Lethal and sublethal effects of sulfoxaflor on the small brown planthopper Laodelphax striatellus

- Sulfoxaflor exhibited higher level toxicity against L. striatellus adults compared with tested seven other insecticides.
- Both LD10 and LD30 induced inhibition effects on L. striatellus.
- LD3 induced hormesis on fecundity and increased the net reproductive rate (R0).
- Sulfoxaflor is a valid candidate for L. striatellus management.

Laodelphax striatellus (Fallén), as an important pest of gramineous crops, has developed resistance to multiple classes of insecticides, impairing control efficiency. However, the application of insecticides is still the main control measure for it. Herein, the lethal effects of seven insecticides as well as sulfoxaflor, which has been introduced and registered for controlling L. striatellus in China, were investigated. The acute toxicity of these insecticides on the L. striatellus adults was ranked as sulfoxaflor > abamectin > dinotefuran > emamectin benzoate > ethofenprox > imidacloprid > chlorantraniliprole > chlorpyrifos. The toxicity of sulfoxaflor against the adults was highest with LD50 at 1.07-1.09 ng/insect. In addition, the sublethal effects of lower lethal dose LD3 (0.06 ng/insect), low lethal dose LD10 (0.15 ng/insect) and moderate lethal dose LD30 (0.49 ng/insect) of sulfoxaflor for L. striatellus were assessed as well. Both LD10 and LD30 induced slower nymphal development period, shorter oviposition period and longer pre-oviposition period in L. striatellus. The LD30 also shortened the longevity of females. Hormesis on fecundity was observed in L. striatellus exposed to LD3. Therefore, the net reproductive rate (R0) was increased by LD3. The intrinsic rate of increase (rm) was reduced by LD10 and LD30 while mean generation time (T) and doubling time (DT) were prolonged. The acute sulfoxaflor doses in its toxicological properties need to be considered when develop L. striatellus control strategy with sulfoxaflor. These results demonstrate that sulfoxaflor is a valid candidate for L. striatellus management.

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