Inter-annual variability of NDVI in response to long-term warming and fertilization in wet sedge and tussock tundra

This study explores the relationship between the normalized difference vegetation index (NDVI) and aboveground plant biomass for tussock tundra vegetation and compares it to a previously established NDVI–biomass relationship for wet sedge tundra vegetation. In addition, we explore inter-annual variation in NDVI in both these contrasting vegetation communities. All measurements were taken across long-term experimental treatments in wet sedge and tussock tundra communities at the Toolik Lake Long Term Ecological Research (LTER) site, in northern Alaska. Over 15 years (for wet sedge tundra) and 14 years (for tussock tundra), N and P were applied in factorial experiments (N, P and N+P), air temperature was increased using greenhouses with and without N+P fertilizer, and light intensity was reduced by 50% using shade cloth. during the peak growing seasons of 2001, 2002, and 2003, NDVI measurements were made in both the wet sedge and tussock tundra experimental treatment plots, creating a 3-year time series of inter-annual variation in NDVI. We found that: (1) across all tussock experimental tundra treatments, NDVI is correlated with aboveground plant biomass (r ²=0.59); (2) NDVI–biomass relationships for tussock and wet sedge tundra communities are community specific, and; (3) NDVI values for tussock tundra communities are typically, but not always, greater than for wet sedge tundra communities across all experimental treatments. We suggest that differences between the response of wet sedge and tussock tundra communities in the same experimental treatments result from the contrasting degree of heterogeneity in species and functional types that characterize each of these Arctic tundra vegetation communities.     

Long-term dynamics of water and carbon in semi-arid ecosystems: a gradient analysis in the Patagonian steppe

We used a soil water simulation model and remotely sensed data to study the long-term dynamics of transpiration, evaporation, drainage and net primary production across a precipitation gradient in Northwestern Patagonia (Argentina). The proportion of precipitation transpired, the precipitation use efficiency and the transpiration use efficiency were constant across the gradient that covered a range of 150 to 600 mm. The proportion of water evaporated was higher than the proportion drained at the driest extreme of the gradient. The opposite relationship was observed at the wet extreme.Two important characteristics of arid-semiarid systems dominated by winter precipitation emerged from our analyses: the importance of drainage losses and the asynchrony between evaporation and transpiration fluxes. These characteristics of the water dynamics influence the relative abundance of plant functional types and are crucial to generate heterogeneity at the landscape level. The coefficient of variation (CV) of transpiration, evaporation and ANPP was, in general, lower than the CV of annual precipitation. This pattern suggests a buffering capacity of the ecosystem. The ecosystem would be able to damp at the functional level inter-annual changes in the availability of resources.     

Divergent patterns of impact of environmental conditions on life history traits in two populations of a long-distance migratory bird

Some areas have experienced recent dramatic warming due to climate change, while others have shown no change at all, or even recent cooling. We predicted that patterns of selection on life history would differ between southern and northern European populations of a long-distance migratory bird, the barn swallow Hirundo rustica, because global patterns of weather as reflected by large-scale weather phenomena such as the North Atlantic Oscillation (NAO) and the El Niño-Southern Oscillation (ENSO) have different effects on environmental conditions in different parts of the world frequented during the annual cycle. We investigated relationships between mean arrival date, dispersal rate and yearling survival rate among years, using two long-term population studies in Spain and Denmark. We found evidence of a difference in the effects of normalized difference vegetation index in North and West Africa on mean arrival date of male barn swallows, with the effect differing significantly between populations. Second, there was a significant interaction between ENSO and population on dispersal rate, showing that conditions in Africa during winter differentially affected dispersal in the two populations. Finally, the NAO index in winter had an effect on yearling survival that differed between populations. These findings highlight the divergent patterns of response to climate change among populations, and they suggest that climate change can differentially affect important life history traits with potential implications for maintenance of viable populations and gene flow among populations.     

