Inheritance of the ability of the planthopper Laodelphax striatellus to transmit barley yellow striate mosaic rhabdovirus.

Barley yellow striate mosaic virus (BYSMV) is a plant rhabdovirus that multiplies in its planthopper vector Laodelphax striatellus . The maximum proportion of infective hoppers is reached with more than 24 hour acquisition access. In the vector, BYSMV has a maximum incubation period of 29 days. Individual planthoppers were exposed to virus-infected barley plants for 3 days, mated during the incubation period on Digitaria sanguinalis (immune t o BYSMV) and then tested for their ability to transmit (=competence). They were classified as T (transmitter) or t (non-transmitter). Their offspring were exposed to BYSMV on infected barlev plants, reared on D. sanguinalis and tested for BYSMV transmission at the end of maximum incubation period. The progenies of T x T had proportions of transmitters between 0.496 and 0.295 (confidence limits for P = 0.01). Progenies of T x t had proportions of transmitters between 0.178 and 0.004 (confidence limits for P= 0.01). No si gnificant difference was detected between offsprings of reciprocal crossings (female T x male t or female t x male T) . Assuming that competence is inherited, these data indicate that a minimum of three loci are involved, and that heritability of competence is not linked t o sex. The heritability of competence for BYSMV was therefore analysed using the liability and threshold approach applied t o the progenies of T x T. The heritability (h^2 ) of competence was between 0.74 and 0.92, suggesting that competence for BYSMV in L. striatellus is heritable . The possible interactions between BYSMV and the phenotype of its vector are discussed, in the light of these and other data .