| 1. |
- Andersson, Annhild, et al.
(författare)
-
Occurrence of aphid vector and genetic tolerance to infection by potyvirus in hot pepper
- 2010
-
Ingår i: Euphytica. - : Springer Science and Business Media LLC. - 0014-2336 .- 1573-5060. ; 172, s. 77-91
-
Tidskriftsartikel (refereegranskat)abstract
- The productivity and marketable quality of hot pepper (Capsicum annuum var. annuum L.) are low in tropical regions mainly due to virus infections and lack of effective virus management strategies. The absence of effective virus management strategies could be attributed to lack of information on virus vectors and host resistance. Parental (P(1) and P(2)) and progeny (F(1), B(1), B(2) and F(2)) generations of five hot pepper crosses were grown in Ethiopia at three sites (Bako, Hawasa and Melkasa) to monitor number and species of potential aphid vectors, disease incidence levels with regards to natural infections by Potato virus Y (PVY) and Ethiopian pepper mottle virus (EPMV) complex, and to determine genetic tolerance of the crop to the viruses. Disease incidence was assessed before the flowering stage of the crop plants using visible disease symptoms due to infections by PVY and EPMV. The serological tests revealed presence of symptomless genotypes of the crop to the virus infections. Aphid species potentially transmitting the viruses, such as Acyrthosiphon pisum (Harris), Aphis fabae (Scopoli), and Myzus persicae (Sulzer), were identified from specimens caught by yellow water traps. The highest number of aphids from yellow water traps was recorded at a dense foliage growth stage of the crop at Melkasa. Highly significant variation was observed among generations of the five crosses in response to infections by PVY and EPMV complex. The most susceptible parents had the levels of disease incidences ranging from 80 to 90%, whereas their progenies had only below 30% incidence levels. The most tolerant parent remained symptomless to the natural infections of PVY- and EPMV-complex. Incidence levels in progenies of a cross from the most susceptible and tolerant parents remained below 20%. Based on serological test, the proportion of PVY-positive plants ranged from 0 to 75% and of EPMV-positive plants from 0 to 25%, with 0 to 17% co-infection by the two viruses. Availability of virus sources in the vicinity, efficiency of aphids in vectoring, weather conditions during the growth period, genetic tolerance and the growth stage of the crop affected natural infection by PVY- and EPMV-complex. Exploitation of the genetic potential of introduced elite genotypes and their progenies along with breeding elite local cultivars for resistance and excluding aphid vectors at young (seedling) stage of the crop plants could be helpful for minimizing losses in yield and quality of hot pepper due to infections by PVY- and EPMV-complex.
|
|
| 2. |
- Bommarco, Riccardo, et al.
(författare)
-
Cereal aphid populations in non-crop habitats show strong density dependence
- 2007
-
Ingår i: Journal of Applied Ecology. - : John Wiley & Sons. - 0021-8901 .- 1365-2664. ; 44:5, s. 1013-1022
-
Tidskriftsartikel (refereegranskat)abstract
- 1.Few studies have addressed how density-dependent and density-independent regulation of population growth and abundance varies among habitats for a species that requires multiple habitat types to complete its life cycle. Understanding such relationships, however, are of direct relevance to the control of crop pest insects that regularly move between crop and non-crop habitats.2.We used autoregressive models to analyse a series of seasonal catches of the cereal aphid Rhopalosiphum padi. The data were collected from regional suction traps and egg counts on the overwintering host, over a period of 14–31 years, at four locations in Sweden. R. padi is an obligate host-alternating species in Sweden and seasonal catches reflect habitat use in a year: the primary woody host in winter and spring, the cereal crops in summer, and the perennial grasslands in the autumn.3.Strong direct density dependence acting within the year was found, but the strength varied between seasons depending on habitat use by the aphids during the year. Only a weak indication or no indication at all of density dependence was found during the period of residency on the primary host in the winter and spring periods.4.Density dependence occurred when R. padi utilized summer cereals (42% of the variation was explained), and even stronger density dependence occurred in the perennial grasslands in the autumn (70% variation explained). Stochastic fluctuations in the winter and spring were balanced by a strong density dependence in the cereal and grassland habitats in the summer and autumn periods, which reduced variability in population fluctuations.5.Weather, measured as seasonal average temperature and accumulated precipitation, did not affect aphid abundance fluctuations much, explaining only 1–9% of the variability.6.Synthesis and applications. Our results suggest that density-dependent regulation of R. padi occurs in late summer grasslands and early summer cereals. The mechanisms causing these patterns are not understood, making it difficult to provide specific pest management recommendations at this stage. The results do indicate, however, that pest management needs to involve a landscape-level approach, taking into account mechanistic information about the plant, herbivore and predator interactions in multiple habitats visited by the herbivorous pest.
|
|
| 3. |
- Bötzl, Fabian, et al.
