scholarly journals Generating and testing hypotheses about the fossil record of insect herbivory with a theoretical ecospace

2021 ◽  
Author(s):  
Sandra R Schachat ◽  
Jonathan L Payne ◽  
C Kevin Boyce ◽  
Conrad C Labandeira

A typical fossil flora examined for insect herbivory contains a few hundred leaves and a dozen or two insect damage types. Paleontologists employ a wide variety of metrics to assess differences in herbivory among assemblages: damage type diversity, intensity (the proportion of leaves, or of leaf surface area, with insect damage), the evenness of diversity, and comparisons of the evenness and diversity of the flora to the evenness and diversity of damage types. Although the number of metrics calculated is quite large, given the amount of data that is usually available, the study of insect herbivory in the fossil record still lacks a quantitative framework that can be used to distinguish among different causes of increased insect herbivory and to generate null hypotheses of the magnitude of changes in insect herbivory over time. Moreover, estimates of damage type diversity, the most common metric, are generated with inconsistent sampling standardization routines. Here we demonstrate that coverage-based rarefaction yields valid and reliable estimates of damage type diversity that are robust to differences among floral assemblages in the number of leaves examined, average leaf surface area, and the inclusion of plant organs other than leaves such as seeds and axes. We outline the potential of a theoretical ecospace that combines various metrics to distinguish between potential causes of increased herbivory. We close with a discussion of the most appropriate uses of a theoretical ecospace for insect herbivory, with the overlapping damage type diversities of Paleozoic gymnosperms and Cenozoic angiosperms as a brief case study.

2018 ◽  
Vol 5 (3) ◽  
pp. 171991 ◽  
Author(s):  
Sandra R. Schachat ◽  
Conrad C. Labandeira ◽  
S. Augusta Maccracken

Sampling standardization has not been fully addressed for the study of insect herbivory in the fossil record. The effects of sampling within a single locality were explored almost a decade ago, but the importance of sampling standardization for comparisons of herbivory across space and time has not yet been evaluated. Here, we present a case study from the Permian in which we evaluate the impact of sampling standardization on comparisons of insect herbivory from two localities that are similar in age and floral composition. Comparisons of insect damage type (DT) diversity change dramatically when the number of leaves examined is standardized by surface area. This finding suggests that surface area should always be taken into account for comparisons of DT diversity. In addition, the three most common metrics of herbivory—DT diversity, proportion of leaves herbivorized and proportion of leaf surface area herbivorized—are inherently decoupled from each other. The decoupling of the diversity and intensity of insect herbivory necessitates a reinterpretation of published data because they had been conflated in previous studies. Future studies should examine the divergent ecological factors that underlie these metrics. We conclude with suggestions to guide the sampling and analysis of herbivorized leaves in the fossil record.


Author(s):  
E.G. Kozlova ◽  
◽  
A.I. Anisimov

The results of evaluating 12 morphometric indicators of 18 varieties of roses grown in a greenhouse have been carried out. The most variable was the area of leaf lobules, and the least variable are the number of leaves per 10 cm of the stem and length of stem. Some correlation (negative) was noted between the population density of the variety with spider mites and individual indicators of the leaf surface area of rose varieties.


2021 ◽  
Author(s):  
Sandra R Schachat ◽  
Jonathan L. Payne ◽  
C. Kevin Boyce

Studies of insect herbivory on fossilized leaves tend to focus on a few, relatively simple metrics that are agnostic to the distribution of insect damage types among host plants. More complex metrics that link particular damage types to particular host plants have the potential to address additional ecological questions, but such metrics can be biased by sampling incompleteness due to the difficulty of distinguishing the true absence of a particular interaction from the failure to detect it---a challenge that has been raised in the ecological literature. We evaluate a range of methods for characterizing the relationships between damage types and host plants by performing resampling and subsampling exercises on a variety of datasets. We found that the components of beta diversity provide a more valid, reliable, and interpretable method for comparing component communities than do bipartite network metrics. We found the rarefaction of interactions to be a valid, reliable, and interpretable method for comparing compound communities. Both of these methods avoid the potential pitfalls of multiple comparisons. Lastly, we found that the host specificity of individual damage types is challenging to assess. Whereas some previously used methods are sufficiently biased by sampling incompleteness to be inappropriate for fossil herbivory data, alternatives exist that are perfectly suitable for fossil datasets with sufficient sample coverage.


