ABSTRACT

In this paper results of infestation of Blatella germanica L with mixed culture of insecticidal fungi belonging to one two species are presented. In the first stage of experiment the insects were infested first with B. bassiana spores and later with P. farinosus spores (strains Ł and P) was used as first and B. bassiana as second with time sequence of only 24 and 72 hours. Out of one species cultures tests were done alternately with strains Ł and P of P. farinosus. The control insects were always infested with fungi applied to cockroach in the first place. From comparison of data it results that irrespective of the time that elapsed from application of the first pathogen to the time of application of the second pathogen the number of dead individuals was always higher in experimental series than in control i.e. when only one pathogen was applied. After 30 days of experiment the hihest mortality in females amounted to, 3,3% and in males - 80,0% whereas in the control it amounted 6,6%and 20,0% . Respectively , after feeding on diet infested only with one pathogen. After 50 years the highest mortality amounted to 20% in females and 100% in mealeswith control of 30% and 53,3% in meals and females, respectively. When the sequence of pathogen application was reversed, mortality after 30 day amounted to 53,3% in females and 36,7% in meals with corresponding numbers in cotrols beging 26,6% and 26,6%, respectively. After elapse of 50 days the highest mortality in females was 90% and in males - 100% with cotrol showing mortality of 36,7% and 63,3% respectively. From comparison of numerical data complied in Table 1 it results that most advantageous time span between first and second infestation with fungi is 48 h. Mortality of cockroaches infested with fungi of two different species was higher than in isects infested with one species of fungi.