Gut bacteria of weevils developing on plant roots under extreme desert conditions

Abstract

BackgroundMany phytophagous insects, whose diet is generally nitrogen-poor, rely on gut bacteria to compensate for nutritional deficits. Accordingly, we hypothesized that insects in desert environments may evolve associations with gut bacteria to adapt to the extremely low nutrient availability. For this, we conducted a systematic survey of bacterial communities in the guts of weevils developing inside mud chambers affixed to plant roots in the Negev Desert of Israel, based on 16S rRNA gene amplicon sequencing.ResultsOur analyses revealed that gut bacterial communities in weevil larvae were similar across a wide geographical range, but differed significantly from those of the mud chambers and of the surrounding soils. Nevertheless, a high proportion of bacteria (including all of the core bacteria) found in the weevils were also detected in the mud chambers and soils at low relative abundances. The genus Citrobacter (of the Enterobacteriaceae family) was the predominant group in the guts of all individual weevils. The relative abundance of Citrobacter significantly decreased at the pupal and adult stages, while bacterial diversity increased. A mini literature survey revealed that members of the genus Citrobacter are associated with nitrogen fixation, recycling of uric acid nitrogen, and cellulose degradation in different insects.ConclusionsThe results suggest that although weevils could potentially acquire their gut bacteria from the soil, weevil host internal factors, rather than external environmental factors, were more important in shaping their gut bacterial communities, and suggest a major role for Citrobacter in weevil nutrition in this challenging environment. This study highlights the potential involvement of gut bacteria in the adaptation of insects to nutritional deficiencies under extreme desert conditions.

Host species identity shapes the diversity and structure of insect microbiota

“…Differences between insect species have been found in aphids (Fakhour et al, 2018; Gallo‐Franco et al, 2019; McLean et al, 2019; Zepeda‐Paulo et al, 2018), mealybugs (Lin et al, 2019), reduviids (Rodríguez‐Ruano et al, 2018), fruit flies (Ventura et al, 2018; Yong et al, 2017), beetles (Hulcr et al, 2012; Kolasa et al, 2019), silkworms (Chen et al, 2018), Lepidoptera (Liu et al, 2020; van Schooten et al, 2018), mosquitoes (Mancini et al, 2018), and bees and wasps (Skrodenytė‐Arbačiauskienė et al, 2019; Suenami et al, 2019). Conversely, other studies did not report differences when comparing different insect species (Berasategui et al, 2016; Meng et al, 2019; Ramalho et al, 2017). Together with the result that host species explains most of the variability of insect‐associate microbial communities, this might suggest the existence of a relationship between host phylogeny and the diversity/structure of insect‐associated microbiota.…”

Host species identity shapes the diversity and structure of insect microbiota

“…Differences between insect species have been found in aphids (Zepeda-Paulo et al, 2018;Fakhour et al, 2018;McLean et al, 2019;Gallo-Franco et al, 2019), mealybugs (Lin et al, 2019), reduviids (Rodríguez-Ruano et al, 2018), fruit flies (Ventura et al, 2018;Yong et al, 2017), beetles (Hulcr et al, 2012;Kolasa et al, 2019), silkworms (Chen et al, 2018), Lepidopera (van Schooten et al, 2018;Liu et al, 2020), mosquitoes (Mancini et al, 2018), bees and wasps (Skrodenytė-Arbačiauskienė et al, 2019;Suenami et al, 2019). Conversely, other studies did not report differences when comparing different insect species (Berasategui et al, 2016;Ramalho et al, 2017;Meng et al, 2019a). Together with the result that host species explains most of the variability of insect-associate microbial communities, this might suggest the existence of a relationship between host phylogeny and the diversity/structure of insect-associated microbiota.…”

Arthropods as the Engine of Nutrient Cycling in Arid Ecosystems

“…High N resorption efficiency in desert plants leaves the remaining litter N locked up in recalcitrant compounds [92]. Therefore, fixation of atmospheric N might be a highly beneficial strategy for desert primary consumers, as a way to bypass this barrier [93]. In Australian arid zones, N fixation by termite gut symbionts is a major source of N in unvegetated patches [94] and of nitrate in groundwater [95].…”