Actinomycete bacteria in firebug guts

Red firebugs (Pyrrhocoris apterus, Hemiptera: Pyrrhocoridae) harbor actinomycete bacteria of the genus Coriobacterium in specific portions of their mid-gut. The bacteria are transmitted vertically via egg-smearing, but horizontal transmission can also occur by the uptake of symbionts from the feces of conspecific individuals.

The bacteria appear to have significant effects on the fitness of the host insect: aposymbiotic (= symbiont-free) bugs show slower growth rates, increased mortality, and lower reproductive success than symbiont-containing bugs. Presumably, the bacteria aid in the nutrition of the host, and we are investigating which nutrients are provided by the bacteria. Additionally, we aim to find out how the insects sustain the bacterial growth within the mid-gut.

Closely related symbiotic bacteria can be found in the African cotton stainer bug (Dysdercus fasciatus, Hemiptera: Pyrrhocoridae). We established methods to successfully exchange Coriobacterium symbionts between the two different Pyrrhocorid host species, and we are currently investigating the effects of symbiont exchange on host fitness as well as on the composition of the microbial community in the mid-gut.