Allometric models for non-destructive leaf area estimation in coffee (Coffea arabica and Coffea canephora)

We aimed to evaluate the currently used allometric models, as well as to propose a reliable and accurate model using non-destructive measurements of leaf length (L) and/or width (W), for estimating the area of leaves of eight field-grown coffee cultivars. For model construction, a total of 1563 leaves were randomly selected from different levels of the tree canopies and encompassed the full spectrum of measurable leaf sizes (0.3–263 cm²) for each genotype. Power models better fit coffee leaf area (LA) than linear models. To validate the model, an independent data set of 388 leaves was used. We demonstrated that the currently used allometric models are biased, underestimating the area of a coffee leaf. We developed a single power model     based on two leaf dimensions [LA = 0.6626 (LW)^1.0116; standard errors: β₀ = 0.0064, β₁ = 0.0019; R² = 0.996] with high precision and accuracy, random dispersion pattern of residuals and also unbiased, irrespective of cultivar and leaf size and shape. Even when the L (but not width) alone was used as the single leaf dimension, the power model developed still predicted with good accuracy the LA but at the expense of some loss of precision, as particularly found for 8% of the leaves sampled with length-to-width ratios below 2.0 or above 3.0.     

Relationships between the lucerne flea, Sminthurus viridis (L.) (Collembola: Sminthuridae), and damage to lucerne

Abstract The effect of lucerne flea, Sminthurus viridis , on plant growth (stem length and leaf number) and damage (percentage of leaves damaged and the percentage reduction in leaf area in the top, mid and lower thirds of stems) was considered at 2-weekly intervals in three consecutive lucerne growth cycles, each with a different mode of attack. The data were analysed to progressively determine relationships leading to a proposal for plant-based thresholds for lucerne flea control. Lucerne flea affected each factor measured, with damage considered more appropriate for making control decisions than plant growth. Damage increased from the base of plants upwards and its effect on yield was carried over into subsequent growth cycles. Damage was significantly related to lucerne flea numbers ( P  < 0.001) in two growth cycles and was higher when large nymphs or adults were dominant in one of these cycles. Yield was closely and best related to the percentage of the total number of leaves damaged ( R ² = 81.3%). The percentage of leaves damaged was also related to loss of final yield estimated at 2 ( R ² = 81.3%), 4 ( R ² = 78.9%) and 6 ( R ² = 66.6%) weeks into the first growth cycle only. Direct damage in the other two cycles did not result in yield loss. The percentage of leaves damaged (± confidence intervals) equating to 5% increments in yield loss were estimated at 2, 4 and 6 weeks into the first growth cycle. These are proposed as damage or treatment thresholds for testing.     

Economic injury level and sequential sampling plan for Bemisia tabaci in outdoor tomato

Abstract:  This work aimed to determine the economic injury levels and to establish sequential sampling plans for nymphs and adults of the whitefly Bemisia tabaci Genn. (Sternorrhyncha: Aleyrodidae) in tomato fields. Densities of nymphs and adults, as well as crop yield were evaluated in 13 commercial tomato fields to determine the economic injury levels. The whitefly nymphs were sampled by direct counting in a leaf from the lower part of the canopy and the adults were sampled by beating an apical leaf against a white plastic tray. The sequential sampling plan was based on data collected in eight commercial tomato fields. The validation of the sequential sampling plan was carried out based on the curves of operational characteristics and average sample numbers. The decisions reached with the conventional and the sequential sampling plans in 21 commercial fields were compared for the intended validation of the sequential plan. The economic injury levels were four nymphs per leaf and one adult per tray. The decisions taken based on the sequential sampling plan were similar to those obtained through the conventional sampling plan. Most of the decisions taken with the sequential sampling plan were obtained through the minimum number of seven samples per field for nymphs and 11 samples per field for adults, with reductions of 84.44% and 54.17% in the number of samples required to reach a decision with the sequential sampling plan compared with the conventional sampling plan.     

