COBISS Code 1.01 Agrovoc descriptors: scaphoideus titanus, pest insects, vineyards, grapevines, vitis vinifera, pest insects, pest surveys, surveys, monitoring, data collection, traps, pest control equipment, plant nurseries Agris category code: h10 Migration of Scaphoideus titanus Ball from the surrounding vineyards into the nursery Primož GRIŽON1, Gabrijel SELJAK2, Irma VUK3,4 Received July 30, 2011; accepted July 23, 2012. Delo je prispelo 30. julija 2011, sprejeto 23. julij 2012. ABSTRACT A one-year study of the mobility of leafhopper Scaphoideus titanus Ball (ST), vector of Flavescence dorée phytoplasma, was conducted in 2009 and included three Slovenian nurseries in the Primorska winegrowing region, as well as two Italian and one Swiss nursery, and was aiming at evaluating the risk of spreading ST with vine propagating material. The presence of ST was monitored by the means of yellow sticky traps that were placed at three distances in the nurseries and the nearby vineyards on three parallel lines (replicates). The traps were equidistantly placed from the nurseries' and vineyards' borders in order to determine the possible distance gradient. The monitoring started in the latest nymphal stages (middle of June) and terminated in the first decade of October. Insecticide treatments with deltamethrin (Decis 2.5 EC) were applied in nurseries, according to the instructions for use and recommendations for suppression of ST. On all Slovenian plots in the vineyards, the population level of ST was high (1796 adults in average / vineyard or 18 adults per trap / week), which indicated a great migration potential of the vector towards the nurseries. Catches were very low (54 adults in average / nursery or 0.4 adults / trap / week) on two nurseries' plots (Lože and Slap), although high numbers of ST adults were caught in the adjacent untreated vineyards. On the Poreče nursery plot, insecticide treatments were not sufficient to avoid high numbers of ST catches (in total 481 adults or 3 adults / trap / week). This could be related to the sub-optimal timing of the first insecticide treatment and/or migration of adults from two nearby untreated vineyards located at a distance of 70 and 150 m. The distance between the nurseries and vineyards did not affect ST catches in the nurseries. Key words: Scaphopideus titanus, Flavescence Dorée, migration, nursery IZVLEČEK MIGRACIJA AMERIŠKEGA ŠKRŽATKA (Scaphoideus titanus Ball) IZ BLIŽNJIH VINOGRADOV V TRSNICO Z namenom preučitve nevarnosti širjenja prenašalca zlate trsne rumenice z razmnoževalnim materialom vinske trte smo v letu 2009 izvedli raziskavo mobilnosti ameriškega škržatka (Scaphoideus titanus Ball) (ST) v treh trsnicah v vinorodni deželi Primorska. V manjšem obsegu je bil poskus izveden tudi pri partnerskih institucijah v Italiji in Švici. Zastopanost in nalet ST smo ugotavljali z rumenimi lepljivimi ploščami, ki so bile postavljene na treh različnih razdaljah od roba trsnice in vinogradov v 3 vzporednih ponovitvah. S postavitvijo lepljivih plošč v enakomernih razmakih od roba trsnice in vinogradov v globino smo želeli ugotoviti morebitni gradient naleta. Z monitoringom naleta smo začeli, ko je bil škodljivec v 5. stadiju ličinke (sredi junija) in ga zaključili v prvi dekadi oktobra. Tretiranje z deltametrinom (Decis 2.5 EC) je bilo izvedeno v trsnici, skladno z navodili za uporabo insekticida in s priporočili za zatiranje ST. Populacija ST v vinogradih je bila na vseh treh lokacija v Sloveniji visoka (v povprečju 1796 odraslih osebkov / vinograd oziroma 18 osebkov / ploščo / teden), kar je predstavljalo velik migracijski potencial prenašalca proti trsnicam. Kljub visoki populaciji ST v bližnjih vinogradih je bilo število ujetih ST v trsnicah na lokaciji Slap in Lože nizko (v povprečju 54 osebkov / trsnico oziroma 0,4 osebka / ploščo / teden). Število ujetih odraslih osebkov na lokaciji Poreče je bilo kljub tretiranju z insekticidom visoko (skupno 481 osebkov ali 3 osebki / ploščo / teden). Vzrok za to gre iskati v neustreznem času prvega tretiranja z insekticidom ali v dodatnem naletu ST iz bližnjih vinogradov, ki so