411 Chemical Control of Chestnut Weevils in Central Italy S. Speranza a and B. Paparatti b Department of Plant Protection Entomology section University of Tuscia Viterbo Italy Keywords: Curculio elephas, Curculio propinquus, Curculionidae, Latium, pest control Abstract In Central Italy Chestnut Gall Wasp Dryocosmus kuriphilus Yasumatsu, Chestnut Weevils and two Chestnut Moths, Cydia fagiglandana (Zeller) and C. spendana (Hübner) are the key insect pests of chestnut orchards. In Latium Region two species of chestnut weevils, Curculio elephas (Gyll.) and C. propinquus (Desbr.), are represented at 5% and 95% respectively. These two carpophagous insects can generate severe yield losses, variable in the years from 20 to 90%. In order to minimize the rate of damaged chestnuts, chemical control trials were carried out comparing two active ingredients: Thiacloprid and Etofenprox. The results show a higher effectiveness of a.i. Thiacloprid with respect to Etofenprox and control treatments. INTRODUCTION The key insect pests in chestnut orchards, at least prior the introduction in Latium (Central Italy) of the chestnut gall wasp (Dryocosmus kuriphilus Yasumatsu) were the chestnut weevils [Curculio elephas (Gyll.) and C. propinquus (Desbr.)] (Cinti et al., 1993; Paparatti and Speranza, 1999, 2003, 2005a; Speranza, 1999; Speranza et al., 2008; Vitagliano et al., 1993). These insects can induce severe yield losses, sometimes up to 90%. Due to this, the growers who follow traditional agricultural practices are used to chemically intervene against these insect pests. This research aims to compare two active ingredients (a.i.) in order to assess the most effective in obtaining a low infested harvest. MATERIALS AND METHODS Experimental Site The field experiment was carried out in a 0.7 ha chestnut orchard, located in the municipality of Canepina (Viterbo, Italy) at an altitude of 455 m a.s.l. In 2005 and 2006, chestnuts were not harvested in this site due to the very high rate of weevil infestation. Three non-contiguous plots have been selected in the orchard. Each plot consisted of five chestnut plants (Castanea sativa Miller), adjacent to each other. The trees were selected according to several homogeneity criteria: hundred-year-old, approximately 25 m high, not belonging to the “marrone” variety. Between the plots, an untreated stripe 30 m wide was considered. The plots were identified and labelled as “A”, “B” and “C”. Samplings of the Adult Population Samplings on the adult weevil population were carried out from August 9 th to October 27 nd every four days with the branch-shaking method. The samplings were performed by placing a white sheet under selected branches, preferably chosen among those exposed to the south and at a medium-low height of the canopy, according to the methodology previously described (Paparatti and Speranza, 2005b). These branches were shaken by the aid of a hook mounted on an extensible shaft. This procedure was a speranza@unitus.it b paparatt@unitus.it Proc. 1 st European Congress on Chestnut - Castanea 2009 Eds.: G. Bounous and G.L. Beccaro Acta Hort. 866, ISHS 2010