Laboratory evaluation of predation rates of two native natural enemies on the exotic pest Bagrada hilaris

Laboratory studies were conducted to determine the consumption rates of two native predators found attacking the exotic invasive stink bug Bagrada hilaris (Burmeister) (Hempitera: Pentatomidae) in field plots in New Mexico, USA. Individual field‐collected adults of the spined soldier bug, Podisus maculiventris (Say) (Hempitera: Pentatomidae) and the soft‐winged flower beetle, Collops vittatus (Say) (Coleoptera: Melyridae), were provided daily with fixed numbers of different life stages of B. hilaris under controlled conditions. Consumption rates were recorded daily for ten consecutive days for a total of 20 adult P. maculiventris and 20 adult C. vittatus per prey life stage. For P. maculiventris, predation rates were obtained in relation to adult, third and fifth instar prey, and for C. vittatus for first, second and third instar prey. On average, predation on third and fifth instar B. hilaris nymphs by P. maculiventris was 0.6 ± 0.1 and 0.9 ± 0.1 per day respectively. Predation rates on adults were slightly higher (1.3 ± 0.1 per day), with female prey being consumed at a significantly higher rate than male prey when three mating pairs of B. hilaris were provided per day (0.8 ± 0.1 females per day vs. 0.5 ± 0.1 males per day). Collops vittatus adults provisioned daily with 20 first instar B. hilaris nymphs killed a mean total of 4.7 ± 0.4 and 9.3 ± 0.6 prey each day (for male and female beetles respectively), with only approximately half that number of prey being fully consumed. Partial consumption of prey by this species was also observed with second and third instar nymphs, but to a lesser degree. Female beetles consumed significantly more prey than did male beetles when fed first and third instar B. hilaris, but not when given second instar prey.     

Temperature and water stress affect plant–pollinator interactions in Borago officinalis (Boraginaceae)

Climate change alters the abiotic constraints faced by plants, including increasing temperature and water stress. These changes may affect flower development and production of flower rewards, thus altering plant–pollinator interactions. Here, we investigated the consequences of increased temperature and water stress on plant growth, floral biology, flower‐reward production, and insect visitation of a widespread bee‐visited species, Borago officinalis. Plants were grown for 5 weeks under three temperature regimes (21, 24, and 27°C) and two watering regimes (well‐watered and water‐stressed). Plant growth was more affected by temperature rise than water stress, and the reproductive growth was affected by both stresses. Vegetative traits were stimulated at 24°C, but impaired at 27°C. Flower development was mainly affected by water stress, which decreased flower number (15 ± 2 flowers/plant in well‐watered plants vs. 8 ± 1 flowers/plant under water stress). Flowers had a reduced corolla surface under temperature rise and water stress (3.8 ± 0.5 cm² in well‐watered plants at 21°C vs. 2.2 ± 0.1 cm² in water‐stressed plants at 27°C). Both constraints reduced flower‐reward production. Nectar sugar content decreased from 3.9 ± 0.3 mg/flower in the well‐watered plants at 21°C to 1.3 ± 0.4 mg/flower in the water‐stressed plants at 27°C. Total pollen quantity was not affected, but pollen viability decreased from 79 ± 4% in the well‐watered plants at 21°C to 25 ± 9% in the water‐stressed plants at 27°C. Flowers in the well‐watered plants at 21°C received at least twice as many bumblebee visits compared with the other treatments. In conclusion, floral modifications induced by abiotic stresses related to climate change affect insect behavior and alter plant–pollinator interactions.     

Stress‐induced changes in abundance differ among obligate and facultative endosymbionts of the soybean aphid

