Polanczyk, Ricardo A.Rossi, Guilherme D.Santos, Ana Letcia Z.Pinto, Ciro Pedro G....
8页
查看更多>>摘要：Using natural enemies for pest control is considered environmentally safe, but risk assessment of the concomitant use of different biological control agents needs deeper investigations. A special attention should be given to interactions between entomopathogenic fungi and parasitoids concomitantly used for sugarcane, once this culture has a remarkable IPM system in Brazil. The exposure of a host to non-lethal entomopathogens may lead to immune modulations potentially harmful for the development of a parasitoid. In this study, we exposed the sugarcane borer larvae to Metarhizium anisopliae and Beauveria bassiana strains, applied in sugarcane fields to manage, respectively, spittlebugs and the sugarcane weevil, but ineffective to kill sugarcane borer larvae, Diatraea saccharalis (Lepidoptera: Crambidae). The selected experimental concentrations of B. bassiana (1.75 x 10(9) spores), M. anisopliae (1.64 x 10(9) spores) and a mixture of B. bassiana + M. anisopliae (1.69 x 10(9) spores) diluted in 0.01% Tween (R) 80 were above field concentrations to expose the insects to an extreme scenario. Eggs of sugarcane borer were exposed to entomopathogens and, at the fifth instar, larvae were parasitized by Cotesia flavipes (Hymenoptera: Braconidae). Measurements of larval humoral and cellular immune responses were made at 5 days after parasitism in larvae exposed or not to the entomopathogenic fungi. Phenoloxidase and lysozyme activities were not altered in D. saccharalis larvae exposed to entomopathogenic fungi or parasitized by C. flavipes. The activity of beta-N-acetyl-D-glucosaminidase, total hemocyte count and total protein titer were not altered by entomopathogenic fungi exposition, but were reduced in parasitized larvae. No side effects of entomopathogenic fungi exposition were observed on biological parameters of D. saccharalis or in C. flavipes developing in hosts exposed to entomopathogenic fungi. These results add information on the risk assessment of this interaction and demonstrate the compatibility of concomitant use of these two entomopathogens and the parasitoid C. flavipes for pest management in sugarcane fields.
查看更多>>摘要：Powdery mildew caused by Erysiphe lonicerae var. lonicerae is a serious disease that causes significant loss to honeysuckle production in China. This disease is difficult to control by chemical measures, thus biological control may constitute a powerful alternative strategy. To develop an environmentally friendly microbial agent for biocontrol of powdery mildew, we screened strains of Bacillus spp. for biocontrol potential. One of the 102 isolates, strain HC-8, demonstrated high antifungal activity against three phytopathogenic fungi and efficiently suppressed the conidia germination of E. lonicerae under in vitro conditions. This isolate, which offered significant biocontrol of powdery mildew disease in honeysuckle, was identified as belonging to Bacillus velezensis. After challenge inoculation with E. lonicerae, honeysuckle plants treated with a concentration of 1 x 10(8) CFU/ml showed the highest protection value (PV). Biocontrol efficacy was highest when strain HC-8 was applied prior to pathogen inoculation, and the minimum PV was recorded when HC-8 was used 1 day after pathogen inoculation. Populations of the GFP-tagged strain HC-8-gfp persisted on honeysuckle leaves up to 25 days after spraying. In addition, we found that B. velezensis HC-8 induced defense-related enzyme activities in the leaves of honeysuckle. Thus, the present study provides a potential high-efficiency strategy for the biological control of powdery mildew disease and shows that B. velezensis HC-8 has significant potential as a biocontrol agent for honeysuckle production.
查看更多>>摘要：Alternaria solani is the main pathogen causing early blight on potato, considered to be one of the most important diseases of potato worldwide. The application of fungicides to control early blight in the field has become more difficult because of the constant appearance of mutated isolates that show fungicide resistance. The potential of Trichoderma as a biological control agent (BCA) to control diseases in other pathosystems has already been shown in several studies. However, only limited knowledge is available for the control of A. solani by BCAs in potato. In particular, little information is available on the effects of BCAs applied to whole potato plants. Therefore, the aim of our study was to evaluate the potential of Trichoderma spp. as a BCA against A. solani on three different scales: axenic culture, in the greenhouse, and in the field. In summary, a controlling effect of Trichoderma against A. solani in potato was shown at all three scales. Additionally, it was demonstrated that the choice of a single Trichoderma strain can strongly influence the outcome and that even strains from the same species show different efficiencies. However, a significant reduction of early blight in the field was only observed in one out of four years of field trials. A significant correlation between in vitro, in vivo, and field performance in one year could not be detected, which highlights the importance of trials under natural conditions to determine the effectivity of BCAs in practical fields. Our research shows the overall potential of Trichoderma spp. as a BCA against A. solani on potato. Therefore, our results serve as a basis for further improvement, which is needed to develop Trichoderma spp. into effective and reliable BCAs against early blight in potato.
da Silva, Valkiria Fabianados Santos, AlexandrePaterno Silveira, Luis ClaudioTomazella, Vitor Barrile...
