Browsing by Subject "biological control"

Sort by: Order: Results:

Now showing items 1-10 of 10
  • Kangas, Niina (Helsingfors universitet, 2013)
    The aim of this study was to look into the possibility of using predatory mites as a biological control agent in the nursery production. This study focuses on the biological control of two phytophagous mites, Tetranychus urticae and Aculus schlectendali that occur as pests in apple seedling production. The directive 2009/128/EY of the European Union obligates the farmers to follow the principles of the integrated pest management and favour other control methods, such as biological control, rather than chemical pesticides. This study is a part of The Finnish Nursery Producers Association’s project that aims to develop biological control practices for the nursery production in Finland and promote integrated pest management in nursery production. The experiments for this study were carried out outdoors in a field and indoors in a seasonal greenhouse, where the population development of T. urticae and A. schlechtendali on apple seedlings was followed. Population density of mites was counted from leaf samples gathered from the seedlings in two week intervals from May until the end of August. Biological control of T. urticae was tested with Phytoseeid mites, Neoseiulus barkeri and Phytoseiulus persimilis. Chemical control was used as a comparison treatment. The effects of the biological control were followed by comparing the population densities of phytophagous mites in the area of biological control to the mite densities in the area of chemical control. N. barkeri and P. persimilis were not able to prevent nor stop T. urticae population growth in the greenhouse where the densities of T. urticae grew higher in the area of biological control than in the area of chemical control. Outdoors the population densities of T. urticae remained low throughout the experiment in both treatment areas. Population densities of A. schlechtendali grew high indoors and outdoors within both treatments. Even though biological control did not succeed in these experiments, the conditions in the greenhouse were suitable for Phytoseeid mites and in theory it should be possible exploit them as control agents in nursery production. The high densities of A. schlechtendali were surprising. In the future it would be important to consider the importance of this species as a pest and find effective means to control it.
  • Varga, Ildiko; Keresztes, Balázs; Poczai, Péter (2012)
    The European mistletoe (Viscum album) is an evergreen, perennial, epiphytic, hemiparasitic shrub, which is widely distributed in Europe. Its occurrence induces extremely sensitive health of host trees further contributing to the phenomenon of forest decline spiral. Besides mechanical pruning a hyperparasitic fungus (Phaeobotryosphaeria visci) could be a successful candidate to develop an effective biocontrol agent against V. album. We were extensively aware of the insect community of European mistletoe in light of finding another potential agent. We collected and identified 22 insect species (4 Sternorrhyncha, 5 Heteroptera, 5 Coleoptera, 5 Hymenoptera, 2 Lepidoptera, 1 Diptera) from which eight are specialists restricted only to European mistletoe (Cacopsylla visci, Carulaspis visci, Hypseloecus visci, Pinalitus viscicola, Ixapion variegatum, Liparthrum bartschti, Synanthedon loranthi, Celypha woodiana). Species associations with this plant are reported here for the first time for two Heteroptera (Campyloneura virgula, Pentatoma rufipes), one Coleoptera (Sericoderus lateralis), one ant species (Lasius brunnes) as well as for an aphid belonging to the Aphis fabae sensu stricto group, respectively. Species assotiation with this plant is reported for the first time in Hungary for the Leptophloeus hypobori species. Based on our observations and literature review only the mass occurrence of different pests would have the potential to effectively control this hemiparasite. From the pests of the green plant parts the mistletoe associated psyllid (Cacopsylla visi), mistletoe scale (Carulaspis visci) and the mistletoe bug, Hypseloecus visci, while from the pests of the woody parts a clearwing moth, Synanthedon loranthi and a bark beetle, Liparthrum bartschti look perspective in light if biological control.