Author(s):  
V. V. Liubych ◽  
◽  
I. O. Polianetska

Under different weather conditions, not all plant varieties successfully adapt to agro-ecosystems. Given that, wheat is the most important food crop It is important to study the possibility of its adaptation to climatic conditions. The choice of plant variety is the first, most important and most difficult stage for wheat producers. Aim. To study the parameters of photosynthetic activity of durum winter wheat plantings depending on the variety. Methods. Laboratory, mathematical and statistical, physical. Results. The article presents the formation of photosynthetic parameters (length, leaf width, number of leaves on one stem, area of one leaf, area of one stem, leaf surface area, apical leaf parameters) of durum winter wheat plantings depending on the variety. The length and width of durum winter wheat leaves varied significantly depending on the variety and stage of plant growth. On the average for three years of researches the number of leaves on one stem in the tillering stage was 4.1–4.5 pieces depending on the variety. In the booting stage, this indicator was the lowest – 3.1–3.3 pieces, and in the earing stage of all varieties was at the level of 4.0 pieces. The number of leaves on the stem almost did not change during the milk stage of grain – 3.9–4.0 pieces. The parameters of the apical leaf also varied significantly with weather conditions. The area of apical leaves in 2013 in the standard and studied varieties was 5.9 and 5.5–7.3 thousand m2/ha, respectively. In the following 2014, the leaf area indicator was higher than in 2013 by 51–60%. The increase in leaf area in durum winter wheat in 2014 is due to the formation of a higher number of stems compared to 2013. Conclusions. Photosynthetic parameters of durum winter wheat plantings have features. The number of leaves on one stem changed the least depending on the year of study, as the variation coefficient was insignificant (V = 1.7–3.6 %). The length and width of durum wheat leaf varied in a wide range - V = 3.7–53.0 %. In the more favourable 2014, the leaf surface area was 40.1–71.0 thousand m2/ha in the earing stage, and in the less favourable – 15.9–29.0 thousand m2/ha in the earing and milk stages of grain depending on the variety. The area of apical leaves varies from 5.7–7.3 to 8.8–14.2 thousand m2/ha depending on the weather conditions of the season


2017 ◽  
Vol 23 (2) ◽  
Author(s):  
NAVALSINGH J. TODAWAT

Sooty mould diseases of Tress from Aurangabad district were surveyed. During the survey of tress, 5 species were found infected by fungal pathogens causing sooty mould diseases. Disease is easily identifiable by the presence of a black, velvety growth covering the leaf surface area. The fungus produces mycelium which is superficial and dark grows on the flowers, leaf, stem and sometime on fruits also. The severity of disease depends on the honeydew secretions by insects. The diseases were found to be caused by 5 species of fungi viz. Capnodium anonae, C. ramosum, Capnodium sp., Meliola bangalorensis and Meliola ranganthii.


Author(s):  
M. G. Markova ◽  
E. N. Somova

Work on going through the adaptation stage of rooted micro-stalks comes down to searching for new growth regulators and studying the influence of external conditions, which include, among other things, light effects. The data of 2018-2019 on the effect of growth regulators Siliplant, EcoFus and experimental LED phytoradiators on the adaptation of rooted micro-stalks of garden strawberries (Fragaria x ananassa duch) in vivo are presented. The object of research is rooted micro-stalks of garden strawberries of the Korona variety. It was revealed that, at the adaptation stage of rooted micro-stalks of strawberries, the most effective was the treatment of plants by spraying with Siliplant at a concentration of 1.0 ml/l and the combined treatment with Siliplant and EcoFus at concentrations of 0.5 ml/l: regardless of lighting, the survival rate averaged 99.4 - 99.7%, the leaf surface area increased significantly from 291.85 mm2 to 334.4 mm2. The number of normally developed leaves of strawberry microplants increased significantly after treatment with all preparations from 3.5 to 6.0, 5.8 and 6.5 pcs/plant, and a significant increase in the height of strawberry rosettes was facilitated by treatment with Siliplant and Siliplant together with EcoFus. Regardless of growth regulators, the most effective was the experimental LED phyto-irradiator with a changing spectrum, which contributed to an increase in leaf surface area, height of rosettes and the number of normally developed leaves in strawberry microplants. When illuminated with a flashing phytoradiator, these indicators are lower than in the control version, but not significantly. By the end of the rooting stage, all microplants of garden strawberries corresponded to GOST R 54051-2010.


2021 ◽  
Author(s):  
Noa Ligot ◽  
Benoît Pereira ◽  
Patrick Bogaert ◽  
Guillaume Lobet ◽  
Pierre Delmelle

