Foliage Type Research Articles

Distribution Pattern of Urban Street Trees in Rome (Italy): A Multifactorial Evaluation of Selection Criteria

Street trees play a significant ecological role in modern urban ecosystems, but usually the selection criteria follow pragmatic reasons rather than bio-ecological suitability. Understanding the influence of such factors can be relevant, especially in cities having a certain complexity and area. This paper aims to analyze the variation in the distribution of street tree species within the city’s municipia of Rome to determine the influence of some factors in the selection process. Here, we have described the species of street trees in fourteen municipia of Rome, and we created five clusters of factors (bio-ecological, aesthetic, historical–cultural, health, and economic) that could constitute selection criteria for street trees. From our data analysis, the municipia of Rome were grouped into four main groups and the choice of trees was based on multiple selection criteria. Foliage type, longevity, fruit type, autochthony, and economic value were the primary criteria. In 90–100% of municipia, deciduous species dominate, with 50–150 years longevity, dry fruits, exotic species, and prices of <€500 per tree. Additionally, the flower type, allergenicity, size class, and cultural value were the secondary criteria. The biological and ecological characteristics of trees are key factors to consider in order to reduce the management of street trees and relative costs.

Hypotheses and lessons from a native moth outbreak in a low‐diversity, tropical rainforest

AbstractOutbreaks of defoliating insects in low‐diversity tropical forests occur infrequently but provide valuable insights about outbreak ecology in temperate environments and in general. We investigated an extensive outbreak of the endemic koa moth (Scotorythra paludicola), which defoliated endemic koa trees (Acacia koa) over a third of their range on Hawai‘i Island during 2013 and 2014. At Hakalau Forest National Wildlife Refuge, we observed the dynamics of the outbreak and its effects on host trees, nutrient cycling, and insectivorous consumers in reforestation stands of densely planted koa and in natural forest stands of mixed koa and ‘ōhi‘a (Metrosideros polymorpha). Contrary to predictions of the resource concentration hypothesis, caterpillar biomass and defoliation severity were greater in the natural forest sites, where koa density was relatively low. Caterpillars preferentially consumed the most palatable koa foliage type (phyllodes), and koa initially refoliated with the least palatable foliage type (true leaves). Lightly defoliated small trees refoliated more quickly than did heavily defoliated ones but the opposite was true for large trees, which also produced a greater proportion of phyllodes. Mortality was greatest for heavily defoliated small koa. Caterpillar frass caused larger increases in soil nitrogen (N) than phosphorus (P) availability, with the greatest N increases in fine‐textured soils. Foliar N increased in alien grasses under koa canopies compared to grasses away from koa and to native woody understory species. Bird activity was influenced by ‘ōhi‘a flower abundance and the severity of koa defoliation; birds switched to outbreaking caterpillar prey, and they gained weight during the outbreak. Bat foraging times decreased during the outbreak, apparently because they became satiated quickly each night. Parasitoid wasps increased with caterpillar abundance but had little influence on outbreak dynamics. Reducing alien grass cover and increasing tree diversity would likely reduce the impacts of insect outbreaks and similar perturbations to native forests.

Предварительные результаты по селекции томата (Lycopersicon) в Республике Дагестан

Abstract. The aim of the work is to separate from hybrid generations (F3-F4) the promising material of high-temperature stress resistance. Scientific novelty. Testing the growth of the germ root at 35, 38 and especially 43 °C is an effective method of differentiating tomato genotypes and identifying their resistance to heat. As a result of our studies of inter-grade and remote hybridization, tomato lines have been obtained, combining heat-resistantness with high productivity and valuable biochemical indicators of fruit quality. Methods. The material for research served 11 promising varieties and lines of tomato. Dedicated genetic sources of heat resistance were included in inter-grade crossings. The selection of genotypes for heat-resistantness in the field was carried out taking into account the complex of morphological and agrochemical features (type and strength of plant growth, bush foliage, phenology, shape and size of the fruit, general productivity of commodity fruits, the mass of the fetus). Results. It has been established that in varieties and lines of tomato, created as a result of inter-grade and interspecies interbreeding, heat-resistant sporophyte varied to large limits depending on the genotype and temperature level. The fruit's product ranged depending on the genotype and the year of cultivation (71.8–98.3 %). All forms turned out to be large-fruited – the weight of the fruit was from 87.8–124.6 g. L132, L204, L112 lines stood out as early forms. The dry matter content of all the genotypes studied is high, as it is above 5.0 %, except for the lines L122, L211 dry matter content of which was 4.74 and 4.58 %, respectively. Vitamin C was highest in L143 (63.32), L141 (62.65), L112 (63.38).

