“…Although the main trigger for EFB is the gram-positive microaerophilic Melissococcus plutonius (Forsgren, 2010;White, 1912) other bacteria, for example, Enterococcus faecalis, Paenibacillus alvei, Brevibacillus laterosporus, Bacillus pumilus, and Achromobacter euridice, have been shown to co-occur with EFB as the so-called secondary invaders (Erler, Denner, Bobiş, Forsgren, & Moritz, 2014;Forsgren, 2010). Whereas, M. plutonius is undoubtedly pathogenic and triggers EFB, P. alvei, B. pumilus, and A. euridice have also been identified as common bacterial species of the adult honeybee intestinal microflora (Gilliam, 1997) and B. laterosporus was detected in honeybee larvae, pupae, and foragers without being pathogenic (Marche, Mura, & Ruiu, 2016). However, besides the co-occurrence with M. plutonius, the role of the secondary invaders during EFB progress is not understood.…”