Integrated Protection in Viticulture IOBC/wprs Bulletin Vol. 36, 2008 pp. 355-361

Grapevine Pests in Sicily Haralabos Tsolakis, Ernesto Ragusa Dipartimetno Senfimizo, Sezione Entomologia, Acarologia E Zoologia - Università Di Palermo, Viale Delle Scienze, 13 -90128 Palermo (Italy) - ([email protected]) Abstract: More than twenty phytophagous species are reported associated with Sicilian vineyards. Only a quarter of them have to be considered of economic importance. Among moths, the grapevine moth Lobesia botrana (Denis & Schiffermüller) is certainly the most frequent species. It is considered the key pest on both table and wine grapes, while the incidence of the grape berry moth Eupoecilia ambiguella (Hübner) is scarce and linked to particular biotopes. Three to four flights are reported for the grapevine moth from February-March to October-November, while no data are available for the grape berry moth. Damages caused by L. botrana are strictly linked to the climatic trends during the summer period, to the microclimatic conditions in the island biotopes, as well as to the micro climate created by the canopy, or to the different grape-clusters of the various cultivars. The cicadellid Jacobiasca lybica (Bergevin) was reported for the first time in 1962, but it is considered an old inhabitant of Sicilian vineyards. Until 1990s it was present mainly on the western part of the island and it was considered of no economic importance for the autochthonous cultivars. Today the cicadellid is distributed on the whole island and often causes severe damages especially on allochthonous cultivars. The mealybug Planococcus ficus (Signoret) has to be considered a serious problem in Sicilian vineyards as in the past two decades an increase of infestations was registered, particularly on new plantings. No data are available up to now on the biology of the species in Sicily, while its presence causes serious concerns for both damages to yields and virus transmission. Calepitrimerus vitis (Nalepa), recorded in Sicily at the beginning of the XX century, is now considered another emergent problem in Sicilian vineyards, on both autochthonous and allochthonous cultivars, especially on newly planted vineyards. Key words: grape moths, Jacobiasca lybica, Planococcus ficus, mites

Introduction Viticulture in Sicily is of ancient origin. The first peoples inhabiting the island (Siculi, Sicani and Elimi) knew grapevine, but ancient Greeks are responsible for cultivation and diffusion on the whole island. For them wine was so important that they had a specific God called Dionysos. Although information was available about the extension of vineyards during dominations of Sicily, as far as pests are concerned, the first information affecting grapes dates to 1880, when phylloxera, Dactulosphaira vitifoliae (Fitch), arrived in Sicily. This aphid, as in other parts of the world, reduced Sicilian vineyards from 320.000 Hectares to 175.000 Hectares in few years. Once the hurdle of phylloxera was cleared using the American rootstocks, Sicilian viticulture remained a marginal culture, although the success of “Marsala”, the popular fortified aged wine, allowed a consistent presence of vineyards mainly in the western part of Sicily (where viticulture is still considered an important crop more although for historical and social reasons than for economic ones).

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Diffusion of the French cultivars (Cabernet, Syrah, Chardonnay etc), after the second half of ’80s, gave the Sicilian viticulture the necessary push. Today this sector is very important from a social and economic point of view and as a consequence also problems related to vine protection have become important. As far as the phytophagous species are concerned, more than twenty species are reported associated with Sicilian vineyards (table 1), but only a quarter of them are to be considered of economic importance in Sicily. In this paper we report some of them in order of economic importance, according to literature and personal knowledge. Grape moths Among grape moths, both Eupoecilia ambiguella (Hübner) and Lobesia botrana (Denis & Schiffermüller) are present in Sicily (Genduso, 1985), even if the presence of the first one is scarce and limited to particular biotopes. Up to now, this species has been found in vineyards up to 400 m a.s.l., but no particular damages were registered for this pest. On the other hand, the grapevine moth L. botrana, as in other Mediterranean countries, is certainly the most frequent species and is considered the key pest in Sicilian vineyards. It should be mentioned that damages caused by this pest are strictly related to the climatic trends during the summer period, to the microclimatic conditions in the island biotopes, as well as to the micro clime created by the canopy, or to the different grape-clusters of the various cultivars.