Age, growth and reproduction of the black scorpionfish, Scorpaena porcus (Pisces, Scorpaenidae), on the Black Sea coast of Turkey

Age, growth and reproduction of the black scorpionfish, Scorpaena porcus were studied in specimens from the coast of the Sinop Peninsula (Black Sea) between March 2002 and April 2003 in order to characterize these population parameters in comparison to specimens from populations of nearby regions. A total of 1086 specimens was captured by beam trawl at the depths between 0 and 30 m. The total number of females (510) was significantly higher than that of males (373). Total length of males and females ranged between 5.7 and 23.6 cm, and 4.9 and 31.7 cm, respectively. The length–weight relationship showed a positive allometric growth. Females grew faster and reached a larger size at age than males ( L _∞ = 111.9 cm, K  = 0.035 year⁻¹, φ' = 2.64 for females, and L _∞ = 74.6 cm, K  = 0.054 year⁻¹, φ' = 2.49 for males). The age range estimated was up to 8 years for females and 5 years for males. Reproduction likely occurs between June and September. Sex ratio varied greatly with season, perhaps indicating different seasonal migratory patterns in adults of different sex. An inverse correlation between gonadosomatic index (GSI) and hepatosomatic index (HSI) was evident during the reproduction seasons. The mean size at first sexual maturity was 17.5 cm TL for females, and 16.7 cm TL for males.     

Population divergence in the amphicarpic species Amphicarpaea edgeworthii Benth. (Fabaceae): microsatellite markers and leaf morphology

Comparative analyses of the genetic differentiation in microsatellite markers ( F _ST) and leaf morphology characters ( Q _ST) of Amphicarpaea edgeworthii Benth. were conducted to gain insight into the roles of random processes and natural selection in the population divergence. Simple sequence repeat analyses on 498 individuals of 19 natural populations demonstrate that a significant genetic differentiation occurs among populations (mean F _ST = 0.578), and A. edgeworthii is a highly self-fertilized species (mean selfing rate s  = 0.989). The distribution pattern of genetic diversity in this species shows that central populations possess high genetic diversity (e.g. population WL with H _E = 0.673 and population JG with H _E = 0.663), whereas peripheral ones have a low H _E as in population JD (0.011). The morphological divergence of leaf shape was estimated by the elliptical Fourier analysis on the data from 11 natural and four common garden populations. Leaf morphology analyses indicate the morphological divergence does not show strong correlation with the genetic differentiation ( R  = 0.260, P  = 0.069). By comparing the 95% confidence interval of Q _ST with that of F _ST, Q _ST values for five out of 12 quantitative traits are significantly higher than the average F _ST value over eight microsatellite loci. The comparison of F _ST and Q _ST suggests that two kinds of traits can be driven by different evolutionary forces, and the population divergence in leaf morphology is shaped by local selections.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 505–516.     

Age and growth analysis of the central mudminnow, Umbra limi (Kirtland, 1840)

A rudimentary understanding of age, growth, and life-span is lacking for many non-game fishes. Growth characteristics of the central mudminnow ( Umbra limi ) have not yet been accurately described using reliable hard part analysis. The utility of scales and otoliths as ageing structures and quantified growth was examined in one lake and one stream population of central mudminnow. Scales were found to be of no utility in determining age due to inconsistent formation of yearly annuli and a high incidence of regenerated scales, while otoliths were easily extracted and considered to be an accurate ageing structure. Ages determined from scales were low compared to those from otoliths, and the difference in age interpreted from the two structures increased with fish age. A power function was fitted to describe the length-weight relationship for this species ( a  = 0.0069, b  = 3.175). Von Bertalanffy growth parameters were estimated and compared for each population (Lake: L _∞ = 114.20 mm, K  = 0.30, t ₀ = −0.93; Stream: L _∞ = 77.59 mm, K  = 0.63, t ₀ = −0.76). The lake population showed greater size at age compared to the stream population, especially at older ages, and achieved a larger maximum size. Growth rate was also greater in the lake population (Lake: 1.74; Stream: 1.09 g year⁻¹). Females were larger at age than males in both populations, however all individuals greater than age 3 were males. This work represents the first successful account of central mudminnow growth using hard part analysis.     