Saportaea Fontaine et White 1880 – An enigmatic, long-ranging, widely distributed but rare type of late Paleozoic and early Mesozoic foliage

New material of the enigmatic plant Saportaea salisburioides Fontaine et White 1880 is described from three localities in the late Permian Umm Irna Formation from the Dead Sea region, Jordan. The preservation and the sedimentology indicate that remains from all three localities were transported over a very short distance. In one of the localities the rich leaf association exclusively comprises Saportaea remains, which show a remarkably large morphological variation. They occur together with a coaly axis with attached petioles and several isolated petioles. The specimens apparently belonged to a single monospecific stand, or maybe even a single plant. Another locality yielded a large leaf portion showing the leaf architecture. Our material leads to the conclusion that Saportaea grandifolia Fontaine et White 1880 and Baiera virginiana Fontaine et White 1880 are to be regarded as synonyms of S. salisburioides. In one locality Saportaea foliage was found in close association with Nystroemia sp., which might suggest that this fructification belongs to Saportaea. Saportaea is a long-ranging, geographically widely distributed but very rare genus that first appears in the Westphalian D (Moscovian, Pennsylvanian) and has its last occurrence in the Carnian (Late Triassic).

A Late Devonian plant assemblage from New South Wales, Australia: Diversity and specificity

Gondwanan floras of Late Devonian age are poorly known. In Australia, the rare studies that have been published on Late Devonian plants are old and need reinvestigation. This paper is an account of the plant macro- and micro-remains found in the Mandowa Mudstone at Barraba, New South Wales. According to the miospores, plants are late to latest Famennian in age. The record of anatomically preserved specimens is diversified, with nine taxa assigned to the Lycopsida, Cladoxylopsida, Iridopteridales and Archaeopteridales. One specimen is referrable to the spermatophytes. Several taxa are specific to Barraba, i.e., the lycopsid genera Cymastrobus and Lycaugea, the iridopteridalean genus Keraphyton, the cladoxylopsid species Polyxylon australe, and possibly a plant represented by a large Hierogramma branch showing exarch protoxylem strands. The adpression record is dominated by axes of the cosmopolitan lycopsid genus Leptophloeum. It also includes specimens interpreted as seed plants such as a possible ovule resembling Pseudosporogonites, and two types of foliage differing by their petiole width. One of this foliage consists of delicate fronds broadly comparable to those of Cosmosperma. The closest flora from Barraba is the late Famennian–earliest Tournaisian flora of the New Albany Shale in eastern USA, suggesting floral connexion and comparable environmental conditions between Northern Gondwana and Southern Laurussia.

