D3438: Cotton leafroll dwarf virus (CLRDV): Host range and effect on its vector behavior

Alternate hosts can act as a reservoir of virus around a cropping system. Cotton leafroll dwarf virus (CLRDV, genus: Polerovirus, family: Solemoviridae ) is transmitted by the cotton/melon aphid, Aphis gossypii (Glover) (Hemiptera; Aphididae) in a persistent, circulative, and non-propagative manner. CLRDV was first reported in the United States from Alabama in 2017 and later from several cotton-producing states including Georgia. Fourteen plant species (hollyhock, marshmallow, country mallow, abutilon, prickly sida, okra, hibiscus, squash, N. benthamiana, chickpea, evening primrose, henbit, amaranthus, and teaweed) were tested as possible alternate hosts of CLRDV via aphid-mediated inoculation using clip cage (@100 viruliferous aphids per plant for a 72h of IAP). CLRDV was detected in hibiscus, okra, N. benthamiana, amaranthus, and teaweed by RT-PCR. Based on CLRDV accumulation, aphid acquisition, and back transmission assay, we found hibiscus as most promising alternate hosts. Later, we conducted one-way emigration assay, two-way settling bioassay, and biological fitness assay with wingless aphids in glasshouse to understand the preference and behavior of viruliferous and non-viruliferous aphids due to CLRDV infection in cotton and hibiscus plants. We found that the preference and fitness of aphids were better in non-infected plants compared to CLRDV-infected plants. However, higher fecundity of viruliferous aphids suggests increase in number of viruliferous aphids that will enhance the spread of CLRDV. Overall, our results suggest that alternate hosts can harbor CLRDV and alteration in aphid fitness upon virus acquisition plays an important role in CLRDV epidemics in the southeastern United States cotton pathosystem.