Insight into the efficient transmission of cucurbit aphid-borne yellows virus (Polerovirus CABYV) by Aphis gossypii glover in bitter gourd

Abstract

The Polerovirus cucurbit aphid-borne yellows virus (CABYV) infecting bitter gourd was efficiently transmitted, manifesting in symptoms like leaf cupping, complete yellowing, chlorotic patches, and orange discoloration of young leaves, accompanied by vein thickening. Older leaves exhibited dark green mottling, yellowing along the margins, and a leathery texture. In field conditions, the aphid population (8.95 per plant) and CABYV incidence (85.6 %) were the highest in Coimbatore district of Tamil Nadu, while the greatest yield loss of up to 72.38 % occurred in Erode district. Molecular characterization confirmed the presence of CABYV in 19 out of 23 plant samples collected from various locations in Tamil Nadu through PCR. The aphid species Aphis gossypii was identified via morphological traits and PCR with MtCOI primers. Aphids required a minimum of 30 min for the acquisition access period (AAP) to become viruliferous, resulting in 30 % transmission of CABYV. The inoculation access period (IAP) of 30 min for viruliferous aphids led to 46.67 % transmission, with a gradual increase in transmission percentage as IAP increased. At 7 h (h) of both AAP and IAP, 100 % transmission was observed. A single viruliferous aphid transmitted CABYV in 33.33 % of cases, while a minimum of ten aphids was necessary for complete transmission. Aphids successfully retained and transmitted CABYV for at least five days, with transmission being sporadic. Despite its significance, no previous studies have investigated the virus-vector interaction in CABYV transmission. This study offers the first comprehensive analysis of CABYV transmission dynamics through Aphis gossypii, providing valuable new insights into its epidemiology.