| 1. |
- Anderson, Peter, et al.
(författare)
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Utilization of synergies between conservation and inoculation biological control through niche partitioning and selective biodiversity
- 2011
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Modern agricultural practices have led to destruction of semi-natural habitats, ecosystems and ecosystem services, and a decrease in the numbers of natural enemies. Conservation biological control (CBC) is the practice of enhancing natural enemy efficacy through modification of the environment or of existing pesticide practices. An additional way to enhance the control effect of pest insects is to combine the strategy of CBC with inoculation biological control (IBC). IBC is the intentional release of a living organism as a biological control agent with the expectation that it will multiply and control the pest for an extended period, but not permanently. Increased natural enemy diversity in biological control has positive effects when the feeding niches of the natural enemies complement each other. By combining biological control agents separated in niche partitioning in time and space, the effect can be greater than the single compartments. In a previous research project we developed a system where two key pests of cabbage and onion (Delia radicum and D. antiqua, respectively are controlled using 1) crop rotation to disrupt their lifecycles and 2) semi-permanent selective flower- and grass strips to enhance the parasitoid wasp Trybliographa rapae and soil inhabitant generalist predators. The specialist larval parasitoid T. rapae as well as the generalist predator/pupal staphylinid parasitoid Aleochara bipustulata attack both Delia pests and, therefore, are not disrupted by the crop rotation which provides a less disturbed system. In a continuation of this project we are studying the impact of complementary biological control strategies on pest control of Delia spp and interactions between the control agents. We will combine IBC, using entomopathogenic fungi, with CBC of T. rapae and A. bipustulata in a crop rotation system. It is a novel ecologically-based management system that relies on the niche complementarity of natural enemies in time and space. The impact of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae on T. rapae and A. bipustulata regarding intraguild interactions, behaviour and fitness will be investigated. The study further combines knowledge of biological control with studies in chemical ecology, to evaluate the role of chemical signals in ecological and as well as behavioural mechanisms. Other host-parasitoid systems have showed that there is fitness costs involved in developing on infected hosts. This will be evaluated for T. rapae and A. bipustulata by measuring fecundity and offspring number, quality (survival, weight, etc.), development and viability in laboratory cage experiments at different host infection levels. The preliminary results of bioassays regarding choice/no-choice and fitness consequences in T.rapae associated with infected host larvae will be presented and discussed in the context of the agroecosystem
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| 2. |
- Cotes Ramal, Belén, et al.
(författare)
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A host-pathogen-parasitoid system in the biological control of the cabbage root fly, Delia radicum
- 2014
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Ingår i: IOBC-WPRS Bulletin. - 1027-3115. ; 107, s. 190-190
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This project will investigate the impact of complementary biological control strategies on pest control of Delia radicum (and D. antiqua) and interactions between the control agents. We will combine inoculation biological control, using the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae, with conservation biological control of the specialist parasitoid Trybliographa rapae and the generalist predator/parasitoid Aleochara bipustulata in a crop rotation system. It is a novel ecologically-based management system that relies on the combined effects of biological control strategies, through niche complementarity of natural enemies in time and space. We will present the preliminary results on the effect of the fungi in the system. The dose-response of the fungi on the third instar larvae of D. radicum will be given together with the preliminary results of bioassays regarding choice/no-choice in T.rapae associated with infected host larvae. Also the role of chemical signals in behavioral mechanisms have been started to be elucidated through studies in a two-choice olfactometer. The first year's data on mortality of D.radicum larvae caused by either/or in combination: T.rapae and M.anisopliae from cage semi-field trials will be presented. The implication of the results will be discussed in the context of the agroecosystem
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| 3. |
- Cotes Ramal, Belén, et al.
(författare)
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Habitat selection of a parasitoid mediated by volatiles informing on host and intraguild predator densities
- 2015
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 179, s. 151-162
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Tidskriftsartikel (refereegranskat)abstract
- To locate and evaluate host patches before oviposition, parasitoids of herbivorous insects utilize plant volatiles and host-derived cues, but also evaluate predator-derived infochemicals to reduce predation risks. When foraging in host habitats infested with entomopathogenic fungi that can infect both a parasitoid and its host, parasitoids may reduce the risk of intraguild predation (IGP) by avoiding such patches. In this study, we examined whether the presence of the entomopathogenic fungi Metarhizium brunneum and Beauveria bassiana in soil habitats of a root herbivore, Delia radicum, affects the behavior of Trybliographa rapae, a parasitoid of D. radicum. Olfactometer bioassays revealed that T. rapae avoided fungal infested host habitats and that this was dependent on fungal species and density. In particular, the parasitoid avoided habitats with high densities of the more virulent fungus, M. brunneum. In addition, host density was found to be important for the attraction of T. rapae. Volatiles collected from host habitats revealed different compound profiles depending on fungal presence and density, which could explain the behavior of T. rapae. We conclude that T. rapae females may use volatile compounds to locate high densities of prey, but also compounds related to fungal presence to reduce the risk of IGP towards themselves and their offspring.
