Effect of cultivars and insecticides on sitonid weevil, Sitona crinitus (Coleoptera: Curculionidae), and on yield, yield components and nodlulation of lentil (Lens culinaris)

Abstract

An experiment was conducted during 2001 and 2002 to determine the effectiveness of different insecticides against sitonid weevil [Sitona crinitus (Herbst)] (Coleoptera : Curculionidae) on 2 cultivars ('Sazak 91' and 'Yerli Kirmizi') of lentil (Lens culinaris Medikus). Yield, yield components and number of nodules fed by larvae were compared between the 2 cultivars as well as among insecticide treatments. Insecticides applied were chlorpyriphos (720 g ai/ha). malathion (1300 g ai/ha) and a systematic insecticide, oxydemeton methyl (265 g ai/ha). Application of oxydemeton methyl decreased the damage on nodules by 52.6 and 41.2% in 2001 and 2003, respectively, resulting in seed yield increase (729 and 1461.6 kg/ ha in 2001 and 2002), biological yield ( 1825.5 kg/ha and 3521.6 kg/ha), pods/plant (23.8 and 25.7). 1000-seed weight (47.7 and 48.4 g), plant height (26.1 cm and 30.0 cm), branches/plant (7.3 and 8.0). root dry weight/plant (0.136 g and 0.106 g) and shoot dry weight/plant (0.859 g and 1.056 g) over the control treatment. 'Yerli Kirmizi' cultivar showed less nodules fed (0.8 and 1.9 respectively) by the sitonid pest and gave higher seed yield (712.6 and 1393.3 kg/ha than 'Sazak 91 '(537.4 and 1301.3 kg/ha) in 2001 and 2002 respectively.