing the distributions and persistence of Bt spores under field conditions. A field trial with spray application in oilseed rape (Brassica napus) as a representative bee-attractive crop was conducted. During the experimental period, different matrices, including honeybee-collected and -stored matrices as well as bee larvae and dead bees, were collected and analyzed using newly established methods. The concentration of Bt spores in the various matrices was quantified. The results show high levels of Bt spores in honey sac and pollen pellets with reduction over time but no reduction of Bt spores in the stored matrices within the colony, i.e., nectar and bee bread, over time. Our results show for the first time the exposure level of bees to Bt spores under realistic field conditions and are fundamentally important for assessing potential exposure and risks for pollinators.

AbstractThis study was aimed at evaluating the effect of a microbial pest-controlling product (MPCP) with the active substance Bacillus thuringiensis ssp. aizawai (strain: ABTS-1857) on adults and larvae of honeybees. To determine the contamination levels of Bt spores in different matrices, a colony-feeding study under semi-field conditions was performed. Furthermore, two chronic adult trials and a chronic larval study were conducted under laboratory conditions to test the effects of different concentrations of the plant protection product (PPP) on the development and mortality. Possible modifications of the chronic oral toxicity test were assessed by additional pollen feeding. Our results showed that Bt spores were detected in all matrices over the entire test duration in different concentrations, decreasing over time. The survival of adult bees and larvae was negatively affected in laboratory conditions after a chronic exposure to the MPCP depending on the tested concentrations. Moreover, the earliest sign of bee mortality, resulting from exposure to ABTS-1857, was recorded only after 96 h at the highest tested concentration. Pollen feeding to adults significantly increased the survival of the treated bees. In conclusion, the PPP with the Bt strain ABTS-1857 showed an effect on the mortality of adults and larvae under laboratory conditions. Further studies with Bt-based PPPs under realistic field conditions are necessary to evaluate the potential risk of those MPCPs on honeybees.

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.