Host expansion in a specialist herbivore is facilitated by whole‐genome duplication in the host plant

Host plant shifts are central to diversification in insect herbivores. Many mechanisms can cause host shifts in insects, but one relatively unexplored mechanism is whole‐genome duplication (WGD) in the host plant. WGD, or polyploidy, is common in plants and causes spontaneous changes in physiology,...

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Published in:Ecological entomology 2023-06, Vol.48 (3), p.317-324
Main Authors: Curé, Anne E., Althoff, David M., Segraves, Kari A.
Format: Article
Language:English
Subjects:
Acyrthosiphon pisum
Alfalfa
Diploids
Fecundity
Genomes
Herbivores
host forms
Host plants
host preference
Insects
neopolyploidy
Palatability
Peas
Plant species
Polyploidy
Red clover
Reproduction (copying)
Trifolium pratense
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Summary:Host plant shifts are central to diversification in insect herbivores. Many mechanisms can cause host shifts in insects, but one relatively unexplored mechanism is whole‐genome duplication (WGD) in the host plant. WGD, or polyploidy, is common in plants and causes spontaneous changes in physiology, morphology, and palatability that could impact the ability of herbivores to feed and develop on newly formed polyploids (neopolyploids). Here the authors tested if WGD affected the preference and performance of the specialist aphid, Acyrthosiphon pisum (pea aphids). Pea aphids seasonally form specialised lineages or ‘host forms’ on many host plant species including alfalfa and red clover. Aphid host forms on alfalfa and red clover naturally exist on different cytotypes of their respective hosts, with red clover aphids feeding on diploid clover and alfalfa aphids feeding on tetraploid alfalfa. Therefore, the authors predicted that these host forms would have a higher preference for and performance on their respective natal host cytotype. Neither host form exhibited a preference for a particular cytotype, but there were modest changes in aphid performance based on host cytotype. Specifically, aphids specialised to red clover had higher fecundity on diploid red clover than on neotetraploid red clover. Together, these results showed that both host forms were able to recognise and accept different cytotypes of the two host species, but only one host form experienced trade‐offs in performance when feeding on neotetraploids. These results suggest that WGD may act as a mechanism of host expansion in pea aphids as plants speciate via WGD. The authors examined how pea aphid (Acyrthosiphon pisum) preference and performance differed on diploid and neotetraploid alfalfa and red clover Preference was not affected by host ploidy level, but red clover aphids had reduced performance when feeding on neotetraploid red clover This suggests insect herbivores may incorporate novel ploidy levels of host plants into their diets, and that in some instances performance differences may facilitate specialisation to different host ploidy levels
ISSN:0307-6946
1365-2311
DOI:10.1111/een.13223