Conclusions
Overall, we did not find any consistent patterns linking CHC profile
variation, CHC biosynthesis transcriptome diversity, and social
complexity across the seven Blattodea species included in our study.
This is partially reflective of the results Kather and Martin (2015)
obtained in their meta-analysis of solitary and eusocial Hymenopteran
CHC diversity, although this study was lacking the genetic component.
This implies that, at least for our representative species spanning
different levels of social complexity within the order Blattodea,
neither their CHC profiles nor their repertoire of CHC biosynthesis gene
transcripts does reflect any social hierarchy or correlate with their
social complexity. Concerning the genetic background of CHC
biosynthesis, however, it must be taken into account that our general
knowledge remains limited and mostly biased towards Drosophila(Holze et al. 2021), so it is quite possible that more
Blattodea-specific CHC biosynthesis genes exist which have not been
functionally characterized yet and have therefore eluded our
comprehensive gene transcript investigation. Nevertheless, our study
challenges the long-standing assumption of a general correlation between
increasing social complexity and chemical profile sophistication for our
Blattodea study species. Therefore, we strongly suggest more cautious
approaches for assessing, comparing, and interpreting chemical
complexity in insects with different levels of social organization.
Tables
Tab 1 : List of 21 genes with a demonstrated function in the CHC
biosynthesis pathway for which we could detect transcripts in at least
one of our tested cockroach and termite species. The numbers correspond
to the position of the respective gene product in the biosynthesis
pathway (compare to Fig. 1). Gene acronyms, (putative) functions, NCBI
(or Genbank when not available in NCBI) IDs and the taxon where the gene
was originally described are indicated along with the detected copy
numbers in our tested species. The CHC biosynthesis genes were retrieved
from Holze et al. (2021).