Diet selection of sheep shifted from quality to quantity characteristics of forages as sward availability decreased

Understanding the dynamic inter-relationship between grazing animals and the pasture sward is critical for sustainable grazing management. A field study was conducted to investigate the relationships between the quantity and quality characteristics of forages and diet selection of 30-kg Mongolian ewes in different seasons in Bromus inermis improved meadow steppe. Using a residual herbage mass method (1 000 kg/ha in spring, 800 kg/ha in summer and 600 kg/ha in autumn) to adjust stocking rate, three seasonal rest grazing strategies (spring rest, summer rest and autumn rest) combined with continuous grazing were studied. In each season, diet selection of sheep, quantified by diet composition and selectivity index, was estimated using a plant wax marker technique. Quantity (dry weight proportion, coverage, frequency, density and height) and quality (CP, NDF, ADF and DM digestibility) characteristics of forages consumed by sheep were determined simultaneously. Our results showed that in spring with the highest sward availability (herbage mass), diet selection of sheep could be predicted by the positive linear relationship between quality characteristics of forages and their selectivity index. In summer, the diet selection could be predicted by both positive linear relationship between quality characteristics and selectivity index, and the relationship between quantity characteristics and diet composition. While in autumn with the lowest sward availability, it could be predicted by the positive linear relationship between quantity characteristics and diet composition. During the whole grazing season, the diet composition of B. inermis (40.4%) and Leymus chinensis (35.1%) were larger than that of Potentilla bifurca (9.5%) and Carex (15.1%) and the selectivity index of P. bifurca was the highest (0.62), followed by Carex (0.17) and B. inermis (0.05), and L. chinensis (?0.29) was the lowest. The two parameters of diet selection above were positively related to their quantity and quality characteristics, respectively. These results suggested that the influence of quality characteristics on diet selection of sheep decreased gradually as a result of the decline in sward availability, while the influence of quantity characteristics increased. This study provides a comprehensive understanding of diet selection of sheep examining the trade-offs between quantity and quality characteristics of forages. The knowledge of diet selection of sheep and the corresponding prediction regressions acquired in this study could give the basis for designing appropriate grazing management strategies.     

Using the movement patterns of reintroduced animals to improve reintroduction success

Despite their importance to conservation, reintroductions are still a risky endeavor and tend to fail, highlighting the need for more efficient post-release monitoring techniques. Reintroduced animals are released into unfamiliar novel environ ments and must explore their surroundings to gain knowledge in order to survive. According to theory, knowledge gain should be followed by subsequent changes to the animal＇s movement behavior, making movement behavior an excellent indicator of reintroduction progress. We aim to conceptually describe a logical process that will enable the inclusion of behavior （in particular, movement behavior） in management decision-making post-reintroductions, and to do so, we provide four basic components that a manager should look for in the behaviors of released animals. The suggested components are release-site fidelity, recurring locations, proximity to other individuals, and individual variation in movement behavior. These components are by no means the only possible ones available to a manager, but they provide an efficient tool to understanding animals＇ decision-making based on ecological theory; namely, the exploration-exploitation trade-off that released animals go through, and which underlies their behavior. We demonstrate our conceptual approach using data from two ungulate species reintroduced in Israel： the Persian fallow deer Dama mesopotamica and the Arabian oryx Oryx leucoryx [Current Zoology 60 （4）： 515-526, 2014] .     

