Evaluation of Population Density and Damage of the sugar beet weevil, Lixus incanescens (Col.: Curculionidae) on six sugar beet cultivars

The sugar beet weevil, Lixus incanescens Boh., is an important insect pest of sugar beet, Beta vulgaris L., in Razavi Khorasan Province. In this research, population densities of the sugar beet weevil eggs and larvae were evaluated on plants of six sugar beet cultivars including Ardabili, Aras, Persia, Flores, Laetitia and Rosire in an experimental field in 2011 and 2012. Also, the percentage of larval damage on petioles, the percentage of weight loss of tuber and the percentage of reduction in sugar content of the tuber were studied in these cultivars infected by five larvae under field condition. The lowest and the highest densities of eggs and larvae were observed on Persia and Ardabili cultivars, respectively in both years. Also, the percentage of larval damage on petioles was significantly lower in Persia and Laetitia than the other cultivars. In addition, the percentage of weight loss of tuber and the percentage of reduction in sugar content of tuber were lowest in infected plants of Persia. Therefore, it can be concluded that the sugar beet weevil damage was both quantitatively and qualitatively least in Persia among the examined cultivars and so this cultivar has the potential for being used in an integrated pest management program of L. incanescens in sugar beet fields.