Bacterial endosymbionts can drive evolutionary novelty by conferring adaptive benefits under adverse environmental conditions. Among aphid species there is growing evidence that symbionts influence tolerance to various forms of stress. However, the extent to which stress inflicted on the aphid host has cascading effects on symbiont community dynamics remains poorly understood. Here we simultaneously quantified the effect of host‐plant induced and xenobiotic stress on soybean aphid (Aphis glycines) fitness and relative abundance of its three bacterial symbionts. Exposure to soybean defensive stress (Rag1 gene) and a neurotoxic insecticide (thiamethoxam) substantially reduced aphid composite fitness (survival × reproduction) by 74 ± 10% and 92 ± 2%, respectively, which in turn induced distinctive changes in the endosymbiont microbiota. When challenged by host‐plant defenses a 1.4‐fold reduction in abundance of the obligate symbiont Buchnera was observed across four aphid clonal lines. Among facultative symbionts of Rag1‐stressed aphids, Wolbachia abundance increased twofold and Arsenophonus decreased 1.5‐fold. A similar pattern was observed under xenobiotic stress, with Buchnera and Arsenophonus titers decreasing (1.3‐fold) and Wolbachia increasing (1.5‐fold). Furthermore, variation in aphid virulence to Rag1 was positively correlated with changes in Arsenophonus titers, but not Wolbachia or Buchnera. A single Arsenophonus multi‐locus genotype was found among aphid clonal lines, indicating strain diversity is not primarily responsible for correlated host‐symbiont stress levels. Overall, our results demonstrate the nature of aphid symbioses can significantly affect the outcome of interactions under stress and suggests general changes in the microbiome can occur across multiple stress types.     

Estimating seed dispersal distance: A comparison of methods using animal movement and plant genetic data on two primate‐dispersed Neotropical plant species

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Effect of temperature on immature development and longevity of two introduced opiine parasitoids on Bactrocera invadens

Temperature‐dependent development, parasitism and longevity of the braconid parasitoids, Fopius arisanus Sonan and Diachasmimorpha longicaudata Ashmed on Bactorcera invadens Drew Tsuruta & White, was evaluated across five constant temperatures (15, 20, 25, 30 and 35°C). Developmental rate decreased linearly with increasing temperature for both the parasitoid species. Linear and Brière‐2 nonlinear models were used to determine the lower temperature threshold at which the developmental rate (1/D) approached zero. For F. arisanus, lower thresholds to complete development estimated with the linear and nonlinear models were 10.1 and 6.9°C, respectively. The total degree‐days (DD) required to complete the development estimated by the linear model for F. arisanus was 360. In D. longicaudata, the linear and nonlinear models estimated lower thresholds of 10.4 and 7.3°C, respectively, and the total DD estimated was 282. In F. arisanus, percentage parasitism differed significantly across all temperatures tested and was highest at 25°C (71.1 ± 2.5) and lowest at 15°C (46.4 ± 1.4). Parasitoid progeny sex ratio was female biased at all temperatures except at 20°C. In D. longicaudata, percentage parasitism was highest at 20°C (52.2 ± 4.0) and lowest at 15°C (27.7 ± 2.5). Parasitoid progeny sex ratio was female biased and similar for all temperatures. Adult longevity of both parasitoids was shortest at 35°C and longest at 15°C, and females lived significantly longer than males at all temperatures tested. Our findings provide some guidance for future mass rearing and field releases of the two parasitoids for the management of B. invadens in Africa.     

Trichobaris weevils distinguish amongst toxic host plants by sensing volatiles that do not affect larval performance

Herbivorous insects use plant metabolites to inform their host plant selection for oviposition. These host‐selection behaviours are often consistent with the preference–performance hypothesis; females oviposit on hosts that maximize the performance of their offspring. However, the metabolites used for these oviposition choices and those responsible for differences in offspring performance remain unknown for ecologically relevant interactions. Here, we examined the host‐selection behaviours of two sympatric weevils, the Datura (Trichobaris compacta) and tobacco (T. mucorea) weevils in field and glasshouse experiments with transgenic host plants specifically altered in different components of their secondary metabolism. Adult females of both species strongly preferred to feed on D. wrightii rather than on N. attenuata leaves, but T. mucorea preferred to oviposit on N. attenuata, while T. compacta oviposited only on D. wrightii. These oviposition behaviours increased offspring performance: T. compacta larvae only survived in D. wrightii stems and T. mucorea larvae survived better in N. attenuata than in D. wrightii stems. Choice assays with nicotine‐free, JA‐impaired, and sesquiterpene‐over‐produced isogenic N. attenuata plants revealed that although half of the T. compacta larvae survived in nicotine‐free N. attenuata lines, nicotine did not influence the oviposition behaviours of both the nicotine‐adapted and nicotine‐sensitive species. JA‐induced sesquiterpene volatiles are key compounds influencing T. mucorea females’ oviposition choices, but these sesquiterpenes had no effect on larval performance. We conclude that adult females are able to choose the best host plant for their offspring and use chemicals different from those that influence larval performance to inform their oviposition decisions.     

