[Evaluation of mirex for the control of pharaoh's ants]

The paper analyses the mode of action of the organic chlorine compound Mirex in laboratory colonies of the pharaoh's ant Monomorium pharaonis under the special view of practical use in control measures in comparison with the related insecticide Chlordecone (Kepone). Similar to Chlordecone the queens are very susceptible towards the action of Mirex. According to the regression lines of the mortality the best concentrations for practical control measures are in the range of 0.1 to 1%, respectively. Under laboratory conditions a reliable eradication is effected by an application of 0.001% Mirex over a period of three weeks. Such a treatment lead to the loss of reproductive capacity of the remaining living queens. These queens do not recover after transmission to normal colonies. The larvae were influenced in the same manner as the adults. At the recommended level of Mirex all of the larvae disappear within the first five days of application of the poison bait. Also a short termed use lead to a long lasting damage of the ant societies. Between different baits no significant difference could be demonstrated even when one bait obviously was better accepted than another. Because of the strong effect on intact colonies Mirex should be recommended for the control of this ant pest.