Leaf xylem embolism, detected acoustically and by cryo-SEM, corresponds to decreases in leaf hydraulic conductance in four evergreen species

Hydraulic conductance of leaves ( K _leaf) typically decreases with increasing water stress. However, the extent to which the decrease in K _leaf is due to xylem cavitation, conduit deformation or changes in the extra-xylary pathway is unclear. We measured K _leaf concurrently with ultrasonic acoustic emission (UAE) in dehydrating leaves of two vessel-bearing and two tracheid-bearing species to determine whether declining K _leaf was associated with an accumulation of cavitation events. In addition, images of leaf internal structure were captured using cryo-scanning electron microscopy, which allowed detection of empty versus full and also deformed conduits. Overall, K _leaf decreased as leaf water potentials ( Ψ _L) became more negative. Values of K _leaf corresponding to bulk leaf turgor loss points ranged from 13 to 45% of their maximum. Additionally, Ψ _L corresponding to a 50% loss in conductivity and 50% accumulated UAE ranged from −1.5 to −2.4 MPa and from −1.1 to −2.8 MPa, respectively, across species. Decreases in K _leaf were closely associated with accumulated UAE and the percentage of empty conduits. The mean amplitude of UAEs was tightly correlated with mean conduit diameter ( R ² = 0.94, P  = 0.018). These results suggest that water stress-induced decreases in K _leaf in these species are directly related to xylem embolism.     

A natural hybrid of Leuciscus cephalus (L.) and Chalcalburnus chalcoides (Güldenstädt)(Osteichthyes‐Cyprinidae) from Lake Tödürge (Sivas, Turkey)

Hybridization between Leuciscus cephalus and Chalcalburnus chalcoides was identified from biometrical features in 55 fish caught from Lake Tödürge, Sivas, Turkey, between April 1994 and November 1997. The hybrid index V _h for metric and meristic characters was intermediate ( V _h = 45·6) compared with their parents ( L. cephalus V _h = 0 or negative and C. chalcoides V _h ≥ 100). Morphological, metric and meristic features of L. cephalus  ×  C. chalcoides also resembled those of the parents. The majority presented an intermediate position which was best shown by the shape of mouth, caudal fin, gill rakers and pharyngeal teeth, and also by the caudal peduncle depth, head and interorbital width, predorsal and preanal distance, height of anal fin, length of anal base and other characters.     

The effect of anoxic treatment on the larvae of six species of dermestids (Coleoptera)

Abstract: Based on surveys of species of museum pest insects commonly found in Finland, Norway, Denmark and Sweden, six species were selected for a study of the effect of exposure to anoxic treatment on the larval stage. An oxygen level of 0.3% (the rest, nitrogen) was applied and lethal exposure times were determined. Anthrenus museorum L. was the most susceptible species (LT₉₉ = 32.2 h), while Attagenus woodroffei Halst. & Green and Attagenus smirnovi Zhantiev (LT₉₉ = 88.1 h) were the most tolerant species. The LT₉₉ value of At. woodroffei was not calculated, as only 50% of the larvae were killed by the treatment. The results indicate that large intraspecific variation is present in these two Attagenus species. Larvae of Anthrenus verbasci (L.) (LT₉₉ = 43.9 h), Reesa vespulae (Milliron) (LT₉₉ = 53.6 h), and Trogoderma angustum (Solier) (LT₉₉ = 57.2 h) showed intermediate tolerance.     

