Connecting phenological predictions with population growth rates for mountain pine beetle,an outbreak insect

It is expected that a significant impact of global warming will be disruption of phenology as environmental cues become disassociated from their selective impacts. However there are few, if any, models directly connecting phenology with population growth rates. In this paper we discuss connecting a distributional model describing mountain pine beetle phenology with a model of population success measured using annual growth rates derived from aerially detected counts of infested trees. This model bridges the gap between phenology predictions and population viability/growth rates for mountain pine beetle. The model is parameterized and compared with 8 years of data from a recent outbreak in central Idaho, and is driven using measured tree phloem temperatures from north and south bole aspects and cumulative forest area impacted. A model driven by observed south-side phloem temperatures and that includes a correction for forest area previously infested and killed is most predictive and generates realistic parameter values of mountain pine beetle fecundity and population growth. Given that observed phloem temperatures are not always available, we explore a variety of methods for using daily maximum and minimum ambient temperatures in model predictions.     

Both native and invasive bark beetles threaten exotic conifers within the spa towns in the Czech part of “The Great Spas of Europe”

Exotic coniferous trees in forests adjacent to spa towns and in parks within spa towns are increasingly being attacked by outbreak populations of native bark beetles in western Bohemia (Central Europe). In the 12 localities in western Czech Republic the current study, we detected a total of 19 native bark beetle species infesting more than 10 % of exotic tree species in the genera Abies, Picea, Pinus, and Pseudotsuga in 1 year. Several exotic tree species were identified as new hosts for native European bark beetles. We also identified three non-native bark beetles, including Phloeosinus aubei, a species that transmits the pathogens that cause cypress canker disease.The numbers of infested trees in the localities were not correlated with the distance from surrounding bark beetle outbreak sites in commercial forests, because all forests adjacent to spas and all forests in spa towns (i.e., “urban forests”) are close to commercial forests with infested trees. Infestations were greater in spa towns than in the forests adjacent to spa towns. We therefore assume that trees within spa towns will be further attacked due to the increasing abundance of native bark beetles.     

Monitoring of Ambrosia Bark Beetle Through Installation of Sticky Color Traps at Different Heights in Mango Trees

ABSTRACT

The present research investigations were carried out on monitoring the population of bark beetle, Hypocryphalus mangiferae(Stebbing) on mango trees through installation of sticky color traps at different heights of mango tree. The results revealed that maximum monthly mean number of adult beetles (507.91) was recorded on green plastic traps followed by 261.75 beetles on black traps, 215.75 beetles on white traps, 109.83 beetles on red traps, 83.75 beetles on blue traps, and 77.75 beetles on yellow traps. With regards to number of bark beetles on color traps at different heights, the maximum monthly mean number of the beetles (429.83) was recorded at height of 1 above ground level followed by 416.00 beetles at 3′level, 334.08 beetles at 6′and 76.83 beetles at 9′level. The results further revealed that the bark beetle population remained higher from February 2006 to June 2006. The mean temperature for that period ranged between 23.12 to 33.46°C with 48.57 to 76.00% RH.     

Fast virtual histology using X-ray in-line phase tomography: application to the 3D anatomy of maize developing seeds

Background

Despite increasing demand, imaging the internal structure of plant organs or tissues without the use of transgenic lines expressing fluorescent proteins remains a challenge. Techniques such as magnetic resonance imaging, optical projection tomography or X-ray absorption tomography have been used with various success, depending on the size and physical properties of the biological material.

Results

X-ray in-line phase tomography was applied for the imaging of internal structures of maize seeds at early stages of development, when the cells are metabolically fully active and water is the main cell content. This 3D imaging technique with histology-like spatial resolution is demonstrated to reveal the anatomy of seed compartments with unequalled contrast by comparison with X-ray absorption tomography. An associated image processing pipeline allowed to quantitatively segment in 3D the four compartments of the seed (embryo, endosperm, nucellus and pericarp) from 7 to 21 days after pollination.

Conclusion

This work constitutes an innovative quantitative use of X-ray in-line phase tomography as a non-destructive fast method to perform virtual histology and extends the developmental stages accessible by this technique which had previously been applied in seed biology to more mature samples.