Fig. 1. Lobesia botrana flights in different years and Sicilian biotopes

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Three and often four flights and the same number of generations of grape moth are reported in Sicily (fig. 1). The first flight starts on the second half of March, even if in some years male catches are registered in the last week of February (Genduso, 1985). This flight lasts until the second half of May, and, as it was shown, has no economic importance (Roehrich & Schmid, 1979; Delrio et al., 1985). The second flight usually starts during the first week of June and lasts 3-5 weeks. For most Sicilian Cultivars also this generation has to be considered almost not harmful, as Brix values until the end of July are maintained below 15.0. For early-harvesting Cultivars (Chardonnay, Viogner etc), for which the harvest occurs within the 1st half of August, both the 2nd and 3rd generation have to be considered harmful. The latter starts with the 3rd flight that occurs in Sicily from the 1st to the last week in July, and lasts until the end of August. This generation has to be considered harmful as the grey mould or the sour bunch rot or ochratoxinogenic fungus establish on damaged bunches. The 4th flight occurs in Sicily from the last week of August to the second week of September and lasts until half October (sometimes until the first week of November). It should be mentioned that larvae of the 4th generation complete their development only on abandoned vineyards or on some cultivars where harvest is very late (October); harvesting takes place in the majority of Sicilian vineyards within the first half of September.

Fig. 2. Trend of male captures and infested bunches on two adjacent vineyards: Cv Grecanico and Cv Catarratto (Tsolakis, unpublished)

Many natural enemies have been found associated with L. botrana (Moleas, 1979; Marchesini e Dalla Montà, 1994; Thiery et al., 2001) and some of them were reported for Sicilian vineyards (Parasitoids, Chrysopids, Coccinellids, spiders etc). However, because of the particular conditions of Sicilian viticulture (that is, absence of hedges and any kind of spontaneous plants in the surroundings of vineyards), the natural biological control is not sufficient to reduce infestations of the grapevine moth under the economic threshold. The vine cultivar is another important factor influencing the infestations by L. botrana. Thiéry and Moreau (2006) demonstrated that some cultivars have an influence on the

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developmental time of the grape moth larvae, while Baldacchino and Moleas (2000) showed a different receptivity among some cultivars. In two organically managed Sicilian vineyards, we found significant differences between two endemic cultivars, Grecanico and Catarratto (Fig. 2). This different receptivity is probably due both to the micro clime created by the canopy of the different cultivars (summer pruning and vegetation conditioning are absent in traditional Sicilian vineyards), and to the different grape-clusters. Both factors play an important role, not only for the grape moth infestations, but also for the damages derived by mould infection (Fig. 3). As we can note in figure 3, both sour bunch rot and grey mould are significantly higher in no conditioned plants in comparison to the canopy managed.

Fig. 3. Bunches damaged at the grape harvest in the two different canopy managed vineyard (Cv Grecanico) (Tsolakis, unpublished)

Among the abiotic factors influencing the infestation trends of grape moth, the most important one is “Scirocco” a hot wind blowing from Africa in summer. This wind usually lasts 2-3 days. During this period temperatures can exceed 40°C, while relative humidity is reduced below 30%. These conditions have lethal effects on the majority of insects associated with Sicilian vineyards. Leafhoppers Among leafhoppers, the cotton jassid Jacobiasca lybica (Bergevin) is considered another important pest in Sicilian vineyards on some red or allochthonous cultivars that have widely spread in Sicily in the last two decades, while it is considered of low or no economic importance on the main white Sicilian cultivars. This species was recorded for the first time in Sicily in 1962 (Vidano, 1962), even if it is considered an old inhabitant of Sicilian vineyards. J. lybica is an important pest in most parts of Northern Africa, various Mediterranean countries (Portugal, Spain, Italy and Cyprus) and in the Midle East. It is reported as a polyphagous species, but in Sicily damages are recorded only on vines, even if specimens were collected on various spontaneous plants near vineyards.

