Lethal and Sublethal Effects of Organically-Approved Insecticides against Bagrada hilaris (Hemiptera: Pentatomidae)

摘要

Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae) is a stink bug species that preferentially attacks cruciferous crops. Because organic growers have limited insecticide tools for combating B. hilaris, the lethal and sublethal effects of organically approved insecticide products and their selected combinations against B. hilaris were examined in laboratory and field settings. In a topical spray assay, spinosad, either alone or in combination with pyrethrins, azadirachtin, and potassium salts, resulted in & 95% mortality relative to the water-only treatment 48 h postapplication; whereas, stand-alone pyrethrins and azadirachtin failed to cause similar mortality rates. When adults were exposed to treated broccoli (Brassica oleracea var. italica Blenck) seedlings for 48 h after 0, 1, and 7 d of application, the number of feeding injury sites was significantly lower with the combined treatment of spinosad, pyrethrins, and azadirachtin than those on seedlings treated with water alone at 0 and 1 d postapplication. However, when adults were exposed to seedlings at 7 d postapplication, only the combined treatment with pyrethrins and azadirachtin reduced the number of feeding sites compared with the water control. When the locomotor activity of adults was evaluated after exposure to dried residues for 20 min and 2 h, adults were found to be more active when exposed to combined treatment with spinosad, pyrethrins, and azadirachtin than the individual treatments. In the field trials, although most of the insecticide products and their combinations failed to provide persistent B. hilaris control, the combined treatment of pyrethrins and potassium salts reduced the number of feeding sites compared with the nontreated control.