Preparation of Cellulose Nanoparticles from Foliage by Bio-Enzyme Methods

There are vast reserves of foliage in nature, which is an inexhaustible precious resource. In this study, the chemical components of five foliage types (pine needles, black locust tree leaves, bamboo leaves, elm leaves and poplar leaves) were analyzed, including cellulose content, hemicellulose content, and lignin content. The bio-enzymatic method was then used to prepare cellulose nanoparticles (CNPs) from these five kinds of leaves, and the prepared CNPs were analyzed using TEM, FTIR, FESEM, and XRD. The results showed that the content of hemicellulose in bamboo leaves was the highest, and the lignin content in the other four leaves was the highest. The cellulose content in the five kinds of foliage was arranged from large to small as pine needles (20.5%), bamboo leaves (19.5%), black locust leaves (18.0%), elm leaves (17.6%), and poplar leaves (15.5%). TEM images showed that the CNPs prepared by the five kinds of foliage reached the nanometer level in width and the micrometer level in length; therefore, the CNPs prepared in this study belonged to cellulose nanofibers (CNFs). The results of FTIR and XRD showed that CNFs prepared by the enzyme treatment exhibited a typical crystalline structure of cellulose II. The degree of crystallinity (DOC) of CNFs prepared from pine needle, poplar leaves, and bamboo leaves are 78.46%, 77.39%, and 81.51%, respectively. FESEM results showed that the CNFs prepared from pine needles, poplar leaves and bamboo leaves by enzymatic method presents a three-dimensional (3D) network structure, and their widths are 31 nm, 36 nm, and 37 nm, respectively. This study provides a meaningful reference for broadening the use of foliage types and improving their added value.

Effects of Hydrological Regime on Foliar Decomposition and Nutrient Release in the Riparian Zone of the Three Gorges Reservoir, China.

Foliar decomposition has significant effects on nutrient cycling and the productivity of riparian ecosystems, but studies on the impact of related hydrological dynamics have been lacking. Here, the litterbag method was carried out to compare decomposition and nutrient release characteristics in situ, including three foliage types [two single-species treatments using Taxodium distichum (L.) Rich., Salix matsudana Koidz., or a mixture with equal proportions of leaf mass], three flooding depths (unflooded, shallow flooding, and deep flooding), two hydrodynamic processes (continuous flooding and flooded-to-unflooded hydrological processes), and one hydrological cycle (1 year) in the riparian zone of the Three Gorges Reservoir. The results showed that both hydrological processes significantly promoted foliage decomposition, and all foliage types decomposed the fastest in a shallow flooding environment (P < 0.05). The mixed-species samples decomposed most quickly in the flooded hydrological process in the first half of the year and the unflooded hydrological process in the second half of the year. Flooding also significantly promoted the release of nutrients (P < 0.05). Mixed-species samples had the fastest release rates of carbon and nutrients in the flooded hydrological process in the first half of the year and the unflooded hydrological process in the second half of the year. Foliage decomposition was also closely related to environmental factors, such as water depth, temperature, and hydrological processes. Our research clarified the material cycling and energy flow process of the riparian ecosystem in the Three Gorges Reservoir area. It also provided a new reference for further understanding of foliage decomposition and nutrient release under different hydrological environments.

Phyllodes and bipinnate leaves of

In Acacia, 90% of species have drought-tolerant phyllodes as their adult foliage, the remaining species have bipinnate leaves. We conducted tests for relationships between foliage type and 35 bioclimatic variables at the continental scale and found significant correlations of both ‘moisture seasonality’ and ‘radiation in the coldest quarter’ with foliage type. Bipinnate species have lower species mean values of each variable, growing in stable soil moisture and generally darker environments (longer nights and lower incident radiation), on average. Evolutionary transformations between bipinnate and phyllodinous adult foliage exhibit asymmetry across the Acacia phylogeny, with transformations from bipinnate leaves to phyllodes occurring times faster than the reverse. At least three (and up to seven) transitions from phyllode to bipinnate adult foliage were inferred. Foliage type in the most recent common ancestor of extant Acacia is unresolved, some analyses favour a phyllodinous ancestor, others a bipinnate ancestor. Most ancestral nodes inferred as having bipinnate adult foliage had median age estimates of less than 5 million years (Ma), half having ages between 3 and 1.5 Ma. Acacia lineages with bipinnate adult foliage diversified during the Pliocene, perhaps in response to wetter climatic conditions experienced by the continental margin during this period.

Foliar Cellulose and Lignin Degradation of Two Dominant Tree Species in a Riparian Zone of the Three Gorges Dam Reservoir, China.