bili oddaljeni 70 in 150 m. Razdalja med trsnico in vinogradom ni vplivala na število ujetih ST v trsnici. Ključne besede: ameriški škržatek, zlata trsna rumenica, migracija, trsnica 1 B. Sc., Ministry of Agriculture and the Environment, Phytosanitary Administration of the Republic of Slovenia, Dunajska 22, SI-1000 Ljubljana, Slovenia; primoz.grizon@gov.si 2 M. Sc., Chamber of Agriculture and Forestry of Slovenia, Agriculture and Forestry Service Nova Gorica, Department for Plant Protection, Pri hrastu 18, SI-5000 Nova Gorica, Slovenia; 3 Ph. D., University of Primorska, Science and Research Center of Koper,Institute for Mediterranean Agriculture and Olive Growing, Garibaldijeva 1, SI-6000 Koper, Slovenia; 4 University of Primorska, Faculty of Mathematics, Natural Sciences and Information Technologies, Glagoljaška 8, SI-6000 Koper, Slovenia; 1 INTRODUCTION The efficacy of insecticide treatments against Scaphoideus titanus Ball (ST) (Hemiptera, Cicadellidae), the vector of Flavescence Dorée phytoplasma (FD), in nurseries depends on the term of treatment regarding the vector's development stage, on the proportion of its mortality, insecticide residues on plants and on the migration of adults from the surrounding vineyards. The previous pesticide registration against ST considered only the situation in spacious vineyards, but did not make any allowances for small-sized nurseries (Boudon-Padieu, 2003). This aspect has to be considered also in adopting a suitable insecticide treatment program. Also the distances between vineyards and nurseries and the mobility range of ST are crucial for determining the risk of spread of ST with the vine grafted plants. ST, a Nearctic leafhopper, was introduced into Europe from the North America before 1958. This univoltine species overwinters in the egg stage. Eggs are deposited into the bark of two or more years old vine branches (Vidano, 1964), rarely also in one-year branches. Nymphs start emerging in the second half of May and adults occur in mid-summer (in the Slovenian climate, at the end of June). They feed exclusively on Vitis spp. and cause indirect damages by transmitting FD from infected vines. Although insecticide treatment against FD vectors is mandatory to prevent the progression of the disease, new contaminations may occur with the movement of infested planting material or ST migrations (Boudon-Padeau et al, 2005). The movement of ST is rather limited to the vine's canopy and is not very likely to fly for more than 2.50 m in high (Lessio F., Alma A., 2004). Seasonal and daily fly of ST is partly influenced by increased temperatures and humidity (Lessio F., Alma A., 2004). In order to determine the risk of FD vector-spreading with the planting material, a one-year study of the mobility of ST was conducted in 2009 in three nurseries in the Slovenian Primorska winegrowing region. The occurrence of ST was monitored using yellow sticky traps. They were placed at three distances in the nurseries and the nearby vineyards in three parallel lines (replicates). The traps were equidistantly placed from the nurseries' and vineyards' borders in order to determine the possible distance gradient. The main part of this study was carried out in Slovenia, where ST is widely spread in all winegrowing regions and the population rates in some vineyards were still fairly large. A small-scale experiment was also conducted in Italy and Switzerland. The objective of the work was to evaluate the effectiveness of insecticide treatments against ST adults in nurseries in order to reduce the risk of immigration of adults from the nearby vineyards. 