| 1. |
- Amelia, Tudoran, et al.
(författare)
-
Using associational effects of European beech on Norway spruce to mitigate damage by a forest regeneration pest, the pine weevil Hylobius abietis
- 2021
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 486
-
Tidskriftsartikel (refereegranskat)abstract
- Forest regeneration can be compromised by insect damage to newly-planted conifer seedlings, with the pine weevil, Hylobius abietis, being the most economically important pest in Europe. Seedling protection strategies include physical barriers, silvicultural measures and insecticides, while the potential benefits of Associational Effects (AE) have been little explored. Associational Resistance (AR) or Susceptibility (AS) arise when neighbouring plants decrease or increase, respectively, the likelihood and extent of attack on a focal plant. We investigated the potential of European beech, Fagus sylvatica, to mediate AE for Norway spruce, Picea abies, seedlings against pine weevil damage. First, we examined the effects of neighbor identity on damage to P. abies at a small scale, using choice arenas in the lab. Then, in the field, we examined these effects at a larger scale using plots containing only Norway spruce, or both species. We found that P. abies seedlings were attacked and damaged less by weevils when beech was their close neighbor, relative to having another Norway spruce as a neighbor in the lab. Yet, no difference in damage between only spruce and mixed seedling plots was found in the field. Our results indicate that the susceptibility of P. abies to H. abietis can be influenced by neighbor identity, and effects can vary with inter-plant distance. In close proximity, the presence of the non-host F. sylvatica can alter pine weevil feeding behaviour and thus, has the potential to mediate AR. However, these associational effects appear not to provide enhanced seedling protection at a larger scale.
|
|
| 2. |
- Ammunét, Tea, et al.
(författare)
-
Northern geometrids and climate change: from abiotic factors to trophic interactions
- 2015
-
Ingår i: Climate change and insect pests. - 9781780643786 ; 7, s. 235-247
-
Bokkapitel (refereegranskat)abstract
- The subarctic mountain birch forests have been periodically disturbed by geometrid moth outbreaks since at least the mid-19th century. The effects of these disturbances can be seen from landscape-level dieback of the birch forest to local-level changes in soil processes. Recent research efforts have demonstrated that the geometrid moth-birch forest system is undergoing changes that could be linked to the ongoing climate warming. Milder winter and spring temperatures influence winter survival and outbreak ranges of the moths, and are also alleviating range expansions and the spread of new species to the area. Moreover, phenology matching with the host plant may be altered. The outcome appears to be intensified outbreaks and a potential for altered species interactions and dynamics with ecosystem-wide consequences.This chapter will first introduce the prevailing dynamics of the mountain birch-geometrid system and the reported ecosystem effects of geometrid outbreaks. Second, the chapter summarizes observations of ongoing abiotic changes in the area and presents the potential known and unknown effects on the study species. Finally, the chapter discusses the future scenarios for this northern ecosystem and the possibility of major ecosystem changes.
|
|
| 3. |
- Berggren Nieto, Kristina, et al.
(författare)
-
Synergistic effects of methyl jasmonate treatment and propagation method on Norway spruce resistance against a bark-feeding insect
- 2023
-
Ingår i: Frontiers in Plant Science. - 1664-462X. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- Utilizing plants with enhanced resistance traits is gaining interest in plant protection. Two strategies are especially promising for increasing resistance against a forest insect pest, the pine weevil (Hylobius abietis): exogenous application of the plant defense hormone methyl jasmonate (MeJA), and production of plants through the clonal propagation method somatic embryogenesis (SE). Here, we quantified and compared the separate and combined effects of SE and MeJA on Norway spruce resistance to pine weevil damage. Plants produced via SE (emblings) and nursery seedlings (containerized and bare-root), were treated (or not) with MeJA and exposed to pine weevils in the field (followed for 3 years) and in the lab (with a non-choice experiment). Firstly, we found that SE and MeJA independently decreased pine weevil damage to Norway spruce plants in the field by 32-33% and 53-59%, respectively, compared to untreated containerized and bare-root seedlings. Secondly, SE and MeJA together reduced damage to an even greater extent, with treated emblings receiving 86-87% less damage when compared to either untreated containerized or bare-root seedlings in the field, and by 48% in the lab. Moreover, MeJA-treated emblings experienced 98% lower mortality than untreated containerized seedlings, and this high level of survival was similar to that experienced by treated bare-root seedlings. These positive effects on survival remained for MeJA-treated emblings across the 3-year experimental period. We conclude that SE and MeJA have the potential to work synergistically to improve plants' ability to resist damage, and can thus confer a strong plant protection advantage. The mechanisms underlying these responses merit further examination.
|
|
| 4. |
- Berggren, Åsa, et al.
(författare)
-
The distribution and abundance of animal populations in a climate of uncertainty
- 2009
-
Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 118, s. 1121-1126
-
Tidskriftsartikel (refereegranskat)abstract
- Current predictions regarding the ecological consequences of climate change on animal populations are generally autecological and species-specific, and/or non-mechanistic extrapolations of recent short-term patterns. To better understand and predict the effects of climate change on the distribution of species and the abundance of populations we offer a novel, broad theoretical framework. Climate-induced changes in trophic structure may actually be more predictable than effects on individual species. The logic is that there are general differences in climatic sensitivity among trophic levels - specifically, that as one moves up trophic levels, there is an increase in the temperature sensitivity of vital rates. More precisely, we provide: (1) a formal mathematical definition of distribution limits that is both operational and conceptual, introducing the concept DL(50), defined as the geographic and climatic isoline representing an equilibrium occupancy of half of the suitable habitats; (2) a matrix of the possible changes in trophic structure from climate change and the general theoretical consequences; and (3) a new idea that predicts broad effects of climatic warming on trophic systems. Our intention is to help meet the challenge of developing and testing general theoretical models that can predict which species will be winners and losers in ecological time, which evolutionary traits will be favoured or selected against, and what will be consequences for ecosystem structure and function.
|
|
| 5. |
- Birkhofer, Klaus, et al.