The riparian zone can affect the degradation of foliar cellulose and lignin by changing the hydrological gradient of the foliage decomposition environment. However, their degradation dynamics during the process of foliage decomposition remain unclear in mixed plantation forests in a riparian zone. Herein, we explored degradation of cellulose and lignin for two dominant riparian species, bald cypress [Taxodium distichum (L.) Rich.] and Chinese willow (Salix matsudana Koidz.), and a combined treatment with equal proportions of foliar mass of these species, involving three water treatments [no submergence (CK), shallow submergence (SS), and deep submergence (DS)] in a riparian zone of the Three Gorges Dam Reservoir (TGDR), China. Throughout an entire year’s incubation, the degradation of cellulose and lignin was 55.57–97.76% and 79.87–93.82%, respectively. In the early stage of decomposition (i.e., the first 30 days), cellulose and lignin were rapidly degraded, and the mass loss of cellulose and lignin in water environments (SS and DS) was greater than that in a non-flooded environment (CK) regardless of the foliage type. The degradation of cellulose and lignin was mainly related to the quality of the leaf litter (as indicated by the concentrations of cellulose and lignin, and the contents of C, N, and P), decomposition period, and local environmental factors (temperature, water gradients, and dissolved oxygen). Our results will provide a clear insight into the material cycling process in a riparian zone of the TGDR and similar ecosystems in other regions.

The effects of elevated CO2, elevated O3, elevated temperature, and drought on plant leaf gas exchanges: a global meta-analysis of experimental studies.

Global change significantly influences plant leaf gas exchange, which affects the carbon-water cycle of terrestrial ecosystems. However, the magnitudes of the effects of multiple global change factors on leaf gas exchanges are currently lacking. Therefore, a global meta-analysis of 337 published articles was conducted to determine the effects of elevated CO2 (eCO2), elevated O3 (eO3), elevated temperature (eT), and drought on plant leaf gas exchanges. The results indicated that (1) the overall responses of photosynthesis rate (Pn) and instantaneous water use efficiency (WUEi) to eCO2 increased by 28.6% and 58.6%. But transpiration rate (Tr) and stomatal conductance (gs) responded negatively to eCO2 (- 17.5% and - 17.2%, respectively). Furthermore, all Pn, gs, and WUEi responded negatively to eO3 (- 32.7%, - 24.6%, and - 27.1%), eT (- 23.2%, - 10.8%, and - 28.9%), and drought (- 53.6%, - 59.3%, and - 4.6%, respectively), regardless of functional groups and various complex experimental conditions. (2) Elevated CO2 increased WUEi combined with eO3, eT, and drought (26.6%, 36.0%, and 58.6%, respectively, for eCO2 + eO3, eCO2 + eT, and eCO2 + drought) and mitigated their negative impacts on Pn to some extent. (3) Plant form and foliage type play an important role in the responses of leaf gas exchanges. Trees responded mostly to eCO2, but responded least to eT in Pn, Tr, gs, and WUEi compared with shrubs and herbs. Evergreen broad-leaved species were more responsive to eCO2 and drought. (4) The stress level of each factor can also significantly influence the responses of leaf gas exchanges to environment change. Hopefully, the quantitative results are helpful for the further assessments of the terrestrial carbon-water cycle.

T0 Early Permian coal-forest preserved in situ in volcanic ash bed in the Wuda Coalfield, Inner Mongolia, China

An early Permian tuff bed between Coal 7 and Coal 6 of the Wuda Coalfield in Inner Mongolia bears T0 peat-forming vegetation preserved in situ. Documentation of the fossil record uncovered in an area of about 80 m2 shows 14 morphotaxa representing 11 whole-plant species with a wide variety of growth forms. The uncovered phytocoenosis is interpreted as a forest dominated by cordaites as the tallest trees, the remains of which covered over 50% of the excavated area. Marattialean tree ferns represent the lower canopy that was not taller than about 3 m. This storey fills gaps between cordaites and covers over 20% of the area. A rare element of lower canopy taxa was the cycadophyte genus Pterophyllum represented by a single plant. Poorly developed herbaceous groundcover includes Sphenophyllum oblongifolium, and four small fern species mostly with sphenopteroid type of foliage. Although members of the herbaceous layer covered only 7% of the excavated area, it was the most diverse storey of the peat-forming forest. Considering the small area excavated, along with the higher diversity known from the same tuff bed in the adjacent, former opencast mine, it appears that species richness in the forest was comparable to some of the less diverse Westphalian peat-forming floras in Euramerica.

