Laboratory studies of the usefulness of the biopreparation Dipel for redukction of the population of german cocroaches [Blattella germanica L.]

Określono wrażliwość prusaków (Blattella germanica L.) różnorodnych pod względem wieku i płci, na owadobójczy biopreparat z Bacillus thuringiensis var. kurs taki (Dipel).In the studies conducted for finding of biological factors effectively controlling insects of hygienic importance German cockroaches were subjected to the action of an insecticide containing spores of Bacillus thuringiensis var. kurstaki. One gram of the insecticide contained 25 miliard (US billion) spores with protein endotoxin crystals. The inscets were given drinking water and food containing 1.0%, 0.5%, 0.25%, 0.125% of the initial preparation. The experiment was carried out on 1800 cockroaches. Half of them (600 mature insects differentiated for sex and age and 300 larvae in stage 1st of development) were treated with the preparation, the remaining insects served for control. The insects were kept at about 28°C. After 9 days o the experiment in the group receiving 1% Dipel on food 76.4% mature insects and 83,0% larvae in 1st stage of development died. After 14 days all males died, and after 17 days died all females. In the control group died in that time 2.3% and 3.4% respectively. In case of lower per cent of the preparation in food the time of dying was prolonged, and at the lowest per cent it was 22 days. The study showed that Dipel effectively reduced the population of German cockroaches, and although in initial period its action was slower than that of chemical agents, it could be used for the control of these insects, especially as it in non-toxic for humans, warm-blooded animals and useful insects