(författare)
-
Methods to identify the prey of invertebrate predators in terrestrial field studies
- 2017
-
Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 7:6, s. 1942-1953
-
Tidskriftsartikel (refereegranskat)abstract
- Predation is an interaction during which an organism kills and feeds on another organism. Past and current interest in studying predation in terrestrial habitats has yielded a number of methods to assess invertebrate predation events in terrestrial ecosystems. We provide a decision tree to select appropriate methods for individual studies. For each method, we then present a short introduction, key examples for applications, advantages and disadvantages, and an outlook to future refinements. Video and, to a lesser extent, live observations are recommended in studies that address behavioral aspects of predator-prey interactions or focus on per capita predation rates. Cage studies are only appropriate for small predator species, but often suffer from a bias via cage effects. The use of prey baits or analyses of prey remains are cheaper than other methods and have the potential to provide per capita predation estimates. These advantages often come at the cost of low taxonomic specificity. Molecular methods provide reliable estimates at a fine level of taxonomic resolution and are free of observer bias for predator species of any size. However, the current PCR-based methods lack the ability to estimate predation rates for individual predators and are more expensive than other methods. Molecular and stable isotope analyses are best suited to address systems that include a range of predator and prey species. Our review of methods strongly suggests that while in many cases individual methods are sufficient to study specific questions, combinations of methods hold a high potential to provide more holistic insights into predation events. This review presents an overview of methods to researchers that are new to the field or to particular aspects of predation ecology and provides recommendations toward the subset of suitable methods to identify the prey of invertebrate predators in terrestrial field research.
|
|
| 6. |
- Björkman, Christer, et al.
(författare)
-
Causes behind insect folivory patterns in latitudinal gradients
- 2011
-
Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 99, s. 367-369
-
Tidskriftsartikel (refereegranskat)abstract
- Summary 1. Adams and Zhang recently published one of the best studies so far of patterns of insect folivory along a latitudinal (climatic) gradient. They show clear negative trends in foliage loss in relation to temperature for certain groups of insect herbivores. 2. Although their suggestion that the plant–herbivore interaction may be more important in cooler climates could be valid, they did not bring up the complementary explanation that interactions between predators and herbivores could also vary with climate. There are indications that insect natural enemies may respond more positively than insect herbivores to an increase in temperature. We argue that higher predator pressure in warmer climates may partly explain the patterns observed by Adams and Zhang. 3. Synthesis. To further develop the important research concerning herbivory in a changing climate, both theoretically and empirically, plant ecologists and entomologists would mutually benefit fromjoining forces. Key-words: climate, herbivory, plant–herbivore interactions, temperature, trophic interactions
|
|
| 7. |
- Björkman, Christer, et al.
(författare)
-
Effects of new forest management on insect damage risk in a changing climate
- 2015
-
Ingår i: Climate change and insect pests. - 9781780643786 ; 7, s. 248-266
-
Bokkapitel (refereegranskat)abstract
- Recent findings suggest that damage by forest insect pests will increase as a consequence of climate warming. Here, we ask whether changes in forest management can alter and possibly mitigate the increased risk of damage and outbreaks. We focus mainly on conditions in northern Europe, particularly Sweden, but conclusions should be valid for northern temperate forests. Three types of insect pests are considered; the regeneration pest,Hylobius abietis(pine weevil), defoliators and the bark beetle,Ips typographus. We compare the expected effect of new management methods with the presently predominant method of even-aged stands, which are thinned two to three times before final harvest by clear-felling. Continuous cover forestry (CCF) is the method most different from the present practice. CCF would lead to a drastic decrease in pine weevils, and also less damage by defoliators, but this latter prediction is uncertain. For the bark beetle, the uncertainty is even greater. In mixed forests, all three insect pest types are expected to become less of a problem. Putative mechanisms involve more abundant and diverse natural enemy fauna, and a more scattered distribution of food resources. A shorter rotation period (including no thinning) is expected to increase the damage by pine weevils, as it will result in more abundant breeding material. For defoliators, it is difficult to foresee the effects. A shorter rotation period will decrease the risk of bark beetle outbreaks, as storm-fellings will be less frequent and young stands more common. The effects of exotic tree species and clonal forestry are complex and will depend on several factors. A general conclusion is that forest management may be used to mitigate the anticipated risk of insect pest damage as a consequence of climate warming, but more research is required to certify these indications
|
|
| 8. |
- Björkman, Christer, et al.
(författare)
-
Insect Pests in Future Forests: More Severe Problems?
- 2011
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 2, s. 474-485
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract: A common concern is that damage by insects will increase in forests as a consequence of climate change. We are assessing the likelihood of this predicted outcome by examining how other factors (especially changes in forest management practices) may interact with effects of climate change. Here we describe the strategies for improving understanding of the causes of insect outbreaks and predicting the likelihood of insect-mediated damage increasing in the future. The adopted approaches are: (i) analyses of historical data, (ii) comparison of life history traits of outbreak and non-outbreak species, (iii) experiments along climatic gradients to quantify the strength of trophic interactions, and (iv) modeling. We conclude that collaboration by researchers from many disciplines is required to evaluate available data regarding the complex interactions involved, to identify knowledge gaps, and facilitate attempts to progress beyond speculation to more robust predictions concerning future levels of insect damage to forests
|
|
| 9. |
|
|
| 10. |
- Björkman, Christer, et al.
(författare)
-
Stand structure of Monocotyledons and Dicotyledons in different successional stages in Corcovado National Park, Costa Rica
- 2011
-
Ingår i: Bois Et Forets Des Tropiques. - 0006-579X. ; , s. 33-40
-
Tidskriftsartikel (refereegranskat)abstract
- The two major groups of angiosperms, monocotyledons and dicotyledons, differ in several of their life history traits. Despite the obvious differences between the two groups, there are few studies elaborating on how these may relate to their ecological succession. The study compares the relative densities of these two fundamental groups of plants with different evolutionary histories in forests in two different successional stages at the Sirena station in Costa Rica's Corcovado National Park, in Central America. The hypothesis was that the monocotyledons/dicotyledons ratio would decrease in later successional stages. A total of 40 right-angled triangular plots ((5 x 5 m)/2) were sampled and the plants were divided into four crown size classes, as well as into monocotyledons and dicotyledons. Plant densities and crown size class distribution were analysed using ANOVA with the general linear model (GLM) procedure. The mean overall plant density in the secondary forest was significantly greater than in the primary forest (P < 0.001). The structure of the crown size class distribution, however, was similar for both monocotyledons and dicotyledons, and for the primary and secondary forest types. There was no significant difference between the two forests in the monocotyledons to dicotyledons ratio (P = 0.99). The crown size class distribution results indicate that there is a similar distribution trend in monocotyledon and dicotyledon succession, although there are always more dicotyledons than monocotyledons. These results led to conclude that a larger difference between successional stages is necessary to perceive the difference anticipated in this study.
|
|
| 11. |
|
|
| 12. |
- Bommarco, Riccardo, et al.