     

Effects of root architecture on response to melon vine decline

Summary

Melon vine decline (MVD) is a complex disease for which only a few genotypes of Cucumis melo have been described as being tolerant. These genotypes were selected under different inoculum conditions, and little is known about the morphological or biochemical mechanisms of their tolerance to MVD. In order to study the tolerance mechanisms acting in different resistant sources, we conducted a comparative analysis of three tolerant (‘Doublon’, ‘Deltex’, and ‘Pat 81’) and two susceptible (‘Piel de Sapo’ and ‘Amarillo Canario’) melon cultivars. Their responses to non-infested soils, naturally infested soils, and soils artificially inoculated with the principal causal agents of MVD – Monosporascus cannonballus and Acremonium cucurbitacearum – were studied in pots in a greenhouse, and the results were compared with their field responses. We performed a combined study on lesions, root architecture, and root:vine balance. A combination of all of these traits can predict the level of MVD tolerance in infested fields better than the severity of root lesions alone. These features should be taken into account in breeding programmes for resistance to MVD.     

Phytophthora nicotianae transmission and growth of potted kalanchoe in two recirculating subirrigation systems

Recirculating subirrigation systems are frequently exposed to the risk of plant pathogens transmission, which may deteriorate the growth and quality of the plants. The transmission of Phytophthora nicotianae was examined using Kalanchoe blossfeldiana cv. New Alter in two recirculating subirrigation systems, a nutrient-flow wick culture (NFW) system and an ebb and flow (EBB) system. When the nutrient solution was infested, the pathogen was recovered from roots in both subirrigation systems. However, foliar blights and browning of roots appeared 4 and 7 weeks, respectively, after inoculation in the EBB system. Only a little discoloration appeared in the NFW system. The fresh and dry weights were lower in the EBB system than in the NFW system. When growing medium was inoculated, the pathogen was unable to be isolated from the plants in the NFW system. However, disease symptoms appeared in the EBB system 4 weeks after inoculation, and the pathogen was observed in the basal leaves and roots. Similar to the infested nutrient solution, the plant growth in the EBB system was inhibited. These results suggested that when the nutrient solution was infested, pathogen transmission could occur in plants in both systems, although differences existed with regard to disease symptoms and the time it took for symptoms to appear. However, we observed that when growing medium was inoculated the pathogen was not transmitted to adjacent plants in the NFW system using wick.     

A positive response of mountain pine beetle to pine forest-clearcut edges at the landscape scale in British Columbia,Canada

In British Columbia, large-scale salvage harvesting has been underway to recover timber value from forest stands infested by mountain pine beetle during the current outbreak. Understanding the response of beetles to clearcut edges particularly at the landscape scale is crucial to understanding the impacts of increased habitat fragmentation due to salvage harvesting on the spread of the beetle infestations. A novel proximity analysis approach based on null models of complete spatial randomness with three different spatial extents was developed to examine the spatial patterns of infestations in relation to cutblocks. Inhomogeneous Poisson point process models were fitted to predict how intensities of infestations varied with distances to the nearest cutblocks. Marked Poisson point process models were also fitted to evaluate the effects of the variables associated with the nearest cutblocks and adjacent infested pine stands on the edge response of beetles. The results clearly illustrated a significant positive edge response of beetles at the landscape scale. The intensities of infestations decreased non-linearly with distances to the nearest cutblocks. The results also suggested that the quality and distribution of key habitat resources could not fully explain the fundamental mechanisms underlying the edge response. The behavioural change of beetle dispersal at edges may also be an important factor contributing to a positive edge response. The results from this study may be useful in improving the efficacy of mountain pine beetle management efforts.     

