1. INTRODUCTION
There are over twenty thousand
species of beetles worldwide, distributed across all continents except
Antarctica. Notably, beetles play a crucial role in ecosystems. They
have the ability to disrupt the breeding habitats of pests and parasites
harmful to livestock(deCastro-Arrazola et al., 2023; Gregory et al.,
2015), thereby facilitating the spread of human pathogens(Nichols &
Gómez, 2014), Additionally, they accelerate the return of nutrients from
feces to soil(Sitters et al., 2014), contributing to improved soil
aeration, water retention, and fertility(Kirsch, 2011). Moreover,
beetles promote plant growth(deCastro-Arrazola et al., 2020), assist in
seed dispersal(Pedersen & Blüthgen, 2022), and even provide essential
pollination services(Pokhrel et al., 2021; Sakai & Inoue, 1999).
The microbial community within the
digestive tract of insects, also known as gut microbiota, comprises
protozoa, fungi, archaea, and bacteria(Rozadilla et al., 2020).
This diverse consortium plays a
crucial role in providing essential nutrients to the host, aiding in
efficient food digestion, enhancing host defense mechanisms, and
enabling detoxification processes(Kaltenpoth, 2020). Moreover, it exerts
a significant influence on various aspects of the host insect’s life,
including its lifespan, developmental cycle, mating behaviors, and
reproductive capacities(Dong et al., 2021). Despite its importance,
research into the gut microbiota of beetles is currently in its early
exploratory stages. However, several studies have already unveiled
noteworthy findings. For instance, Franzini et al. conducted a
comparison of the gut microbiota among two distinct small desert beetle
species, revealing intriguing intra-species variations(Franzini et al.,
2016). In a separate investigation by Suarez-Moo et al., greater
similarity in gut microbiota was observed between the larvae ofCopris incertus Say and the female adults, suggesting a potential
mode of vertical transmission that shapes the composition and diversity
of offspring gut microbiota(Suárez-Moo et al., 2020). Furthermore, a
novel yeast species named Trichosporon heliocopridis , extracted
from the gut of Heliocopris bucephalus Fabricius , has exhibited
the remarkable ability to assimilate various carbon sources while
withstanding environmental stressors such as high temperature, salt,
sugar, and ethanol concentrations(Nwaefuna et al., 2021). Additionally,
the gut of Thorectes lusitanicus harbors several species
belonging to the Actinobacteria phylum, known to produce an array of
secondary metabolites with antibiotic properties, thus contributing to
host protection(Kaltenpoth, 2009). It’s worth noting that symbiotic
bacteria within insects also serve as a significant source for
discovering new bioactive small molecules, presenting valuable
opportunities for the identification and utilization of beneficial
natural products.
Dung beetles, exemplified by Catharsius molossus , are a
distinctive group of coprophagous insects that confront specific
nutritional challenges within their daily dietary regime. Being reliant
on fecal matter as their primary food source, they encounter limitations
in accessing adequate nitrogen nutrition, as feces typically harbor low
nitrogen content(Madzivhe et al., 2020). Moreover,
fecal matter is laden with diverse
parasites and pathogens that could potentially impact the health of dung
beetles(Woo et al., 2023). In this study, we utilized advanced 16S rRNA
high-throughput sequencing technology to extensively scrutinize the
diversity and differential composition of the gut microbiota ofCatharsius molossus under conditions of both starvation and
refeeding. Our endeavor is centered on unraveling the consequences of
periods of food deprivation followed by subsequent refeeding on the
structural dynamics of the gut microbiota in Catharsius molossus .
This research holds substantial promise in enhancing our comprehension
of the intricate ecological functionalities of the gut microbiota in
dung beetles, with particular emphasis on the roles assumed by
nitrogen-fixing bacteria and the prospective development and application
of antimicrobial agents. The outcomes anticipated from this study are
poised to contribute significantly to the foundational knowledge of dung
beetle ecosystems and the broader domain of physiological ecology,
thereby ushering in novel insights and perspectives to this realm of
scientific inquiry.