Light environments affect herbivory patterns but not reproductive performance of a multivoltine specialist moth, Pareuchaetes pseudoinsulata

Unravelling the responses of insect herbivores to light-environment-mediated variation in the traits of their host plants is central to our understanding of the nutritional ecology of, and factors driving the population dynamics in, these species. This study examined the effect of light environment (shaded vs full-sun habitat) on leaf toughness and leaf nutritional quality in Chromolaena odorata (an invasive species in West Africa) and related these attributes to the abundance, herbivory patterns and reproductive performance of a multivoltine specialist moth, Pareuchaetes pseudoinsulata (a biological control agent). In this system, plants growing in shaded areas in the field experienced more herbivory and had higher herbivore abundance than those growing in full-sun. In the laboratory, P. pseudoinsulata larvae consumed significantly greater amounts of shaded foliage relative to full-sun foliage. However, reproductive performance metrics such as mating success, pre-oviposition period, number of eggs laid, duration of egg laying, egg hatchability, and adult longevity in P. pseudoinsulata did not differ according to foliage types. Reduced leaf toughness, increased water and nitrogen contents in shaded leaves coincided with increased leaf consumption by the larvae of P. pseudoinsulata. In summary, this study showed for the first time that light environments affect herbivory patterns but not reproductive performance of P. pseudoinsulata and hypothesized that high foliar nitrogen and water contents in shaded leaves resulted in feedback and necessity consumption patterns.

Artificial neural network classification of surface reflectors and volume scatterers using sequential echoes acquired with a biomimetic audible sonar.

This paper investigates classifying two target groups, surface reflectors (SR) and volume scatterers (VS), using echo envelope features. SR targets have convex surface patches that exhibit echo persistence over aspect angle, while VS targets are composed of random range-distributed and oriented reflectors producing echoes that become uncorrelated with small changes in aspect angle. The SR target group contains single-post (P1) and multiple-post (PM) types and the VS group contains Ficus benjamina (F) and Schefflera arboricola (S) foliage types with leaf areas that differ by a factor of 4. A biomimetic sonar emitting audible clicks acquired sequences of up to three binaural echoes from target views separated by 18°. Two artificial neural networks performing linear and nonlinear classification first differentiated SR/VS target groups and then P1/PM and F/S types. Classification performance improved with echo number, from a single monaural echo to three pairs of binaural echoes, demonstrating the benefit of sequential echoes. Linear and nonlinear classification of SR/VS targets achieved a minimum generalization error probability PEG = 0.003. Nonlinear P1/PM classification achieved PEG = 0.009 that was four times smaller than linear classification. Nonlinear F/S classification achieved PEG = 0.220, indicating that envelope features by themselves are inadequate to accurately differentiate foliage targets.

Comparative evaluation of different Allium accessions for allicin and other allyl thiosulphinates

Allicin and other allyl thiosulphinates possess broad antimicrobial and health-promoting properties, which makes them natural and safe substitutes for synthetic preservatives. These thiosulphinate compounds were investigated in 33 Allium accessions representing 14 species, and these species differed significantly in their content of allicin, allyl methyl thiosulphinates (AMThs), and allyl trans-1-propenyl thiosulphinates (ATPThs) as ascertained using liquid chromatography tandem mass spectrometry. Total thiosulphinates were the highest in Allium sativum, Allium guttatum, Allium tuberosum, and Zimmu (an interspecific hybrid of Allium cepa L. and Allium sativum L.). Allicin and other allyl thiosulphinates content was higher in flat and non-waxy leaves than in fistular and waxy leaves. Total thiosulphinates content was also significantly higher in cultivated and semi-domesticated species. Cluster analysis revealed that both foliage type and thiosulphinate content had played a major role in the clustering. These findings are useful in finding alternative sources of allicin and other thiosulphinates, and some of the accessions may serve as sources of natural preservatives for application in other research-related or commercial activities.

