Toxicity of water pepper, Persicaria hydropiper (L.) extracts against Nilaparvata lugens (Stål) and non-targeted effect on earthworm

Nilaparvata lugens is a monophagous pest of rice crop. Various strategies have been employed to manage this pest. We evaluated the toxicity of Persicaria hydropiper (L.) leaf extracts against N. lugens along with chemical insecticide, imidacloprid. P. hydropiper leaf extracts produced significant mortality against N. lugens nymphal and adult stages in a dose dependent manner. Different concentration of P. hydropiper extracts with two controls (acetone and water) in toxicity assay revealed LC50 values of 620 ppm against N. lugens adults, whereas 230 and 130 ppm for larger and smaller nymphs, respectively. Imidaloprid yielded an LC50 of 510–560 ppm against nymphs and adults. Nine vital compounds were identified from the P. hydropiper extracts based on gas chromatography-mass spectrometry analysis (GC-MS). Additionally, P. hydropiper extracts was found harmless to non-target organism, as they did not produce any toxicity on earthworm, Eisenia foetida. Hence, present results indicated that P. hydropiper extracts can be used as efficient alternate to synthetic insecticides against N. lugens in rice.