Identification and antifungal activity analysis of two biocontrol antagonists to Colletotrichum musae

Postharvest anthracnose of banana caused by Colletotrichum musae is one of the major diseases resulting in huge economic losses worldwide. To control this disease using biocontrol agents, two antagonistic strains SD7 and NB20 with significant inhibitory effects on mycelial growth and conidial germination of C. musae were identified and evaluated in this study. The inhibitory effects of cell‐free culture filtrates of SD7 and NB20 on conidial germination of C. musae were both 100%, and those on mycelial growth of C. musae were 97.7 ± 0.9% and 95.0 ± 0.6%, respectively. The antifungal activities of cell‐free culture filtrates of both strains were still stable after they were stored at 4°C for 6 months. The control efficacies of cell‐free culture filtrates of SD7 and NB20 on postharvest anthracnose of banana were 55.9 ± 4.1% and 33.2 ± 3.9%, respectively. The disease severity (mean scale value) in banana fruit fingers was significantly lower after the treatment with a cultural suspension of the bacterial strain SD7 (1.4 ± 0.49) or actinomycete strain NB20 (2.0 ± 0.63), compared to that in the control (4.8 ± 0.40). After subculturing for 10 generations, the antifungal efficiency of NB20 remained stable, whereas that of strain SD7 declined obviously. Lastly, based on the morphological, physio‐biochemical and molecular characteristics, the bacterial strain SD7 was identified as Burkholderia cepacia, while the actinomycete strain NB20 was identified as Streptomyces katrae. The results from this study will provide the basis for developing an effective and novel biofungicide to control banana anthracnose disease.     

Genetically manipulated Brassica genotypes affect demography and performance of Diadegma semiclausum parasitizing Plutella xylostella

The performance of Diadegma semiclausum (Hellen) (Hymenoptera: Ichneumonidae) on Plutella xylostella (L.) (Lepidoptera: Plutellidae) reared on canola's progenitor (Brassica rapa L.), two cultivated canola cultivars (Opera and RGS₀₀₃), one hybrid (Hyula₄₀₁), one gamma‐ray mutant‐RGS₀₀₃ and one transgenic (PF) genotype was compared using the age‐stage, two‐sex life table parameters. All experiments were carried out in a growth chamber at 25 ± 1°C, 65 ± 5% RH and a photoperiod of 16 : 8 (L : D) h. There were significant differences in duration of different life stages of D. semiclausum on its host larvae reared on different plant genotypes. The shortest (12.27 days) and longest (15.21 days) pre‐adult developmental times were observed on cultivar‐RGS₀₀₃ and hybrid‐Hyula₄₀₁, respectively. The intrinsic rate of increase (r) in D. semiclausum ranged between 0.189/day (cultivar‐Opera) and 0.141/day (transgenic‐PF). Moreover, the highest (20.078 offspring) and lowest (12.027 offspring) net reproductive rates (R₀) were observed on cultivar‐Opera and hybrid‐Hyula₄₀₁. The mean generation time (T) of D. semiclausum was the highest (18.34 days) and lowest (15.05 days) on mutant‐RGS₀₀₃ and cultivar‐RGS₀₀₃. The maximum and minimum parasitism values of this parasitoid were observed on canola's progenitor (44.28%) and hybrid‐Hyula₄₀₁ (37.09%). The heaviest pupae (3.82 mg) and females (3.22 mg) of the parasitoid were found on canola's progenitor and cultivar‐Opera, respectively. The results showed that performance of this parasitoid was better on canola's progenitor and cultivated plants known to have higher levels of glucosinolates concentration than others.     