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| 4. |
- Delshammar, Tim, et al.
(författare)
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Stadsodling – reflektioner och perspektiv från SLU Alnarp
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Det är uppenbart att det mediala intresset för stadsodling har vuxit påtagligt de senaste åren. En sökning i databasen Retriever visar en ökande användning av begreppet ”urban odling” och en starkt ökande användning av ordet “stadsodling”. Olika medier påverkar så klart varandra. Radioprogrammet Odla med stadsgrönt började sändas våren 2009. Medier påverkar politiken som i sin tur påverkar medier. Den förste oktober 2009 lämnades motionen ”Stadsodling viktig i hållbara städer” in till riksdagen. Såväl media som politik påverkar och påverkas av praktiken. Våren 2009 började projektet Barn i stan odla i stadsdelen Seved i Malmö, ett projekt som uppmärksammats flitigt i media. Samma år började organisationen Stadsjord odla i stadsdelen Högsbo i Göteborg, även det flitigt uppmärksammat i media. Den statliga Delegationen för hållbara städer har beviljat bidrag till åtminstone fyra planeringsprojekt med inriktning mot stadsodling: SLU (sökt 2009), Plantagon (två projekt sökta 2010) samt Falun kommun (sökt 2012). Även investeringsprojekt har haft inslag av stadsodling, till exempel Malmö stads ansökan “Hållbar stadsomvandling Malmö, Fokus Rosengård” ( sökt 2010). Stadsodling finns med som ett inslag i flera aktuella stadsförnyelse- och stadsbyggnadsprojekt. Det har fått fungera som en symbol för kombinationen av ekologisk och social hållbarhet. En viktig fråga att reflektera över är därför hur hållbar stadsodling är. Vad kan vi ha för nytta av stadsodling? Hur kan odling ta plats i städerna? Hur kan vi stadsodla på ett hållbart sätt?
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| 5. |
- Hill, Sharon, et al.
(författare)
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Evaluation of entomopathogenic fungi Metarhizium anisopliae against dengue virus mosquitoes Aedes aegypti (Diptera: Culicidae)
- 2018
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Ingår i: Entomon. - 0377-9335. ; 43, s. 7-18
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the bio-potential of the entomopathogenic fungus Metarhizium anisopliae was tested against Aedes aegypti under laboratory conditions. The study includes the analysis of the attractive response, survival and fecundity rate of non-blood and blood fed female mosquitoes exposed to the volatiles of two M. anisopliae strains. The attractive response was analysed using a two-choice behavioural bioassay, with three different sizes of dry spore plates (full, 1/4 and 1/16 plates). The survival and fecundity bioassay was conducted simultaneously in plastic pots. Log-rank survival curve analysis was used for statistical comparisons of the attractive response, survival and fecundity. Non-blood and blood fed mosquitoes were highly attracted to M. anisopliae30 volatiles compared with that of the M. anisopliae-131 strain. Moreover, attraction was dependent on the size of the dry spore plate. Survival was completely abolished in unfed mosquitoes 5 and 6 days after treatment with 109 spores/mL of M. anisopliae-30 and M. anisopliae -131, respectively, whereas almost 80% of untreated unfed females survived more than 28 days. Survival in blood fed mosquitoes treated with same dose of M. anisopliae-30 and M. anisopliae-131was abolished after 6 and 7 days, respectively, while over 80% of untreated blood fed females survived more than 28 days in the controls. Mean number of eggs laid by blood fed mosquitoes treated with 109 spores/mL of M. anisopliae-131 was 26 ± 3 compared to control (67 ± 4). However for M. anisopliae-30, 19 ± 3 eggs were laid compared to control 72 ± 5 eggs. This study concludes that both the strains of M. anisopliae reduce egg laying capacity and survival rate in Ae. aegypti. As such, these strains can be useful for the development of mycoinsecticides for the control of the dengue fever vector mosquito, Ae. aegypti
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| 6. |
- Nilsson, Ulf, et al.