2 MATERIALS AND METHODS 2.1 Slovenian trials In Slovenia, the monitoring was carried out in 2009 at three locations in the Primorska winegrowing region, winegrowing district of Vipava valley (Slap - 45° 50' 73,55" N, 13° 56' 31,57" E, 99 m altitude; Lože - 45° 49' 52,80" N, 13° 56' 43,68" E, 109 m altitude; Poreče - 45° 50' 57,72" N, 13° 56' 20,30" E, 95 m altitude) with four evaluating plots. Distances between the vineyards and nurseries were different, because the major part of vineyards were grown on hilly sides, while nurseries were situated along the river Vipava. Distances between nurseries and vineyards included in experimental plots are shown in the Table 1. Table 1: Sizes of experimental plots and distances between them Location (size) Vineyard nr. 1 Vineyard nr. 2 1. Slap Nursery (0.8 ha) 126 m 188 m Vineyard nr. 1 (0.65 ha) / Vineyard nr. 2 (2.0 ha) / 2. Poreče Nursery (4.5 ha) 150 m 70 m Vineyard nr. 1 (0.5 ha) / Vineyard nr. 2 (1.1 ha) / 3. Lože Nursery nr. 1 (2.5 ha) 18 m Nursery nr. 2 (0.6 ha) 18 m Vineyard nr. 1 (2.2 ha) / Vineyard nr. 2 (0.43 ha) / Except for the second location where a tree-barrier was grown between the nursery and vineyards, no other spatial obstacles were noticed. Yellow sticky traps (Unichem, 17 x 24 cm) were placed on the plots on 17 June. The traps were placed on the nurseries' and vineyards' edges and in at least three parallel lines (replications). They were placed on the inner side of borders, considering the distance of 10 m between traps. Replications were designated in order to cover the whole area of the vector's mobility; distances between them were 20 m. In vineyards, planted with varieties Merlot, Sauvignon and Cabernet sauvignon, traps were attached with a wire inside the leaf canopy between 1.3 and 1.8 m altitude, depended on the growing type. In nurseries, traps were fixed on 0.5 m long iron stakes. The traps were checked weekly and replaced every three weeks. The monitoring was finished on 8 October. In nurseries, two insecticide treatments against ST were applied. Application data are given in Table 2. Table 2: Data of insecticide treatments in nurseries in Slovenian experiment in 2009 Plot First treatment Second treatment Slap 13. 7. 6. 8. Poreče 9. 7. 31. 7. Lože 20. 7. 7. 8. For all treatments, the insecticide deltametrin (Decis 2.5 EC) in dosage 0.5 L of the product per hectare was used. Data analysis Data were analyzed using nested analysis of variance, where time of sampling were nested within trap distance from border, distance were nested within a plot use (nursery and vineyard), and plot use were nested in location. With this analysis the amount of variability contributed by each factors were estimated. Analysis was performed using STATGRAPHIC 5.0 statistical software. A small-scale experiment was conducted also in Switzerland (one plot) and Italy (two plots). In order to facilitate trial activities and compare results between the three countries, a common protocol had been established before starting the activities. 2.2 Italian trials The experiment performed by the Italian partner (IVC) was done on two plots (Pordenone - 46° 2' 48" N, 12° 52' 23" E, 70 m altitude and Verona - 45° 33' 19" N; 10° 46' 42" E; 200 m altitude). The trials started on 16 June 2009 in Verona and on 30 June 2009 in Pordenone, and were finished on 1 October. Insecticide treatments were applied in nurseries and in vineyards. The period of application as well as the number of treatments was different for the locations, as presented here below: Pordenone Vineyard - four treatments (18 April -deltametrin, 23 May indoxacarb -, 26 June and 21 July chlorpyrifos ethyl). Nursery - three treatments (deltametrin, chlorpyrifos ethyl). Verona Vineyard - one treatment (chlorpyrifos methyl - 14 July). Nursery - seven treatments (20 May - fenazaquin, 29 May - spinosad, 10 June - chlorpyrifos ethyl, 25 June - spinosad, 10 July, 30 July and 20 August - chlorpyrifos ethyl) 2.3 The Swiss trial A small-scale experiment was carried out on one plot (Anieres - 6° 13' 23,5" E, 46° 16' 24,9" N, 412 m altitude). Traps were set on 3 July 2009 and the trial finished on 5 October. Two insecticide treatments against the leafhopper were applied only in the nursery: on 13 July and 27 July. The insecticide used was lambda-cyhalotrine (Kararate with Zeon Technology (9.43% 100 g/l) in dosage 1.2 l/ha. 3 RESULTS 3.1 Slovenian trials On all three Slovenian plots, the population level of ST in vineyards was very high, which indicates a high immigration potential of the vector towards the nurseries. It should also be stressed that all Slovenian experimental