(författare)
-
Insecticides Suppress Natural Enemies and Increase Pest Damage in Cabbage
- 2011
-
Ingår i: Journal of Economic Entomology. - 0022-0493 .- 1938-291X. ; 104, s. 782-791
-
Tidskriftsartikel (refereegranskat)abstract
- Intensive use of pesticides is common and increasing despite a growing and historically well documented awareness of the costs and hazards. The benefits from pesticides of increased yields from sufficient pest control may be outweighed by developed resistance in pests and killing of beneficial natural enemies. Other negative effects are human health problems and lower prices because of consumers' desire to buy organic products. Few studies have examined these trade-offs in the field. Here, we demonstrate that Nicaraguan cabbage (Brassica spp.) farmers may suffer economically by using insecticides as they get more damage by the main pest diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), at the same time as they spend economic resources on insecticides. Replicated similarly sized cabbage fields cultivated in a standardized manner were either treated with insecticides according common practice or not treated with insecticides over two seasons. Fields treated with insecticides suffered, compared with nontreated fields, equal or, at least in some periods of the seasons, higher diamondback moth pest attacks. These fields also had increased leaf damage on the harvested cabbage heads. Weight and size of the heads were not affected. The farmers received the same price on the local market irrespective of insecticide use. Rates of parasitized diamondback moth were consistently lower in the treated fields. Negative effects of using insecticides against diamondback moth were found for the density of parasitoids and generalist predatory wasps, and tended to affect spiders negatively. The observed increased leaf damages in insecticide-treated fields may be a combined consequence of insecticide resistance in the pest, and of lower predation and parasitization rates from naturally occurring predators that are suppressed by the insecticide applications. The results indicate biological control as a viable and economic alternative pest management strategy, something that may be particularly relevant for the production of cash crops in tropical countries where insecticide use is heavy and possibly increasing.
|
|
| 13. |
- Bylund, Helena
(författare)
-
Angreppen av mätare kan förutsägas
- 2013
-
Ingår i: Svampar och insekter : Rapport från Future Forests 2009-2012. ; 2013:5, s. 18-19
-
Bokkapitel (populärvet., debatt m.m.)
|
|
| 14. |
- Bylund, Helena
(författare)
-
Larval crowding during an insect outbreak reduces herbivory pressure on preferred shrubs in a warmer environment
- 2018
-
Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923 .- 1873-2240. ; 263, s. 180-187
-
Tidskriftsartikel (refereegranskat)abstract
- With warming climate many species are predicted to shift their distributions toward the poles. However, climate change models developed to predict species distributions do not always incorporate interactions between them. The northerly shift of the boreal forest and associated dwarf shrub communities will be directly affected by warming. But warming will also indirectly affect plant communities via impacts on the intensity and frequency of associated insect outbreaks. We present a general model exploring plant host herbivory in response to the balance between insect crowding, host consumption and climate. We examined how these factors dictate the feeding preference of Epirrita autumnata larvae during an outbreak on dwarf shrub vegetation in Sub-arctic Fennoscandia. Data were collected from an outdoor experiment investigating future climate change scenarios (elevated CO2 and temperature) on the dwarf shrub community that included deciduous (Vaccinium myrtillus) and evergreen species (V. vitis-idaea and Empetrum nigrum). We observed that larval crowding was independent of treatment under outbreak conditions. We also tested and confirmed model predictions that larvae would prefer monospecific stands of either deciduous shrubs or its evergreen competitors. For current climate conditions, larvae had a preference to consume more deciduous shrubs in mixed stands. However, at elevated temperature bilberry consumption and herbivore pressure was lower, particularly in mixed stands. Our results show that during future warming, E. autumnata herbivory could promote the success of thermophile deciduous species and possible northward migration. Insect behaviour and preferences should therefore be considered when predicting future vegetation movements responding to warming.
|
|
| 15. |
- Chen, Yayuan, et al.
(författare)
-
Comparing Exogenous Methods to Induce Plant-Resistance Against a Bark-Feeding Insect
- 2021
-
Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- Exogenous application of the plant hormone methyl jasmonate (MeJA) can trigger induced plant defenses against herbivores, and has been shown to provide protection against insect herbivory in conifer seedlings. Other methods, such as mechanical damage to seedlings, can also induce plant defenses, yet few have been compared to MeJA and most studies lack subsequent herbivory feeding tests. We conducted two lab experiments to: (1) compare the efficacy of MeJA to mechanical damage treatments that could also induce seedling resistance, (2) examine if subsequent insect damage differs depending on the time since induction treatments occurred, and (3) assess if these induction methods affect plant growth. We compared Scots pine (Pinus sylvestris) seedlings sprayed with MeJA (10 or 15 mM) to seedlings subjected to four different mechanical bark damage treatments (two different bark wound sizes, needle-piercing damage, root damage) and previous pine weevil (Hylobius abietis) damage as a reference treatment. The seedlings were exposed to pine weevils 12 or 32 days after treatments (early and late exposure, hereafter), and resistance was measured as the amount of damage received by plants. At early exposure, seedlings treated with needle-piercing damage received significantly more subsequent pine weevil feeding damage than those treated with MeJA. Seedlings treated with MeJA and needle-piercing damage received 84% less and 250% more pine weevil feeding, respectively, relative to control seedlings. The other treatments did not differ statistically from control or MeJA in terms of subsequent pine weevil damage. For the late exposure group, plants in all induction treatments tended to receive less pine weevil feeding (yet this was not statistically significant) compared to control seedlings. On the other hand, MeJA significantly slowed down seedling growth relative to control and all other induction treatments. Overall, the mechanical damage treatments appeared to have no or variable effects on seedling resistance. One of the treatments, needle-piercing damage, actually increased pine weevil feeding at early exposure. These results therefore suggest that mechanical damage shows little potential as a plant protection measure to reduce feeding by a bark-chewing insect.
|
|
| 16. |
- Chen, Yayuan, et al.
