CONTROL TECHNIQUES OF THE ARTICHOKE MOTH (GORTYNA XANTHENES GERMAR): MONITORING OF POPULATION DYNAMICS AND EFFICIENCY OF THE ORGANIC INSECTICIDES BACILLUS THURINGIENSIS VAR. KURSTAKI AND SPINOSAD IN A FIELD TRIAL FOR ORGANIC PRODUCTION...

Abstract

Monitoring of artichoke moth larvae (Gortyna xanthenes) (Germar, 1842) was performed during the early stages before their penetration into the plant. In order to apply the insecticide at the optimal time, a threshold for intervention was established at a point when 15% of eggs had hatched. These eggs are collected in each season in different parts of the Parc Agrari del Baix L lobregat and kept under field conditions to observe their development before and during hatching. This article will give details on the 2008-2009 and 2009-2010 seasons. During the 2008-2009 season, a field trial was conducted on a commercial farm to monitor the efficiency of two organic insecticide products based on Bacillus turingiensis var. kurstaki and spinosad. The trial consisted of a biweekly application of the two treatments plus an untreated control group during hatching. Two crops from the same farm were used, separated by four metres; one was a first-year crop and the other a second-year crop. The pest pressure was much higher in the second-year than in the first-year crop, which confirms that the presence of the pest in chrysalis form is crucial for the stumps (p ≤ 0.005). Treatment with spinosad gave the best results both in the first-year field with 89% of buds without larvae compared to about 69% of the control plants (p ≤ 0.005), and the second-year crop with 61% of buds without larvae compared to 23% of control plants (p ≤ 0.005). The B. thuringiensis var. kurstaki gave positive results in the first-year crop, with 80% of buds without larvae. This trend, however, was not reproduced in the secondyear crop.

Keywords: Gortyna xanthenes, artichoke moth, hatching, Bacillus thuringiensis, spinosad, organic production.