Susceptibility of Rice Planthoppers Nilaparvata lugens and Sogatella furcifera (Homoptera: Delphacidae) to Insecticides as Influenced by Level of Resistance in the Host Plant

The susceptibility of the whitebacked planthopper, Sogatella furcifera , and the brown planthopper, Nilaparvata lugens , to insecticides is affected by the level of varietal resistance in the host plants on which they are reared. Hoppers reared on moderately resistant rice varieties had lower LD50 values when topically treated, and higher mortality when sprayed in the Potter spray tower and when placed on sprayed plants, than did those reared on susceptible varieties.