Root formation,bud growth and survival of ornamental shrubs propagated by cuttings on different planting dates

Summary

Semi-hardwood cuttings of Cornus alba ‘Sibirica’, Deutzia ‘Mont Rose’, Forsythia × intermedia ‘Lynwood’, Ligustrum vulgare ‘Liga’, Philadelphus × virginalis, Potentilla fruticosa ‘Goldfinger’, and Spiraea × vanhouttei were planted on seven dates from July to October in two years and at three locations to investigate the effect of planting date on root formation, axillary bud growth, and plant survival. Cuttings were planted directly in the field and covered with polyethylene. Generally, root formation, bud growth, and plant survival were similar both years and at the three locations. All species except Deutzia had relatively constant rooting percentages at planting dates until mid August. For all species rooting percentages declined from mid August to October. Except for Deutzia, plant survival the following spring was constant or decreasing with planting date. For all species except Potentilla axillary bud growth and survival of cuttings planted in late September or October tended to increase while rooting percentages continued to decrease. In all species there was a close relationship between axillary bud growth and survival. Results revealed that many roots per cutting accelerated axillary bud growth.     

Object-based classification of urban plant species from very high-resolution satellite imagery

Cities are facing too many challenges. Urban vegetation, in particular trees, are essential as they provide services in terms of air pollution mitigation, freshness, biodiversity, and citizens’ well-being. Accurate data on location, species, and structural characteristics are essential for quantifying their benefits. However, the cost of measuring thousands of individual trees through field campaigns can be prohibitive and reliable information on domestic gardens is lacking due to difficulties in acquiring systematic data. The main objective of this study was to investigate the suitability of very-high resolution satellite imagery, e.g., WorldView-2, for detecting, delineating, and classifying the urban plant species in both public and private areas. The characterization of urban vegetation is difficult due to the complexity of the urban environment (buildings, shadows, open courtyards), the diversity of species and the spatial proximity between trees. To overcome these constraints, an object-based classification was developed with the selection of new relevant spectral and texture-based features for each plant species. Four spectral bands (blue, green, yellow, red) and four texture features (i.e., energy, entropy, inverse difference moment, Haralick correlation) were found to be the most efficient attributes for object-based classification from WV-2 images. Then, a classification of plant species, by using a Random Forest classifier, and ground validation were performed. In the two study areas, Aix-en-Provence (France) and Florence (Italy), 22 and 20 dominant plant species, and grassland, were identified and classified with an overall accuracy of 84% and 83%, respectively. The highest classification accuracy was obtained for Pinus spp. and Platanus acerifolia in Aix-en-Provence, and for Celtis australis and Cupressus sempervirens in Florence. The lowest classification accuracy was obtained for Quercus spp. in Aix-en-Provence, and Magnolia grandiflora in Florence.     

Investigations on Chlorosis of Fruit Trees.: III.—A Chlorosis of Plums Due to Potassium Deficiency.

Summary

Grafting is a suitable method to control soil-borne diseases in melon (Cucumis melo L.) crops. To date, several Cucurbita species and their inter-specific hybrids have been tested as rootstocks. However, graft-scion incompatibility and lower fruit quality have prevented their commercial use. The wild accession ‘Pat 81’ ssp. agrestis of C. melo is highly resistant to Monosporascus cannonballus Pollack et Uecker root rot, and develops a root system that is more suitable to withstand infested soils than that of cultivated melon. The potential of ‘Pat 81’ as a rootstock for melons (e.g., ‘Piel de Sapo’ type, C. melo ssp. melo) compared with the popular rootstock ‘RS 841’ (Cucurbita maxima Cucurbita moschata) has been evaluated here. The response of grafted plants to Monosporascus root rot disease, and rootstock effects on plant performance and fruit quality have been investigated using both classical methods and modern technologies (e.g., root image analysis and real-time PCR). The results indicate that, during infection, the root system of ‘Pat 81’ adapts to the needs of the aerial part of the ‘Piel de Sapo’ scion, displays a high level of resistance to M. cannonballus (similar to ‘RS 841’), and provides the plant with more healthy roots, with a higher root/vine biomass ratio compared with non-grafted ‘Piel de Sapo’. In addition, ‘Pat 81’ rootstock retains its favourable root structure (i.e., larger total length and root area) to withstand soil stress. In healthy soils, ‘Pat 81’ rootstocks had less effect on fruit quality than ‘RS 841’, leading to a lower percentage of non-marketable products. The high resistance of ‘Pat 81’, and its reduced effect on fruit quality, point to it as a good rootstock for the grafting of melons to resist M. Cannonballus infested soils.     