(författare)
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Comparison of nectar use and preference in the parasitoid Trybliographa rapae (Hymenoptera: Figitidae) and its host, the cabbage root fly, Delia radicum (Diptera: Anthomyiidae)
- 2011
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Ingår i: Biocontrol Science and Technology. - : Informa UK Limited. - 0958-3157 .- 1360-0478. ; 21, s. 1117-1132
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated differences in flower preferences between the parasitoid Trybliographa rapae Westwood (Hymenoptera: Figitidae) and its host, the economically important pest of cruciferous crops, the cabbage root fly, Delia radicum L. (Diptera: Anthomyiidae). The data obtained were used to suggest selective food plants in conservation biological control programmes for control of D. radicum. The attraction of both insect species to floral odours emitted from nine different plant species, their ability to access nectar from four of these species and the effect of the most promising plant species on insect longevity were determined. Naive T. rapae females were significantly attracted to flower odours from Fagopyrum esculentum Moench. (Polygonaceae) and repelled by Coriandrum sativum L. (Apiaceae) and Borago officinalis L. (Boraginaceae). In addition, T. rapae gained weight when exposed to F. esculentum, Anethum graveolens L. (Apiaceae) and Lobularia maritima Desv. (Brassicaceae). In contrast, naive D. radicum females showed attraction to most of the flowers. The longevity of both T. rapae and D. radicum increased significantly when they were provided with flowering A. graveolens and F. esculentum. In addition to the laboratory studies, a semi-field experiment was made to study the impact of flowering F. esculentum on the ability of T. rapae to parasitise D. radicum larvae. Significantly more larvae were parasitised in cages where a floral resource was present. The findings are discussed in the context of a Brassica agroecosystem.
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| 7. |
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| 8. |
- Nilsson, Ulf, et al.
(författare)
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Effects of conservation strip and crop type on natural enemies of Delia radicum
- 2016
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Ingår i: Journal of Applied Entomology. - : Wiley. - 0931-2048 .- 1439-0418. ; 140, s. 287-298
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Tidskriftsartikel (refereegranskat)abstract
- This 3-year field study investigated the combined effect of floral resources and perennial shelter habitats (i.e. conservation strips), and crop rotation in supporting natural enemies of the cabbages root fly, Delia radicum. Habitat manipulation with conservation strips increased the overall catches of hymenopteran parasitoids. However, conservation strips did not increase parasitism by either of the two dominant parasitoid species, Trybliographa rapae and Aleochara bipustulata, in any study year. In fact, higher parasitism was found in control plots in the second year. This could be explained by parasitoid mobility and higher patch detectability, as more plants in the control plots were infested with D.radicum larvae. Conservation strips did not result in increased predation of D.radicum eggs. However, the activity densities of two Bembidion species were correlated with egg predation. The species assemblage distribution of epigeal predators was best explained by seasonal period, followed by year and, to a low extent, crop type, while treatment with conservation strips had no effect. However, during the egg laying peak of D.radicum, a higher number of A.bipustulata, an important larval predator was observed in conservation strips during one study year. In conclusion, positive effects of conservation strips were demonstrated for abundance of some natural enemies of D.radicum, but a consistent increase in performance could not be adequately demonstrated due to experimental set-up, the short timescale and the complex landscape in which our study site was located.
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| 9. |
- Nilsson, Ulf, et al.
(författare)
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Herbivore response to habitat manipulation with floral resources: a study of the cabbage root fly
- 2012
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Ingår i: Journal of Applied Entomology. - : Wiley. - 0931-2048 .- 1439-0418. ; 136, s. 481-489
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Tidskriftsartikel (refereegranskat)abstract
- Biological control of pest insects can be improved by providing natural enemies with additional food resources such as floral nectar within the production field. However, herbivores may also benefit from this practice. The aim of this 3-year field study was to investigate if dill and buckwheat, aimed as food resources for natural enemies, could increase the densities of the cabbage root fly, Delia radicum L. (Diptera: Anthomyiidae), a severe pest on crucifers. Differences in egg density, numbers of pupae and sex ratio were compared between cabbage plots with or without flowers. Habitat manipulation by intercropping flowering plants with cabbage did not increase the overall D.similar to radicum egg density in our 3-year study, and there were no significant differences in egg numbers between treatments in any year. No effect on the fecundity of D.similar to radicum was observed, most likely because of the high mobility and feeding behaviour of the female flies, combined with high abundance and diversity of other food sources around the fields during this period. Despite equal egg numbers, fewer pupae were found in plots with flowers than without in one of three studied years. This finding suggests that natural enemies attacking larvae and pupae of D.similar to radicum were either more abundant or efficient in cabbage plots with flowers.
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| 10. |
- Nilsson, Ulf, et al.
(författare)
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Växtskydd
- 2015
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Annan publikation (populärvet., debatt m.m.)abstract
- Förebyggande åtgärder för att förhindra eller minska angrepp av skadegörare är en grundläggande princip inom den ekologiska odlingen. Använd alla tänkbara odlingsmetoder för att hindra skadegöraren eller minska angreppet samt för att gynna de naturliga fienderna. Odlingsmetoderna måste också syfta till att hindra skadegörarens utveckling såväl kortsiktigt som långsiktigt. Detta innebär att du måste gripa in någonstans i skadegörarens livscykel och påverka denna. För att kunna göra det behöver du goda kunskaper om skadegörarens biologi, populationsdynamik och ekologi.
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