Molecular Rationale of Insect-Microbes Symbiosis—From Insect Behaviour to Mechanism

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.

Host phylogeny drives the structure and diversity of insect microbiota

Microorganisms have an enormous impact on most of the life that inhabits our planet. Insects are an excellent example, as research showed that several microbial species are essential for insect nutrition, reproduction, fitness, defence and many other functions. More recently, we assisted to an exponential growth of studies describing the taxonomical composition of bacterial communities across insects' phylogeny. However, there is still an outstanding question that needs to be answered: which factors contribute most in shaping insects' microbiomes? This study tries to find an answer to this question by taking advantage of publicly available sequencing data and reanalysing over 4,000 samples of insect-associated bacterial communities under a common framework. Results suggest that insect taxonomy has a wider impact on the structure and diversity of their associated microbial communities than the other factors considered (diet, sex, life stage, sample origin and treatment). Also, a survey of the literature highlights several methodological limitations that needs to be considered in future research endeavours. This study proofs the amount of collective effort that lead to the current understanding of insect-microbiota interactions and their influence on insect biology, ecology and evolution with potential impact on insect conservation and management practices.

Can edible insects complement conventional livestock? Desirability of insect nutrition for food security of a World Heritage Site and Biosphere Reserve

Background:: Background: Insects have formed a part of the human diet since pre-historic times. Entomophagy has garnered recent attention due to its increased role in food security as nutrient-rich alternatives of conventional livestock. Methods: We have made an effort in this paper to study the edible insect composition of Manas National Park, a UNESCO Natural World Heritage Site and Biosphere Reserve, located in the Indo-Burma biodiversity hotspot of Southern Asia. Edible insect variety was determined through a field reconnaissance while the nutrient composition (macronutrient and micronutrient) of each edible insect species was computed through biochemical analyses with a view to explore the possibility of promoting them as food/feed or as a base for nutritive products. We conducted nutrient profiling using the Nutrient Value Score (NVS) model and UK Ofcom nutrient profiling (NP) model. Results: Hymenoptera and Orthoptera were found to be the dominant orders with 4 species each followed by Hemiptera with 3 species, Lepidoptera with 2 species, Mantodea, Blattodea and Coleoptera with 1 species each. The nutrient analysis show that insects have rich nutrient composition that are comparable with typical livestock. Conclusion: Therefore, as realised during COVID-19, insects may prove to be an alternative, sustainable and cheaper sources of nutrients, necessary for ensuring global food security.

Using light stable isotopes to understand nutrient cycling in soils and how these isotopic techniques can be leveraged to investigate the ecology and biology of insects – A review

Summary At first glance, there appears little to link nitrogen cycling with entomology other that the use of isotope techniques. Soil management requires a contextual, adaptive, flexible approach that is based on understanding the factors that regulate the soil’s fundamental processes. Using stable isotope techniques for the analysis of the inherent biogeochemical processes can explain the complex soil–plant interactions, the determining factors of the nitrogen cycle, and the impacts of applying external inputs. Using the same stable isotope tools enables an interdisciplinary collaboration between soil science and entomology. Emerging plant pests, for instance, non-native insect species, are a threat to the agroecosystems. The knowledge of the origin and movement of invasive insects by using the intrinsic stable isotope signatures embedded in the environment allows identification of entry pathways and thus the establishment of effective management strategies to reduce the potential crop damage. Moreover, the feeding and mating biology of insects can also be understood using isotope techniques. Finally, the movement of mosquitoes can be understood by isotopic labeling so that these dangerous disease vectors can be more effectively managed. This and further research has led to a fuller understanding of insect feeding ecology and leading neatly around to how insect nutrition impacts soil organic matter turnover.