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Bumblebees of Bombus terrestris are indispensiblepollinators for ecosystems and for various agriculturalcrops. Unfortunately, bumblebees are challengedby various stress factors including insecticide applications. Today sublethal effects of various insecticides need to bethoroughly investigated to allow their combined use withpollinators and other beneficial organisms. In this study, weused lambda-cyhalothrin as a model pyrethroid insecticideand investigated lethal and sublethal effects by differentdilutions, ranging from 1/10 to 1/100 of its maximum fieldrecommended dosage (MFRC, 37.5 ppm), with the use of achronic toxicity tests in the laboratory and in flight cages inthe greenhouse. In the laboratory, small microcolonies withfive bumblebee workers with one being pseudo-queen wereused, while in the greenhouse we used queen-right minihiveswhere the bumblebees need to fly for pyrethroidcontaminatedfood. We observed strong sublethal effects inthe laboratory with treatments of 1/10 and 1/20 of theMFRC: the nest reproduction was reduced by 49 and 32 %,respectively, and the sugar water consumption by 36 %.With free-flying bumblebees, the toxic effects at 1/10 ofthe MFRC were more pronounced. A mortality of88 ± 8 % was observed after only 2 weeks, being twicethe mortality in the laboratory microcolonies test(43 ± 11 %). Besides, it should be mentioned that in thegreenhouse experiment all queens were dead and most ofthe workers showed signs of incoordination and convulsionand gradually became apathetic. In conclusion, our resultsdemonstrated the pyrethroid lambda-cyhalothrin with arange of lethal and sublethal effects, both crucial for thedevelopment and survival of the B. terrestris colonies.Moreover, this study supports the demand to test insecticidecompounds on their safety, especially when the beeshave to perform complex tasks such as foraging for theirfood.