Pronounced fluctuations of spruce bark beetle (Scolytinae: Ips typographus) populations do not invoke genetic differentiation     

Felix Gugerli  Rolf Gall  Franz Meier  Beat Wermelinger 《Forest Ecology and Management》2008,256(3):405-409

The dynamics of a recent outbreak of the spruce bark beetle (Ips typographus) in Switzerland was ruled by a devastating winter storm in 1999 and the drought and heat of the summer 2003. Starting from a similar level of population sizes, estimated as the rate of infested growing stock, beetle populations increased differently in magnitude and time among different regions in Switzerland. Accordingly, we expected local or regional genetic differentiation as a result of such repeated population expansion/breakdown dynamics. We analyzed 5 nuclear microsatellites of spruce bark beetles sampled from pheromone traps at 30 locations distributed over Switzerland. Our genetic results did not indicate any sign of population differentiation, structure, isolation by distance, or recent bottlenecks. This complete lack of genetic structure suggests that spruce bark beetles are highly mobile, precluding the formation of a spatial structure at neutral molecular markers. Thus, this molecular–genetic approach does not allow us to discriminate among regional gene pools and to identify the origin of expanding beetle populations.  相似文献   

Evaluation of cultural control and resistance‐breeding strategies for suppression of whitefly infestation of cassava at the landscape scale: a simulation modeling approach     

Hazel Parry  Andrew Kalyebi  Felix Bianchi  Peter Sseruwagi  John Colvin  Nancy Schellhorn  Sarina Macfadyen 《Pest management science》2020,76(8):2699-2710

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Augmentative releases of the soil predatory mite Gaeolaelaps aculeifer reduce fruit damage caused by an invasive thrips in Mediterranean citrus     

Cristina Navarro‐Campos  Aleixandre Beltr  Altea Calabuig  Ferran Garcia‐Marí  Felix L Wckers  Apostolos Pekas 《Pest management science》2020,76(7):2500-2504

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Regional variability in landscape effects on forest bird communities     

Spake  Rebecca  Soga  Masashi  Kawamura  Kazuhiro  Cooke  Robert S.  Yamaura  Yuichi  Eigenbrod  Felix 《Landscape Ecology》2020,35(5):1055-1071

Landscape Ecology - Functional responses to landscape heterogeneity are context-dependent, hampering the transferability of landscape-scale conservation initiatives. Japan provides a unique...  相似文献   

Variation in parasitoid attraction to herbivore-infested plants and alternative host plant cover mediate tritrophic interactions at the landscape scale     

Aartsma  Yavanna  Hao  Yueyi  Dicke  Marcel  van der Werf  Wopke  Poelman  Erik H.  Bianchi  Felix J. J. A. 《Landscape Ecology》2020,35(4):907-919

Landscape Ecology - Tritrophic interactions may be affected by local factors and the broader landscape context. At small spatial scales, carnivorous enemies of herbivorous insects use...  相似文献   

When natural enemies go to sleep: diapause induction and termination in the pear psyllid predator Pilophorus gallicus (Hemiptera: Miridae)     

Maria J Ramírez‐Soria  Felix Wckers  Juan A Sanchez 《Pest management science》2019,75(12):3293-3301

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Optimizing aphid biocontrol with the predator Aphidoletes aphidimyza,based on biology and ecology     

Franois‐Xavier Boulanger  Sarah Jandricic  Karel Bolckmans  Felix L Wckers  Apostolos Pekas 《Pest management science》2019,75(6):1479-1493

Aphidoletes aphidimyza is one of the most important predators used in the augmentative biological control of aphids, key pests of many crops worldwide. Adult females are very efficient in locating aphid infestations over a relatively long range, up to 45 m, and deposit eggs near or within aphid colonies. The predatory larvae are aphid generalists preying on several agriculturally important aphid species. The successful use of this biocontrol agent in agricultural systems depends on several biotic and abiotic factors. Among biotic factors, aphid species, plant structure, interspecific competition and intraguild predation may significantly impact the predator´s population dynamics. Key abiotic conditions include day lengths (above a critical threshold to prevent diapause), availability of mating sites in the crop, temperature (above 15 °C to enable egg laying), air relative humidity (above 70%) and availability of pupation sites. Although several successes have been reported in open field crops with naturally occurring or released populations, commercial releases are primarily used in protected crops. Optimized emergence boxes combining provisioning of food sources for the adults, integration with the technological advances that occurred in the greenhouse environment lately, insights into the nutritional ecology in open field crops and exploration of the genetic variability are proposed as future directions to improve adoption and efficacy of A. aphidimyza in crop protection. © 2018 Society of Chemical Industry  相似文献   