  • Karlsson, Magnus; Durling, Mikael Brandstrom; Choi, Jaeyoung; Kosawang, Chatchai; Lackner, Gerald; Tzelepis, Georgios D.; Nygren, Kristiina; Dubey, Mukesh K.; Kamou, Nathalie; Levasseur, Anthony; Zapparata, Antonio; Wang, Jinhui; Amby, Daniel Buchvaldt; Jensen, Birgit; Sarrocco, Sabrina; Panteris, Emmanuel; Lagopodi, Anastasia L.; Poeggeler, Stefanie; Vannacci, Giovanni; Collinge, David B.; Hoffmeister, Dirk; Henrissat, Bernard; Lee, Yong-Hwan; Jensen, Dan Funck (2015)
  • Salmi, Andreas (Helsingfors universitet, 2017)
    Biological sprout control with Chondrostereum purpureum (Pers. ex Fr.) Pouzar was integrated to mechanized early cleaning. In this method, liquid with hyphae of C. purpureum was sprayed on the freshly cut stumps. C. Purpureum has been studied for biological sprout controlling since 1980’s. This species is a common basidiomycete saprophytic fungus found in Finland, and thus does not cause a biological risk. Early cleaning and pre-commercial cleaning of young forests have not experienced major innovations since the brush saw. Mechanizing of work has been thought to be a solution for increasing working costs. Chemical sprout control has been restricted to special targets, which addresses more interest on alternative biological methods. In this research, effectivity of biological stump treatment and factors affecting the results were investigated. Early cleaning was done in eight study sites during June–September 2014. Inside the sites, area was partly treated with mechanical cutting and by applying C. purpureum stump on freshly cut stumps, and partly with mechanical cutting only (a control treatment). 15 circular sample plots with a radius of one meter per treatment were founded in studied young forest stands (altogether 480). All stumps and saplings with a diameter over 5 mm were studied in 9-10/2015. The data includes altogether 2030 hardwood stumps. Stump mortality, number of living sprouts and the height of the sprouts were modelled for birch, rowan, aspen and willow. Results revealed that sprout control with C. Purpureum affected mortality, sprout number and height of birch sprouts. Mortality increased with time lag after treatment and with increasing stump diameter. The results showed that mortality level of 50 % was reached after two growing seasons. Sprout number increased with increasing stump basal area and decreased with time lag after treatment. Number of other saplings on the plot and soil moisture effected negatively on sprout number. Sprout height increased with increasing stump basal area and stump height. Number of other saplings and stumps on the plot affected birch sprout height negatively. Results of C. Purpureum stump treatment were weaker for other studied hardwood species (rowan, aspen, willow) and other factors affected more than biological sprout control. Effectiveness of sprout control in this study was weaker than in other studies presented recently. Time span of this study was considerably short and final results are seen some years after stump treatment. Another factor to consider is the spreading method used in this study. Stump treatment integrated to mechanized early cleaning of young conifer plantations need to be developed further so that this method would be profitable in practical silviculture.
  • Poutanen, Jari (Helsingfors universitet, 2014)
    Gray mold (Botrytis cinerea) is an important disease of strawberry. The pathogen is spread by spores to strawberry flowers, from where the disease spreads to the developing berries. It progresses fast especially in high humidity and without any control. It can destroy even half of the crop. In conventional production, the strawberries have been sprayed by fungicides several times in beginning of summer. Only approved biological fungicides in Finland are Prestop- ja Prestop mix (Verdera Oy), and those can be spread to strawberries by honey bees (Apis mellifera), witch visits in the flowers of strawberry. For this task, the special additional equipment must been installed to hives. Inquiry survey have been made for the strawberry growers, witch have used the entomovectoring control method. The survey clarifies the problems of beginning to use the method, laboured and profitability, problems relating to bees and the needs of develop. Result of the survey is, that the growers have quite committed to use entomovectoring control method, even that many growers told that it was laboured and the efficency could not been seen clearly. The main reasons for the use of method were control of gray mold, reduce of chemical control and safety for user and environment. In addition to method gave image benefit to grower and improved pollination of strawberry. Getting started and use of method were more often trouble-free. The main development points were to extent the time between the addition of pesticide to the spreader equipment and to develop the method for commercial bumble-bee (Bombus terrestris) hives.