Access to mates in a territorial ungulate is determined by the size of a male's territory, but not by its habitat quality

1. Territoriality is commonly associated with resource defence polygyny, where males are expected to gain access to females by anticipating how resources will influence female distribution and competing for resource-rich sites to establish their zone of dominance. 2. We tested this hypothesis in European roe deer (Capreolus capreolus) by simultaneously assessing the influence of resources on female distribution and the influence of female distribution on male distribution and breeding success using paternity analyses. 3. Females did not fully distribute themselves among male territories in relation to resources. As a result, relative female abundance in a male's territory depended on territory size, but not on its habitat quality. In turn, relative female abundance in a male's territory determined, at least partially, his breeding success. 4. Interestingly, male territory size, and hence access to females, was partly determined by male body mass (all males) and by residual antler size (subadults only). The latter result suggests that large antlers may be important to young males for establishing their first territory, which is then usually retained for all subsequent reproductive seasons. 5. To conclude, although territoriality of male roe deer has certainly evolved as a tactic for ensuring access to mates, our results suggest that it does not really conform to a conventional resource defence polygyny strategy, as males seem to gain no obvious benefit from defending a territory in an area of high habitat quality in terms of enhanced access to mates. 6. This may explain the stability of male territories between years, suggesting that male territoriality conforms to an 'always stay' and 'low risk-low gain' mating strategy in roe deer.     

Carcass and meat quality of finished and non-finished Limousin heifers from alpine livestock systems differing in altitudinal origin of the forage

Effects of the alpine origin of the forage and of finishing on carcass and beef quality were quantified by modelling different alpine livestock system alternatives. Thirty-five Limousin heifers, initially weighing 383 ± 45 kg, were fed fresh grass at 400 or 2000 m above sea level, or a 1:1 mixture of alpine grass and lowland grass hay at 2000 m. After 9 weeks, the six heaviest and oldest animals per group were slaughtered. The remaining animals were finished for 8 weeks on a silage-concentrate diet in the lowlands to similar age and body weight as the first slaughtered group. Carcass and meat quality (M. longissimus thoracis) were assessed in various respects. The average daily gains achieved were of about 600 g/d and similar between forage-type groups. Dressing percentage was 53.5% in the alpine and 57.2% in the lowland group. Carcass conformation and fat cover scores did not differ between forage-type groups. The meat from the alpine groups had greater ultimate pH and smaller redness, yellowness and protein contents. Still, these differences were of minor practical relevance. There was no forage-type effect on water-holding capacity and shear force of the meat. The alpine systems enhanced the proportion of α-linolenic acid in intramuscular fat and decreased the levels of some volatile compounds in perirenal fat. Finishing resulted in compensatory growth, especially in the animals previously fed lowland grass. There was a trend for the finished compared with the non-finished groups towards greater carcass fat cover and intramuscular fat content. Additionally, ultimate pH was smaller and cooking loss was greater with than without finishing. Meat colour differences were also observed. Shear force was not affected by finishing. The finished animals had a smaller α-linolenic acid proportion in the intramuscular fat. In conclusion, the forage type had small effects on carcass and meat quality. Finishing did not substantially improve carcass and meat quality. The (alpine) grass-specific differences in fatty acid profile found in the unfinished cattle were not present in the finished animals.     

Studies on the patterns of nitrogen uptake and translocation to the grain of winter barley intended for malting

In five experiments carried out between 1987 and 1989, crops of winter barley were grown under a range of agronomic treatments to study the way the treatments influenced the patterns of nitrogen uptake, dry matter production, translocation of assimilates and malting quality. Rate and timing of nitrogen fertiliser had large effects. Increased and late applications invariably increased nitrogen concentration in the grain by affecting the partitioning of nitrogen between the vegetative and reproductive parts of the plant. Foliar fungal diseases also affected nitrogen partitioning, apparently by interfering with the transport of stored nitrogen to the developing grain. Seasonal influences, especially rainfall during the grain filling period, were found to have profound effects on the pattern of change in ear and grain nitrogen concentration, and hence malting quality. The ability to predict final grain nitrogen concentration from measurements made earlier in the season is not therefore likely to be feasible.     

