Arthropods Vector Grapevine Trunk Disease Pathogens

Abstract

Arthropod-mediated dispersal of pathogens is known in many cropping systems but has never been demonstrated for grapevine trunk disease pathogens. Arthropods from vineyards were screened for the presence of pathogens associated with Petri disease and esca using cultural and molecular techniques. The ability of the most abundant pathogen-carrying species to inoculate healthy grapevine vascular tissues was also determined. Millipedes and ants were allowed to associate with a DsRed- Express-transformed Phaeomoniella chlamydospora, after which they were exposed to freshly pruned healthy grapevines under controlled conditions and wounds were monitored for subsequent infection. In addition, the possibility of millipede excreta, commonly found on pruning wounds in the field, to act as inoculum source was determined. A diverse arthropod fauna was associated with declining grapevines and many of these carried trunk disease pathogens. However, spiders, the ant Crematogaster peringueyi, and the millipede Ommattoiulus moreleti were the most abundant pathogen carriers. The ant and millipede species fed on pruning wound sap and effectively transmitted trunk disease pathogens. Millipede excreta contained viable spores of Phaeomoniella chlamydospora and may serve as an inoculum source. Numerous arthropods, including beneficial predators, are potential vectors of grapevine trunk disease pathogens. Our results highlight the need for an integrated approach, including targeted management of ants and millipedes at the time of pruning, to limit the spread of grapevine trunk diseases.

Ants suppressing plant pathogens: a review

“…On grapevine the release of 10 artificially infected Crematogaster peringueyi ants per plant led to a 27% infection of pruning wounds with the trunk disease Phaeomoniella chlamydospora, whereas control plants with non-infected ants showed no symptoms (Moyo et al 2014). Lastly, healthy red rasperry plants Rubus idaeus that were caged with 10 Tetramorium caespitum ants and a neighboring plant infected with fire blight Erwinia amylovora started to show disease symptoms within 18 days, whereas none of the control plants in cages with ants and healthy neighbor plants developed any symptoms.…”

“…To address this, ants have evolved a number of mechanisms to reduce disease transmission -mechanisms that protect the ant itself, but also can extend beyond the individual ant to 1) nest mates, 2) food, 3) nest materials, 4) trophobionts and 5) host plants. On the other hand, it is also known that ants may disperse or act as vectors of plant pathogens (Moyo et al 2014). It remain to be established if one of these two contrasting effects prevail in ant-plant interactions.…”

Phaeoacremonium: From esca disease to phaeohyphomycosis

“…The length of time that viable propagules of Phaeoacremonium remain in the soil is also unknown and may influence the capacity of the pathogen to infect the plants through the root system. Regarding the dissemination, although recent research demonstrated the presence of Phaeoacremonium inoculum on arthropods and the potential of pruning shears for spread of Phaeoacremonium infection under controlled conditions (Moyo et al 2014;Agust ı-Brisach et al 2015), further studies are needed to confirm the role of arthropods on vine infections through pruning wounds or even if viable fungal inoculum can be spread by pruning operators in the field. Finally, the whole geographical distribution and host range of Phaeoacremonium spp.…”

“…The identification of Phaeoacremonium isolates from plant hosts to species level are commonly done by sequencing multiple genes (Groenewald et al 2001;Mostert et al 2005Mostert et al , 2006Damm et al 2008;Essakhi et al 2008;Graham et al 2009;Gramaje et al 2009bGramaje et al , 2014Urbez-Torres et al 2014) or by comparing only b-tubulin gene sequences (Moyo et al 2014). Phaeoacremonium isolates obtained from human infections are identified using either b-tubulin gene sequences (Baddley et al 2006 Since it is known that ITS does not distinguish all species of Phaeoacremonium (Mostert et al 2005;, the use of this gene region alone is not advised.…”

Advances in Propagation of Grapevine in the World

“…HALLEEN et al (2007) conducted pathogenicity studies in nurseries and vineyards with declining plants and found that symptomatic plants were contaminated by Cadophora luteo-olivaceae, Phialemonium cf. curvatum and Pleurostomophora richardsiae, whereas Moyo et al (2014) identified species of arthropods also acting in the transmission of trunk diseases.…”