Insecticides based on crystalline toxins of Bacillus thuringiensis are very good biological plant protection products. However, the spectrum of activity of some toxins is narrow or resistance among insects has been developed. We tested the insecticidal activity of crystals of the B. thuringiensis MPU B9 strain alone and supplemented with Vip3Aa proteins against important pests: Spodoptera exigua Hübner (Lepidoptera: Noctuidae), Cydia pomonella L. (Lepidoptera: Tortricidae) and Dendrolimus pini L. (Lepidoptera: Lasiocampidae). The Cry toxins were more active for D. pini but less active against S. exigua and C. pomonella than Vip3Aa. Supplementation of Cry toxins by small amounts of vegetative insecticidal proteins demonstrated synergistic effect and significantly enhanced the toxicity of the insecticide. The results indicate the utility of Cry and Vip3Aa toxins mixtures to control populations of crops and forests insect pests.

We determined the distribution of microbial endosymbionts as possible agents of parthenogenesis in Oribatida. We screened mites from 20 species of 14 families suspected to be parthenogenetic from absence or rarity of males. Our research included parthenogenesis-inducing bacteria Wolbachia sp., Cardinium sp., Rickettsia sp., and additionally Arsenophonus, Spiroplasma, and microsporidia that also can manipulate the host reproduction. We were detecting the endosymbionts by PCR-based methods and electron microscopic observation of fixed and stained preparations of host cells. We detected Wolbachia only in one Oribatida species - Oppiella nova by identifying Wolbachia genes with PCR method. The observation of transmission electron micrograph confirmed the infection by endosymbiont in O. nova and its lack in other Oribatida species. The sequence analysis of hcpA and fbpA genes showed that the Wolbachia strain from O. nova is diverged from strains characterized in some insects, crustaceans Isopoda, mites Tetranychidae, springtails Hexapoda, and roundworms Nematoda. The analysis strongly suggests that the Wolbachia sp. strain found in O. nova does not belong to supergroups A, B, C, D, E, F, H, and M. We found clearly that the sequences of Wolbachia from O. nova are distantly related to sequences from the bacteria of the other supergroups. This observation makes O. nova a unique Wolbachia host in terms of the distinction of the strain. The role of these microorganisms in O. nova remains unknown and is the issue to investigate.

The aim of our study was to determine the usefulness of mixtures of carvacrol andBacillus thuringiensiscrystalline proteins Cry against pests of two different species:Cydia pomonellaL. (Lepidoptera: Tortricidae) andSpodoptera exiguaHübner (Lepidoptera: Noctuidae). The novelty of our work lies in showing the interactions between carvacrol and bacterial toxins against insect pests. Moreover, we have demonstrated that carvacrol applied via ingestion exerts toxicity against lepidopteran caterpillars. We have shown that the botanical compound and Cry proteins act in synergy and their mixtures are most effective in reducing the number of L1 and L3 larvae whenB. thuringiensistoxins constitute up to 0.1% and 0.05% of the mixtures, respectively. Carvacrol and crystalline proteins act in synergy in these combinations and have the potential to be effective in protecting crops against lepidopteran pests. The nature of the interaction between the components depended on the proportion of their concentrations in the mixture. Mixtures containing Cry toxin concentrations equal or higher than 20% caused lower observed mortality of insects compared to the expected one. Furthermore, we showed that crystalline proteins ofB. thuringiensisMPU B9, carvacrol and their mixture did not affect the morphology of insect haemocytes, and additionally, had no effect on the immune system.