Plastic aphids

Christie Paterson reported on recent study of aphid plasticity, with respect to their host plant species. It was published by Hong Lu et al. in Nature Scientific Reports:
Aphids become specialised to plant hosts as they evolve to overcome plant defences. In this paper by Hong Lu et al., the ability of pea aphids to adapt to other plants was examined. This was done by examining the demography, feeding behaviour, and gene expression in the salivary glands of the aphids, after short term and long term acclimation.

It was found that when moved to non host plant species, aphids grew to a smaller size, had a lower reproductive rate, slower population growth, slower individual development, but longer life span. Aphids on non host plant spent less time consuming phloem from the plant than they did on their host plant. However, it was found that after a period of long acclimation, feeding success increased in two out of three of the plants. It was also found that aphids expressed different salivary gland genes when on different plants, and that the number of these host specific genes expressed negatively correlated with the success of the aphid on that plant.

Together these results how that, although the pea aphid has evolved to feed from just one host plant, it still exhibits plasticity to other, similar plants though with reduced success. This could have implications for pest management and provides important information on host plant specialisation in aphids generally.

Although this paper brought some important and interesting information to light, there are some aspects which could be improved upon. Firstly, winged aphids were excluded from the population demography analysis. Neglecting a sub set of the population means that the results are not conclusive of the population as a whole.  Secondly, despite the inferred importance of it, leaf characteristics were not well controlled for or tested in the experiment.

In conclusion, this paper found that despite high levels of selection, pea aphids have retained an element of plasticity and can adapt to some other plant species. Further research should investigate the effect of plant leaf characteristics, and determine whether this is observed in other plant and aphid species.