Unity Makes Strength: A Review on Mutualistic Symbiosis in Representative Insect Clades

Abstract

Settled on the foundations laid by zoologists and embryologists more than a century ago, the study of symbiosis between prokaryotes and eukaryotes is an expanding field. In this review, we present several models of insect–bacteria symbioses that allow for the detangling of most known features of this distinctive way of living, using a combination of very diverse screening approaches, including molecular, microscopic, and genomic techniques. With the increasing the amount of endosymbiotic bacteria genomes available, it has been possible to develop evolutionary models explaining the changes undergone by these bacteria in their adaptation to the intracellular host environment. The establishment of a given symbiotic system can be a root cause of substantial changes in the partners’ way of life. Furthermore, symbiont replacement and/or the establishment of bacterial consortia are two ways in which the host can exploit its interaction with environmental bacteria for endosymbiotic reinvigoration. The detailed study of diverse and complex symbiotic systems has revealed a great variety of possible final genomic products, frequently below the limit considered compatible with cellular life, and sometimes with unanticipated genomic and population characteristics, raising new questions that need to be addressed in the near future through a wider exploration of new models and empirical observations.

The Role of Bacterial Symbionts in Triatomines: An Evolutionary Perspective

“…Insects, however, are not limited to bipartite interactions with single microorganisms as they also harbor and interact with a microbiota comprised of many non-pathogenic and potentially pathogenic bacteria, fungi, viruses, and protozoans (= the holobiont) that can affect the insects’ diet, physiology, immunity, and reproduction. In many cases, beneficial symbionts from the microbiota are essential and have allowed insects to expand and adapt to different environments [ 1 , 2 , 3 , 4 ]. The abundance, tissue specificity, taxa represented, and location (including intra-or extracellular) of these symbionts and the general microbiota is variable among insects, and in many cases depict tight coevolutionary histories [ 5 , 6 , 7 ].…”

Characterization of CRISPR-Cas Systems in Serratia marcescens Isolated from Rhynchophorus ferrugineus (Olivier, 1790) (Coleoptera: Curculionidae)

“…However, studies of CRISPR diversity can also greatly help in the understanding of evolutionary dynamics of specific bacteria populations [44]. The symbiotic association between eukaryotes and prokaryotes is now recognised as one of the main forces shaping life on our planet [45]. Concerning this, the data presented here supply both a comprehensive characterization of CRISPR-Cas systems in S. marcescens symbionts of RPW and the first comparative analysis of CRISPR loci in S. marcescens .…”

When bacteria meet mitochondria: The strange case of the tick symbiont Midichloria mitochondrii †

“…Douglas, ), but advances are limited by the paucity of genetically amenable systems and culturable symbionts. Arthropods are among the most studied symbiotic hosts, due to their extreme species‐richness, broad distribution and importance as pathogen vectors, but also due to their strong propensity to harbour symbionts (Gil & Latorre, ). Many intracellular mutualists of arthropods play fundamental nutritional roles, supplementing the diets of hosts that feed on unbalanced substrates such as phloem sap or blood (Moran, McCutcheon, & Nakabachi, ).…”

“…importance as pathogen vectors, but also due to their strong propensity to harbour symbionts (Gil & Latorre, 2019). Many intracellular mutualists of arthropods play fundamental nutritional roles, supplementing the diets of hosts that feed on unbalanced substrates such as phloem sap or blood (Moran, McCutcheon, & Nakabachi, 2008).…”