Symbiotic Interactions and Natural Products in Insect-Microbe Systems

Insect–microbe symbioses encompass a spectrum of interactions in which microbial partners contribute essential functions to their hosts, notably through the production of specialised natural products. These associations range from defensive mutualisms—where bacteria shield their insect hosts from pathogens and parasitoids—to nutritional partnerships that supplement insect diets with vitamins, digestive enzymes or fixed nitrogen. Molecular studies reveal that many symbionts undergo genome reduction as they become increasingly dependent on their insect hosts, often retaining or acquiring biosynthetic gene clusters that encode antimicrobial polyketides, non-ribosomal peptides and other bioactive compounds. Such chemical defences underpin ecological success in diverse habitats, from fungus-farming termites preserving monocultures of Termitomyces to solitary wasps provisioning offspring with antibiotic-laden brood chambers. Understanding the ecology, evolution and biosynthetic logic of insect-associated microbes has far-reaching implications for drug discovery, agricultural pest management and the study of co-evolutionary dynamics.

Research from Nature Portfolio

Recent work has demonstrated that insect-associated Streptomyces represent an underexploited reservoir of antimicrobial diversity. Large-scale isolations followed by genomics and metabolomics revealed that these strains possess distinct evolutionary lineages and a rich array of biosynthetic gene clusters, culminating in the discovery of cyphomycin, a novel antifungal agent active against multidrug-resistant pathogens. In a complementary study, the defensive mutualism of Lagria beetles was shown to hinge on an antifungal polyketide, lagriamide, produced by a genome-reduced Burkholderia symbiont. Horizontal acquisition of its biosynthetic cluster was implicated in the symbiont’s specialised lifestyle, illustrating how gene transfer and genome streamlining converge to generate chemical defences essential for insect survival in pathogen-rich soils.

Symbiotic Interactions and Natural Products in Insect-Microbe Systems publication trend

The graph below shows the total number of articles in symbiotic interactions and natural products in insect-microbe systems across all publications each year (not limited to Nature Index journals).

Technical terms

Symbiosis: A close and long-term biological interaction between two different biological organisms, often mutually beneficial.

Polyketide: A class of natural products assembled by polyketide synthase enzymes, noted for structural diversity and pharmacological properties.

Non-ribosomal peptide: Short bioactive peptides synthesised by non-ribosomal peptide synthetases, independent of the ribosomal machinery.

Biosynthetic gene cluster (BGC): A contiguous genomic locus encoding the enzymes and regulators necessary for the biosynthesis of a specialised metabolite.

Genome reduction: The evolutionary process by which an obligate symbiont loses non-essential genes, often resulting in a streamlined genome reliant on host resources.

References

1. Defensive symbioses of animals with prokaryotic and eukaryotic microorganisms. Natural Product Reports (2015).
2. Natural products from microbes associated with insects. Beilstein Journal of Organic Chemistry (2016).
3. An antifungal polyketide associated with horizontally acquired genes supports symbiont-mediated defense in Lagria villosa beetles. Nature Communications (2018).
4. Adaptations of Pseudoxylaria towards a comb-associated lifestyle in fungus-farming termite colonies. The ISME Journal: Multidisciplinary Journal of Microbial Ecology (2023).
5. Host hydrocarbons protect symbiont transmission from a radical host defense. Proceedings of the National Academy of Sciences of the United States of America (2023).
6. Non-ribosomal peptide synthase profiles remain structurally similar despite minimally shared features across fungus-farming termite microbiomes. ISME Communications (2024).