Diversity of Symbiotic Organs and Bacterial Endosymbionts of Lygaeoid Bugs of the Families Blissidae and Lygaeidae (Hemiptera: Heteroptera: Lygaeoidea)
ABSTRACT
Here we present comparative data on the localization and identity of intracellular symbionts among the superfamily Lygaeoidea (Insecta: Hemiptera: Heteroptera: Pentatomomorpha). Five different lygaeoid species from the families Blissidae and Lygaeidae (sensu stricto; including the subfamilies Lygaeinae and Orsillinae) were analyzed. Fluorescence
in situ
hybridization (FISH) revealed that all the bugs studied possess paired bacteriomes that are differently shaped in the abdomen and harbor specific endosymbionts therein. The endosymbionts were also detected in female gonads and at the anterior poles of developing eggs, indicating vertical transmission of the endosymbionts via ovarial passage, in contrast to the posthatch symbiont transmission commonly found among pentatomoid bugs (Pentatomomorpha: Pentatomoidea). Phylogenetic analysis based on 16S rRNA and
groEL
genes showed that the endosymbionts of
Ischnodemus sabuleti
,
Arocatus longiceps
,
Belonochilus numenius
,
Orsillus depressus
, and
Ortholomus punctipennis
constitute at least four distinct clades in the
Gammaproteobacteria
. The endosymbiont phylogeny did not agree with the host phylogeny based on the mitochondrial cytochrome oxidase I (
COI
) gene, but there was a local cospeciating pattern within the subfamily Orsillinae. Meanwhile, the endosymbiont of
Belonochilus numenius
(Lygaeidae: Orsillinae), although harbored in paired bacteriomes as in other lygaeoid bugs of the related genera
Nysius
,
Ortholomus
, and
Orsillus
, was phylogenetically close to “
Candidatus
Rohrkolberia cinguli,” the endosymbiont of
Chilacis typhae
(Lygaeoidea: Artheneidae), suggesting an endosymbiont replacement in this lineage. The diverse endosymbionts and the differently shaped bacteriomes may reflect independent evolutionary origins of the endosymbiotic systems among lygaeoid bugs.