(författare)
-
Seasonal timing and recurrence of methyl jasmonate treatment influence pine weevil damage to Norway spruce seedlings
- 2021
-
Ingår i: New Forests. - : Springer Science and Business Media LLC. - 0169-4286 .- 1573-5095. ; 52, s. 431-448
-
Tidskriftsartikel (refereegranskat)abstract
- Defense can be induced in conifer seedlings to reduce pine weevil (Hylobius abietis) damage, by treatment with the plant hormone methyl jasmonate (MJ). Few studies have addressed important practical issues regarding the use of MJ such as treatment incidence and timing, seedling age and its compatibility with plant nursery practices. We examined if levels of pine weevil damage depend on seasonal timing and recurrence of MJ treatment, and if the observed effects depend on plant age. Norway spruce (Picea abies) seedlings from two age cohorts (1 year and 1.5 years old) received four MJ treatments: MJ application before winter storage in the previous year, after winter storage but before spring/summer planting, repeated MJ application (both before winter storage, and before planting) or no MJ application at all. Pine weevil damage was evaluated in a lab and field experiment. We found that the timing and recurrence of MJ treatment affected the amount of damage inflicted by pine weevils in different ways, but these effects were consistent among age cohorts. MJ application before winter storage provided the most effective protection, and this reduction in damage was comparable to that provided by a currently used physical protection method against pine weevil feeding. Our results indicated that MJ can be applied in line with nursery practices (before winter storage) and provides adequate protection for two growing seasons.
|
|
| 17. |
- Evengård, Birgitta, 1952-, et al.
(författare)
-
Healthy ecosystems for human and animal health : Science diplomacy for responsible development in the Arctic
- 2021
-
Ingår i: Polar Record. - : Cambridges Institutes Press. - 0032-2474 .- 1475-3057. ; 57
-
Tidskriftsartikel (refereegranskat)abstract
- Climate warming is occurring most rapidly in the Arctic, which is both a sentinel and a driver of further global change. Ecosystems and human societies are already affected by warming. Permafrost thaws and species are on the move, bringing pathogens and vectors to virgin areas. During a five-year project, the CLINF - a Nordic Center of Excellence, funded by the Nordic Council of Ministers, has worked with the One Health concept, integrating environmental data with human and animal disease data in predictive models and creating maps of dynamic processes affecting the spread of infectious diseases. It is shown that tularemia outbreaks can be predicted even at a regional level with a manageable level of uncertainty. To decrease uncertainty, rapid development of new and harmonised technologies and databases is needed from currently highly heterogeneous data sources. A major source of uncertainty for the future of contaminants and infectious diseases in the Arctic, however, is associated with which paths the majority of the globe chooses to follow in the future. Diplomacy is one of the most powerful tools Arctic nations have to influence these choices of other nations, supported by Arctic science and One Health approaches that recognise the interconnection between people, animals, plants and their shared environment at the local, regional, national and global levels as essential for achieving a sustainable development for both the Arctic and the globe.
|
|
| 18. |
- Kilsgård, Ola, et al.
(författare)
-
Peptidylarginine deiminases present in the airways during tobacco smoking and inflammation can citrullinate the host defense peptide LL-37, resulting in altered activities.
- 2012
-
Ingår i: American journal of respiratory cell and molecular biology. - 1535-4989 .- 1044-1549. ; 46:2, s. 240-8
-
Tidskriftsartikel (refereegranskat)abstract
- Bacterial colonization of the lower respiratory tract is frequently seen in chronic obstructive pulmonary disease (COPD), and may cause exacerbations leading to disease progression. Antimicrobial peptides comprise an important part of innate lung immunity, and not least the cathelicidin human cationic antimicrobial protein-18/LL-37. Peptidylarginine deiminases (PADIs) post-translationally modify proteins by converting cationic peptidylarginine residues to neutral peptidylcitrulline. An increased presence of PADI2 and citrullinated proteins was demonstrated in the lungs of smokers. In this study, preformed PADI4, stored in granulocytes and extracellularly in the lumina of bronchi, was found in lung tissue of individuals suffering from COPD. In vitro, recombinant human PADI2 and PADI4 both caused a time- and dose-dependent citrullination of LL-37. The citrullination resulted in impaired antibacterial activity against Staphylococcus aureus, Streptococcus pneumoniae, and nontypable Haemophilus influenzae, but less so against Pseudomonas aeruginosa. Using artificial lipid bilayers, we observed discrete differences when comparing the disrupting activity of native and citrullinated LL-37, suggesting that differences in cell wall composition are important during interactions with whole bacteria. Furthermore, citrullinated LL-37 showed higher chemotactic activity against mononuclear leukocytes than did native LL-37, but was less efficient at neutralizing lipolysaccharide, and also in converting apoptotic neutrophils into a state of secondary necrosis. In addition, citrullinated LL-37 was more prone to degradation by proteases, whereas the V8 endopetidase of S. aureus cleaved the modified peptide at additional sites, compared with native LL-37. Together, these findings demonstrate novel mechanisms whereby the inflammation-dependent deiminases PADI2 and PADI4 can alter the activites of antibacterial polypeptides, affecting the course of inflammatory disorders such as COPD.
|
|
| 19. |
- Klapwijk, Maartje, et al.
(författare)
-
Forest management and natural biocontrol of insect pests
- 2016
-
Ingår i: Forestry. - : Oxford University Press (OUP). - 0015-752X .- 1464-3626. ; 89, s. 253-262
-
Tidskriftsartikel (refereegranskat)abstract
- Current silvicultural practices are under revision as result of changing demands and pressing environmental issues. We compared the monoculture clear-cut regime commonly used during the recent decades in Europe, especially in Fennoscandia, and in North America, with three alternative forest management methods, short rotation forestry, mixed forest stands and continuous cover forestry. We evaluate how these alternative management methods are Likely to affect the natural control of forest insect (regeneration pests, defoliators and bark beetles). Particular emphasis was placed on the effects of forest management on natural enemy pressure. We argue that changing forest management to any of the methods discussed will, in most cases, decrease the relative effects of bottom-up forces (resource quality and quantity) and increase the relative effects of top-down forces (natural enemy pressure) on forest pests. As population growth of the pest species presently causing most damage in European managed forests (i.e. pine weevil and spruce bark beetle) is mainly Limited by bottom-up forces (quantity of suitable breeding material), changes in forest management could increase the relative importance of top-down forces by modifying stand characteristics to actively support the natural enemies. However, it remains to be investigated to what extent such alterations will result in decreased damage to trees even though some evidence points in that direction.
|
|
| 20. |
- Kollberg, Ida, et al.