Combined effects of spray‐drying conditions and postdrying storage time and temperature on Salmonella choleraesuis and Salmonella typhimurium survival when inoculated in liquid porcine plasma

The objective of this study was to determine the effectiveness of the spray‐drying process on the inactivation of Salmonella choleraesuis and Salmonella typhimurium spiked in liquid porcine plasma and to test the additive effect of immediate postdrying storage. Commercial spray‐dried porcine plasma was sterilized by irradiation and then reconstituted (1:9) with sterile water. Aliquots of reconstituted plasma were inoculated with either S. choleraesuis or S. typhimurium, subjected to spray‐drying at an inlet temperature of 200°C and an outlet temperature of either 71 or 80°C, and each spray‐drying temperature combinations were subjected to either 0, 30 or 60 s of residence time (RT) as a simulation of residence time typical of commercial dryers. Spray‐dried samples were stored at either 4·0 ± 3·0°C or 23·0 ± 0·3°C for 15 days. Bacterial counts of each Salmonella spp., were completed for all samples. For both Salmonella spp., spray‐drying at both outlet temperatures reduced bacterial counts about 3 logs at RT 0 s, while there was about a 5·5 log reduction at RT 60 s. Storage of all dried samples at either 4·0 ± 3·0°C or 23·0 ± 0·3°C for 15 days eliminate all detectable bacterial counts of both Salmonella spp.

Significance and Impact of the Study

Safety of raw materials from animal origin like spray‐dried porcine plasma (SDPP) may be a concern for the swine industry. Spray‐drying process and postdrying storage are good inactivation steps to reduce the bacterial load of Salmonella choleraesuis and Salmonella typhimurium. For both Salmonella spp., spray‐drying at 71°C or 80°C outlet temperatures reduced bacterial counts about 3 log at residence time (RT) 0 s, while there was about a 5.5 log reduction at RT 60 s. Storage of all dried samples at either 4.0 ± 3.0°C or 23.0 ± 0.3°C for 15 days was effective for eliminating detectable bacterial counts of both Salmonella spp.     

Effects of tree architecture on pollen dispersal and mating patterns in Abies pinsapo Boiss. (Pinaceae)

Plant architecture is crucial to pollination and mating in wind‐pollinated species. We investigated the effect of crown architecture on pollen dispersal, mating system and offspring quality, combining phenotypic and genotypic analyses in a low‐density population of the endangered species Abies pinsapo. A total of 598 embryos from three relative crown height levels (bottom, middle and top) in five mother plants were genotyped using eleven nuclear microsatellite markers (nSSRs). Paternity analysis and mating system models were used to infer mating and pollen dispersal parameters. In addition, seeds were weighed (N = 16 110) and germinated (N = 736), and seedling vigour was measured to assess inbreeding depression. Overall, A. pinsapo shows a fat‐tailed dispersal kernel, with an average pollen dispersal distance of 113–227 m, an immigration rate of 0.84–26.92%, and a number of effective pollen donors (N_ep) ranging between 3.5 and 11.9. We found an effect of tree height and relative crown height levels on mating parameters. A higher proportion of seeds with embryo (about 50%) and a higher rate of self‐fertilization (about 60%) were found at the bottom level in comparison with the top level. Seed weight and seedling vigour are positively related. Nevertheless, no differences were found in seed weight or in seedling‐related variables such as weight and length of aerial and subterranean parts among the different relative crown height levels, suggesting that seeds from the more strongly inbred bottom level are not affected by inbreeding depression. Our results point to vertical isotropy for outcross‐pollen and they suggest that self‐pollen may ensure fertilization when outcross‐pollen is not available in low‐density population.     

Chemical Composition,Antibacterial, Schistosomicidal,and Cytotoxic Activities of the Essential Oil of Dysphania ambrosioides (L.) Mosyakin & Clemants (Chenopodiaceae)

We have investigated the chemical composition and the antibacterial activity of the essential oil of Dysphania ambrosioides (L.) Mosyakin & Clemants (Chenopodiaceae) (DA‐EO) against a representative panel of cariogenic bacteria. We have also assessed the in vitro schistosomicidal effects of DA‐EO on Schistosoma mansoni and its cytotoxicity to GM07492‐A cells in vitro. Gas chromatography (GC) and gas chromatography‐mass spectrometry (GC/MS) revealed that the monoterpenes cis‐piperitone oxide (35.2%), p‐cymene (14.5%), isoascaridole (14.1%), and α‐terpinene (11.6%) were identified by as the major constituents of DA‐EO. DA‐EO displayed weak activity against Streptococcus sobrinus and Enterococcus faecalis (minimum inhibitory concentration (MIC) = 1000 μg/ml). On the other hand, DA‐EO at 25 and 12.5 μg/ml presented remarkable schistosomicidal action in vitro and killed 100% of adult worm pairs within 24 and 72 h, respectively. The LC₅₀ values of DA‐EO were 6.50 ± 0.38, 3.66 ± 1.06, and 3.65 ± 0.76 μg/ml at 24, 48, and 72 h, respectively. However, DA‐EO at concentrations higher than 312.5 μg/ml significantly reduced the viability of GM07492‐A cells (IC₅₀ = 207.1 ± 4.4 μg/ml). The selectivity index showed that DA‐EO was 31.8 times more toxic to the adult S. mansoni worms than GM07492‐A cells. Taken together, these results demonstrate the promising schistosomicidal potential of the essential oil of Dysphania ambrosioides.     

