A description of the products and the application dosage and frequency is given in Table 1. Each year, an untreated control was added to the experimental design. A sample of 100 leaves was taken from the five plots of each treatment (20 leaves/replication). Each leaf was collected from a different plant. This sampling selleck chemical was repeated twice during the cropping period; in year 1, the samplings were

made 61 and 67 days after planting, and in year 2, the samplings were collected 68 and 75 days after planting. For each sample, we counted the number of apterae adults of the four most abundant potato colonizing species in Switzerland: Myzus persicae (Sulzer), Macrosiphum euphorbiae (Thomas), Aulacorthum solani (Kaltenbach) and Aphis nasturtii (Kaltenbach) (Derron and Goy 1995). In addition, two tubers were manually collected from each plant 4 weeks after haulm killing and tested by ELISA (Gugerli and Gehriger 1980)]. We used monoclonal antibodies specific to serotype N (Bioreba, Reinach, Switzerland). Selleckchem BAY 73-4506 The two-year results

were analysed using Statistica® (Statsofts, Tulsa, OK, USA). For each leaf sampling, we examined the average aphid count (two replications). The analysis was carried out for the different aphid species separately. The number of aphids was converted using the square root transformation method (Dagnelie 1975). For each plot, we examined the percentage of PVY-infected tubers at harvest (five replications). The percentage of tuber infection was converted using the angular data transformation method (Dagnelie

1975). For both aphids and PVY analysis, we ran a two-factor (year and treatment) analysis of variance (anova) with an α error level of 0.05 (Gomez and Gomez 1984). A treatment was considered effective in controlling aphid populations or PVY if the following three conditions were met. First, the results of the anova showed statistically significant differences at the 5% level. Second, the treatment and the control belonged to different homogeneity medchemexpress groups, according to the Newman–Keuls post hoc analysis test (Dagnelie 1975). Third, the treatment had a positive value of efficacy. Treatment efficacy is given by the following formula: . The efficacy varies from 0% to 100%, 0% signifying that the treatment had no effect and 100% that it was fully effective. A negative efficacy can be obtained when the result of the treatment is higher than the result of the control. The effect of the treatment strategies could not be assessed on A. solani, because the number of captures was too low to detect any differences among treatments (F(3;6) = 1.57; P > 0.05, Fig. 1). The oil and the elicitor were not effective in controlling A. nasturtii populations, and a high variability was observed in plots treated with oil (from 9 to 61 insects sampled on 100 leaves). The insecticide was effective in controlling A.