Survival of third-instar gypsy moth larvae reared without enteric bacteria (antibiotics) or with enteric bacteria (no antibiotics) fed bacterial cell-derived compounds and B. thuringiensis (Bt). Two formulations of B. thuringiensis, DiPel 50 IU (upper) and MVPII 20 μg (lower), were assayed. All experimental treatments were provided on artificial diet without antibiotics, gray shading indicates days on which larvae received treatments. The effects of the compounds were assessed in comparison to B. thuringiensis toxin and significance of treatments was determined using the log-rank analysis of PROC LIFETEST (SAS 9.1, Table 2, Additional file 2). Treatments with a survival distribution function that differ significantly from B. thuringiensis toxin alone (p < 0.05) are shown; p-values of all treatments are presented in Table 2. Three independent cohorts of larvae were assayed. No mortality was observed when larvae were fed the compounds alone (Additional file 3).