Insecticide Resistance of the Small Brown Planthopper, Laodelphax striatellus FALLEN (Hemiptera : Delphacidae), Collected in Kyushu and on the East China Sea

Abstract

Topical LD₅₀ values for eight insecticides were determined in five populations of the small brown planthopper, Laodelphax striatellus FALLEN, (SBH), collected in fields in districts of Kyushu and on the East China Sea in 1980. No significant local variabilities in LD₅₀ values were observed with the ABPH collected from the four localities in Kyushu but they showed the most remarkable increase of resistance ratios to malathion. The tested population had developed 90- to 270-fold resistance as compared with the Chikugo population tested in 1967, and also showed 20- to 70-fold resistance to fenitrothion, diazinon, MTMC, carbaryl and MIPC. The SBPH population collected on the East China Sea gave LD₅₀ values coincident with these four populations.