Role of the Helix aspersa snail as a vector of Phytophthora citrophthora causing branch cankers on clementine trees in Spain

Abstract

This study investigated the suspected role of invertebrate vectors in the transmission of phytophthora branch canker, a severe disease of clementine cultivars in Spain, caused by Phytophthora citrophthora. Ants (Lasius grandis) and snails (Helix aspersa and Rumina decollata) were collected in spring and autumn 2005 from 15 commercial citrus fields which were severely affected by the disease. Isolations made from L. grandis and R. decollata bodies did not yield positive results. However, P. citrophthora was isolated from 5AE0% of bodies of H. aspersa and 4AE8% of samples of their faeces. In one assay, after snails were allowed to feed for 5 h on citrus branches which had been artificially infected with P. citrophthora, the pathogen was isolated from 79% of their faeces. In another experiment, snails were infested by placing them in contact with a substrate colonized by P. citrophthora and then transferred to the base of potted 4-year-old trees of cvs Clemenules, Fortune and Nova in the glasshouse. One day after their release, infested snails were widely distributed throughout the tree canopies and 10 days later bark discoloration and gum exudations were observed on the trees. Phytophthora citrophthora was readily isolated from tissues showing symptoms.

Citrus gummosis incidence and role of ants (Lasius grandis) and snails (Helix aspersa) as vectors of the disease in Tunisia

“…These results are in agreement with those of Alvarez et al (2009) and El-Hamalawi and Menge (1996) who found viable propagules of P. citrophthora and P. citricola in the snails' faeces. Husely and Burnett (1970) noted that Phytophthora cell walls are unaffected by cellulose and cited evidence for the existence of an outer protective layer.…”

“…Melero (2004) mentioned that the brown garden snail are able to ascend into the trees in the spring and cause damage within the aerial parts by feeding on the ripe and ripening fruits or the leaves of young trees. Furthermore, sprinkler and low-volume irrigation equipment often allow the development of high concentrations of both snail and Phytophthora species populations (Alvarez et al, 2009). This result suggests that the infection of trees could be through micro-wounds generated by the hydration of the cells when the trees were watered or by wounds created by snail feeding.…”

“…The ability of snail as a dispersal agent of Oomycetes has been established, also, by Alvarez, Gramaje, Abad-Campos, and Garcıa-Jimenez (2009) who demonstrated that ants and snails transport propagules of Pythium spp., P. citrophthora and P. palmivora, from the branch cankers on infected citrus trees in Spain. Magnano di San Lio and Pennisi (1984) reported that the unarmoured snails (Agriolimax agrestis L.) transmit, directly or indirectly, propagules of P. citrophthora associated with brown rot of fallen citrus fruits on the orchard floor.…”

The protein and volatile components of trail mucus in the Common Garden Snail, Cornu aspersum

“…It is a serious pest of citrus orchards in California [ 3 ] and wine growing areas of South Africa and Australia [ 2 , 4 ]. In addition to the consumption of crops, it has also been implicated as a vector of plant pathogens, including the pathogenic fungus-like organism, Phytophthora citrophthora , also known as branch canker, on citrus trees [ 5 ]. Current control strategies for land snails include baiting with toxic molluscicides, commonly methiocarb and metaldehyde [ 6 – 9 ], which can have a detrimental effect on native wildlife and crops [ 10 ].…”

Spread of <i>Phytophthora capsici</i> in Black Pepper (<i>Piper nigrum</i>) in Vietnam

“…Besides that, within a bush, the foliar infection outbreaks via rain splashes from lower portions to upper portions, while the adjacent plants, spreads through both rain splashes and windblown water droplets [19]. Several studies reported spores transported by insects, snails and feral pigs [1]; live plants, organic matter, soils and irrigation water [25]. Therefore, it is often impractical to screen live plants, organic matter, and soil and irrigation water for Phythopthora species.…”