Divergence in Gut Bacterial Community Among Life Stages of the Rainbow Stag Beetle Phalacrognathus muelleri (Coleptera: Lucanidae)

Abstract

Although stag beetles are popular saprophytic insects, there are few studies about their gut bacterial community. This study focused on the gut bacterial community structure of the rainbow stag beetle (i.e., Phalacrognathus muelleri) in its larvae (three instars) and adult stages, using high throughput sequencing (Illumina Miseq). Our aim was to compare the gut bacterial community structure among different life stages. The results revealed that bacterial alpha diversity increased from the 1st instar to the 3rd instar larvae. Adults showed the lowest gut bacterial alpha diversity. Bacterial community composition was significantly different between larvae and adults (p = 0.001), and 1st instar larvae (early instar) had significant differences with the 2nd (p= 0.007) and 3rd (p = 0.001) instar larvae (final instar). However, there was little difference in the bacterial community composition between the 2nd and 3rd instar larvae (p = 0.059). Our study demonstrated dramatic shifts in gut bacterial community structure between larvae and adults. Larvae fed on decaying wood and adults fed on beetle jelly, suggesting that diet is a crucial factor shaping the gut bacterial community structure. There were significant differences in bacterial community structure between early instar and final instars larvae, suggesting that certain life stages are associated with a defined gut bacterial community.

Integrative Insight into Relationships between Florivorous Thrips Haplothrips leucanthemi and H. niger (Insecta, Thysanoptera)

“…Surprisingly, the SIMPROF analysis did not support the groups of profiles that were identified according to the developmental stage of the host. Differences in the associated microbiota, which are congruent with the host's development, have been previously reported for the fungivorous thrips Hoplothrips carpathicus [57] and other insect species (e.g., the oriental fruit flies Bactrocera dorsalis [60] and B. tryoni [61], the stag beetle Phalacrognathus muelleri [62], or the fungivorous beetle Bolitophagus reticulatus [63]), where significant dissimilarities were especially observed between the microbiota associated with larvae and adults. In the present study, the sample size was limited and additional microbiota profiles associated with those two developmental stages of H. leucanthemi and H. niger should be analyzed to confirm the lack of significant differences among their associated bacterial communities (especially taking into account that the results of the pairwise PERMANOVA tests supported the significant differences between the profiles associated with H. leucanthemi larvae and adults, and between the profiles determined for both H. leucanthemi and H. niger larvae).…”

Complete metamorphosis and microbiota turnover in insects

“…Studies of the dipteran Musca domestica (20) and the coleopteran Phalacrognathus muelleri (21) have found a similar pattern.…”

“…Hammer et al (2014) also found distinct gut microbiota communities in the leaf‐chewing larvae and nectar‐ and pollen‐feeding adults in the lepidopteran Heliconius erato . Studies of the dipteran Musca domestica (de Jonge et al, 2020) and the coleopteran Phalacrognathus muelleri (Wang et al, 2020) have found a similar pattern.…”

Complete metamorphosis and microbiota turnover in insects

“…Hammer, McMillan, & Fierer (19) also found distinct gut microbiota communities in the leaf-chewing larvae and nectar- and pollen-feeding adults in the lepidopteran Heliconius erato. Studies of the dipteran Musca domestica (20) and the coleopteran Phalacrognathus muelleri (21) have found a similar pattern.…”