pubmed.ncbi.nlm.nih.gov

Increased survival in the red flour beetle after oral priming with bacteria-conditioned media - PubMed

Increased survival in the red flour beetle after oral priming with bacteria-conditioned media

Barbara Milutinović et al. J Innate Immun. 2014.

Abstract

Immune priming is defined as enhanced protection upon secondary exposure to a pathogen. Such enhanced resistance after prior exposure has been demonstrated for a number of insect species including the red flour beetle, Tribolium castaneum. In testing this phenomenon, the majority of studies have focused on introducing the pathogen into the insect's hemocoel via septic wounding through the cuticle. Although such septic injury can occur in nature, many pathogens enter their hosts via the oral route, i.e. by ingestion. Bacillus thuringiensis bacteria are well-known insect pathogens that infect their host orally. We found that T. castaneum larvae showed increased survival after oral exposure to B. thuringiensis, when they had been orally primed with filter-sterilized media in which spores of B. thuringiensis had been raised. Such priming was achieved only with a naturally pathogenic strain of B. thuringiensis and a strain that was made pathogenic by transfer of plasmids. Moreover, primed larvae were smaller in size 24 h after priming and had a longer developmental time, indicating that investment in such a response comes at a cost. However, the increased survival in primed larvae was not caused by larval size differences upon challenge.

© 2013 S. Karger AG, Basel.

PubMed Disclaimer

Figures

Fig. 1
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.

Fig. 2
Fig. 2

Costs of priming. Proportion of different developmental stages of T. castaneum 20 days after exposure to the priming diet (36 days after oviposition). Treatment groups and media controls are as described in figure 1. Samples size at the time point of transfer to naïve diet (see Materials and Methods section) was as follows: Btt: 177, Bt 407gfpcry-: 183, medium control: 176, naïve: 173, Bt 407gfp-neocry+: 175 and medium control with neomycin (neo): 181. * p < 0.0001.

Fig. 3
Fig. 3

Relationship between priming and larval size. a Survival in relation to priming treatment. Survival is shown 3 days after constant exposure to 5 × 109 ml-1 of live Btt spores in flour. Larvae were primed with supernatants of Btt, Btk, Bt 407cry-. Larvae exposed to the plain (unconditioned) medium and buffer (PBS) served as control. b Growth (difference in larval area before challenge and before priming) of T. castaneum larvae after exposure to the priming diet and the medium control. Since size class had no influence on priming, survival and growth data are shown pooled for small and large size class. Significant differences are indicated with asterisks. Pooled sample sizes at the time point of challenge were as follows: Btt: 188, Btk: 182, Bt 407cry-: 182, medium control: 187 and naïve: 178. * p < 0.0001.

Similar articles

Cited by

References

    1. Chambers MC, Schneider DS. Pioneering immunology: insect style. Curr Opin Immunol. 2011;24:1–5. - PubMed
    1. Kurtz J, Franz K. Evidence for memory in invertebrate immunity. Nature. 2003;425:37–38. - PubMed
    1. Kurtz J. Specific memory within innate immune systems. Trends Immunol. 2005;26:186–192. - PubMed
    1. Little TJ, Kraaijeveld AR. Ecological and evolutionary implications of immunological priming in invertebrates. Trends Ecol Evol. 2004;19:58–60. - PubMed
    1. Schmid-Hempel P. Evolutionary ecology of insect immune defenses. Annu Rev Entomol. 2005;50:529–551. - PubMed

Publication types

MeSH terms

Substances