Compatibility of Beauveria bassiana and alternative phytosanitary products.

AIMS: To assess the compatibility of alternative phytosanitary products (APPs) with the entomopathogenic fungus Beauveria bassiana (Bals.) Vuillemin. METHODS AND RESULTS: The APPs used were Baicao, Orobor® , Topneem, Rotenat and Compostonat at concentrations recommended by the manufacturers (CR), and then half (1/2CR) and double (2CR). To evaluate the compatibility, the following parameters were analysed: germination, colony forming units (CFUs), vegetative growth and conidia production. Compatibility was assessed using rates of toxicity and biological index. The association of APPs and B. bassiana was also evaluated for pathogenicity against larvae of third instar Anagasta kuehniella Zeller (Lepidoptera: Pyralidae) (1·0 × 108 conidia per ml). The germination of conidia of B. bassiana was reduced only by the product Orobor® . The CFUs were not affected by any products. The colony diameter was reduced when in contact with the products Baicao and Orobor® . For conidia production per colony, all products reduced this parameter. None of the products affected the pathogenicity of the fungus on A. kuehniella. CONCLUSIONS: All APPs tested are compatible with B. bassiana. SIGNIFICANCE AND IMPACT OF THE STUDY: The natural products tested and used in the field are considered compatible with B. bassiana under laboratory conditions, making possible new studies and the use of these in insect control.

Action of natural phytosanitary products on Bacillus thuringiensis subsp. kurstaki S-1905.

The objective of this study was to evaluate the effects of natural phytosanitary products (NPs) on spores and crystals of Bacillus thuringiensis subsp. kurstaki S-1905 (Btk S-1905). For the spore assay, NPs and bacteria were applied in combination and individually. For the combined application, Btk S-1905 + NP mixtures were inoculated on nutrient agar (NA), and for the separate applications, the NPs were spread on NA plates, which were later inoculated with the pathogen. The number of colony-forming units (CFU) per milliliter was quantified after 18 h of incubation. For the crystal protein degradation assay, the Btk S-1905 + NP mixtures were added to the diet of Anticarsia gemmatalis (Lepidoptera: Erebidae), and mortality was evaluated at the following time points: 12, 24, 48, and 72 h. Scanning electron microscopy and agarose gel electrophoresis were carried out. Biogermex and Ecolife® reduced the CFU ml-1 in both combined and separate applications. Biogermex, Ecolife®, and Planta Clean were antagonistic to the action of bacterial toxins, and no product affected the morphology or resulted in the degradation of the crystal proteins. The remaining products evaluated did not reduce the CFU ml-1 and had additive effect when combined with the crystal toxin.

Potential Side Effects of the Entomopathogenic Fungus Metarhizium anisopliae on the Egg Parasitoid Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) Under Controlled Conditions.

The purpose was to evaluate the side effects of strains Metarhizium anisopliae (Metsch.) Sorokin sensu lato Unioeste 43 and M. anisopliae sensu stricto ESALQ 1641 on Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) under controlled conditions. A free-choice test for parasitism was performed, with the confinement of T. pretiosum females mated with cards (1 × 5 cm) containing age-standardized Anagasta kuehniella Zeller eggs, either sprayed with a fungal strain (109 conidia/ml) or 0.01% v/v Tween 80 (control). For the no-choice tests, T. pretiosum females mated were confined with cards sprayed with fungal strains before or after parasitism, and cards with fungal applications at different times. The number of parasitized eggs, percentage of emergence, longevity, egg-to-adult period, sex ratio, total and confirmed mortality by the fungus, and longevity of females that parasitized previously sprayed eggs, were assessed. Histological analysis of immature phases was also performed. The fungus was repellent to T. pretiosum in the free-choice test, while in the no-choice test, fungal applications before and after parasitism did not affect the number of eggs parasitized by T. pretiosum or the sex ratio of emerging adults. However, both strains affected adult emergence rates, the egg-to-adult period, and longevity. Overall, both M. anisopliae strains had minor effects on these biological parameters of T. pretiosum under controlled conditions. Hyphae were not detected in histological observations of immature stages of the parasitoid.