Trials on the Timing of Chemical Control of Lentil weevil, Bruchus lentis Frӧlich (Coleoptera: Chrysomelidae: Bruchinae) in Lentil Field in Gachsaran Region (Iran

The lentil weevil, Bruchus lentis Frӧlich, (Coleoptera: Chrysomelidae: Bruchinae) is the most serious pest of lentil in Iran. Economic losses due to this pest reach up to 40% of the lentil crop. Over a two-year study (2012 and 2013) in Agricultural Research Station of Gachsaran Region, best timing of chemical control of B. lentis was determined. A field experiment with cultivation of lentil Sina variety Lens culinaris Medik was conducted in a randomized complete block design with five treatments and three replications. The treatments consisted of spraying four times (respectively, during the early flowering, 10 days after the first spraying, 10 days after the second spraying; 10 days after the third spraying) and control (without spraying). For the spraying from Endosulfan insecticide EC50% at ratio one liter per hectare was used. Three samples were taken from the pods and totally 150 pods from each replicate for contaminations of seeds were investigated. After the determination of the percent of seeds contamination, results were statistically analysed. Based on the results obtained, first spray treatment, with the mean contamination of 15.45% and second spray treatment with the mean contamination of 12.25% had the highest impact on reducing contamination lentil seeds to B. lentis and between them there was no statistically significant difference and were in one group. Therefore, spraying one time during the early flowering until 15 days after it was the best time to control of B. lentis.