Indoxacarb Resistance In The German Cockroach After Bait Selection

Abstract:
In this study, we examined the resistance status of six field-collected strains from Singapore to eight insecticides, as well as the resistance of the parental through F5 generations after they were selected with indoxacarb bait. All strains showed no resistance to acetamiprid (0.7–1.9x), imidacloprid (1.6–2.5x), chlorantraniliprole (2.3–4.0x), and bendiocarb (2.1–2.7x); low levels of resistance to indoxacarb (2.5–9.9x) and chlorpyrifos (2.6–8.7x); and moderate levels of resistance to DDT (>2.6x) and deltamethrin (5.8–55.6x). Very low resistance levels were detected in the indoxacarb bait assay test. Cross-resistance between deltamethrin and indoxacarb was found where LD50 and RR50 values for deltamethrin and indoxacarb were positively correlated (P < 0.01). Subsequent selection with indoxacarb bait on three strains significantly (P < 0.05) increased indoxacarb resistance (up to >30x), but it reduced deltamethrin resistance.