Some biological, ecological characteristics of brown planthopper (Nilaparvata lugens Stal.) and chemical prevention measures in Dien Khanh District, Khanh Hoa Province

Brown planthopper Nilaparvata lugens Stal. is one of the current serious rice pests that significantly reduce the productivity of rice plants. Some biological and ecological characteristics of brown planthopper has been studied in different laboratory conditions using VHC rice as food. The experimental conditions included: room temperature at 260C, humidity of 72%; room temperature at 280C, humidity of 70%; room temperature at 300C, humidity of 68%. Their life cycle was recorded 28.80 ± 0.83 days, 27.83 ± 0.82 days and 26.64 ± 0.90 days, respectively. In the condition of temperature at 260C and humidity at 72%, brown planthopper has the highest fertility at 81.35 ± 13.62 eggs/adult, hatching rate is 96.3 ± 2.30%. In the Winter-Spring crop in 2018-2019 in Dien Khanh District, Khanh Hoa Province, brown planthoppers appeared from the tillering stage of rice. The highest density was reached at the stage of milk-ripening rice. The density of brown planthoppers in the early rice crop was lower than that of the main and late rice crops. The VHC rice was higher infected with planthoppers than TH6 variety. Using three chemical insecticides to control brown planthopper including in laboratory and field conditions indicates that Chess 50WG had the highest effectiveness after 7 days of treatment.