(författare)
-
Multiple effects of temperature, photoperiod and food quality on the performance of a pine sawfly
- 2013
-
Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 38, s. 201-208
-
Tidskriftsartikel (refereegranskat)abstract
- Many entomologists strive to understand what consequences climate change will have on insect performance. Such understanding is important, not least, when trying to predict the future impact of pest insects. In this study, it was reported how the multiple effects of temperature, photoperiod, and food quality affected the survival, development, and the final weight of the European pine sawfly (Neodiprion sertifer Geoffr.), an herbivorous outbreak species in boreal pine (Pinus spp.) forests. Sawfly larvae were reared in two different temperatures (15 and 20 degrees C) and under two different light regimes (20 and 18 h light). The larvae were fed pine needles either low or high in diterpene content. A 5 degrees C higher temperature did not affect the survival of the larvae, but reduced the development time by 3741%. The final weight was reduced by 22% in the warmer temperature, but only in combination with a short day length. A high content of diterpenes in the needles reduced the susceptibility to the virus by 31%, but did not otherwise affect the performance of the larvae. This study shows that the larval development could be shortened in a warmer climate and thereby decreasing the risk of predation. This per se may increase the risk for insect outbreaks, but the interactive effects of warmer temperatures with other abiotic and biotic factors such as day length and food quality (indicated in this study), and potential better performance of natural enemies and pathogens, illustrate the possibility for complex outcomes in a climate change perspective.
|
|
| 21. |
- Kollberg, Ida, et al.
(författare)
-
Regulation of forest defoliating insects through small mammal predation: reconsidering the mechanisms
- 2014
-
Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 176, s. 975-983
-
Tidskriftsartikel (refereegranskat)abstract
- Population densities of forest defoliating insects may be regulated by small mammal predation on the pupae. When outbreaks do occur, they often coincide with warm, dry weather and at barren forest sites. A proposed reason for this is that weather and habitat affect small mammal population density (numerical response) and hence pupal predation. We propose an alternative explanation: weather and habitat affect small mammal feeding behaviour (functional response) and hence the outbreak risks of forest pest insects. We report results from laboratory and field-enclosure experiments estimating rates of pupal predation by bank voles (Myodes glareolus) on an outbreak insect, the European pine sawfly (Neodiprion sertifer), at different temperatures (15 and 20 A degrees C), in different microhabitats (sheltered and non-sheltered), and with or without access to alternative food (sunflower seeds). We found that the probability of a single pupa being eaten at 20 A degrees C was lower than at 15 A degrees C (0.49 and 0.72, respectively). Pupal predation was higher in the sheltered microhabitat than in the open one, and the behaviour of the voles differed between microhabitats. More pupae were eaten in situ in the sheltered microhabitat whereas in the open area more pupae were removed and eaten elsewhere. Access to alternative food did not affect pupal predation. The results suggest that predation rates on pine sawfly pupae by voles are influenced by temperature- and habitat-induced variation in the physiology and behaviour of the predator, and not necessarily solely through effects on predator densities as previously proposed.
|
|
| 22. |
|
|
| 23. |
- Leibovici, Didier G., et al.
(författare)
-
Associating land cover changes with patterns of incidences of climate-sensitive infections : An example on tick-borne diseases in the nordic area
- 2021
-
Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 18:20
-
Tidskriftsartikel (refereegranskat)abstract
- Some of the climate-sensitive infections (CSIs) affecting humans are zoonotic vector-borne diseases, such as Lyme borreliosis (BOR) and tick-borne encephalitis (TBE), mostly linked to various species of ticks as vectors. Due to climate change, the geographical distribution of tick species, their hosts, and the prevalence of pathogens are likely to change. A recent increase in human incidences of these CSIs in the Nordic regions might indicate an expansion of the range of ticks and hosts, with vegetation changes acting as potential predictors linked to habitat suitability. In this paper, we study districts in Fennoscandia and Russia where incidences of BOR and TBE have steadily increased over the 1995–2015 period (defined as ’Well Increasing districts’). This selection is taken as a proxy for increasing the prevalence of tick-borne pathogens due to increased habitat suitability for ticks and hosts, thus simplifying the multiple factors that explain incidence variations. This approach allows vegetation types and strengths of correlation specific to the WI districts to be differentiated and compared with associations found over all districts. Land cover types and their changes found to be associated with increasing human disease incidence are described, indicating zones with potential future higher risk of these diseases. Combining vegetation cover and climate variables in regression models shows the interplay of biotic and abiotic factors linked to CSI incidences and identifies some differences between BOR and TBE. Regression model projections up until 2070 under different climate scenarios depict possible CSI progressions within the studied area and are consistent with the observed changes over the past 20 years.
|
|
| 24. |
- Linge, Helena, et al.
(författare)
-
Midkine is expressed and differentially processed during COPD exacerbations and ventilator-associated pneumonia associated with Staphylococcus aureus infection.
- 2013
-
Ingår i: Molecular medicine (Cambridge, Mass.). - : Springer Science and Business Media LLC. - 1528-3658 .- 1076-1551. ; 19, s. 314-323
-
Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus is sometimes isolated from the airways during acute exacerbations of chronic obstructive pulmonary disease (COPD) but more commonly recognized as a cause of ventilator-associated pneumonia (VAP). Antimicrobial proteins, among them midkine (MK), are an important part of innate immunity in the airways. In this study, the levels and possible processing of MK in relation to S. aureus infection of the airways were investigated, comparing COPD and VAP, thus comparing a state of disease with preceding chronic inflammation and remodeling (COPD) with acute inflammation (i.e. VAP). MK was detected in the small airways and alveoli of COPD lung tissue but less so in normal lung tissue. MK at below micromolar concentrations killed S. aureus in vitro. Proteolytic processing of MK by the staphylococcal metalloprotease AL but not cysteine protease SA, resulted in impaired bactericidal activity. Degradation was foremost seen in the COOH-terminal portion of the molecule that harbors high bactericidal activity. In addition, MK was detected in sputum from patients suffering from VAP caused by S. aureus but less so in sputum from COPD-exacerbations associated with the same bacterium. Recombinant MK was degraded more rapidly in sputum from the COPD patients than from the VAP patients and a greater proteolytic activity in COPD sputum was confirmed by zymography. Taken together, proteases of both bacteria and the host contribute to degradation of the antibacterial protein MK, resulting in an impaired defense of the airways, in particular in COPD where the state of chronic inflammation could be of importance.
|
|
| 25. |
- Miranda, Freddy, et al.
