Effect of high temperature on Wolbachia density and impact on cytoplasmic incompatibility in confused flour beetle, Tribolium confusum (Coleoptera: Tenebrionidae).

OBJECTIVES

Environmental constraints, especially temperature, have been identified as a key in understanding host-symbiont relationships, as they can directly impact the fitness of the symbiont population and the host development. Here we investigated the effect of temperature during the host development on the density of intracellular bacteria of the Wolbachia, wTcon strain within the confused flour beetle, Tribolium confusum. The wTcon can induce a complete cytoplasmic incompatibility (CI) in T. confusum beetles; therefore, we observed the effect of heat stress on the symbiont-mediated CI.

RESULTS

The density of CI inducing Wolbachia in the Tribolium confusum is temperature-specific. Our observation of the beetles reared in five different temperatures (30-34 °C) measured the highest Wolbachia density at 30-31 °C and lowest at 34 °C within a single insect generation. In this species, changes in the density of Wolbachia related to higher temperature did not influence CI. However, the fertility of beetles reared in higher temperatures showed a substantial decrease in the number of laid and hatched eggs. Thus, we can confirm the effect of high temperature on lowering the wTcon density and no impact on induction of cytoplasmic incompatibility (CI) in T. confusum beetles.