Browsing by Subject "BIOLOGICAL-CONTROL"

Sort by: Order: Results:

Now showing items 1-6 of 6
  • Tollenaere, C.; Pernechele, B.; Mäkinen, H. S.; Parratt, S. R.; Nemeth, M. Z.; Kovacs, G. M.; Kiss, L.; Tack, A. J. M.; Laine, A. -L. (2014)
  • Hokkanen, H. M. T.; Menzler-Hokkanen, I. (2018)
    In this review, we examine how the principles of ecostacking could be used to manage the pollen beetle Brassicogethes aeneus in oilseed crucifer crops. We further describe hindrances preventing progress of keeping the pest under full biological control across Europe, and for other similar pest management situations. Ecological processes at different levels need to be considered and understood. The beneficial functions, which the various ecosystem service providers offer, need to be combined and exploited in an additive or synergistic manner, i.e., ecostacked. Levels to consider include landscape and off-crop habitats (e.g., field margins) and their effects on pest management in the rapeseed crop; and possibilities to generate the key ecosystem services within the crop itself; for example, by vegetation management (e.g., undersowing, variety mixtures, companion and trap crops), soil management (biotic and abiotic; fostering and steering soil microbial communities to benefit biocontrol), and crop management, including crop protection treatments and their impacts on ecosystem service provision. All these processes affect the populations of the pollen beetle. Abundant information exists about most of the key processes important in this context. Utilizing this knowledge and stacking the various beneficial ecosystem service functions into a comprehensive management strategy for the pollen beetle, has not been attempted nor described. After illustrating the potential of ecostacking in solving crop protection problems, as it is apparent in the case of the pollen beetle, we analyze a situation where our approach was lost in translation. The European Union Horizon 2020 program chose to support our vision of ecostacking with a 10million euro grant. Administrative decisions by the coordinating university (not to accept to host the grant), and subsequent failure of the European Commission and its Research Executive Agency to demonstrate leadership on issues of research policy, integrity, and ethics in the handling of the project, resulted in a shift of emphasis away from solutions based on integrative biocontrol.
  • Kaitala, Veijo; Koivu-Jolma, Mikko; Laakso, Jouni (2021)
    An infective prey has the potential to infect, kill and consume its predator. Such a prey-predator relationship fundamentally differs from the predator-prey interaction because the prey can directly profit from the predator as a growth resource. Here we present a population dynamics model of partial role reversal in the predator-prey interaction of two species, the bottom dwelling marine deposit feeder sea cucumber Apostichopus japonicus and an important food source for the sea cucumber but potentially infective bacterium Vibrio splendidus. We analyse the effects of different parameters, e.g. infectivity and grazing rate, on the population sizes. We show that relative population sizes of the sea cucumber and V. Splendidus may switch with increasing infectivity. We also show that in the partial role reversal interaction the infective prey may benefit from the presence of the predator such that the population size may exceed the value of the carrying capacity of the prey in the absence of the predator. We also analysed the conditions for species extinction. The extinction of the prey, V. splendidus, may occur when its growth rate is low, or in the absence of infectivity. The extinction of the predator, A. japonicus, may follow if either the infectivity of the prey is high or a moderately infective prey is abundant. We conclude that partial role reversal is an undervalued subject in predator-prey studies.
  • Kovalchuk, Andriy; Mukrimin, Mukrimin; Zeng, Zhen; Raffaello, Tommaso; Liu, Mengxia; Kasanen, Risto; Sun, Hui; Asiegbu, Fred O. (2018)
    Plant microbiome plays an important role in maintaining the host fitness. Despite a significant progress in our understanding of the plant microbiome achieved in the recent years, very little is known about the effect of plant pathogens on composition of microbial communities associated with trees. In this study, we analysed the mycobiome of different anatomic parts of asymptomatic and symptomatic Norway spruce trees naturally infected by Heterobasidion spp. We also investigated the primary impact of the disease on the fungal communities, which are associated with Norway spruce trees. Our results demonstrate that the structure of fungal communities residing in the wood differed significantly among symptomatic and asymptomatic Heterobasidion-infected trees. However, no significant differences were found in the other anatomic regions of the trees. The results also show that not only each of individual tree tissues (wood, bark, needles and roots) harbours a unique fungal community, but also that symptomatic trees were more susceptible to co-infection by other wood-degrading fungi compared to the asymptomatic ones.
