Polyphagy in the agricultural pest <em>Diaprepes abbreviatus</em> and the possible role of its gut microbiota

Abstract

<em>Diaprepes abbreviatus</em> (Coleoptera: Curculionidae), a polyphagous pest affecting over 300 plant species in the Caribbean and United States, is primarily controlled using environmentally harmful chemical pesticides. Because it has been shown that the microbiome may influence the development and growth of many insects, safer control methods are being tested by targeting digestive processes. However, data on adult <em>D. abbreviatus</em> gut anatomy, pH, and microbiota remain scarce. This study investigates the gut microbiome of adult <em>D. abbreviatus</em> as a potential target for safer pest control methods. We examined the effects of diet on fecal microbial profiles, characterized gut anatomy and pH, and analyzed gut microbiota composition across different gut regions and between genders. Fecal microbial profiles of weevils fed exclusively on lemon, guava, or passion fruit leaves were analyzed using 16S rRNA gene amplicon sequencing, revealing potential diet-based differences in bacterial abundance and diversity, with the insects fed with passion fruit leaves having the more diverse and abundant fecal microbiome. Gut anatomy was described using Scanning Electron Microscopy (SEM), which showed structural differences between gut regions but did not allow for the observation of bacteria. Colorimetry analysis indicated that gut pH of adult <em>D. abbreviatus</em> ranged from 2.8 to 4.0, with the middle and posterior gut being most acidic, although no differences were observed by gender. Shotgun metagenomic profiling of gut microbiota revealed an abundance of <em>Propionibacteriaceae</em> and <em>Enterobacteriaceae</em> in the posterior and complete gut of both males and females. Additionally, trends in sex-specific microbial composition were noted, although not significant. The complete gut showed, overall, higher observed genera median values. This gut region along with females seemed to have higher diversity and abundance of bacteria, but we did not observed differences in the alpha and beta diversity at the genus level. Additionally, the gut microbiota was al analyzed by a 16S rRNA gene sequencing done with Oxford Nanopore Technologies MinION. Similar to the shotgun data, the results suggest variances in bacterial phyla by gut region and gender, with the complete gut and females having the most abundant and diversity of bacterial phyla. As expected, we found all the phyla and genera in the complete gut, confirming the presence of the bacteria in the gut regions. This may indicate a specific microbiota by gut region pH, functions and gender, but more information is needed at the species or strain levels. These findings provide insights into the digestion process of polyphagous insects and may contribute to the development of environmentally friendly, cost effective and targeted biocontrol strategies.