(författare)
-
Population Density and Killing Capacity by Predators of Eggs and Larvae of the Diamondback Moth in Nicaragua
- 2011
-
Ingår i: Environmental Entomology. - 0046-225X .- 1938-2936. ; 40, s. 333-341
-
Tidskriftsartikel (refereegranskat)abstract
- The diamondback moth Plutella xylostella (L.) (Lepidoptera: Plutellidae) is a serious pest of economically important brassica crops such as cabbage (Brassica oleracea Linne). To address the current lack of baseline information concerning predators of P. xylostella, and their potential role as biological control agents, especially in Central America, we aimed to 1) identify predators in northern Nicaragua, and estimate their population densities; 2) assess their killing rate of eggs and larvae of P. xylostella; and 3) assess if predators feed more of smaller P. xylostella larvae. Individuals of selected predator groups were offered eggs, second- or third-instar larvae. Our results indicate that there exists a broad spectrum of predators, within and around cabbage fields in Nicaragua that have the capacity to feed on P. xylostella eggs and larvae under laboratory conditions. Predators with the highest killing rates were adult and larval rove beetles (Staphylinidae), sheet weaving spiders (Linyphiidae), and larger jumping spiders (Salticidae). Although all predator densities varied in space and time the consistently most abundant predator groups with the highest consumption or killing rate, and consequently the highest potential for suppressing P. xylostella populations were wolf spiders (Lycosidae) and rove beetles (Staphylinidae), although sheet weaving spiders, jumping spiders, assassin bugs (Reduviidae), and damsel bugs (Nabidae) also can be important. We conclude that those generalist predators exhibiting the highest killing rates in the laboratory should be considered for further study in the field as candidate species with a role in the management of pest P. xylostella.
|
|
| 26. |
- Omazic, Anna, et al.
(författare)
-
Identifying climate-sensitive infectious diseases in animals and humans in Northern regions
- 2019
-
Ingår i: Acta Veterinaria Scandinavica. - : BioMed Central. - 0044-605X .- 1751-0147. ; 61:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: General knowledge on climate change effects and adaptation strategies has increased significantly in recent years. However, there is still a substantial information gap regarding the influence of climate change on infectious diseases and how these diseases should be identified. From a One Health perspective, zoonotic infections are of particular concern. The climate in Northern regions is changing faster than the global average. This study sought to identify climate-sensitive infectious diseases (CSIs) of relevance for humans and/or animals living in Northern regions. Inclusion criteria for CSIs were constructed using expert assessments. Based on these principles, 37 potential CSIs relevant for Northern regions were identified. A systematic literature search was performed in three databases using an explicit stepwise approach to determine whether the literature supports selection of these 37 potential CSIs.Results: In total, 1275 nominated abstracts were read and categorised using predefined criteria. Results showed that arthropod vector-borne diseases in particular are recognised as having potential to expand their distribution towards Northern latitudes and that tick-borne encephalitis and borreliosis, midge-borne bluetongue and the parasitic infection fasciolosis can be classified as climate-sensitive. Many of the other potential CSIs considered are affected by extreme weather events, but could not be clearly classified as climate-sensitive. An additional literature search comparing awareness of climate influences on potential CSIs between 1997-2006 and 2007-2016 showed an increase in the number of papers mentioning effects of climate change.Conclusions: The four CSIs identified in this study could be targeted in a systematic surveillance programme in Northern regions. It is evident that climate change can affect the epidemiology and geographical range of many infectious diseases, but there were difficulties in identifying additional CSIs, most likely because other factors may be of equal or greater importance. However, climate-ecological dynamics are constantly under change, and therefore diseases may fall in or out of the climate-sensitive definition over time. There is increasing awareness in the literature of the effects of climate change on infectious diseases over time.
|
|
| 27. |
- Rodrigues De Miranda, Joachim, et al.
(författare)
-
Characterization of a Novel RNA Virus Discovered in the Autumnal Moth Epirrita autumnata in Sweden
- 2017
-
Ingår i: Viruses. - : MDPI AG. - 1999-4915. ; 9:8
-
Tidskriftsartikel (refereegranskat)abstract
- A novel, 10 kb RNA virus-tentatively named 'Abisko virus'-was discovered in the transcriptome data of a diseased autumnal moth (Epirrita autumnata) larva, as part of a search for the possible causes of the cyclical nature and mortality associated with geometrid moth dynamics and outbreaks in northern Fennoscandia. Abisko virus has a genome organization similar to that of the insect-infecting negeviruses, but phylogenetic and compositional bias analyses also reveal strong affiliations with plant-infecting viruses, such that both the primary host origin and taxonomic identity of the virus remain in doubt. In an extensive set of larval, pupal, and adult autumnal moth and winter moth (Operophtera brumata) outbreak samples, the virus was only detected in a few adult E. autumnata moths as well as the single larval transcriptome. The Abisko virus is therefore unlikely to be a factor in the Fennoscandia geometrid population dynamics.
|
|
| 28. |
- Seipel, Peter, et al.
(författare)
-
Spionchips kontrollerar dig
- 2004. - 7
-
Annan publikation (populärvet., debatt m.m.)abstract
- Peter Seipel, Kia Höök, Gunnar Sjödin, Markus Bylund, Olle Olsson, Helena Andersson, Anders R Olsson
|
|
| 29. |
- Stockfelt, Marit, et al.
(författare)
-
Activated low-density granulocytes in peripheral and intervillous blood and neutrophil inflammation in placentas from SLE pregnancies
- 2021
-
Ingår i: Lupus Science and Medicine. - : BMJ. - 2053-8790. ; 8:1
-
Tidskriftsartikel (refereegranskat)abstract
- Objective Women with SLE face an increased risk of adverse pregnancy outcomes compared with healthy women, but the underlying immunological mechanisms are unknown. Given the recognised association of neutrophil activation with SLE pathogenesis, we examined whether there is increased neutrophil activation and inflammation in blood and placenta in SLE relative to healthy pregnancy. Methods At delivery, peripheral blood, maternal-derived intervillous blood and placentas were collected from 12 SLE and 10 healthy control pregnancies. The proportion of low-density granulocytes (LDGs) and the activation status of LDG and normal-density granulocytes were examined with flow cytometry. The chemokines CXCL8 and CXCL1 were quantified with a cytometric bead-based assay and interferon alpha (IFNα) protein levels with a Simoa method. IFNα-stimulated maternal-derived decidual stromal cells were examined for CXCL8 gene expression with qPCR. A pathologist, blinded to the patient background, examined all placentas. Results Women with SLE had significantly higher proportions of LDG in peripheral blood compared with controls (p=0.02), and LDG in both peripheral and intervillous blood were more activated in SLE relative to healthy pregnancies (peripheral blood: p=0.002 and intervillous blood: p=0.05). There were higher levels of CXCL8 and CXCL1 in intervillous compared with peripheral blood in women with SLE (p=0.004 and p=<0.0001, respectively) but not in controls. In SLE pregnancy, IFNα was detectable in 6 out of 10 intervillous blood samples but only in one control. Stimulation with IFNα upregulated CXCL8 gene expression in decidual stromal cells from both SLE and healthy pregnancy. Histological chorioamnionitis was present in 6 out of 12 placentas from women with SLE and in 1 out of 10 controls. Conclusions In women with SLE, locally produced chemokines in the placenta are increased and may attract and activate neutrophils. This in turn could contribute to placental inflammation and dysfunction and increased risk of placenta-related pregnancy complications.
|
|
| 30. |
- Tenow, Olle, et al.
