<p>Gut lactic-acid bacteria (LAB) are symbionts crucial for many physiological functions in insects and provide protection against diseases and intoxication by xenobiotics. Thus, changes in LAB communities facilitate the infection by pathogens or increase the susceptibility to pesticides. We aimed to evaluate the protective role of LAB isolates from the gut of the stingless bee <i>Scaptotrigona mexicana</i> and the honey bee <i>Apis mellifera</i> against four insecticides (malathion, imidacloprid, cypermethrin, and spinetoram). First, we estimated the oral median lethal dose (LD₅₀) in both bee species. Next, LAB were isolated from both bee species and subjected to sensitivity tests against the four pesticides. Finally, bees fed with those LAB strains that were not inhibited by the pesticides were orally exposed to the LD₅₀ of the insecticides. <i>Scaptotrigona mexicana</i> was more susceptible to spinetoram and cypermethrin compared to <i>A. mellifera</i>, which displayed greater susceptibility to malathion and imidacloprid. Sixteen LAB strains were selected for further scrutiny, ten from <i>S. mexicana</i> and six from <i>A. mellifera</i>. All strains from <i>A. mellifera</i> were discarded since they were susceptible to at least one insecticide. Conversely, none of the <i>S. mexicana</i> LAB strains was inhibited by them and was evaluated for any potential protective role against insecticides. Both <i>S. mexicana</i> and <i>A. mellifera</i> bees fed with LAB experienced a reduction of nearly 50% in the mortality by cypermethrin. No significant difference was observed between fed and unfed groups with the other insecticides. This is the first report of LAB providing interspecies protection against an insecticide in both a stingless bee and the honey bee.</p>