Experimental transmission of Barley yellow dwarf virus by using the vectorRhopalosiphum padi parasitized by Aphidius rhopalosiphi (Hymenoptera : Braconidae)

The influence of the parasite Aphidius rhopalosiphi De Stefani-Perez on the efficiency of Rhopalosiphum padi L. to transmit the PAV strain of Barley y ellow dwarf virus (BYDV) was studied, During a 21 h acquisition feeding per iod on Avena byzantina K. Koch, an equal percentage (80.1 and 81.0 %) of pa rasitized and non-parasitized aphids became infected. The non-parasitized a phids survived about three times longer than the parasitized ones (under ou r trial conditions, the survival of R. padi was not influenced by BYDV). Af ter a latent period, both the parasitized and non-parasitized aphids remain ed infectious in average 4.5 and 7.1 days and transmitted BYDV to 2.0 and 3 .3 test plants, respectively. A high number (37 %) of the parasitized aphid s were able to transmit the virus until to the last day of their life. As a n epidemiological consequence from the results, we can assume that parasito ids have more complex effect on BYDV than generally believed. The influence of parasitism on the spread of both aphids and BYDV in field as well as on the virus acquisition by the vector will be studied.