Transmission efficiency of Grapevine leafroll-associated virus 3 (GLRaV-3) by the mealybugs Planococcus ficus and Pseudococcus longispinus (Hemiptera: Pseudococcidae)

Abstract

Grapevine leafroll-associated virus 3 (GLRaV-3) is transmitted from grapevine to grapevine through grafting infected material, as well as mealybug and soft scale insect vectors. We determined the transmission efficiency of GLRaV-3 by two mealybug vectors, Planococcus ficus and Pseudococcus longispinus, by examining the relationship between the number of nymphs per plant, using groups of 1, 5, 10, 20 and 40 first-to second-instar nymphs, and the infection rate of healthy grapevine plants. Plants and single nymphs were tested for GLRaV-3 with nested reverse transcription polymerase chain reaction (nested RT-PCR). The results of this study showed the infection rate of P. ficus and P. longispinus nymphs with GLRaV-3 after acquisition access and inoculation access periods of 5 days each to be similar between intra-and interspecific groups, ranging from 5% to 19%, except for the '40-nymph group' of P. longispinus, which had a higher number of infected nymphs (63%). The number of nymphs used per group did not influence the infection rate of plants, which ranged from 11% to 80% and 20% to 70% for P. ficus and P. longispinus, respectively. Transmission of GLRaV-3 with single P. ficus and P. longispinus nymphs resulted in 70% GLRaV-3 positive plants in both cases. This study has shown both species to be equally efficient as vectors of GLRaV-3. We have further shown for the first time that a single individual of either P. ficus or P. longispinus is capable of transmitting GLRaV-3 and infecting a healthy grapevine plant. The results of the study highlight the importance of implementing vector control measures.

Citrus Mealybug (Hemiptera: Pseudococcidae) Movement and Population Dynamics in an Arbor-Trained Vineyard

“…Therefore, movements of mealybugs among plants seem scarce. These data and the low transmission rates obtained in the laboratory assays (Cabaleiro and Segura 1997b, Golino et al 2002, Krü ger et al 2006, Douglas and Kruger 2008 suggest a very low spread of GLRaV-3 in the Þeld. Nevertheless, the spread was higher than that expected by analysis of the mealybug activity Segura 2006, Cabaleiro et al 2008).…”

“…Determination of the transmission rate of mealybug-borne viruses is a very difÞcult task. The cryptic behavior of the mealybugs and the complexity of the pathosystem make the results of the assays very variable, even when carried out in the same laboratory (Posnette and Strickland 1948, Roivainen 1980, Krü ger et al 2006, Douglas and Kruger 2008. Therefore, important errors may be made in determining the transmission rates, and the actual rates may be much higher.…”

An Overview of the Vine Mealybug (Planococcus ficus) in South African Vineyards and the Use of Entomopathogenic Nematodes as Potential Biocontrol Agent

“…Symptoms of GLRaV-3 vary, depending on the cultivar grown and on the different environmental conditions that prevail (Carstens, 2002). Leaves generally show symptoms of downward-rolled margins, green veins and red interneural discolouration (Carstens, 2002;Douglas & Kruger, 2008). More so, P ficus is a virus vector of both Shiraz and corky-bark diseases (Walton & Pringle, 2004b;HoIm, 2008).…”

Manejo integrado de plagas en viñedos, desafío sólo para amantes de la sustentabilidad

“…Closteroviridae, famosa no solo por la rápida dispersión que ha tenido nivel mundial, sino además porque está considerada la enfermedades viral más seria asociada a este cultivo [1,[12][13][14]. Una alta tasa de transmisión ha podido ser comprobada ya para los virus GLRaV-3 y GLRaV-5, por parte de Planococcus ficus S [14].…”