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Biological methods of monitoring insecticides resistant populations of selected oilseed rape pests
Zdražil, Adam ; Kazda, Jan (advisor) ; Josef, Josef (referee)
The literary part of the thesis describes biology, economic importance and methods of chemical protection against pollen beetle, cabbage seed weevil and cabbage stem flea beetle. The resistance of these pests against zoocides in the Czech republic and in some parts of neighbour European countries is decribed and principles of antiresistance strategies are outlined. Each group of insecticides is describd and their active components are rated in the practical part of the thesis. Findings about pest resistance are summarized - resistance types and mechanisms in particular. Then monitoring of resistent populations of plant pests are described.
New findings concerning the resistance of three oilseed rape pests were acquired using biological methods. For cabage seed weevil six areas were evaluated, for pollen beetle seven and for cabbage stem flea beetle two areas were evaluated. All the evaluated areas are in the Czech republic.
The adult-vial test number 11, nr. 25, nr. 27 accordinng to IRAC methodology and topical aplication test were used to rate the resistance. The efficiency of five pyrethroids (deltamethrin, lambda-cyhalothrin, esfenvalerate, etofenprox, tau-fluvalinate, cypermethrin), one organophosphate (chlorpyrifos - cabbage stem flea beetle only) and one oxadiazin (indoxacarb) in different concentrations were rated.
The mortality of the pests was rated 24 hours after active component functioning for pollen beetle and cabbage seed weevil and after 48 hours for cabage stem flea beetle. Then lethal concentration LC50 and LC95 values were assessed.
For ppollen beetle, the resistance against pyrethroids was confirmed with the exception, the effect of neonicotinoids was variable, acetamiprid and thiacloprid showed reduced efficiency in populations of some areas. Assessed populations of cabbage seed weevil and cabbage stem flea beetle were very sensitive to pyrethroids, but neonicotinoids showed insufficient efficiency. The indoxacarb sensitivity of pollen beetle and cabbage stem flea beetle was high.
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