(författare)
-
Predicting crop injury caused by flea beetles in spring oilseed rape through pest monitoring in the autumn
- 2024
-
Ingår i: Agricultural and Forest Entomology. - 1461-9555 .- 1461-9563. ; 26, s. 62-69
-
Tidskriftsartikel (refereegranskat)abstract
- 1. Reliably predicting pest damage would allow farmers to reduce insecticide use without incurring economic losses and thus contribute to agricultural sustainability. However, means to predict pest severity are lacking.2. We assessed whether crop feeding injury caused by flea beetles in spring oilseed rape can be predicted from flea beetle pest densities in the previous season using 22 years of suction trap catches of flea beetles in combination with crop feeding injury data from 293 fields.3. We found a strong positive relationship between the densities of flea beetles of the genus Phyllotreta in the summer and autumn activity period of the previous year and crop feeding injury caused by flea beetles in spring oilseed rape the following year. Autumn weather or the total cover of spring oilseed rape in the study region did not improve the prediction further.4. Pest monitoring using suction traps is thus a promising tool to predict crop feeding injury and can reduce insecticide use in years with low pest pressures.
|
|
| 4. |
|
|
| 5. |
- Emery, Sara, et al.
(författare)
-
Cold winters drive consistent and spatially synchronous 8-year population cycles of cabbage stem flea beetle
- 2022
-
Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 92, s. 594-605
-
Tidskriftsartikel (refereegranskat)abstract
- 1. Population cycles have been observed in mammals as well as insects, but consistent population cycling has rarely been documented in agroecosystems and never for a beetle.2. We analysed the long term population patterns of the cabbage stem flea beetle Psylliodes chrysocephala in winter oilseed rape over 50 years.3. Psylliodes chrysocephala larval density from 3045 winter oilseed rape fields in southern Sweden showed strong 8 year population cycles in regional mean density. Fluctuations in larval density were synchronous over time across five subregional populations. Subregional mean environmental variables explained 90.6% of the synchrony in P. chrysocephala populations at the 7-11 year time-scale. The number of days below -10 degrees C showed strong anti phase coherence with larval densities in the 7-11 year time-scale, such that more cold days resulted in low larval densities. High levels of the North Atlantic Oscillation weather system are coherent and anti phase with cold weather in Scania, Sweden.4. At the field-scale, later crop planting date and more cold winter days were associated with decreased overwintering larval density. Warmer autumn temperatures, resulting in greater larval accumulated degree days early in the season, increased overwintering larval density.5. Despite variation in environmental conditions and crop management, 8 year cycles persisted for cabbage stem flea beetle throughout the 50 years of data collection. Moran effects, influenced by the North Atlantic Oscillation weather patterns, are the primary drivers of this cycle and synchronicity. Insect pest data collected in commercial agriculture fields is an abundant source of long term data. We show that an agricultural pest can have the same periodic population cycles observed in perennial and unmanaged ecosystems. This unexpected find- ing has implications for sustainable pest management in agriculture and shows the value of long term pest monitoring projects as an additional source of time series data to untangle the drivers of population cycles.
|
|
| 6. |
- Jonsson, Mattias, et al.
(författare)
-
Suction-trap catches partially predict infestations of the grain aphid Sitobion avenae in winter wheat fields
- 2016
-
Ingår i: Journal of Applied Entomology. - : Wiley. - 0931-2048 .- 1439-0418. ; 140, s. 553-557
-
Tidskriftsartikel (refereegranskat)abstract
- Effective pest monitoring programmes are needed for providing reliable advice on when pest populations require active management. We studied whether suction-trap catches of the grain aphid Sitobion avenae during the period 1989-2009 can be used to predict field infestations of this aphid in Swedish winter wheat fields. We found that suction-trap catches of S.avenae until the time of crop heading (GS51) were significantly related to both number of aphids per tiller (R-2=0.69 at GS 59 and R-2=0.27 at GS 69) and proportion of fields with infestations above economic threshold (R-2=0.49 at GS 59 and R-2=0.40 at GS 69). This effect was consistent across Swedish regions and years. This information could be used by advisory services and farmers to decide whether field inspection to estimate the profitability of insecticide treatment at heading is needed. To improve the predictive ability further, suction-trap catches could be combined with weather data and information about biological control potential in different landscapes.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Sigvald, Roland
(författare)
-
A diagnostic real-time PCR assay for the rapid identification of the tomato-potato psyllid, Bactericera cockerelli (Sulc, 1909) and development of a psyllid barcoding database
- 2020
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 15
-
Tidskriftsartikel (refereegranskat)abstract
- The accurate and rapid identification of insect pests is an important step in the prevention and control of outbreaks in areas that are otherwise pest free. The potato-tomato psyllid Bactericera cockerelli (Sulc, 1909) is the main vector of 'Candidatus Liberibacter solanacearum' on potato and tomato crops in North America and New Zealand; and is considered a threat for introduction in Europe and other pest-free regions. This study describes the design and validation of the first species-specific TaqMan probe-based real-time PCR assay, targeting the ITS2 gene region of B. cockerelli. The assay detected B. cockerelli genomic DNA from adults, immatures, and eggs, with 100% accuracy. This assay also detected DNA from cloned plasmids containing the ITS2 region of B. cockerelli with 100% accuracy. The assay showed 0% false positives when tested on genomic and cloned DNA from 73 other psyllid species collected from across Europe, New Zealand, Mexico and the USA. This included 8 other species in the Bactericera genus and the main vectors of 'Candidatus Liberibacter solanacearum' worldwide. The limit of detection for this assay at optimum conditions was 0.000001ng DNA (similar to 200 copies) of ITS2 DNA which equates to around a 1:10000 dilution of DNA from one single adult specimen. This assay is the first real-time PCR based method for accurate, robust, sensitive and specific identification of B. cockerelli from all life stages. It can be used as a surveillance and monitoring tool to further study this important crop pest and to aid the prevention of outbreaks, or to prevent their spread after establishment in new areas.
|
|
