engleski

Results with Spinosad against resistant strains of Colorado Potato Beetle in Croatia

In Croatia the Colorado Potato Beetles (CPB) is highly resistant to all organophosphourus, carbamate and pyrethroid insecticides (Maceljski, Igrc, 1992 ; Maceljski, 1995). Therefore new groups of insecticides are investigated. Spinosad is a mixture of spinosyns which compounds naturally derives from an Actinomycetes-Saccharopolyspora spinosa. Spinosad contains the two most active natural factors-spynosin A and D. It is producted by DowElanco. In laboratory trials using the modified IRAC No. 7 method, the formulation Spinosad DE 105 containig 480 g/ha of spinosad as active ingredient was highly efficient against larvae of resistant strains of the CPB, and expressed a delayed, but at the end satisfactory action against adults also. A field trail was conducted in a region where the resistance of the CPB to OP, C and pyrethroid insecticides was previously proven. Spinosad DE 105 used in a dosage rate of 48 g/ha prevented any damages of larvae until 21 days, 36 g/ha until 18 days and 24 g/ha until 12 days after treatment. On the 21th day the degree of leaf protection was 99 %, 97 % resp. 90 % compared with 3 % on standard pyrethroid treatments. In spite of a late treatment on an early cultivar of potatoes the yields on plots treated with Spinosad DE 105 48 g/ha were 40 %, 36 g/ha 33, 9 % and 24 g/ha 23, 5 % higher than the yield on untreated. These differencies are statistically significant. The yield on untreated plots was not significantly different from the yields on plots treated with OP and pyrethroid insecticides.

Colorado Potato Beetle; spinosad

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