Influence of azadirachtin on development and reproduction of Nezara viridula L. (Het., Pentatomidae)

Abstract:  The potential of azadirachtin as an insect growth regulator was evaluated in Nezara viridula L. by applying different doses to fifth instar nymphs. At doses of 200–500 ng per insect almost all the individuals died during moulting to adults and the survivors showed a great number of nymphal characteristics, and also died very soon after. At lower doses, from 2 to 50 ng per insect, approximately 50% of the adults seemed normal. No effect was observed during the last nymphal instar, even at the highest dose applied. The fertility and fecundity of adults, males and females, developing from nymphs treated with different low doses of azadirachtin were also studied. When azadirachtin was applied at 20 ng per insect on fifth instar nymphs, females developing from these nymphs showed a conspicuous reduction of fecundity. This same effect was evident when untreated females mated with males obtained from treated nymphs. Finally, azadirachtin applied at 1  μ g/cm² to the oviposition surface showed a remarkable oviposition repellency.     

Nitrogen/phosphorus leaf stoichiometry and the scaling of plant growth

We adopted previous N : P stoichiometric models for zooplankton relative growth to predict the relative growth rates of the leaves μ _L of vascular plants assuming that annual leaf growth in dry mass is dictated by how leaf nitrogen N _L is allocated to leaf proteins and how leaf phosphorus P _L is allocated to rRNA. This model is simplified provided that N _L scales as some power function of P _L across the leaves of different species. This approach successfully predicted the μ _L of 131 species of vascular plants based on the observation that, across these species, N _L scaled, on average, as the 3/4 power of P _L, i.e. N _L ∝  P     . When juxtaposed with prior allometric theory and observations, our findings suggest that a transformation in N : P stoichiometry occurs when the plant body undergoes a transition from primary to secondary growth.     

Inverse association of high-fat diet preference and anxiety-like behavior: a putative role for urocortin 2

The aim of this study was to investigate whether the preference for a palatable high-fat diet (HFD) is associated with response to novelty and with anxiety-like behavior in rats and whether such fat preference correlates with gene expression of hypothalamic neuropeptides related to feeding. We subjected male rats to two tests of exploration of novel environments: the multivariate concentric square field (MCSF) and the elevated plus maze (EPM). The rats were then exposed to a 5 - day test of preference for a palatable HFD versus reference diets. Messenger RNA (mRNA) levels of 21 neuropeptides were investigated by quantitative polymerase chain reaction. We found a strong positive correlation of HFD preference and open-arm activity in the EPM (% open-arm time, r _s = 0.629, df = 26, P   <   0.001). Thus, HFD preference was inversely associated with anxiety-like behavior. The same association was found for HFD preference and behavior in the MCSF (bridge entries, r _s = 0.399, df = 23, P  = 0.048). In addition, the HFD preference was positively correlated ( r _s = 0.433, df = 25, P  = 0.021) with hypothalamic mRNA levels of urocortin 2 (Ucn 2). Moreover, behavior in the EPM was significantly correlated with expression levels of the receptor for Ucn 2, the corticotropin-releasing factor receptor 2, in the hypothalamus ( r _s = 0.382, df = 33, P  = 0.022, pituitary ( r _s = 0.494, df = 31, P  = 0.004) and amygdala ( r _s = 0.381, df = 30, P  = 0.032). We conclude that preference for palatable HFD is inversely associated with anxiety and propose that Ucn 2 signaling may play a role in this association.     

Age, growth and feeding of the common stingray (Dasyatis pastinaca, L., 1758) in the Cilician coastal basin, northeastern Mediterranean Sea

Growth and feeding of stingray ( Dasyatis pastinaca ) were studied using 346 specimens from the Cilician Basin coastal area (northeastern Mediterranean). Age classes between 0 to XII were found. The total length of all specimens ranged from 14.6 to 100.9 cm, and total weight was between 22.5 and 6800 g. Total length (TL)-weight (W) and disc width (DW)-weight (W) relationships were W = 0.0033*L^3.1429 and W = 0.0039*DW^3.4914, respectively. The age data, derived from central readings, were used to estimate the von Bertalanffy length and weight growth parameters. The results were L_∞ = 294.9 cm, W_∞ = 198690.1 g, K = 0.029 year⁻¹; t₀ = −2.2 year. The D. pastinaca diet was composed mainly of crustaceans.     

