The susceptibility of rapeseed pollen beetle (Brassicogethes aeneus) to Azadirachtin, Alphacypermetrin, Imidacloprid and Matrin in laboratory and field conditions

The rapeseed pollen beetle, Brassicogethes aeneus is one of the key and important pests of rapeseed in the northern provinces of Iran. In this research, the effectiveness of two botanical insecticides, Matrin and azadirachtin, as well as chemical insecticides, Alphacypermetrin and Imidacloprid, were investigated against this pest in laboratory and field conditions. Laboratory bioassay was performed by exposing the insects to different concentrations of the insecticides (five concentrations for each insecticide). In these assays, the highest susceptibility was recorded to Alphacypermetrin (LC50 = 0.1 mg ai/L) and after that, Matrin (1.2), Imidacloprid (60.0), and Azadirachtin (100.7 mg ai/L), respectively. A field experiment, in the form of a randomized complete block design, was implemented in three different creating a barrier (lace fabric) before or after conducting the treatments and plots without any barriers. In the field conditions (common treatment; no barrier), the efficacy of botanicals was slower but after four days, their appropriate effectiveness was observed. However, after one week, the efficiency of all four treatments was more than 90 percent. At the endpoint of the experiment (four weeks), Imidacloprid was the most effective (73.4 %) and after that, there were Alphacypermetrin (59 %), Matrin (51.4 %), and Azadirachtin (47.9 %) treatments. The results of this research showed that Alphacypermetrin can be used as an alternative to Imidacloprid (the prevalent treatment) in pest outbreak conditions. In addition, the data showed the appropriate and competitive efficiency of Matrin, to control rapeseed pollen beetle.