Thrips are some of the most economically important pests in agriculture. There are thousands of thrips species worldwide, but the most common pest species are Western flower and onion thrips. They have wide host ranges that include both monocotyledonous and dicotyledonous plants. Although there are numerous methods employed to help the fight against this pest, chemical methods are the most common. Over time the repeated applications of insecticides have resulted in numerous cases of pesticide resistance and as a result reduced the effectiveness of spray programmes. Insecticide resistance is well documented with this pest and with chemical control being an important pillar of any IPM control strategy, it becomes increasingly imperative to maintain the effectiveness of your chemical applications.
There are four documented insecticide resistance strategies in thrips. The first is a delayed penetration through the integument, the external protective layer of the insect, reducing the effectives of the active ingredient at its target site. Internally, detoxification enzymes may metabolize the active ingredient and in the process deactivate its lethal action, or thrips may alter the target site of the insecticide rendering in ineffective. The last strategy is a change in the insects movement behavior to avoid coming into contact with the insecticide. This strategy is the one we are targeting here.
The potential improvement in thrips control in a commercial onion field by simply making a change to the spray mixture was evaluated. The result of adding a pesticide synergist to the mixture increased the efficiency of the control programme without any additional sprays or increasing dosages. The synergist has an attractant in its formulation which draws the thrips to areas where they come into contact with the insecticide. This method significantly reduced adult thrips numbers by 28% when compared to the control after just 3 applications.
Written by Ralston Hans – Technical Sales Manager
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