Genetic and morphological variability of the endangered Syngonanthus mucugensis Giul. (Eriocaulaceae) from the Chapada Diamantina, Brazil: implications for conservation and taxonomy

Allozymic and morphometric studies were carried out on ten populations of Syngonanthus mucugensis (Eriocaulaceae), a species from north-eastern Brazil threatened by extinction. Genetic and morphological variability was low or moderately low in all populations, being lower in populations from Rio de Contas/Catolés ( P _L = 14.3–21.4, A  = 1.1–1.2, H _e = 0.026–0.059, D2M = 26.893–33.157) than in those from Mucugê ( P _L = 28.6–35.7, A  = 1.3–1.5, H _e = 0.078–0.164, D2M = 28.999–45.077). A high coefficient of endogamy ( F _is = 0.257) was found, which can be explained by the reproductive characteristics and distribution of the species. The values for genetic and morphological structuring ( F _st = 0.512 and A _MRPP = 0.175, respectively) were high as a result of the differentiation between populations from the two areas. The mean genetic identity between populations from the two areas (0.812) was much lower than between populations from the same area (Mucugê, 0.980; Rio de Contas/Catolés, 0.997). These results indicate that we are dealing with two distinct taxa and, as a result of the nature of the morphological differences found, a new subspecies is described for the populations of the region of Rio de Contas and Catolés, Syngonanthus mucugensis ssp. riocontensis . Such conclusions raise important implications for the conservation of Syngonanthus mucugensis , and will be used in the drawing up of management plans for its conservation.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 401–416.     

Reproduction, age and growth of Sillago maculata in south-eastern Australia

Sillago maculata is endemic to the east coast of Australia where it is harvested by recreational and commercial fishers; however, little is known of the important aspects of its biology and ecology to assist with fisheries management planning. This situation is redressed here by investigating aspects of the reproduction, age and growth of estuarine populations of S. maculata in south-eastern Australia. Gonadosomatic index (GSI) values indicated peak spawning occurred between September and February and that the estimated mean fork length at maturity (L₅₀) was 14.6 cm for males and 15.2 cm for females. Females displayed an asynchronous pattern of oocyte development, with individuals probably spawning multiple times in a spawning season. A validated aging protocol using thin sectioned otoliths was used to estimate the age of fish. The maximum ages for males and females were 9.5 and 12.0 years, respectively. Growth differed between sexes, with males ( L ∞ = 24.04, K  = 0.70, t ₀ = −0.09) attaining a smaller maximum length than females ( L ∞ = 25.01, K  = 0.72, t ₀ = −0.04). The age composition of gill-net and beach-seine samples mainly consisted of individuals aged 2–4 years, and there was evidence of variable recruitment. Management implications are also discussed.     

Effect of Artemisia annua oil on development and reproduction of Dysdercus koenigii F. (Hem., Pyrrhocoridae)

The effect of topical application of Artemisia annua oil on the development and reproduction of Dysdercus koenigii was studied. On the basis of 48 h mortality, the LD₅₀ for fifth instar nymphs was 0.48 μl/nymph. The treated nymphs showed 2 days delay in development, and also produced intermediates. The treatment decreased haemolymph protein concentration and disturbed its electrophoretic protein pattern. The adults which emerged from treated nymphs showed poor ovary development. There was a greater median neurosecretory activity in the treated insects compared with control insects till day 6 of adult life.     