Towards the implementation of quality by design to the production of therapeutic monoclonal antibodies with desired glycosylation patterns

Quality by design (QbD) is a scheme for the development, manufacture, and approval of pharmaceutical products. The end goal of QbD is to ensure product quality by building it into the manufacturing process. The main regulatory bodies are encouraging its implementation to the manufacture of all new pharmaceuticals including biological products. Monoclonal antibodies (mAbs) are currently the leading products of the biopharmaceutical industry. It has been widely reported that glycosylation directly influences the therapeutic mechanisms by which mAbs function in vivo. In addition, glycosylation has been identified as one of the main sources of monoclonal antibody heterogeneity, and thus, a critical parameter to follow during mAb manufacture. This article reviews the research on glycosylation of mAbs over the past 2 decades under the QbD scope. The categories presented under this scope are: (a) definition of the desired clinical effects of mAbs, (b) definition of the glycosylation‐associated critical quality attributes (glycCQAs) of mAbs, (c) assessment of process parameters that pose a risk for mAb glycCQAs, and (d) methods for accurately quantifying glycCQAs of mAbs. The information available in all four areas leads us to conclude that implementation of QbD to the manufacture of mAbs with specific glycosylation patterns will be a reality in the near future. We also foresee that the implementation of QbD will lead to the development of more robust and efficient manufacturing processes and to a new generation of mAbs with increased clinical efficacy. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010     

Fermentanomics: Relating quality attributes of a monoclonal antibody to cell culture process variables and raw materials using multivariate data analysis

Fermentanomics is an emerging field of research and involves understanding the underlying controlled process variables and their effect on process yield and product quality. Although major advancements have occurred in process analytics over the past two decades, accurate real‐time measurement of significant quality attributes for a biotech product during production culture is still not feasible. Researchers have used an amalgam of process models and analytical measurements for monitoring and process control during production. This article focuses on using multivariate data analysis as a tool for monitoring the internal bioreactor dynamics, the metabolic state of the cell, and interactions among them during culture. Quality attributes of the monoclonal antibody product that were monitored include glycosylation profile of the final product along with process attributes, such as viable cell density and level of antibody expression. These were related to process variables, raw materials components of the chemically defined hybridoma media, concentration of metabolites formed during the course of the culture, aeration‐related parameters, and supplemented raw materials such as glucose, methionine, threonine, tryptophan, and tyrosine. This article demonstrates the utility of multivariate data analysis for correlating the product quality attributes (especially glycosylation) to process variables and raw materials (especially amino acid supplements in cell culture media). The proposed approach can be applied for process optimization to increase product expression, improve consistency of product quality, and target the desired quality attribute profile. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1586–1599, 2015     

Identification of soil quality indicators for assessing the effect of different tillage practices through a soil quality index in a semi-arid environment

Tillage is known to potentially affect soil quality in various ways. In this study, a soil quality index (SQI) was developed by quantifying several soil attributes either sensitive or insensitive to physical disturbance, using factor analysis as a dimension reduction technique, in order to discriminate different tillage systems. Soil properties including physical (MWD), chemical (pH, organic C, total N, available P and POM contents) and microbial (MBC, MBN, PCM, PNM and three enzymes) parameters were measured to establish a minimum data set (MDS) for the assessment of overall SQI. The soil attributes were determined on samples (0–20 cm depth) collected under moldboard (MP) and disk (DP) plows as conventional tillage (CT), and rotary (RP) and chisel (CP) plows as reduced tillage (RT) systems with a similar plant C input rate and cover crop over a period of six years (2005–2011) in a semi-arid calcareous soil (Calcixerepts) from Central Iran. Results indicated a clear difference in soil quality among the tillage systems with a significant increase of SQI under RT over time, particularly under CP practices. Although RT improved most soil microbial attributes, not all attributes contributed to SQI because of their close interrelationship. The final SQI consisted only of geometric mean of microbial activity (GMA, the square root of the product of PCM and PNM) and geometric mean of enzyme activity (GME, the cube root of the product of enzyme activities). Soil GME and GMA were found to be as key indicators contributing 55% and 36% to SQI, respectively. Therefore, the GME and GMA were the most important indicators effectively discriminating tillage systems, and could be used to monitor the enhancement of soil quality under RT in this semiarid environment. The influence of tillage year on SQI was greater than that of tillage practices. In conclusion, RT systems were characterized by a higher value of SQI, suggesting a good recovery of soil capacity and functions after abandoning CT in the studied area. Smallholder farmers should therefore be aware of the potential for high soil quality in future as a result of continuing RT systems, especially with surface tillage using CP practices.     