locations are exposed to frequent and strong NO-SW winds that may influence the movement direction and distance of ST. Table 3: Results from nested ANOVA analyses of ST catches Source Sum of Df Mean F Variance % variance squares square component component Location 6640.6 2 3320.30 0.12 0.00 0.00 Manner of land use 82043.1 3 27347.70 23.34 ** 116.86 28.75 Trap distance from border 16403.7 14 1171.69 1.90 * 8.64 2.13 Time of sampling Error 172895.0 280 617.48 3.34 ** 96.14 23.65 194083.0 1050 184.84 184.84 45.47 Significance of F values indicated as follows: *p < 0.05; **p < 0.01 The results of nested ANOVA indicate that manner of land use and time of sampling contributes significantly (p < 0.01, F statistic) to the total variance of number of ST. Manner of land use contribute 28.75% of the total variation, and time of 01 f\ sampling contributed 23.65%. The large variance component for the error (45.47%) indicates large variation among replicates within time of sampling. Trap distance from Slap location 14,0 -i At the first location, the number of captured ST in the nurseries was very low (34 adults in total, 0.0 adults / trap / day) in contrast to the captures in the two vineyards in the neighbourhood, where the average number of adults per trap per day was 0.7 for the vineyard No. 1 and 3.6 for the vineyard No. 2. In this case, the high population rate of ST in vineyards didn't imply the population of ST in the nursery; the reason might be fairly long distances between the nursery and vineyards (126 m and 188 m). Also the position of traps regarding the distance from the nursery edge didn't show differences. Insecticide treatments didn't show reduction of population level, especially the second application of 5. August. border is significant at p < 0.05, but not at p < 0.01 and contribute only 2.13% of the total variation. rsery îeyard nr.1 îeyard nr.2 Porece locatioin The trial conducted on the second plot revealed a high number of ST captures (481 adults in total or 0.4 adults / trap / day in average) in the nursery, with a pick at the end of July (49% of all captures in the nursery). Since the nursery was treated two times with an insecticide, the high number of ST captures could be explained either by the movement of ST from the neighbourhood untreated vineyards (Vineyard nr. 2) or by insufficient efficacy of the first treatments. After the second treatment (31. July), the population rate in the nursery dropped considerably, but still relatively numerous captures afterwards suggest that one or two additional treatments against ST would be necessary. 12,0 > ra ^ 10,0 W 'S <5 _Q E 3 8,0 6,0 4,0 2,0 0,0 'It * T -IT Tl M □ nu Cl vin □ vin 26.6. 3.7. 9.7. 17. 7. 24.7. 31.7. 7.8. 14.8. 21.8. 28.8. 4.9. 11.9. 18.9. 28.9. 8.10. Figure 1: Number of captured adults of ST per trap and day in location Slap 6,0 5,0 ro TJ 4,0 cp ro H 3,0 V) 4— O <Ü E 2,0 3 1,0 0,0 "It *ít TL \A Ji □ nursery □ vineyard nr.2 □ vineyard nr. 1 26.6. 3.7. 9.7. 17. 7. 24.7. 31.7. 7.8. 14.8. 21.8. 28.8. 4.9. 11.9. 18.9. 28.9. 8.10. Figure 2: Number of captured adults of ST per trap and day in location Porece The highest number of adults was captured on the traps placed 20 meters from the nursery border (182 adults in total or 0.6 adults / trap / day in average). On traps placed on the border line, the mean capture was 0.4 adults / trap /day. 45% of all adults captured at the end of July were found 20 meters from the border line. Lože location At this location, two different plots were evaluated because of the different position of the vineyards. In contrast to the previous locations, in this case the distance between the nursery and vineyard was quite short (18 m) so that the possibilities for the movement of ST from the adjacent vineyard to the nursery were much more reliable. 9,0 -| 8,0 -7,0 -ra6,0 4 £5,0 4 1-4,0 - w > 4 m f 2,0 - c Z 1,0 - 0,0 *r *r *r ÜJ i J *l i n nursery nr. 1 □ vineyard nr.1 Ü 26.6. 3.7. 9.7.17. 7.24.7.31.7. 7.8. 14.8.21.8.28.8. 4.9. 11.9.18.9.28.9.8.10. Figure 3: Number of captured adults of ST per trap and day in Lože nursery nr. 1 14,0 -i 12,0 H f 10,0 i ro iO ,0 6,0 -