Chickpea variety and phenology affect acquisition of Pea enation mosaic virus, subsequent plant injury and aphid vector performance

Acquisition of Pea enation mosaic virus (PEMV) by chickpea (Cicer arietinum) when fed on by viruliferous pea aphid (Acyrthosiphon pisum) was tested for combinations of two chickpea varieties ('Bronic', a kabuli type and 'Sierra', a desi type) and three plant ages (14, 28 and 42 days after germination). It was determined whether inoculation with PEMV influenced plant growth and yield components, and the effect of variety x age combinations on the survival and fecundity of aphid vectors was evaluated. Three important findings emerged: (a) Acquisition of PEMV by chickpea depended on plant age. When inoculated at 14 or 28 days, most plants tested positive for PEMV at harvest, while rates of virus acquisition were reduced for 42 day-old plants. (b) Plant age at inoculation affected growth and yield parameters, and this effect differed between chickpea varieties. For both varieties, PEMV infection reduced plant height and biomass at harvest when plants were inoculated at 14 days. Only 'Sierra' exhibited significant reductions in plant height and biomass when inoculated at 28 days. Seed set was severely diminished for both varieties when plants were inoculated at 14 and 28 days after germination, but mature plants were not damaged in terms of growth or seed set. (c) The performance of pea aphid was influenced by both chickpea age and variety, with higher fecundities and longer lifespan when colonising 42 day-old plants as compared with younger plants, and better performance overall on 'Sierra'. This study reveals that chickpea can acquire PEMV at all ages tested, but the most damaging effects for growth and yield parameters occur when plants are inoculated at early phenological stages. Chickpea is a poor host for A. pisum in general, but plants can support vector populations long enough for PEMV transmission and subsequent yield reduction to occur.