The normalised difference vegetation index obtained from agrometeorological standard radiation sensors: a comparison with ground-based multiband spectroradiometer measurements during the phenological development of an oat canopy

Following the methodology of K. F. Huemmrich and colleagues [Huemmrich et al. (1999) J Geophys Res 104:27,935–27,944], agrometeorological standard radiation sensors, i.e. two photosynthetically active radiation sensors and an albedometer, were used to measure the broadband visible and optical–infrared reflectance of an oat plot during its whole growth period. From these reflectance data – recorded as 15-min averages and pooled to daily means – the seasonal cycle of the normalised difference vegetation index (NDVI) was calculated. In addition, a ground-based multi-channel spectroradiometer was used as a reference to estimate narrowband “green” and “red” NDVIs at weekly intervals near noon. The narrowband “green” NDVI was shown to be consistent with the simultaneous broadband 15-min NDVI. This shows that the configuration of agrometeorological radiation sensors is suitable to adequately track phenological crop dynamics.

Contrasting patterns of photosynthetic acclimation to the light environment are dependent on the differential expression of the responses to altered irradiance and spectral quality

Chl, chlorophyll
Chl a/b, ratio of chlorophyll a to chlorophyll b
Cyt f, cytochrome f
FR, far-red light
LFR, low irradiance, far-red enriched growth light
LHCII, light harvesting complex associated with PSII
LW, low irradiance, white growth light
MW, moderate irradiance, white growth light
PAR, photosynthetically active radiation
P_max, light and CO₂ saturated photosynthetic rate
PSI, photosystem I
PSII, photosystem II

Four plant species (Chamerion angustifolium, Digitalis purpurea, Brachypodium sylvaticum and Plantago lanceolata) which have previously been shown to demonstrate contrasting photosynthetic acclimatory responses to the light environment ( 33 , Plant, Cell and Environment 20, pp. 438–448) were analysed at a biochemical level. Plants were grown under low irradiance with a shade-type spectrum (LFR: 50μmol quanta m^–2 s^–1), moderately high white light (MW: 300μmol quanta m^–2 s^–1) and low irradiance white light (LW: 50μmol quanta m^–2 s^–1). The effects of light quality upon chlorophyll content and photosynthetic capacity were found to be species-dependent. A far-red dependent reduction in chlorophyll was found in three species, and an irradiance-dependent reduction was found in B. sylvaticum, which showed the greatest alteration in the xanthophyll cycle pool size of all species tested under these conditions. Chlorophyll a/b ratios were sensitive to both light quality and quantity in C. angustifolium and D. purpurea, being highest in MW, lowest in LFR, and intermediate in LW, whilst the other species showed no response. Ratios of photosystem II to photosystem I (PSII and PSI) demonstrated a strong irradiance-associated increase in all species except B. sylvaticum, whereas an increase in PSII/PSI in LFR compared to LW conditions was present in all species. A change in chlorophyll a/b was not always associated with a change in PSII/PSI, suggesting that the level of LHCII associated with each PSII varied in some species. Cytochrome f content showed an irradiance-dependent effect only, indicating a relationship with the capacity of electron transport. It is concluded that differing strategies of acclimation to the light environment demonstrated by these species results from differing strengths of expression of a series of independently regulated changes in the levels of photosynthetic components.     