Differential Organ Distribution,Pathogenicity and Benomyl Sensitivity of Colletotrichum spp. from Blackberry Plants in Northern Colombia

Blackberry anthracnose, caused by Colletotrichum spp., is an important disease of cultivated blackberry in the world. In Colombia, it is the number one limiting factor for commercial production. This study was conducted to determine the species of Colletotrichum infecting blackberry plants as well as the organ distribution, pathogenicity and response to benomyl of the isolated strains. Sixty isolates from stems (n = 20), thorns (n = 20) and inflorescences (n = 20) were identified as Colletotrichum acutatum and Colletotrichum gloeosporioides by a species‐specific polymerase chain reaction (PCR). Both Colletotrichum species were found in the same plant but on different organs. Colletotrichum gloeosporioides species predominated in thorn lesions (n = 16) and C. acutatum in stems (n = 15) and inflorescence (n = 15). Pathogenicity assays on detached blackberry organs demonstrated differences between the two species with an average period of lesion development of 8.7 days for C. gloeosporioides and 10.3 days for C. acutatum. Wound inoculated organs had 90% disease development compared to 17.5% in non‐wounded. All C. acutatum isolates (n = 34) were benomyl tolerant, whereas C. gloeosporioides isolates (n = 26) were 30.7% sensitive and 69.2% moderately tolerant. Phylogenetic analysis with ITS sequences of a subset of 18 strains showed that strains classified as C. gloeosporioides had 100% identity to Colletotrichum kahawae, which belongs to the C. gloeosporioides species complex, whereas C. acutatum strains clustered into two different groups, with high similarity to the A2 and the A4 molecular groups. These data demonstrate for the first time the differential distribution of both species complexes in blackberry plant organs and further clarifies the taxonomy of the strains.     

Primary ecological succession in vascular epiphytes: The species accumulation model

Epiphytes are integral to tropical forests yet little is understood about how succession proceeds in these communities. As trees increase in size they create microhabitats for late‐colonizing species in both small and large branches while maintaining small tree microhabitats for early colonizing species in the small and young branches. Thus, epiphyte succession may follow different models depending on the scale: at the scale of the entire tree, epiphytes may follow a species accumulation model where species are continuously added to the tree as trees increase in size but at the scale of one zone on a branch (e.g., inner crown: 0–2 m from the trunk), they may follow the replacement model of succession seen in terrestrial ecosystems. Assuming tree size as an indicator of tree age, I surveyed 61 Virola koschnyi trees of varying size (2.5–103.3 cm diameter at breast height) in lowland wet tropical forest in Costa Rica to examine how epiphyte communities change through succession. Epiphyte communities in small trees were nested subsets of those in large trees and epiphyte communities became more similar to the largest trees as trees increased in size. Furthermore, epiphyte species in small trees were replaced by mid‐ and late‐successional species in the oldest parts of the tree crown but dispersed toward the younger branches as trees increased in size. Thus, epiphyte succession followed a replacement model in particular zones within treecrowns but a species accumulation model at the scale of the entire tree crown.     

Endozoochorous dispersal of forest seeds by carnivorous mammals in Sierra Fría,Aguascalientes, Mexico