English

In tropical and subtropical countries, livestock productivity may be affected by the availability of food resources and the high prevalence of gastrointestinal pathogenic nematodes. The classical method of control using anthelmintic drugs is becoming decreasingly efficient because of a generalised resistance of the gastrointestinal nematodes suppress (GIN) to most of the drugs. In small farms, protein-rich biomasses with significant amounts of condensed tannins (CT), which are known to have anthelminbtic properties, might be good candidates to produce nutraceuticals. This experiment was conducted to determine the feasibility of producing nutraceutical pellets from Manihot esculenta sp., Cajanus cajan and Leucaena leucocephala, considering the influence of agro-pedo-climatic conditions plant species and technological factors, such as drying and pelleting. The samples were harvested in two different agro-pedo-climatic zones and sundried under shelter (at 25 to 35&deg;C) or in a ventilated oven (45&deg;C) before pelleting. Chemical analysis on crude protein and condensed tannins were conducted. The chemical composition of the plants did not vary significantly with agro-pedo-climatic conditions. Sun-drying and oven-drying decreased the CT content of the plants. No effect of pelleting was recorded on crude protein and CT contents, except for C. cajan, for which a small decrease in CT content was observed. Protein-rich foliage types with CT contents above 50 g/kg of dry matter are potentially good candidates to produce nutraceutical pellets if they are dried using mild drying conditions, like sun-drying under shelter. &nbsp; Key words: Condensed tannins, nutraceuticals, Biological variability; drying, pelleting processes.

Preference and restorative potential for landscape models that depict diverse arrangements of defoliated, foliated, and evergreen plants

Increasing temperatures and exposure to sunlight in spring causes many deciduous, broadleaf plant species in temperate climates to foliate; decreasing temperatures and exposure to sunlight in fall prompts complete defoliation. Evergreen plants defoliate seasonally, yet retain green foliage throughout the year. One’s mood may also be affected by seasonal changes, though few studies have investigated whether seasonally induced visual changes to plants affect landscape preference and measures related to attention restoration. To address this need, we manipulated three variables in a Latin square to model nine color digital landscape views. Stimuli depicted scattershot, clustered, or formal compositions of defoliated, foliated, or evergreen plant species quantities that equaled zero, two, or four bits of Shannon’s Information Entropy, a mathematical measure of complexity. The dataset contained 59 respondents’ ratings of preference and restorative potential from September, and 47 respondents’ ratings of preference and restorative potential from January. Mann-Whitney test results indicate that September respondents rated evergreen scenes significantly lower in restorative potential than January respondents. Wilcoxon test results indicated that the foliage type and plant entropy values significantly affected preference and restorative potential ratings in September and January; results varied between the evaluation date, and preference and restorative potential ratings. The results of simple mediation analyses indicated that only the depiction of defoliation indirectly affected September and January restorative potential ratings through preference.

Frond morphology and epidermal anatomy of Compsopteris wongii (T. Halle) Zalessky from the Permian of Shanxi, China

Compsopteris wongii (T. Halle) Zalessky is an enigmatic foliage type with unknown systematic affinities endemic to the Permian Cathaysia flora. Here we describe the frond morphology and epidermal anatomy of C. wongii based on material from the Palougou Section in Shanxi Province, China. Fronds are petiolate (i.e., possess a naked stipe), are once pinnate, and have alethopteroid, linear-oblong pinnules and a forked apex composed of two equally sized terminal pinnules. Fronds are amphistomatic, with haplocheilic, monocyclic to incompletely tricyclic stomata occurring on all parts. The epidermal anatomy, especially the distribution of stomata, and the lack of features suggestive of xeromorphy indicate that C. wongii had a high photosynthetic capacity and high assimilation rates, and was adaptated to an everwet environment. With regard to frond morphology and epidermal anatomy, the species corresponds well to supposedly related peltasperms from Euramerica, such as Glenopteris Sellards and Protoblechnum Lesquereux. We attribute C. wongii to the glenopteroid group of peltasperms.