An application of different bioindicators for assessing water quality: a case study in the rivers Alfeios and Pineios (Peloponnisos, Greece)

A number of bioindicators and biotic indices and scores based on benthic macroinvertebrates, diatoms, fishes, aquatic and riparian vegetation in relation to physicochemical parameters have been applied in assessing the water quality of the rivers Alfeios and Pineios (Peloponnisos, Greece). According to the findings, the water quality in both rivers varied from very poor to very good. Among the bioindicators used, the benthic macroinvertebrates seem to be the most reliable. The BBI and IBE were the most applicable indexes while the applicability of the IBMWP and IASPT in the Greek region can be enforced with the inclusion of the Diptreran family Rhagionidae and the Coleopteran family Elminthidae.     

Statistical and multivariate statistical techniques to trace the sources and affecting factors of groundwater pollution in a rapidly growing city on the Chinese Loess Plateau

Abstract

Groundwater quality is defined by various water quality parameters. The aims of the research are to understand the relationships among different groundwater quality parameters and to trace the sources and affecting factors of groundwater pollution via statistical and multivariate statistical techniques. The 36 shallow groundwater samples collected from shallow pumping wells in Yan’an City were analyzed for various water quality parameters. Correlation analysis, principal component analysis (PCA), hierarchical cluster analysis (HCA), and multivariable linear regressions (MLR) were jointly used in this study to explore the sources and affecting factors of groundwater pollution. The study reveals that the mineral dissolution/precipitation and anthropogenic input are the main sources of the physicochemical indices and trace elements in the groundwater. Groundwater chemistry is predominantly regulated by natural processes such as dissolution of carbonates, silicates, and evaporates and soil leaching, followed by human activities as the second factor. Climatic factors and land use types are also important in affecting groundwater chemistry. Cl^– is the greatest contributor to the overall groundwater quality revealed by the two regression models. The first model which has eight dependent variables is high in model reliability and stability, and is recommended for the overall groundwater quality prediction. The study is helpful for understanding groundwater quality variation in urban areas.     

On the way to a quality control of the essential oil of fennel by means of Raman spectroscopy

Essential oils are one of the most valuable natural products. The price of special essential oils that can be purchased on the market strongly depends on the quality of the product. The quality, which depends on the quantitative and qualitative variation of different monoterpenes, varies with respect of the origin and the harvesting period. This contribution reports on a Raman spectroscopic study on the essential oil occurring in fennel. Cross-sections of fennel seed were investigated by use of Raman spectroscopy and Raman mapping to localize the essential oil and to analyze its chemical composition directly in the plant. Furthermore the practicability of a home-built mobile transportable Raman spectrometer to perform on-site measurements was successfully tested.     

Application of multivariate statistics and toxicity indices to evaluate the water quality suitability for fish of three rivers in the Kruger National Park,South Africa

The water quality of the Olifants, Letaba and Luvuvhu rivers within the Kruger National Park was assessed for their suitability to sustain fish populations. Since water quality assessments result in huge datasets, principal component analysis and an aquatic toxicity index (ATI) were employed to reduce these to more manageable indices. Water quality changed over time, with metal concentrations decreasing, and high flows resulted in increased concentrations of suspended metals. The ATI indicated that metals had no major effect on lowering index values in any of the rivers, and that these values were affected by turbidity in both the Olifants and Letaba rivers, whilst nutrients such as ammonium and orthophosphates negatively affected index scores in the Luvuvhu River. Water quality has improved from the 1990s to 2011.     