8页
查看更多>>摘要：The push-pull cropping system can be a promising alternative for reducing pests by increasing and maintaining their natural enemies in different farming configurations. However, there is still a lack of information on its application, based on the diversification between plants in tropical conditions. In this experiment, we evaluated the effect of the push-pull system on the main pests and natural enemies in brassica crops. We evaluated two treatments: (a) kale as a monocrop; and (b) kale in a push-pull (marigold-mustard) system. In our study, the push-pull cropping system significantly suppressed the incidence of the main kale pests. In addition, the push-pull system offered higher abundance and richness of predator populations, as well as an increased rate of parasitism compared to the monocrop. These results suggest that the plants used to compose the diversification system are promising for composing the push-pull system in brassica crops. However, there is a need for further research to characterize the resources offered by these plants and their volatiles, as well as to understand how the landscape structure can affect the behavior of pests and natural enemies in the push-pull cropping system, especially in vegetable diversification in tropical agroecosystems.
查看更多>>摘要：The historical record of releases of 288 species of weed biological control agents in Australia was analysed to examine if considering the damage/host type relationship of agents can offer insights into why some agents and not others have proved to be effective in producing partial or complete control of the target weed. Specifically, the effectiveness of agents released in Australia was examined in relation to their feeding guild and the functional group (growth form) of the target weed. Biotrophic pathogens (rusts/smuts), sap feeders and root/crown feeders were effective in producing control more often than other guilds. Effectiveness of biological control across weed functional groups was somewhat similar, although herbaceous biennials/perennials tended to be more effectively controlled than other functional groups. Significant biological control was recorded for at least one case in each of the 31 of the 37 feeding-guild/weed functional group combinations for which there were data. Possible explanations for the greater success of some guilds are explored, as are caveats with using such inductive approaches to predict effectiveness in classical weed biological control.
查看更多>>摘要：The invasive alien species Halyomorpha halys (Stal) (Hemiptera: Pentatomidae) is a major pest of kiwifruit and other fruit crops. Adventive populations of the Asian egg parasitoid Trissolcus mitsukurii (Ashmead) (Hymenoptera: Scelionidae) were found in the north of Italy in 2016. Halyomorpha halys abundance was monitored in 14 kiwifruit orchards located in north-eastern Italy, and H. halys egg masses were sampled within kiwifruit orchards to assess the impact of egg parasitoids. Both H. halys populations and parasitoid impacts were evaluated considering the influence of ecological structures, and in particular the distance from semi-natural habitats constituted by riparian vegetation buffers and the presence of hedgerows surrounding the orchard. Halyomorpha halys populations fluctuated during the two seasons surveyed, and adults were more abundant during the first year of the study. In addition, more adults were detected in kiwifruit orchards located close to the riparian vegetation and decreased along with the distance from this habitat. Trissolcus mitsukurii had higher parasitism rates on H. halys eggs than the native Anastatus bifasciatus (Geoffroy) (Hymenoptera: Eupelmidae). No effect of hedgerows was observed on parasitoid impacts in orchards, while a relationship was detected with distance from riparian vegetation: a high T. mitsukurii parasitism rate was observed in kiwifruit orchards close to riparian vegetation buffers. Our findings demonstrate that semi-natural habitats constituted by large patches of unmanaged vegetation promote biological control of H. halys by the introduced egg parasitoids.
查看更多>>摘要：Phytophthora sojae is an important pathogen that causes soybean root rot. In this study, 200 rhizosphere bacteria were isolated from soybean rhizosphere soil. Six rhizosphere strains that showed antagonistic activity against Phytophthora sojae, SN337-SN342, were screened with further confrontation experiments. The biocontrol activities of the 6 strains, especially SN337, were subsequently characterized and evaluated. In vitro experiments showed that SN337, as a newly developed biocontrol agent, had good antagonistic activity against Phytophthora sojae. In the evaluation of soybean growth promotion, a fermented broth of strain SN337 increased shoot height and root length by 13% and 37.5%, respectively, compared with a control. Importantly, the incidence caused by P. sojae decreased in soybean plants treated with SN337. The fermentation broth of strain SN337 also clearly disintegrated zoospores of P. sojae. The biocontrol effects were further investigated based on the changes in rhizosphere soil microorganisms before and after inoculation with pathogens. Compared to P. sojae infection without SN337 treatment, the abundance of bacteria, fungi, actinomycetes and total microbes were increased, whereas P. sojae was decreased in the rhizosphere of soybean infected by P. sojae inoculation with SN337 treatment. The results indicated that strain SN337 played a role in the maintenance of the soybean rhizosphere environment by increasing the proportion of beneficial microorganism in the soil. In this study, the biocontrol effects of strain SN337 were evaluated based on antagonistic activity and biocontrol assays and on soil microbial analysis. Our results provide new practical clues for developing fungicides for the sustainable management of soybean root rot caused by P. sojae.
NSTL
Elsevier