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From information collected from old vine growers, we can say that the leafhopper was present in Belice Valley before its first report in 1962. After 1995, occasional infestations of the leafhopper have been reported, while in 2001 very strong infestations were registered in most parts of western Sicilian vineyards. Damage caused by J. lybica on the leaf is similar to the one provoked by Empoasca vitis Gothe. The damage, called hopperburn, is mechanically caused by plugging the xylem and destroying the phloem, but mainly injecting toxins during feeding (Vidano, 1963; DeLong, 1971). Different cultivars, then, react in different ways to jassid’s attack. This is the principal cause of different damage levels among the various cultivars located in the same territory, rather than the repellence of the cultivar towards J. lybica (Tsolakis, 2003). Fortunately, “scirocco” very often inhibits early infestations which are very dangerous even at low population level: 0.5-1 nymph/leaf during July-August, causes a significant reduction of must soluble solids (Lentini et al., 2000). On the other hand Zygina rhamni Ferrari is very common in all Sicilian vineyards, but no damages have been reported until now, for both autochthonous and allochthonous cultivars. Planococcus ficus (Signoret) The vine mealybug Planococcus ficus Signoret is another economically important pest. In the last decades, infestations by P. ficus have become more frequent, especially in newly planted vineyards. No data are available in literature about its biology in our region. From our observations in an organically managed vineyard, this species overwinters under the bark or on the main roots of the plant mainly as female. The population increases in spring and trunks are usually wet by honeydew produced by the vine mealybug. Colonies of crawlers were observed, during June, at the base of leaf stem before their migration along the ribs of the leaf. In July a great number of crawlers migrate to bunch causing severe damages. Franco et al. (2004) report three generations/year in the Mediterranean vineyards, but we do not have data confirming this statement for Sicily. Mites As far as mite species are concerned, three tetranychid species are common in Sicilian vineyards: Tetranychus urticae Koch, Panonychus ulmi (Koch) and Eotetranychus carpini (Oudemans). Sporadic but severe infestations of T. urticae were registered during ’80s in various Sicilian vineyards, most probably, related to the abuses of Carbaryl or other insecticides and the consequent elimination of phytoseiid fauna, more than to climatic or cultivar factors (Ragusa, unpublished). P. ulmi shows a constant presence in Sicilian vineyards but it is considered of economic importance only on table vines (Buonocore et al., 1992). No data are available for E. carpini in Sicilian vineyards. As far as Eriophyid mites are concerned, both the grape rust mite Calepitrimerus vitis (Nalepa) and the grape erineum mite Colomerus vitis (Pagenstecher) are present in Sicily. Both species are considered obligate pests of Vitis vinifera L. (Jeppson et al., 1975) and their diffusion coincide with vine diffusion. First recorded in Sicily in 1911 (Pantanelli, 1911), the grape rust mite causes leaf and shoot distortions and retarded shoot growth during springtime (Duso & De Lillo, 1996; Duffner et al., 2001). Despite its long-time presence in Sicily, no damages were reported for this eriophyid until the last decade, when in different new planted vineyards severe damages were registered (Tsolakis & Ragusa, unpublished). Finally, the grape erineum mite Col. vitis is to be considered of no economic importance in Sicilian vineyards even if the leaf symptoms (erinea) sometimes worry Sicilian growers.

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Considerations Entomofauna of Sicilian vineyards is very similar to that occurred in other Meditarranean countries but the different microclimatic conditions of the biotopes present in the island strongly influence the specific composition of vine pests. The absence, up to now, of Scaphoideus titanus Ball or other phytoplasmas vectors in Sicily subjected to mandatory insecticide sprayings, allow a drastic reduction of the number of sprayings. As a matter of fact, in some environments no pesticides are needed while inmost parts of vineyards one or two sprayings are sufficient to guarantee an efficient control of key pests.

Acknowledgements Authors are deeply indepted to Prof. E. Chiavetta who checked the English text. This work carried out with funds by “Progetto per lo sviluppo dell’Agricoltura biologica in Sicilia” Assessorato Agricoltura e Foreste-Servizio IV.

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