Enhancing the quality of life in elderly women through a programme to improve the condition of salivary hypofunction

doi: 10.1111/j.1741‐2358.2011.00594.x Enhancing the quality of life in elderly women through a programme to improve the condition of salivary hypofunction Objective: The purposes of this study were to examine the effects of oral exercise intended to improve the function of the oral cavity in the elderly and their quality of life to pave the way for the development of oral‐health promotion programmes geared towards the elderly. Methods: The subjects were 78 female Koreans who resided in Seoul and were aged 65 years and older. During a 3‐month period, an oral function promotion programme was conducted twice a week, between 10.00 am and 12.00 pm , applying oral exercise suggested by a Japanese public health centre. A survey was conducted by interviewing the selected women to determine the state of their subjective dry mouth, quality of life related to oral health and jaw functional limitation. Their opening, unstimulated whole saliva and pronunciation speed were measured before and after the oral function exercise programme. Results: The subjects showed a significant improvement in subjective dry mouth symptoms, relevant behaviour, the level of discomfort caused by dry mouth and subjective jaw functional limitation during mastication and swallowing and emotional expression after receiving the oral exercise. After the oral exercise, there was a significant increase in mouth opening, unstimulated whole saliva and speaking speed (‘patakala’ pronunciation) after oral exercise. There was also significant progress in their quality of life related to oral health. Overall improvement in subjective dry mouth symptoms and relevant behaviour over time after oral exercise had a positive correlation with the level of improvement in discomfort triggered by dry mouth and mastication. The level of improvement in OHIP‐14 had a positive correlation with the level of overall improvement in dry mouth symptoms and behaviour, the level of improvement in discomfort by dry mouth and that in mastication and swallowing. Conclusion: This study showed the effects of the oral function promotion programme and correlation of oral condition and oral health‐related quality of life. It is suggested that this oral function promotion programme has positive effects on both objective and subjective oral conditions. It is strongly recommended that this programme, along with other oral health promotion programmes, be implemented to improve oral function and oral health‐related quality of life for the elderly.     

Applicability of a generic index for diatom assemblages to monitor pollution in the tropical River Tsanwun, Taiwan

A generic index (GI) utilizing epilithic diatom assemblages as abioindicator of water pollution in subtropical rivers in Taiwan was applied toastudy of a tropical river. Seven sites on the River Tsanwun were sampledseasonally from August 1995 to June 1998. Although there is a marked differencein water chemistry between tropical and subtropical rivers in Taiwan, thedominant genera of their diatom assemblages are quite similar. The six generaused for the calculation of GI in the subtropical rivers were also the maincomponents of diatom assemblages in the River Tsanwun. The calculated valuesdisplayed a close correlation with water quality, evaluated on the basis ofphysical and chemical variables. A strong correlation was found between this GIand other diatom-based indices of water quality.     

How two different host species influence the performance of a gregarious parasitoid: host size is not equal to host quality

1. Hyssopus pallidus Askew (Hymenoptera, Eulophidae) is a gregarious ectoparasitoid of the two tortricid moths species Cydia molesta Busck and C. pomonella L. (Lepidoptera, Tortricidae). It paralyses and parasitizes different larval instars of both species inside the apple fruit, which leads to the death of the caterpillar. 2. We assessed the influence of host species characteristics and host food on the performance of the parasitoid female in terms of clutch size decisions and fitness of the F(1) generation. 3. A comparison of clutch size revealed that female parasitoids deposited similar numbers of eggs on the comparatively smaller C. molesta hosts as on the larger C. pomonella hosts. The number of parasitoid offspring produced per weight unit of host larva was significantly higher in C. molesta than in C. pomonella, which is contrary to the general prediction that smaller hosts yield less parasitoid offspring. However, the sex ratio was not influenced by host species that differed considerably in size. 4. Despite the fact that less host resources were available per parasitoid larva feeding on C. molesta caterpillars, the mean weight of emerging female wasps was higher in the parasitoids reared on C. molesta. Furthermore, longevity of these female wasps was neither influenced by host species nor by the food their host had consumed. In addition we did not find a positive relationship between adult female weight and longevity. 5. Parasitoid females proved to be able to assess accurately the nutritional quality of an encountered host and adjust clutch size accordingly. These findings indicate that host size is not equal to host quality. Thus host size is not the only parameter to explain the nutritional quality of a given host and to predict fitness gain in the subsequent generation.