Determining the Economic Damaging Level of the Egyptian Alfalfa Weevil Hypera brunneipennis (Bohemian)

摘要

An experiment was conducted to ascertain the population level of Egyptian alfalfa weevil Hvpera brunneipennis (EAW) at which chemical control becomes economically justified. Four treatments were established by applying malathion at 1 lb. a.i./acre when an average of 5,10,15, or 20 weevil larvae were found per five sweeps; one treatment was sprayed every week (0 larvae) and the controls received no chemical treatment. Five 180- degree sweeps were taken weekly in each plot with a standard 15 -inch net and net contents were emptied into a white plate for counting. EAW larvae and adults were counted and insecticide was applied when the larval number reached the designated level. Hay from each plot was cut twice manually, air dried and weighed. Significant yield differences (P =0.05) occurred between the 0 larvae treatment and the other treatments for the first cutting but no yield differences occurred for the second cutting.