Some carnivorous mammals ingest fruit and disperse seeds of forest plant species capable of colonizing disturbed areas in ecosystems. The objective of the present study was to evaluate the dissemination of Arctostaphylos pungens and Juniperus deppeana seeds by the gray fox (Urocyon cinereoargenteus), coyote (Canis latrans), and other carnivores in the Protected Natural Area Sierra Fría, in Aguascalientes, Mexico. Scat collection was undertaken via transects using the direct search method, while the seasonal phenology of A. pungens and J. deppeana was evaluated by recording flower and fruit abundance on both the plant and the surrounding forest floor ground. Seed viability was assessed by optical densitometry via X‐ray and a germination test. It was found that the gray fox, coyote, ringtail (Bassariscus astutus), and bobcat (Lynx rufus) disseminated seeds of A. pungens (212 ± 48.9 seeds/scat) and J. deppeana (23.6 ± 4.9 seeds/scat), since a large proportion of the collected scat of these species contained seeds (28/30 = 93.33%, 12/43 = 27.9%, 6/12 = 50% and 7/25 = 28% respectively). The gray fox, coyote, ringtail, and bobcat presented an average of seed dispersion of both plant species of 185.4 ± 228.7, 4.0 ± 20.0, 12.1 ± 30.4, and 0.8 ± 1.5 per scat; the seed proportions in the gray fox, coyote, ringtail, and bobcat were 89.6/10.4%, 82.3/17.7%, 90.4/9.6%, and 38.1/61.9% for A. pungens and J. deppeana, respectively. The phenology indicated a finding related to the greater abundance of ripe fruit in autumn and winter (p < .01). This coincided with the greater abundance of seeds found in scats during these seasons. Endozoochory and diploendozoochory enhanced the viability and germination of the seeds (p > .05), except in those of A. pungens dispersed by coyote. These results suggest that carnivores, particularly the gray fox, the coyote, and the bobcat, play an important role in forest seed dissemination, and thus forest regeneration, by making both a quantitative and qualitative contribution to the dispersal of the two pioneer species under study.     

New insights into the molecular phylogeny and taxonomy of mormyrids (Osteoglossiformes,Actinopterygii) in northern East Africa

Based on morphological data and analysis of mitochondrial cytochrome b gene and nuclear (S7 intron 1) DNA sequences, the phylogenetic relationships of all Pollimyrus species known from the Omo‐Turkana enclosed basin and Nile system below the Murchison Falls were solved. A mormyrid “Pollimyrus” petherici is distantly related to all other studied Pollimyrus species and clusters together with Cyphomyrus species forming with the later a monophyletic group. Moreover, the West African (but not the Congo River) populations of Cyphomyrus psittacus, the type species of the genus, seem to be conspecific to C. petherici. That is, the range of the genus Cyphomyrus is extended toward the Nile and Omo‐Turkana basins. This genus belongs to the large clade widely distributed in sub‐Saharian Africa and characterized by the presence of a chin appendage. Significance of this character for mormyrid phylogeny is discussed. Two distinct lineages of Pollimyrus occurring sympatrically in the White Nile tributaries and previously reported as the light and dark forms of Pollimyrus isidori together with five other congeneric species studied form a monophyletic group. The light form apparently represents P. isidori distributed in the Nile system downstream of the Murchison Falls and West Africa; the dark‐colored form (designated as Pollimyrus “D”) represents a distinct phylogenetic lineage inhabiting both the Omo‐Turkana and the White Nile basin. Morphological and ecological data suggest that this form may be conspecific to East African Pollimyrus nigricans or most probably represents a new species.     

Uptake kinetics and storage capacity of dissolved inorganic phosphorus and corresponding dissolved inorganic nitrate uptake in Saccharina latissima and Laminaria digitata (Phaeophyceae)

Uptake rates of dissolved inorganic phosphorus and dissolved inorganic nitrogen under unsaturated and saturated conditions were studied in young sporophytes of the seaweeds Saccharina latissima and Laminaria digitata (Phaeophyceae) using a “pulse‐and‐chase” assay under fully controlled laboratory conditions. In a subsequent second “pulse‐and‐chase” assay, internal storage capacity (ISC) was calculated based on V_M and the parameter for photosynthetic efficiency F_v/F_m. Sporophytes of S. latissima showed a V_S of 0.80 ± 0.03 μmol · cm^?2 · d^?1 and a V_M of 0.30 ± 0.09 μmol · cm^?2 · d^?1 for dissolved inorganic phosphate (DIP), whereas V_S for DIN was 11.26 ± 0.56 μmol · cm^?2 · d^?1 and V_M was 3.94 ± 0.67 μmol · cm^?2 · d^?1. In L. digitata, uptake kinetics for DIP and DIN were substantially lower: V_S for DIP did not exceed 0.38 ± 0.03 μmol · cm^?2 · d^?1 while V_M for DIP was 0.22 ± 0.01 μmol · cm^?2 · d^?1. V_S for DIN was 3.92 ± 0.08 μmol · cm^?2 · d^?1 and the V_M for DIN was 1.81 ± 0.38 μmol · cm^?2 · d^?1. Accordingly, S. latissima exhibited a larger ISC for DIP (27 μmol · cm^?2) than L. digitata (10 μmol · cm^?2), and was able to maintain high growth rates for a longer period under limiting DIP conditions. Our standardized data add to the physiological understanding of S. latissima and L. digitata, thus helping to identify potential locations for their cultivation. This could further contribute to the development and modification of applications in a bio‐based economy, for example, in evaluating the potential for bioremediation in integrated multitrophic aquacultures that produce biomass simultaneously for use in the food, feed, and energy industries.     