Applicability of ground‐penetrating radar as a tool for nondestructive soil‐depth mapping on Pleistocene periglacial slope deposits     

Rolf Gerber  Peter Felix‐Henningsen  Thorsten Behrens  Thomas Scholten 《植物养料与土壤学杂志》2010,173(2):173-184

Soil depth plays a decisive role in determining soil properties in mountainous regions for ecological site assessment. To evaluate the use of ground‐penetrating radar (GPR) for fast and high‐resolution mapping within mountainous regions, we examined the possibilities and limitations of GPR to determine soil depth over bedrock and to delineate individual substrate layers formed during the Pleistocene in a periglacial environment (Pleistocene periglacial slope deposits, PPSD). Selected catenae in representative subregions of the study area (Dill catchment, SE Rhenish Massif, Germany) have been successfully mapped using GPR. A practicable method was developed using a 400 MHz antenna to reach a mean penetration depth of 1.5 m and to map different substrates and layers of PPSD based on calibrations of the GPR at soil pits along 12 catenae. Colluvium, the three types of PPSD layers, as well as the in situ bedrock could be distinguished in most sections of the GPR surveys. Characteristic GPR facies caused by intrinsic material properties of the different substrates, such as stone content and soil moisture content, could be distinguished in different geomorphologic and lithological settings. A layer‐based velocity distribution was determined for characteristic substrate layers at soil pits enabling us to considerably enhance the accuracy of soil‐depth prediction. Compared to traditionally surveyed soil profiles, our results demonstrate an accuracy of layer thickness surveying within a standard deviation of approx. 0.1 m. It is demonstrated that the combination of GPR with conventional soil‐pit mapping is an efficient and valid method to produce high‐resolution data of substrate distribution.  相似文献   

Competitive ability of selected Cyclopia Vent. rhizobia under glasshouse and field conditions     

Amy C. Spriggs  Felix D. Dakora 《Soil biology & biochemistry》2007,39(1):58-67

This study tested the competitive ability of three locally isolated Cyclopia rhizobia and strain PPRICI3, the strain currently recommended for the cultivation of Cyclopia, a tea-producing legume. Under sterile glasshouse conditions, the three locally isolated strains were equally competitive with strain PPRICI3. In field soils, the inoculant strains were largely outcompeted by native rhizobia present in the soil, although nodule occupancy was higher in nodules growing close to the root crown (the original inoculation area). In glasshouse experiments using field soil, the test strains again performed poorly, gaining less than 6% nodule occupancy in the one soil type. The presence of Cyclopia-compatible rhizobia in field soils, together with the poor competitive ability of inoculant strains, resulted in inoculation having no effect on Cyclopia yield, nodule number or nodule mass. The native rhizobial population did not only effectively nodulate uninoculated control plants, they also out-competed introduced strains for nodule occupancy in inoculated plants. Nonetheless, the Cyclopia produced high crop yields, possibly due to an adequate supply of soil N.  相似文献   

High genetic diversity of Fusarium circinatum associated with the first outbreak of pitch canker on Pinus patula in South Africa     

Felix F Fru  Emma T Steenkamp  Michael J Wingfield 《Southern Forests》2019,81(1):69-78

The disease known as pitch canker results from infection of Pinus species by the fungus Fusarium circinatum. This fungus also causes a serious root disease of Pinus seedlings and cuttings in forestry nurseries. Pinus radiata and P. patula are especially susceptible to the pathogen, but there are no records of pitch canker on P. patula in established plantations. To date, only planting material of this tree species in nurseries or in plantations at the time of establishment have been infected by F. circinatum. Symptoms of pitch canker have recently emerged in an established P. patula plantation in South Africa and this study sought to determine whether the symptoms were caused by F. circinatum. Isolates from cankers were identified as F. circinatum using morphology and DNA-based diagnostic markers. Microsatellite markers were then used to determine the genetic diversity of a collection of 52 isolates. The entire population included 17 genotypes representing 30 alleles, with a greater number of genotypes collected from younger (three- to six-year-old) than older (12- to 19-year-old) trees. Both mating types of F. circinatum were present, but no evidence of sexual recombination was inferred from population genetic analyses. This is the first record globally of pitch canker on P. patula trees in managed plantations. It is of significant concern to South Africa, where P. patula is the most important Pinus species utilised for plantation forestry.  相似文献