This 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.

本研究旨在评估含有活性物质苏云金芽孢杆菌ssp的微生物害虫防治产品 (MPCP) 的效果。相泽（菌株：ABTS-1857）对蜜蜂的成虫和幼虫。为了确定不同基质中 Bt 孢子的污染水平，进行了半田条件下的菌落饲养研究。此外，在实验室条件下进行了两项慢性成虫试验和一项慢性幼虫研究，以测试不同浓度的植物保护产品 (PPP) 对发育和死亡率的影响。通过额外的花粉喂养评估了慢性经口毒性试验的可能修改。我们的结果表明，在整个测试持续时间内，所有基质中都检测到不同浓度的 Bt 孢子，随着时间的推移而减少。根据测试浓度，长期接触 MPCP 后，成年蜜蜂和幼虫的存活在实验室条件下受到负面影响。而且，由于暴露于 ABTS-1857 导致蜜蜂死亡的最早迹象仅在最高测试浓度下 96 小时后记录。给成虫喂食花粉显着提高了经过处理的蜜蜂的存活率。总之，带有 Bt 菌株 ABTS-1857 的 PPP 在实验室条件下显示出对成虫和幼虫死亡率的影响。有必要在实际现场条件下对基于 Bt 的 PPP 进行进一步研究，以评估这些 MPCP 对蜜蜂的潜在风险。