The genus Pseudo-nitzschia (Bacillariophyceae) in a temperate estuary with description of two new species: Pseudo-nitzschia plurisecta sp. nov. and Pseudo-nitzschia abrensis sp. nov.

The genus Pseudo‐nitzschia contains potentially toxic species of problematic taxonomy, making it one of the most intensively studied diatom genera. The study of 35 clonal strains isolated from the Bilbao estuary, an area that experiences recurrent blooms of Pseudo‐nitzschia, revealed the presence of two new species, P. abrensis and P. plurisecta, differing from their congeners in both morphology and gene sequence. The morphological features were analyzed by LM and EM, whereas molecular analyses were based on the internal transcribed spacer (ITS) and large subunit (LSU) regions of the rDNA. P. plurisecta appears closely related to P. cuspidata/P. pseudodelicatissima in the phylogenetic tree, whereas P. abrensis forms a moderately supported clade with P. heimii/P. subpacifica and P. caciantha/P. circumpora. Comparison of the secondary structure of ITS2 regions reveals marked differences in the most highly conserved regions among related taxa. Morphologically, the new species differ from their closest congeners in the arrangement of the poroid sectors and the density of valve striae and fibulae. The two species share similar pigment composition, and belong to the group of Pseudo‐nitzschia species containing only chlorophyll c₂ and c₃.     

Identification of a bacterial pathogen associated with Porites white patch syndrome in the Western Indian Ocean

Porites white patch syndrome (PWPS) is a coral disease recently described in the Western Indian Ocean. This study aimed to isolate and identify potential pathogens associated with PWPS utilizing both culture and nonculture screening techniques and inoculation trials. A total of 14 bacterial strains (those dominant in disease lesions, absent or rare in healthy tissues and considered potential pathogens in a previous study) were cultured and used to experimentally inoculate otherwise healthy individuals in an attempt to fulfil Henle–Koch's postulates. However, only one (P180R), identified as closely related (99–100% sequence identity based on 1.4 kb 16S RNA sequence) to Vibrio tubiashii, elicited signs of disease in tank experiments. Following experimental infection (which resulted in a 90% infection rate), the pathogen was also successfully re‐isolated from the diseased tissues and re‐inoculated in healthy corals colonies, therefore fulfilling the final stages of Henle–Koch's postulates. Finally, we report that PWPS appears to be a temperature‐dependent disease, with significantly higher tissue loss (anova : d.f. = 2, F = 39.77, P < 0.01) occurring at 30 °C [1.45 ± 0.85 cm² per day (mean ± SE)] compared to ambient temperatures of 28 and 26 °C (0.73 ± 0.80 cm² per day (mean ± SE) and 0.51 ± 0.50 cm² per day (mean ± SE), respectively).     

Identification and validation of single nucleotide polymorphisms as tools to detect hybridization and population structure in freshwater stingrays

Single nucleotide polymorphism (SNP) markers were identified and validated for two stingrays species, Potamotrygon motoro and Potamotrygon falkneri, using double digest restriction‐site associated DNA (ddRAD) reads using 454‐Roche technology. A total of 226 774 reads (65.5 Mb) were obtained (mean read length 289 ± 183 bp) detecting a total of 5399 contigs (mean contig length: 396 ± 91 bp). Mining this data set, a panel of 143 in silico SNPs was selected. Eighty‐two of these SNPs were successfully validated and 61 were polymorphic: 14 in P. falkneri, 21 in P. motoro, 3 in both species and 26 fixed for alternative variants in both species, thus being useful for population analyses and hybrid detection.