Relative contribution of contemporary pollen and seed dispersal to the effective parental size of seedling population of California valley oak (Quercus lobata, Née)

For plant populations, gene movement through pollen and seed dispersal governs the size of local genetic neighbourhoods and shapes the opportunities for natural selection and genetic drift. A critical question is how together these two processes influence the evolutionary dynamics of local populations. To assess the respective contributions of pollen and seed flow, we propose a novel indirect assessment of the separate male and female gametic contributions to total effective parental size ( N _e), based on parental correlations estimated via kinship coefficients, that can be applied to data sets that include unambiguous genotypes for male and female gametic contributions. Using the endemic Californian valley oak ( Quercus lobata ) as our study species, we apply this method to a set of microsatellite genotypes for two distinct ecological sets of naturally recruiting seedlings with acorns attached. We found that the effective numbers of contributing male parents ( N _ep) exceed effective numbers of female parents ( N _em) for seedlings established beneath adult trees ( N _ep = 8.1 and N _em = 1.1), as well as for seedlings established away from adult trees ( N _ep = 15.4 and N _em = 2.7), illustrating that seed dispersal enhances pollen dispersal and increases the effective number of seed sources in open seedling patches. The resulting effective parental size of seedling populations translates into smaller effective numbers of parents for undispersed vs. dispersed seedlings ( N _e = 3.6 and N _e = 6.7, respectively). This study introduces a novel statistic method and provides important new evidence that, on a short-term temporal scale, seed dispersal shapes the local neighbourhood size of new recruits.     

Resting spore formation of aphid-pathogenic fungus Pandora nouryi depends on the concentration of infective inoculum

Resting spore formation of some aphid-pathogenic Entomophthorales is important for the seasonal pattern of their prevalence and survival but this process is poorly understood. To explore the possible mechanism involved in the process, Pandora nouryi (obligate aphid pathogen) interacted with green peach aphid Myzus persicae on cabbage leaves under favourable conditions. Host nymphs showered with primary conidia of an isolate (LC₅₀: 0.9–6.7 conidia mm⁻² 4–7 days post shower) from air captures in the low-latitude plateau of China produced resting spores (azygospores), primary conidia or both spore types. Surprisingly, the proportion of mycosed cadavers forming resting spores ( P _cfrs ) increased sharply within the concentrations ( C ) of 28–240 conidia mm⁻², retained high levels at 240–1760, but was zero or extremely low at 0.3–16. The P _cfrs – C relationship fit well the logistic equation P _cfrs  = 0.6774/[1 + exp(3.1229–0.0270 C )] ( r ² = 0.975). This clarified for the first time the dependence of in vivo resting spore formation of P. nouryi upon the concentration of infective inoculum. A hypothesis is thus proposed that some sort of biochemical signals may exist in the host–pathogen interaction so that the fungal pathogen perceives the signals for prompt response to forthcoming host-density changes by either producing conidia for infecting available hosts or forming resting spores for surviving host absence in situ .     

The reproduction, age and growth of the spotted rockling

Biology of the Macaronesian endemic rockling Gaidropsarus guttatus was studied in the Azores. The overall sex ratio from the samples was highly in favour of females (1 : 6·33). The growth parameters were L _∞ = 24·23, k  = 1·219 and t ₀ = −0·059. Fish matured at 15 cm L _T and the spawning season was strongly clustered in April.     

Age, growth, sexual maturity and food composition of Sciaena umbra in the south-eastern Black Sea, Turkey

Studied were the age, growth, maturity and food composition of the brown meager, Sciaena umbra, caught off Trabzon, south-eastern Black Sea (Turkey) in 2002–2003. A total of 329 individuals was collected by spear fishing and hand nets. The thin sectioning method was used for aging the fish otoliths. Fitted von Bertalanffy growth parameters for all fish were: L _∞ = 51.14 (±1.19) cm, k  =   0.27 (±0.02) year⁻¹ and t ₀ = −0.93 (±0.07) year. This study revealed that S. umbra is a relatively slow-growing and long-lived species with a life span in excess of 18 years. Sexual maturity begins when they reach a length of about 15 cm. Lengths at which 50% of brown meagre become mature are 19.50 for males and about 22 cm for females. Spawning begins in June, when the temperature is approximately 18°C, and ends in August. Gut content analysis indicated that this species feeds mainly on crustaceans, then switches to fish as they grow. Sciaena umbra appears to be an apex predator in the upper littoral zone.