Selected combinations of (Z)-5-decenyl, (Z)-7-dodecenyl, and (Z)-9-tetradecenyl acetates, the pheromone components of the turnip mothAgrotis Segetum were tested for field attractancy at six, two, and three sites in Europe, Asia, and Africa, respectively. At all of the sites in Eurasia and in northern Africa the ternary mixture of the acetates captured most males, while at the sites south of the Sahara in Africa, (Z)-5-decenyl acetate alone was responsible for attraction. Differences in male attraction among the populations studied confirm the existence of significant population variation in the pheromone ofA. segetum. Interpretation of the present results together with earlier studies suggests that this variation is more or less continuous in Eurasia and north Africa, while a clearly distinct pheromone type is present in the areas south of the Sahara desert.

During initial screening of the synthetic pyrethroid lamdacyhalothrin (PP 321) at a concentration of 44 and 22 mg/1 and applied as a 30 ml drench over each plant against third to fourth instar cutworms, Agrotis segetum (Denis & Schiffermuller) in microplots, few died but they did not damage the plants.Reducing the concentrations to 11 and 5.5 mg/1 increased mortality and plant damage. When A. segetum were confined on soil treated with the insecticide at concentrations of 22, 11 and 5.5 mg/1 and sprayed at an equivalent rate of 500 1/ha, they all died within one day. The higher concentrations appeared to have a repellent and/or antifeedant effect, and it has been possible to reduce the concentration of lamdacyhalothrin to 12.5 mg/1 (=5.6g a.i./ha) for the drench treatment without risking economic plant damage. For insecticides that have repellent and/or antifeedant properties, it should be possible to balance lower concentrations with adequate protection of plants from pest damage.

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