Comprehensive measurement and modeling in foliage environments using UHF UWB ground-based radar

The precise knowledge of the statistical properties of clutter plays a key role in radar target detection in foliage environments. Owing to a wealth of multiple scattering, the selection of an appropriate model for diverse foliage environments remains a conundrum. Thus the statistical modeling of the foliage clutter in different environments is focused on in this paper. In particular, the primary contribution is to characterize and parameterize the amplitude of the foliage clutter in three typical foliage environments of different densities, including line-of-sight (LOS) forest environment, non line-of-sight (NLOS) forest-penetration environment, and NLOS bush-penetration environment. Based on the real clutter data acquired with an ultra-high frequency (UHF) ultra-wideband (UWB) ground-based radar, the experimental results show that the specific foliage type and configuration has a significant impact on the distribution of foliage clutter. Furthermore, by means of Kullback–Leibler distance (KLD), log-logistic, and distributions with estimated parameters are demonstrated to be the best choice to model the clutter in the LOS forest environment, NLOS forest-penetration environment and NLOS bush-penetration environment, respectively. The proposed models are great advantages on understanding and prediction of the clutter in foliage environments.

Foliage Type and Deprivation Alters the Movement Behavior of Late Instar European Gypsy Moth Lymantria dispar (Lepidoptera: Erebidae)

The movement behavior of insects characterizes their ability to disperse, establish, compete, forage, seek mates, and ultimately reproduce. Understanding the movement of invasive insects is particularly important for developing management policies. We conducted laboratory experiments in Minnesota, USA to determine how host type and food deprivation affected the movement of late instars of the European gypsy moth Lymantria dispar (Lepidoptera: Erebidae), an invasive forest insect in North America. Gypsy moth larvae can feed on over 300 species of trees and shrubs. During outbreaks food availability to conspecifics can become severely restricted as developing instars consume increasing amounts of foliage. Larvae were raised on one of five foods: Quercus macrocarpa, Larix laricina, Acer platanoides, Acer saccharinum, or artificial diet. Subsets of fifth and sixth instar larvae were also deprived of food for zero, 24, or 48 h. After the food deprivation period, late instar larvae were placed on a servosphere and their movement paths were recorded. Larvae raised on Q. macrocarpa, a preferred host, were unlikely to move unless starved. They moved farther the longer they were starved. In contrast, when larvae were raised on less preferred hosts, they were more likely to move without prior starvation. These results suggest that feeding on optimal hosts provides gypsy moth larvae with the energy and nutritional requirements to move more quickly to more food when there is none immediately available.

Assessment of a non-destructive method to estimate the leaf area of Armoracia rusticana

The aim of the study was to analyze horseradish growth for developing a mathematical model to estimate the leaf area based on linear measurements of the leaf surface. Leaf area (LA), number, and morphometric characteristics of the leaves including lamina length (L) and width (W) were evaluated on two horseradish accessions (Cor and Mon) throughout a 2 year growing cycle. In both accessions, increased values of LA and leaf number were found by comparing the second with the first-growing season. Leaf development occurs along with variations in size and not in shape during the plant growth. The leaves are elliptical in shape but tend to be wider and bigger in Cor accession and tapered and similar to narrow ellipses in Mon showing different length/width relationship. Consequently, several regression models relating to the LA and L, W, L2, and W2 individually or in combination were fitted for each accession based on a set of 1000 leaves. The horseradish LA can be predicted based on either length or width alone. However, the regression linear model LA = aLW + b (LA = 0.71LW − 0.27 and LA = 0.76LW − 3.22 for Cor and Mon, respectively) provided the best LA estimation (R2 > 0.95). The validation of this latter model showed high correlation between LA measured and LA predicted in both accessions (R2 = 0.98). Considering the type of foliage of horseradish, the proposed model can be used to estimate the leaf area throughout the entire crop cycle.