The efficacy of the fungus Lecanicillium lecanii and two bacteria, Bacillus thuringiensis and Streptomyces avermitilis against the two-spotted spider mite Tetranychus urticae Koch and side effects on its predatory mite Phytoseiulus persimilis A.-H. was studied under laboratory conditions. Both S. avermitilis and B. thuringiensis based biopesticides resulted in maximum mortality rates of 90–100% and 91–99% for spider mite adults and larvae, respectively. The mortality of spider mite larvae under fungus L. lecanii treatment was around 60%. These bacteria and fungus also had toxic effects against P. persimilis on the same day of applying insecticides and releasing the predatory mite. The release of predatory mites one day post-treatment of plants with L. lecanii and 7 days post-treatment with B. thuringiensis or S. avermitilis did not negatively affect the survival of predators released. These findings support the potential use of entomopathogenic fungi and bacteria in combination with predatory mites in spider mite biocontrol.

The use of Bacillus thuringiensis (Bt) to control insect pests has already been established in various agronomic and forest crops. It is a bacterium that does not pollute the environment, is safe for mammals and vertebrates, lacks toxicity to plants and specifically targets insects. To date in-depth studies have not been conducted about the use of Bt to control the main pest of mahogany (Swietenia macrophylla King) and other Meliaceae species, the Hypsipyla grandella Zeller (Lepidoptera: Pyralidae). Therefore, this study aimed to test the pathogenicity of Bt strains on H. grandella caterpillars, as well to determine the lethal concentration required to kill 50% of the population (LC50) of the most promising strains. Ten strains of Bt toxic to lepidopteran proven in previous trials were used and these were incorporated into a natural diet with mahogany seeds to check their mortality. The LC50 of the top five strains was determined. The results indicate that H. grandella is highly susceptible to Bt toxins and the S1905 strain is highly toxic. Therefore, the use of Bt strains may be a tool to be incorporated into the integrated management of this important pest.

In the years 2002–2004 strains of Bacillus thuringiensis and 37 species of entomopathogenic fungi were isolated and identified in the Polish and Belarussian parts of Białowieża Forest (BF). Mitosporic fungi and bacteria dominated in litter sperficial soil layer, forest, litter and floor vegetation whereas entomophtoralen fungi prevailed in bushy undergrowth layers and tree crowns. The dominant species Beauveria bassiana was observed in forest floor, subcortical habitats on dead trees, meadows and rushes. The species Entomophthora israelensis, Beauveria cf. bassiana, Paecilomyces suffultus and P. tenuipes were for the first time described as insect pathogens in BF. Entomophthorales seem to hold much greater part than mitosporic forms in the whole diversity of entomopathogenic fungi. Relatively rich sets of these fungi recognised in BF during last decades confirm the predestination of this area as highly significant refuge for other groups of arthropod pathogens, and it should encourage scientists to widen their research and contribute to a rather scarce knowledge in this field.