(författare)
-
Geometrid outbreak waves travel across Europe
- 2013
-
Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 82:1, s. 84-95
-
Tidskriftsartikel (refereegranskat)abstract
- We show that the population ecology of the 9- to 10-year cyclic, broadleaf-defoliating winter moth (Operophtera brumata) and other early-season geometrids cannot be fully understood on a local scale unless population behaviour is known on a European scale. Qualitative and quantitative data on O. brumata outbreaks were obtained from published sources and previously unpublished material provided by authors of this article. Data cover six decades from the 1950s to the first decade of twenty-first century and most European countries, giving new information fundamental for the understanding of the population ecology of O. brumata. Analyses on epicentral, regional and continental scales show that in each decade, a wave of O. brumata outbreaks travelled across Europe. On average, the waves moved unidirectionally ESE-WNW, that is, toward the Scandes and the Atlantic. When one wave reached the Atlantic coast after 9-10 years, the next one started in East Europe to travel the same c. 3000 km distance. The average wave speed and wavelength was 330 km year-1 and 3135 km, respectively, the high speed being incongruous with sedentary geometrid populations. A mapping of the wave of the 1990s revealed that this wave travelled in a straight E-W direction. It therefore passed the Scandes diagonally first in the north on its way westward. Within the frame of the Scandes, this caused the illusion that the wave moved N-S. In analogy, outbreaks described previously as moving S-N or occurring contemporaneously along the Scandes were probably the result of continental-scale waves meeting the Scandes obliquely from the south or in parallel. In the steppe zone of eastern-most and south-east Europe, outbreaks of the winter moth did not participate in the waves. Here, broadleaved stands are small and widely separated. This makes the zone hostile to short-distance dispersal between O. brumata subpopulations and prevents synchronization within meta-populations. We hypothesize that hostile boundary models, involving reciprocal host-herbivore-enemy reactions at the transition between the steppe and the broadleaved forest zones, offer the best explanation to the origin of outbreak waves. These results have theoretical and practical implications and indicate that multidisciplinary, continentally coordinated studies are essential for an understanding of the spatio-temporal behaviour of cyclic animal populations.
|
|
| 31. |
|
|
| 32. |
- Torell, Agnes, 1993, et al.
(författare)
-
Low CD4+T cell count is related to specific anti-nuclear antibodies, IFNα protein positivity and disease activity in systemic lupus erythematosus pregnancy.
- 2024
-
Ingår i: Arthritis research & therapy. - : BioMed Central (BMC). - 1478-6362 .- 1478-6354. ; 26:1
-
Tidskriftsartikel (refereegranskat)abstract
- Lymphopenia, autoantibodies and activation of the type I interferon (IFN) system are common features in systemic lupus erythematosus (SLE). We speculate whether lymphocyte subset counts are affected by pregnancy and if they relate to autoantibody profiles and/or IFNα protein in SLE pregnancy.Repeated blood samples were collected during pregnancy from 80 women with SLE and 51 healthy controls (HC). Late postpartum samples were obtained from 19 of the women with SLE. Counts of CD4+and CD8+T cells, B cells and NK cells were measured by flow cytometry. Positivity for anti-nuclear antibodies (ANA) fine specificities (double-stranded DNA [dsDNA], Smith [Sm], ribonucleoprotein [RNP], chromatin, Sjögren's syndrome antigen A [SSA] and B [SSB]) and anti-phospholipid antibodies (cardiolipin [CL] and β2 glycoprotein I [β2GPI]) was assessed with multiplexed bead assay. IFNα protein concentration was quantified with Single molecule array (Simoa) immune assay. Clinical data were retrieved from medical records.Women with SLE had lower counts of all lymphocyte subsets compared to HC throughout pregnancy, but counts did not differ during pregnancy compared to postpartum. Principal component analysis revealed that low lymphocyte subset counts differentially related to autoantibody profiles, cluster one (anti-dsDNA/anti-Sm/anti-RNP/anti-Sm/RNP/anti-chromatin), cluster two (anti-SSA/anti-SSB) and cluster three (anti-CL/anti-β2GPI), IFNα protein levels and disease activity. CD4+T cell counts were lower in women positive to all ANA fine specificities in cluster one compared to those who were negative, and B cell numbers were lower in women positive for anti-dsDNA and anti-Sm compared to negative women. Moreover, CD4+T cell and B cell counts were lower in women with moderate/high compared to no/low disease activity, and CD4+T cell count was lower in IFNα protein positive relative to negative women. Finally, CD4+T cell count was unrelated to treatment.Lymphocyte subset counts are lower in SLE compared to healthy pregnancies, which seems to be a feature of the disease per se and not affected by pregnancy. Our results also indicate that low lymphocyte subset counts relate differentially to autoantibody profiles, IFNα protein levels and disease activity, which could be due to divergent disease pathways.
|
|
| 33. |
- Torell, Agnes, 1993, et al.
(författare)
-
Low-density granulocytes are related to shorter pregnancy duration but not to interferon alpha protein blood levels in systemic lupus erythematosus.
