Contact toxicity of six plant extracts to different larval stages of Colorado potato beetle (Leptinotarsa decemlineata SAY (Col: Chrysomelidae))
Discovery of new eco-friendly methods for management of insect-pests is very important in integrated pest management. Contact toxicity of six plant extracts i.e. Acanthus dioscoridis L. (Acanthaceae), Achillea millefolium L. (Asteraceae), Bifora radians Bieb. (Apiaceae), Heracleum platytaenium Boiss (Apiaceae), Humulus lupulus L. (Cannabaceae) and Phlomoides tuberosa (L.) Moench (Lamiaceae), were tested on the 1st to 4th instar larvae of Colorado potato beetle [Leptinotarsa decemlineata Say. (Coleoptera: Chrysomelidae)]. The H. platytaenium and H. lupulus extracts were most effective among the tested extracts, so dose–response bioassay was carried out only by using H. lupulus and H. platytaenium against larval stages of Colorado potato beetle. The H. platytaenium extract was the most effective with calculated LD50 values 0.126, 0.204, 0.206 and 0.458 μg insect-1, LD90 values were calculated as 0.345, 0.342, 0.402, 0.566 μg insect-1 for 1st, 2nd, 3rd and 4th instars larvae respectively. These results indicate that H. platytaenium and H. lupulus extracts have great potentials as insecticides in the management of larvae of L. decemlineata.
Key words: Colorado potato beetle; Plant extracts; Heracleum platytaenium; Humulus lupulus; Contact toxicity