<p>Volcanic ashfall negatively affects crops, causing major economic losses and jeopardising the livelihood of farmers in developing countries where agriculture is at volcanic risk. Ash on plant foliage reduces the amount of incident light, thereby limiting photosynthesis and plant yield. An excessive ash load may also result in mechanical plant damages, such as defoliation and breakage of the stem and twigs. Characterising crop vulnerability to ashfall is critical to conduct a comprehensive volcanic risk analysis. This is normally done by describing the relationship between the ash deposit thickness and the corresponding reduction in crop yield, i.e. a fragility function. However, ash depth measured on the ground surface is a crude proxy of ash retention on plant foliage as this metrics neglects other factors, such as ash particle size, leaf pubescence and condition of humidity at leaf surfaces, which are likely to influence the amount of ash that stays on leaves.</p><p>Here we report the results of greenhouse experiments in which we measured the percentage of leaf surface area covered by ash particles for one hairy leaf plant (tomato, Solanum lycopersicum L.) and one hairless leaf plant (chilli pepper, Capsicum annuum L.) exposed to simulated ashfalls. We tested six particle size ranges (≤ 90, 90-125, 125-250, 250-500, 500-1000, 1000-2000 µm) and two conditions of humidity at leaf surfaces, i.e. dry and wet. Each treatment consisted of 15 replicates. The tomato and chilli pepper plants exposed to ash were at the seven- and eight-leaf stage, respectively. An ash load of ~570 g m<sup>-2 </sup>was applied to each plant using a homemade ashfall simulator. We estimated the leaf surface area covered by ash from pictures taken before and immediately after the simulated ashfall. The ImageJ software was used for image processing and analysis.</p><p>Our results show that leaf coverage by ash increases with decreasing particle size. Exposure of tomato and chilli pepper to ash ≤ 90 μm always led to ~90% coverage of the leaf surface area. For coarser particles sizes (i.e. between 125 and 500 µm) and dry condition at leaf surfaces, a significantly higher percentage (on average 29 and 16%) of the leaf surface area was covered by ash in the case of tomato compared to chilli pepper, highlighting the influence of leaf pubescence on ash retention. In addition, for particle sizes between 90 and 500 µm, wetting of the leaf surfaces prior to ashfall enhanced the ash cover by 19 ± 5% and 34 ± 11% for tomato and chilli pepper, respectively.</p><p>These findings highlight that ash deposit thickness alone cannot describe the hazard intensity accurately. A thin deposit of fine ash (≤ 90 µm) will likely cover the entire leaf surface area, thereby eliciting a disproportionate effect on plant foliage compared to a thicker but coarser deposit. Similarly, for a same ash depth, leaf pubescence and humid conditions at the leaf surfaces will enhance ash retention, thereby increasing the likelihood of damage. Our study will contribute to improve the reliability of crop fragility functions used in volcanic risk assessment.</p>


2021 ◽  
Vol 29 ◽  
pp. 35-40
Author(s):  
O. I. Zhuk ◽  
O.O. Stasik

Aim. The goal of this work was to study the effect of drought in the critical phase of ontogenesis on the growth and productivity of breed winter wheat plants (Triticum aestivum L.). Methods. Wheat plants of cultivars Darunok Podillya and Podolyanka were grown under optimal nutrition and well-water conditions until the earing-flowering phase, after that the experimental plants were transferred to drought regime for 8 days, after that the optimal water supply was restored to the end of vegetation. During the experiment, the leaf surface area, the mass of internodes and ear were determined. Ripened plants were analyzed according to the structure of the yield. Results. It was established that the effect of drought in the critical phase of ontogenesis the earing-flowering caused to the decreasing in leaf surface area, mass of internodes, ear, mass and number of grains in the ear and plant, weight of 1000 grains. Conclusions. Water deficit in the soil in the critical phase of earing-flowering led to a decrease in the productive of breed winter wheat plants due to the inhibition of growth of ear, decreasing grain number and the mass of ear and grains. Keywords: Triticum aestivum L., internode, ear, productivity, drought.


2019 ◽  
pp. 117-121
Author(s):  
Alexander Dikan ◽  
Domnica Kashirina ◽  
Irina Ryff

Приводятся результаты трехлетних исследований по клону 337 сорта Каберне-Совиньон в Западном предгорно-приморском районе Крыма. Показано влияние различной нагрузки на куст (11, 17 и 22 глазка) и зеленых операций (чеканка побегов, нормирование урожая, удаление листьев в зоне гроздей с восточной стороны) на величину урожая и коэффициент полезного действия (КПД) фотосинтетически активной радиации (ФАР). Установлено, что максимальная величина КПД ФАР была 0,52% при нагрузке на куст в две лозы плодоношения без последующих зеленых операций. Изменение КПД ФАР на 93,4% зависит от изменения площади листовой поверхности куста. Между КПД ФАР и урожаем винограда с куста существует сильная линейная корреляционная связь и регрессионная зависимость. Изменение массы урожая винограда с куста на 99,9% зависит от изменения площади листовой поверхности куста и КПД ФАР. Увеличенная нагрузка до 17-22 глазков при обрезке будет способствовать наиболее рациональному использованию ресурсов продуктивности кустов клона 337 сорта Каберне-Совиньон в Западном предгорно-приморском районе Крыма.The paper summarizes results of a three-year study on clone 337 of ‘Cabernet Sauvignon’ cultivar in the western piedmont-coastal region of Crimea. The paper demonstrates the influence of various bush loads (11, 17 and 22 eyes) and green operations (shoot trimming, harvest regulation, leaf removal in the bunch area on the eastern side) on the yield size and efficiency coefficient of photosynthetically active radiation. It was found that the maximum efficiency of photosynthetically active radiation made 0.52% with the bush load of two fruiting canes without subsequent green operations. The 93.4% variance of the efficiency coefficient of photosynthetically active radiation is dependent on leaf surface area variations of the bush. There is a strong linear correlation and regressional relationship between the efficiency of photosynthetically active radiation and the yield of grapes per bush. The 99.9% increase of the yield per bush weight depends on the change in the leaf surface area of the bush and the efficiency coefficient of photosynthetically active radiation. Increasing the load up to 17-22 buds when pruning will contribute to the most rational use of bush productivity resources of clone 337 of ‘Cabernet Sauvignon’ in the western piedmont-coastal region of Crimea.


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