Impact of Mononychellus progresivus and Oligonychus gossypii (Acari: Tetranychidae) on cassava growth and yield in Central Africa

Growth of cassava was investigated in Central Africa (Congo) on crops attacked by two phytophagous mites: Mononychellus progresivus and Oligonychus gossypii. Change and distribution of dry matter in leaves, stems and roots were monitored for the 24 month crop cycle on infested and mite-free plants. Leaf dry matter increased during the rainy season and decreased during the dry season. Stems contain the reserves used for initiating plant growth after the dry season. Dry matter increased in the roots which form true storage organs. At the start of the second year of cultivation, one third of the root biomass was used to support the recovery of plant growth and development. Mite densities fewer than 50 mobile forms per leaf (maximum number of mites) were not sufficient to cause significant loss of leaf, stem and root dry matter. Nevertheless the mites diverted part of the biomass allocated to the roots thereby reducing the efficiency of storage root production in the infested plot.     

The roles of cytokinins and abscisic acid in the pericarp of litchi (Litchi chinensis Sonn.) in determining fruit size

Summary

Variations in the concentrations of cytokinins (CTKs) and abscisic acid (ABA) were studied in the pericarp of litchi (Litchi chinensis Sonn.) fruit using the large-fruited cv. ‘Erdanli’ (55.3 g per fruit) and the small-fruited cv. ‘Huaizhi’ (20.9 g per fruit), as well as large fruit (32.4 g) from early blooms and small (20.8 g) fruit from late blooms on the same inflorescences of cv. ‘Feizixiao’ from the same commercial orchard in Guangdong, China in 2000. ‘Erdanli’ had higher concentrations of CTKs than cv. ‘Huaizhi’ on three out of six sampling dates during fruit development, and lower concentrations of abscisic acid (ABA) from 40 d after anthesis. In cv. ‘Feizixiao’, fruit from early blooms had higher concentration of CTKs than fruit from late blooms at all sampling dates, and lower concentrations of ABA on three out of five sampling dates. Therefore, the former had a higher CTK:ABA ratio. These data suggest that a high CTK:ABA ratio favours fruit growth in litchi.     

Thermal imaging to detect spatial and temporal variation in the water status of grapevine (Vitis vinifera L.)

Thermal imaging can detect variation in stomatal conductance and therefore spatial variation in the water status of grapevine. Temporal variation can also be assessed, using indices that relate canopy temperature to reference temperatures, but, as yet, there is no standard approach to obtain these reference values. Also, the potential of above-canopy imaging is uncertain for vine rows with mainly vertically oriented leaves. Thermal images of the side (vertical leaves) and top (horizontal leaves) of ‘Tempranillo’ (Vitis vinifera L.) grapevine rows were captured on different dates and in different plots in a vineyard in the Rioja, Spain. Reference temperatures were determined separately (i) as the temperature of artificial leaves placed in the grapevine canopy, or (ii) by calculation from the leaf energy budget. With respect to imaging the side of grapevine rows, the two approaches exhibited similar potential to indicate variation in stomatal conductance or stem water potential within a single date and time of day. Over different dates (implying temporal as well as spatial variability) and both sides of the grapevines, the use of the artificial surfaces resulted in stronger correlations between thermal indices and physiological variables than the application of energy budget models. The use of such reference surfaces would allow a standardised approach to thermography. Imaging the top of rows produced some highly significant correlations between thermal indices and physiological variables. Modified artificial leaves could be developed to standardise the determination of reference temperatures, at the same spatial resolution as the leaves of interest. That imaging the top of grapevine canopies provides useful information on water status suggests that aerial imaging could be used to assess spatial variation in water status across entire vineyards.     

Growth of Black Currant Infested with Currant-Lettuce Aphid

Young, pot-grown black currant bushes, var. Wellington XXX, were artificially infested with the currant-lettuce aphid (Hyperomyzus lactucae L.) and their growth until mid-July was compared with unsprayed, aphid-free, controls.     

