Abstract
Insects nurture a panoply of microbial populations that are often obligatory and exist mutually with their hosts. Symbionts not only impact their host fitness but also shape the trajectory of their phenotype. This co-constructed niche successfully evolved long in the past to mark advanced ecological specialization. The resident microbes regulate insect nutrition by controlling their host plant specialization and immunity. It enhances the host fitness and performance by detoxifying toxins secreted by the predators and abstains them. The profound effect of a microbial population on insect physiology and behaviour is exploited to understand the host–microbial system in diverse taxa. Emergent research of insect-associated microbes has revealed their potential to modulate insect brain functions and, ultimately, control their behaviours, including social interactions. The revelation of the gut microbiota–brain axis has now unravelled insects as a cost-effective potential model to study neurodegenerative disorders and behavioural dysfunctions in humans. This article reviewed our knowledge about the insect–microbial system, an exquisite network of interactions operating between insects and microbes, its mechanistic insight that holds intricate multi-organismal systems in harmony, and its future perspectives. The demystification of molecular networks governing insect–microbial symbiosis will reveal the perplexing behaviours of insects that could be utilized in managing insect pests.
Highlights
The advancement in sequencing and polymerase chain reaction (PCR)-based technologies has dramatically expanded our insight into microbial systems
Besides various factors that affect the gut microbiome composition, there is firm evidence indicating the influence of the insect gut immunity in shaping the resident microbial community structure
Bacterial symbionts found in mosquitoes, sandflies, and ticks dominantly belong to Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria [90,91,92,93]
Summary
The American author Frederick Lenz beautifully said, “Symbiosis is a much higher reflection of intelligent life.” He termed a symbiotic relationship as reciprocity between two people governed by specific terms under certain conditions for a balanced relationship. Notwithstanding, the failure to cultivate these microbes in vitro impedes the dissection of the functional aspects of these interactions This is primarily the reason behind the elusiveness of microbial consortiums [1,2]. Compared to higher eukaryotes, which harbour a panoply of commensal organisms, less-diverse microbial symbionts colonize insects. The symbiotic microbiome maintains and/or enhances the host immune system in insects serving as disease vectors. It influences its vector competence [15]. To increase host insect fitness, the maintenance of chlorophyll and nutrient-rich “green island” (insect feeding site) in senescent leaves of the host plant
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
