Abstract
The coffee berry borer (CBB); Hypothenemus hampei (Coleoptera: Curculionidae), is widely recognized as the major insect pest of coffee crops. Like many other arthropods, CBB harbors numerous bacteria species that may have important physiological roles in host nutrition, detoxification, immunity and protection. To date, the structure and dynamics of the gut-associated bacterial community across the CBB life cycle is not yet well understood. A better understanding of the complex relationship between CBB and its bacterial companions may provide new opportunities for insect control. In the current investigation, we analyzed the diversity and abundance of gut microbiota across the CBB developmental stages under field conditions by using high-throughput Illumina sequencing of the 16S ribosomal RNA gene. Overall, 15 bacterial phyla, 38 classes, 61 orders, 101 families and 177 genera were identified across all life stages, including egg, larva 1, larva 2, pupa, and adults (female and male). Proteobacteria and Firmicutes phyla dominated the microbiota along the entire insect life cycle. Among the 177 genera, the 10 most abundant were members of Ochrobactrum (15.1%), Pantoea (6.6%), Erwinia (5.7%), Lactobacillus (4.3%), Acinetobacter (3.4%), Stenotrophomonas (3.1%), Akkermansia (3.0%), Agrobacterium (2.9%), Curtobacterium (2.7%), and Clostridium (2.7%). We found that the overall bacterial composition is diverse, variable within each life stage and appears to vary across development. About 20% of the identified OTUs were shared across all life stages, from which 28 OTUs were consistently found in all life stage replicates. Among these OTUs there are members of genera Pantoea, Erwinia, Agrobacterium, Ochrobactrum, Pseudomonas, Acinetobacter, Brachybacterium, Sphingomonas and Methylobacterium, which can be considered as the gut-associated core microbiota of H. hampei. Our findings bring additional data to enrich the understanding of gut microbiota in CBB and its possible use for development of insect control strategies.
Highlights
Mutualistic bacteria and fungi provide advantageous services to insect hosts by facilitating the digestion of recalcitrant food (Genta et al, 2006; Brune, 2014), providing essential nutrients (Feng et al, 2019), promoting immunity or protection against pathogens, parasites, or predators (Koch and SchmidHempel, 2011; Muhammad et al, 2019), contributing to interand intraspecific communication (Engl and Kaltenpoth, 2018; Calcagnile et al, 2019), and modulating the interaction of phytophagous insects with host plants (Acevedo et al, 2017)
We found that Proteobacteria and Firmicutes dominate the microbiota in the coffee berry borer (CBB) gut in all life stages (Figure 2A), which was similar to observations in previous studies for the CBB adult under field conditions (Mariño et al, 2018) and in other insects (Engel et al, 2012; Yun et al, 2014; Chen et al, 2018), including 13 species of the Scolytinae bark beetle Dendroctonus (HernándezGarcía et al, 2017)
The findings presented here improve the knowledge concerning the dynamics of the gut microbial community associated with the CBB gut during the insect life history
Summary
Mutualistic bacteria and fungi provide advantageous services to insect hosts by facilitating the digestion of recalcitrant food (Genta et al, 2006; Brune, 2014), providing essential nutrients (Feng et al, 2019), promoting immunity or protection against pathogens, parasites, or predators (Koch and SchmidHempel, 2011; Muhammad et al, 2019), contributing to interand intraspecific communication (Engl and Kaltenpoth, 2018; Calcagnile et al, 2019), and modulating the interaction of phytophagous insects with host plants (Acevedo et al, 2017) This complex mutualistic relationship between microbial symbionts and insect hosts has likely played a special role in the adaptive radiation and diversification of phytophagous insect species due to the potential microbial influence on host plantassociated ecological opportunity and divergent natural selection (Janson et al, 2008). An increasing number of agriculturally relevant pest insects are the focus for microbiome-insect mutualism studies thanks to the development of culture-independent techniques such as gene amplicon high-throughput sequencing (e.g., 16S rRNA) and shotgun metagenomics (Bharti and Grimm, 2019; Gurung et al, 2019)
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