  • Kallio, Tauno (Suomen metsätieteellinen seura, 1976)
  • Kallio, Tauno (Suomen metsätieteellinen seura, 1973)
  • Ojanperä, Taru (Helsingfors universitet, 2008)
    The causal agents of Potato scab, S. scapies, S. turbidiscapies and S. aureofaciens spoil the quality of tubers, slow down the formation of potato seedlings, increase the number of small sized tubers and therefore can have a significant impact on the potato harvest. Sometimes the technical methods applied in the potato farming are not effective enough and there are no chemical means available to prevent potato scab. In this work the properties of selected Finnish Actinomyces-isolates were studied from the point of view of biological control. Both potato scab forming and stains that do not cause visible signs of potato scab in tubers were selected for the study. The purpose was to study the ability of the stains to inhibit the growth of potato scab bacteria in different pH-conditions. In addition the ability of Streptomyces-strains to inhibit the growth of silver scurf, stem cancer and black scurf was studied. The competitive balance between different Actinomyces and fungal strains was tested on plates. Greenhouse tests were used to study the root infesting of Actinomyces strains. Streptomyces strains inhibited each others growth. This inhibition was not linked to scab. All strains tested prevented the growth of silver scurf and ps pathogens but strains S.griseoviridis ja 16IV turned out being especially effective in preventing. All strains grew in pH-conditions 5.5-8.0. An unknown Streptomyces strain 16IV did not grow well in pH 5.5 and S. turbidiscapies which is known to persist in acidic conditions grew well also in pH 8.0. All tested strains colonized potato root. The study showed that some of the isolates had potential for future studies in biological control. More research is needed to study the root colonization and the antagonism properties of selected strains in root conditions. The causal agents of Potato scab, S. scapies, S. turbidiscapies and S. aureofaciens spoil the quality of tubers, slow down the formation of potato seedlings, increase the number of small sized tubers and therefore can have a significant impact on the potato harvest. Sometimes the technical methods applied in the potato farming are not effective enough and there are no chemical means available to prevent potato scab. In this work the properties of selected Finnish Actinomyces-isolates were studied from the point of view of biological control. Both potato scab forming and stains that do not cause visible signs of potato scab in tubers were selected for the study. The purpose was to study the ability of the stains to inhibit the growth of potato scab bacteria in different pH-conditions. In addition the ability of Streptomyces-strains to inhibit the growth of silver scurf, stem cancer and black scurf was studied. The competitive balance between different Actinomyces and fungal strains was tested on plates. Greenhouse tests were used to study the root infesting of Actinomyces strains. Streptomyces strains inhibited each others growth. This inhibition was not linked to scab. All strains tested prevented the growth of silver scurf and ps pathogens but strains S.griseoviridis ja 16IV turned out being especially effective in preventing. All strains grew in pH-conditions 5.5-8.0. An unknown Streptomyces strain 16IV did not grow well in pH 5.5 and S. turbidiscapies which is known to persist in acidic conditions grew well also in pH 8.0. All tested strains colonized potato root. The study showed that some of the isolates had potential for future studies in biological control. More research is needed to study the root colonization and the antagonism properties of selected strains in root conditions.
  • Mäkelä, Tommi (Helsingin yliopisto, 2015)
    The great web-spinning pine-sawfly is a common species in Finland. Few mass outbreaks have occurred in Europe, but they have last a long time. Yet first outbreak in Finland was observed at Yyteri region near Pori in 2006. Larvae use pine needles as nutrient. It is estimated that 100–200 larvae/m2 is a level for severe forest damage. There have been many locations containing 200–500 larvae/m2 at the Yyteri region. There is tourism and nature value in Yyteri and so chemical control was not the first option. That is why biological control was used and the most promising seem to be Steinernema feltiae. It was commercially available and spraying it was simple. The purpose of the research was to find out how S. feltiae could be used to reduce the great web-spinning pine-sawfly on a large scale. Spraying was done by using agricultural spraying equipment attached to tractors. Photoelecton traps were used and soil samples of larvae were collected. Control traps gathered 65.0 % of adults in 2011 while treatment traps gathered 35.0 %. In 2012 traps collected 48.6 % and 51.4 %, respectively. Traps gathered 120 adults in 2011. Main swarming was 2012 and 469 adults were caught. Some unreliability is involved in results because of the high spatial distribution of larvae in soil. Differences between years might be explained by earlier metamorphosis of the great web-spinning pine-sawfly to adult, increased deviation of trap results and grassier field conditions. Chilly weather might also have prevented nematodes performing at maximum capacity in 2012. In soil samples 88.6 % of the great web-spinning pine-sawflies were alive. It seems that most of them would be overwinter for fourth year. Most of the dead great web-spinning pine-sawflies (90.3 %) were found in organic soil layers. However, the clear-cut area has stayed at 200 ha for now.