Comparison of methods for estimating the onset of the respiration climacteric in unpicked apples

The rate of deterioration of apples in storage is influenced by their maturity at harvest. Three methods based on the occurrence of the rise in ethylene production which is coincident with the climateric rise in respiration, have been used to assess the maturity of the crop for various apple cultivars.

In the first method internal ethylene concentrations (IEC) were measured in fruit samples soon after picking at weekly intervals. The onset of the climacteric was defined as the date when the internal concentration passed 0.1 μ l^-1. The other two methods were based on ethylene production by bulk samples picked at weekly intervals. In one, the mean delay between picking and the rise in ethylene production (DEP) was calculated, and the other recorded the first date on which at least half the replicate samples showed immediate ethylene production (IEP).

The dates determined by IEC and IEP were generally in agreement for each cultivar but there was little evidence of correlation in respect to site and season. Although low DEP values were loosely correlated with early IEP dates this relationship was not sustained over the full range of the data. Modifications to attain greater precision in estimating the progress of maturity in unpicked apples are suggested.     

Strategic removal of host trees in isolated,satellite infestations of emerald ash borer can reduce population growth

Emerald ash borer is an invasive beetle causing significant mortality of ash trees (Fraxinus spp.) in North America and western Russia. The invasive range has expanded to more than half of the states in the United States since the initial detection in Michigan, USA in 2002. Emerald ash borer is typically managed with a combination of techniques including surveys/trapping, insecticide treatments, host tree removal, biological control, and public education/outreach. The insect’s rapid spread rate and cryptic life history and a lack of resistance among most North American Fraxinus spp. have limited opportunities to gather empirical data on how aggressive tree removal may slow population growth in isolated, satellite infestations if detected early. An early detection of an isolated population of emerald ash borer in 2009 in Minnesota, USA was managed by using a selective host-tree removal program (i.e., sanitation). Trees were preferentially removed based on the assumption that evidence of woodpecker foraging (i.e., pecking) was a good indicator of infestation by emerald ash borer. Extensive sampling and survey data on larval densities and the presence/absence of pecking on ash trees in a 6-km² area for the Twin Cities, Minnesota were used to parameterize a model of population growth over the next four years. We found that removing ∼63% of the total trees across four years reduced the cumulative number of beetles produced in the core infested area by ∼54%. However, we also found that increases in efficacy, i.e., larger decreases in beetle production per removed tree, could be achieved by preferentially removing trees with pecking. The invasive range of emerald ash borer in North America and western Russia continues to expand via natural and human-aided dispersal. While silvicultural control tactics alone will not be an adequate management strategy, tree removal is an important component of both a broader pest management program and the systematic replacement of ash canopies in urban forests. Increasing understanding of the efficacy of different management techniques in slowing population growth of emerald ash borer will be useful to support decision–making by land managers.     

Effects of landscape composition on spread of an herbicide-resistant weed

Widespread adoption of genetically modified glyphosate-resistant (GR) crops in the US has dramatically changed the agricultural landscape to one that selects for establishment and spread of weedy species resistant to glyphosate, a commonly applied herbicide. Weed species that possess the means to readily spread across the landscape will be contained by weed management strategies that limit weed establishment and prevent seed set. An empirically-derived simulation model was developed to explore GR Conyza canadensis spread in relation to characteristics of the agricultural landscape. C. canadensis seeds are carried in the wind and move among fields and therefore, access high quality habitat (GR crops) at long distances. The baseline scenario was the current GR adoption levels in many US agricultural landscapes with corn and soybean rotated annually. Alternate scenarios examined the interacting effects of management uniformity (GR crop adoption) and increased landscape richness (three crops: corn, soybean, alfalfa, instead of two), over a 10 year simulation period. When landscape uniformity increased (increased GR corn adoption), 3× more fields would be infested with the resistant biotype and a specific field would have up to 24% greater likelihood of being infested compared to the current GR crop adoption levels. Increased landscape richness (adding alfalfa as a third crop) slightly decreased GR C. canadensis abundance. Reduced GR management uniformity by way of reducing GR soybeans to half their current adoption levels had the greatest impact on spread and prevented GR C. canadensis from reaching high abundance. Large-scale reliance on glyphosate for weed management has increased high-fitness habitat and will result in rapid spread of glyphosate-resistant weeds. Without significant reductions of glyphosate use and without spatial coordination of weed and crop management practices, GR weeds will continue to spread rapidly and impact agricultural practices in areas reliant on glyphosate.     