  • Parratt, Steven R.; Laine, Anna-Liisa (2018)
    1. The relative importance of bottom-up versus top-down control of population dynamics has been the focus of much debate. In infectious disease biology, research is typically focused on the bottom-up process of host resistance, wherein the direction of control flows from the lower to the higher trophic level to impact on pathogen population size and epidemiology. However, the importance of top-down control by a pathogen's natural enemies has been mostly overlooked. 2. Here, we explore the effects of, and interaction between, host genotype (i.e., genetic susceptibility to pathogen infection) and infection by a hyperparasitic fungus, Ampelomyces spp., on the establishment and early epidemic growth and transmission of a powdery mildew plant pathogen (Podosphaera plantaginis). We used a semi-natural field experiment to contrast the impacts of hyperparasite infection, host-plant resistance and spatial structure to reveal the key factors that determine pathogen spread. We then used a laboratory-based inoculation approach to test whether the field experiment results hold across multiple pathogen-host genetic combinations and to explore hyperparasite effects on the pathogen's later life-history stages. 3. We found that hyperparasite infection had a negligible effect on within-host infection development and between-host spread of the pathogen during the onset of epidemics. In contrast, host-plant resistance was the major determinant of whether plants became infected, and host genotype and proximity to an infection source determined infection severity. 4. Our laboratory study showed that, while the interaction between host and pathogen genotypes was the key determinant of infection outcome, hyperparasitism did, on average, reduce the severity of infection. Moreover, hyperparasite infection negatively influenced the production of the pathogen's overwintering structures. 5. Synthesis and applications. Our results suggest that bottom-up host resistance affects pathogen spread, but top-down control of powdery mildew pathogens is likely more effective against later life-history stages. Further, while hyperparasitism in this system can reduce early pathogen growth under stable laboratory conditions, this effect is not detectable in a semi-natural environment. Considering the effects of hyperparasites at multiple points in pathogen's life history will be important when considering hyperparasite-derived biocontrol measures in other natural and agricultural systems.
  • Hiltunen, Lea H.; Tarvainen, Oili; Kelloniemi, Jani; Tanskanen, Jaakko; Karhu, Jouni; Valkonen, Jari P. T. (2021)
    Disease suppressive soils are important for managing soil-borne diseases that cannot be controlled with chemicals. One such disease is the potato common scab caused by Streptomyces species. Suppressiveness against common scab can develop spontaneously in fields where potato is grown for years without interruption, and this has been attributed to non-pathogenic Streptomyces strains. Streptomyces spp. have been used as inoculants in biological control, but their long-term effects have gained less attention. In our previous studies, a nonpathogenic Streptomyces strain (Str272) isolated from a potato common scab lesion suppressed common scab in field trials lasting over 5 years. In this study, bacterial communities in the tuberosphere i.e. in the soil adjacent to potato tubers, were analysed by next generation sequencing (NGS). The aim was to compare bacterial communities in untreated control plots to those in which seed tubers were treated with Str272 in one or several growing seasons. Str272 applications increased soil bacterial diversity and affected the bacterial composition in the potato tuberosphere. The most pronounced differences were observed between the untreated control and the treatments in which the antagonist had been applied in three or four consecutive years. The differences remained similar until the following growing season. Bacterial composition after repeated antagonist applications was associated with lower common scab severity. The antagonist applications had no or only slight effect on the number or abundance of OTUs belonging to Actinobacteria or Streptomyces, and no differences in quantities of pathogenic Streptomyces populations were detected by qPCR. This indicates that suppression of common scab by Str272 may not be based on direct effect on the common scab pathogens but is more likely to be associated with the alterations of the soil bacterial community. The most abundant bacteria phyla in the potato tuberosphere were Actinobacteria, Proteobacteria and Acidobacteria. However, the OTUs responding greatest to the antagonist treatments belonged to Bacterioidetes and Gemmatimonadetes. Results indicate that repeated applications of Str272 can change the bacterial community in the potato tuberosphere and lead to development of soil that is suppressive against potato common scab for several growing seasons after the last application.