Host Range Evolution in Herbivorous Insects

Herbivorous insects display remarkable diversity in the breadth of plants they utilise, ranging from extreme specialists that feed on a single host species to generalists capable of exploiting dozens of plant taxa. Evolution of host range is shaped by a complex interplay of ecological, genetic and physiological factors. Plant secondary metabolites impose chemical barriers to herbivore colonisation, driving adaptation in detoxification pathways and chemosensory systems. Concurrently, insects may exhibit phenotypic plasticity in feeding behaviour and developmental timing, enabling transient use of marginal hosts. Trade-offs often arise when adaptation to one host reduces performance on alternatives, leading to local specialisation and, in some cases, host-associated differentiation or speciation. Conversely, generalist lineages may evolve polygenic architectures that mitigate such costs, facilitating host expansions with minimal fitness penalties. At a global scale, host-range evolution influences pest emergence, biocontrol efficacy and ecosystem resilience. Improved understanding of these processes offers avenues for sustainable crop protection by anticipating potential host shifts and identifying vulnerabilities in insect detoxification and sensory mechanisms.

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Research from all publishers

Recent work has combined experimental evolution with population-genomic analyses in seed beetles to dissect the genetic architecture of adaptation to a marginal host. Researchers imposed replicate lines on lentil and tracked allele frequency shifts alongside performance traits, revealing a polygenic basis for weight and development time and implicating detoxification genes such as cytochrome P450s in host colonisation. Differential gene expression analyses highlighted that parallel changes during adaptation often involve loci beyond those directly tied to measured performance traits.

A transcriptomic comparison of two sibling moth species specialised on maize and various dicotyledons has identified chemosensory receptors and metabolic pathways underlying host discrimination. Adult females of the maize borer and the adzuki bean borer exhibited distinct expression profiles in olfactory receptors, detoxification enzymes and immune-related genes when exposed to their native versus non-host plants. One olfactory receptor emerged as a strong candidate for mediating plant odour recognition during oviposition.

An integrative study of a native butterfly’s recent colonisation of an exotic forage plant investigated phytochemical variation, larval performance and female oviposition preference across multiple host populations. Although phytochemical diversity predicted colonisation patterns, larval survival and growth did not align straightforwardly with chemical profiles, and adult females sometimes preferred hosts that conferred lower larval performance. These findings underscore the stage-specific axes of selection that shape host-range dynamics.

Host Range Evolution in Herbivorous Insects publication trend

The graph below shows the total number of articles in host range evolution in herbivorous insects across all publications each year (not limited to Nature Index journals).

Technical terms

Host range: The spectrum of plant species on which an herbivorous insect can complete its life cycle.

Ecological specialisation: The adaptation of an organism to a narrow set of environmental or resource conditions.

Phenotypic plasticity: The capacity of a genotype to produce different phenotypes in response to environmental variation.

Trade-off: A situation where improvement in one trait leads to reduction in another due to limited resources or genetic constraints.

Local adaptation: The process whereby populations evolve traits that confer higher fitness in their specific environments compared to non-native populations.

References

1. The Many Dimensions of Diet Breadth: Phytochemical, Genetic, Behavioral, and Physiological Perspectives on the Interaction between a Native Herbivore and an Exotic Host. PLOS ONE (2016).
2. Transcriptomic response of female adult moths to host and non-host plants in two closely related species. BMC Ecology and Evolution (2018).
3. Combining Experimental Evolution and Genomics to Understand How Seed Beetles Adapt to a Marginal Host Plant. Genes (2020).