Fig. 1.

Oral priming with spore culture supernatants increases survival of T. castaneum larvae. The figure shows the survival of T. castaneum larvae 3 days after constant exposure to 5 × 10⁹ ml^-1 of live Btt spores in the flour in relation to the different priming treatments and the corresponding media controls. Larvae primed with supernatants of Btt and Bt 407gfpcry^- were compared to larvae exposed to the plain (unconditioned) medium without supernatant as control (black bars). In addition, the medium control for Bt 407gfp-neocry⁺ supernatant primed larvae contained neomycin, since this strain of bacteria was raised with this antibiotic (striped bars). Naïve group (white bar) larvae were exposed to diet mixed with buffer (PBS) only. Significant differences are indicated with asterisks. Sample size at the time point of challenge was as follows: Btt: 91, Bt 407gfpcry^-: 94, medium control: 93, naïve: 93, Bt 407gfp-neocry⁺: 92 and medium control with neomycin (neo): 95. * p < 0.01.