engleski

Sensitivity of cabbage flea beetles (Coleoptera: Chrysomelidae) to insecticides

Cabbage flea beetles (Phyllotreta sp.) are very important rapeseed pests in the germination period. Feeding causes round holes in the leaves, that increase in size as leaf surface area increases, and leaf margins necrotize. Young plants are stunted in growth and produce lower yields. The main control measure is chemical control with insecticides. In Hong Kong and Japan, flea beetles have been found to be resistant to certain insecticides[1]. The objective of this study was to test cabbage flea beetle populations for active ingredients from the pyrethroid, organophosphorus insecticide, and neonicotinoid groups. During the study period (2019, 2020, and 2021), sensitivity testing was conducted using IRAC test methods 011 for pyrethroids, 021 for neonicotinoids, 025 for organophosphorus insecticides[2], and the protocol of Heimbach et al.[3]. Adult forms of cabbage flea beetles were collected from untreated crops (at 30 sites) and delivered to the laboratory. Solutions based on the active ingredients dimethoate, alphacypermethrin, cypermethrin, deltamethrin, and thiacloprid were prepared at 100% and 20% dosages. The prepared solutions were transferred into glass vials, which were placed on a roller. After the vials were dried, ten adult cabbage flea beetles were placed in each vial. The experiment was evaluated after 24 hours and individuals that showed no coordinated movements for 60 seconds were considered dead. In 2019, 86% of the tested populations were sensitive to dimethoate, while 79% of the tested populations were sensitive to the active ingredient alphacypermethrin and only 14% of the populations were sensitive to the active ingredient thiacloprid. In 2020, all populations tested were sensitive to the active ingredients cypermethrin and deltamethrin. In 2021, 64% of the populations tested were sensitive to the active ingredient cypermethrin and all cabbage flea beetle populations were sensitive to the active ingredient deltamethrin.

cabbage flea beetles, oilseed rape, inseciticides, resistance

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