- 2023
-
Ingår i: Arthritis research & therapy. - : BMC. - 1478-6362 .- 1478-6354. ; 25
-
Tidskriftsartikel (refereegranskat)abstract
- An increased risk of pregnancy complications is seen in women with systemic lupus erythematosus (SLE), but the specific immunopathological drivers are still unclear. Hallmarks of SLE are granulocyte activation, type I interferon (IFN) overproduction, and autoantibodies. Here we examined whether low-density granulocytes (LDG) and granulocyte activation increase during pregnancy, and related the results to IFNα protein levels, autoantibody profile, and gestational age at birth.Repeated blood samples were collected during pregnancy in trimesters one, two, and three from 69 women with SLE and 27 healthy pregnant women (HC). Nineteen of the SLE women were also sampled late postpartum. LDG proportions and granulocyte activation (CD62L shedding) were measured by flow cytometry. Plasma IFNα protein concentrations were quantified by single molecule array (Simoa) immune assay. Clinical data were obtained from medical records.Women with SLE had higher LDG proportions and increased IFNα protein levels compared to HC throughout pregnancy, but neither LDG fractions nor IFNα levels differed during pregnancy compared to postpartum in SLE. Granulocyte activation status was higher in SLE relative to HC pregnancies, and it was increased during pregnancy compared to after pregnancy in SLE. Higher LDG proportions in SLE were associated with antiphospholipid positivity but not to IFNα protein levels. Finally, higher LDG proportions in trimester three correlated independently with lower gestational age at birth in SLE.Our results suggest that SLE pregnancy results in increased peripheral granulocyte priming, and that higher LDG proportions late in pregnancy are related to shorter pregnancy duration but not to IFNα blood levels in SLE.
|
|
| 34. |
|
|
| 35. |
- Uwamahoro, Florence, et al.
(författare)
-
Host range and banana cultivars’ susceptibility to Xanthomonas campestris pv. musacearum in Rwanda
- 2019
-
Ingår i: African Crop Science Journal. - : African Journals Online (AJOL). - 1021-9730 .- 2072-6589. ; 27, s. 463-478
-
Tidskriftsartikel (refereegranskat)abstract
- Xanthomonas campestris pv. musacearum (Xcm), a bacterium causing banana xanthomonas wilt (BXW) disease, is widely spread in the East and Central Africa and infects all cultivated bananas. The first objective of this study was to identify plant species produced in banana cropping systems of Rwanda that may act as host of Xcm, and to evaluate the susceptibility of different banana cultivars in Rwanda. Eighteen plant species including banana, banana-intercrop species and plant species closely related to banana were used to study the host range of Xcm. Similarly, five banana cultivars (Fhia-17, Fhia-25, Injagi, Mpologoma and Nkazikamwa) were used to assess their susceptibility level to Xcm. Tested plant species and banana cultivars were inoculated with Xcm isolate in a controlled environment. Only banana and its relatives (enset, blood banana, achira, African arrowroot, and Indian shot) developed xanthomonas wilt symptoms. Time to first symptoms expression and to complete wilting varied significantly (P < 0.0001) between susceptible plant species. Longer survival times (P < 0.0001) were observed in wild (blood) banana, Canna species and enset compared to cultivated banana. Since these susceptible plant species could host the bacteria, they should be avoided in farms or gardens neighbouring banana fields. All the five banana cultivars tested were susceptible to Xcm. Among the cultivars, Mpologoma was first to express disease symptoms and to wilt completely; while the longest incubation period and time to complete wilting were recorded in cultivar Fhia-17. Due to the broad host range and high susceptibility of banana cultivars to Xcm, information about how to limit the spread of the bacteria is crucial for disease control.
|
|
| 36. |
- Uwamahoro, Florence, et al.
(författare)
-
Management strategies for banana Xanthomonas wilt in Rwanda include mixing indigenous and improved cultivars
- 2019
-
Ingår i: Agronomy for Sustainable Development. - : Springer Science and Business Media LLC. - 1774-0746 .- 1773-0155. ; 39
-
Tidskriftsartikel (refereegranskat)abstract
- Xanthomonas wilt is a major constraint to banana production in the East and Central Africa. The disease can cause up to 100% yield losses if proper management strategies are not well implemented. Understanding of disease status, driving factors and farmers' knowledge provide insights towards a sustainable management approach. A total of 120 and 150 banana farms from eight and ten districts of Rwanda were surveyed for disease occurrence in 2015 and 2016 respectively. The owners of the farms were interviewed about disease knowledge, management practices, and source of information in these aspects. The results show that Xanthomonas wilt was present in all surveyed districts with high incidence (above 45% in both 2015 and 2016) in major banana growing areas, highlighting the risk of increasing yield losses. High Xanthomonas wilt incidence and severity was associated with Impara and Eastern plateau agro-ecological zones, intercropping systems, brewing bananas, dense spacing, and homogenous cultivars. Here, we demonstrate for the first time the gravity of Xanthomonas wilt in major banana growing areas of Rwanda. This agrees with the finding that proper implementation of management practices by the farmers remains limited. Disease management difficulties could be attributed to inaccessibility to the right information since some information sources may be unreliable. We also report for the first time that fields with a mixture of indigenous and improved cultivars are likely to have low Xanthomonas wilt disease severity (p<0.005), and this could be considered in banana Xanthomonas wilt management package. Our findings are essential to understand the urgency of improving extension services with updated practices and reinforcing disease monitoring efforts in order to stop new infections and further spread of the Xanthomonas wilt disease, a threat to sustainable banana production in Rwanda.
|
|
| 37. |
- Uwamahoro, Florence, et al.
(författare)
-
Potato bacterial wilt in Rwanda: occurrence, risk factors, farmers' knowledge and attitudes
- 2018
-
Ingår i: Food Security. - : Springer Science and Business Media LLC. - 1876-4517 .- 1876-4525. ; 10, s. 1221-1235
-
Tidskriftsartikel (refereegranskat)abstract
- Potato is an important food commodity and efforts to increase its productivity should focus on addressing production limiting factors. Potato bacterial wilt (PBW) caused by Ralstonia solanacearum is one of the major constraints to potato production in Rwanda and no single method effectively controls the disease. Development of a sustainable management approach requires understanding of PBW distribution, risk factors, farmers' knowledge and management attitudes. Therefore, we surveyed PBW disease and interviewed farmers in eight districts of Rwanda during March-April 2015. We detected PBW in all the surveyed districts and it was ranked as the major potato disease constraint. Among districts, disease incidence and severity varied from 5 to 24% and 3 to 13%, respectively, and was significantly higher in minor compared to major potato growing districts. Low PBW incidence and severity were associated with high altitude and low planting density, intercropping, crop rotation and avoidance of sharing farm tools. In all districts, farmers had little knowledge about PBW detection and spread, and the farmers' awareness of PBW management was often inconsistent with their practices. This incomplete knowledge about PBW was likely caused by inadequate extension services since most information about PBW was acquired from fellow farmers, parents or other relatives. Thus raising awareness of PBW and integrated disease management, including practices that are associated with low PBW, could limit the impact of this disease and help to secure food and income for potato growing farmers in Rwanda.
|
|