A Laboratory Method for Testing the Toxicity of Protective Fungicides

SUMMARY

The improvement in shoot production of filbert (Corylus avellana L.) adult tissues by sequential in vitro subcultures and intensive pruning was studied. Improved and sustained production of adult shoots is possible by repeated subculturing in the presence of high cytokinin concentrations, which seem important for stabilizing the response and inducing a transient increase in proliferation. Intensive pruning increases proliferation in initial explants and facilitates the establishment and maintenance of culture lines. Rooting capacity is also enhanced by sequential in vitro subcultures, but stabilizing the response takes longer than with shoot proliferation. The increased capacity of adult tis-sues for shoot proliferation and rooting are similar to those obtained using juvenile plants as a source of explants, and could be explained as a reinvigoration induced by in vitro sequential subcultures.     

Incoming! Association of landscape features with dispersing mountain pine beetle populations during a range expansion event in western Canada

Mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae, Scolytinae), is a forest insect that undergoes intermittent population eruptions, causing landscape-level mortality to mature pines. Currently, an outbreak covers over 16.3 million ha of British Columbia and Alberta in western Canada. Recent incursion into the jack pine (Pinus banksiana Lamb.) of northwestern Alberta threatens further range expansion through the boreal forest to central and eastern Canada. The spread from British Columbia into northwestern Alberta has been facilitated by above-canopy dispersal of the insect by meso-scale atmospheric currents. At these scales, dispersing D. ponderosae may behave like inert particles, causing terrain-induced tropospheric convective and advective currents to influence population dispersal and establishment. We use spatial point process regression models to examine the association of meso-scale variables, including landscape features and their orientations, habitat suitability, elevation and treatment efforts, with occurrence of D. ponderosae infestations in 2004, 2005, and 2006. Infestations of D. ponderosae primarily established in canyons and valleys, before moving into more open-sloped areas. Southwestern slopes of midslope ridges and small hills, southwest facing open slopes, and valleys that run in a northeast–southwest cardinal direction were positively associated with higher intensities of infestation. This study provides insight into the influences of complex terrain on landscape disturbance by a forest insect, and can be used to prioritize areas for potential management.     

Can Mineral Analysis be Used as a Tool to Predict ‘Braeburn’ Browning Disorders (BBD) in Apple in Commercial Controlled Atmosphere (CA) Storage in Central Europe?

‘Braeburn’ apples stored in controlled atmosphere (CA) frequently present internal flesh browning physiological disorder which is commonly referred as ‘Braeburn’ Browning Disorder (BBD). Apples from different orchards, years or site conditions can vary considerably in their sensitivity. The aim of this research was to evaluate the relationship between the mineral status of ‘Braeburn’ apples before-harvest (18 days) and at early and normal harvest, to correlate the data with the BBD incidence found in apples post storage and to investigate possible reasons for differences in disorder sensitivity. Fruits from seven orchards in the Lake Constance area (South-Western Germany) were harvested at two picking dates and the mineral content was measured before-harvest, at-harvest and during storage. Fruit were stored at 1.5?°C under CA conditions (1 kPa O₂ and 0.5 kPa CO₂) using either a 10 days or a 24 days delayed establishment of CA conditions. Fruit were evaluated after 6 months of storage plus 10 days of shelf life at 18?°C for mineral status and the browning disorder incidence. Results indicate no significant changes of the mineral concentrations in the fruit during CA-storage. Significant correlations between the post storage BBD incidence with K, and in some cases also for the K/Ca ratio and for P at-harvest were found.