عنوان مقاله [English]
نویسندگان [English]چکیده [English]
A study was carried out to determine the suitable spraying time for phosalone against alfalfa weevil, Hypera postica (Gyllenhal) (Col.: Curculionidae), with the least adverse effects on its major parasitoid, Bathyplectes curculionis (Thomson) (Hym.: Ichneumonidae). Plots of 10 m2 were sprayed with phosalone (35%) at 3.0 kg/ha, using a knapsack sprayer. The residues of phosalone in parasitoid cocoon and alfalfa foliage were measured at different time intervals after treatment using high performance liquid chromatography. Residues of phosalone on B. curculionis cocoons treated by dipping method were 0.751, 0.466, 0.245, 0.115, 0.075, 0.044 and 0.019 Âµg/cocoon in 2 hours, 1, 3, 7, 14, 22 and 30 days after treatment, respectively. Results of this experiment revealed that there was no penetration of the insecticide into the cocoon. In fresh foliage, the residues of phosalone were 74.066 ï± 6.9, 47.319 ï± 2.1, 16.345 ï± 1.99 and 3.743 ï± 0.33 mg/kg at 2, 4, 7 and 14 days after spraying, respectively. The residue level on foliage at day 7 is critical and this must be considered as the least interval time between the application of the phosalone and the peak of parasitoid population.