Memecylon trunciflorum sp. nov. (Melastomataceae–Olisbeoideae) from the Udzungwa Mountains,southern Tanzania

Described and illustrated is Memecylon trunciflorum R. D. Stone, an evidently localized endemic of the Udzungwa Mountains in southern Tanzania. The new species was previously confused with the vegetatively similar but distantly related M. erythranthum Gilg and M. semseii A. Fern. & R. Fern., from which it is distinguished by its anther connectives bearing a dorsal oil‐gland and by its ellipsoid to obovoid fruits (vs anther connective gland absent and fruits globose in M. erythranthum and M. semseii). The new species is placed in M. sect. Magnifoliata R. D. Stone together with M. magnifoliatum A. Fern. & R. Fern., from which it differs by its smaller leaves mostly 9.5–15.0 × 3.5–6.0 cm (vs 18–35 × 8–13 cm), transverse veins 8–18 pairs (vs 25–28 pairs), short‐pedunculate inflorescences with secondary axes well developed (vs peduncles and secondary axes absent), white flowers (vs bluish purple), and smaller fruits mostly 11.5–14.5 × 9–11 mm on longer fruiting pedicels 8.0–13.5 mm (vs fruits 17–20 × 12–14 mm on pedicels 5.0–7.5 mm). Despite its local endemism, Memecylon trunciflorum has been assessed as ‘Least Concern’ according to IUCN criteria, although this assessment is dependent on the continued safeguarding of the Udzungwa Mountains National Park.     

Seeding tallgrass prairie in monospecific patches promotes native species establishment and cover

In tallgrass prairie reconstruction, the way desired seeds are arranged on the landscape may affect species establishment, species persistence, and the establishment and persistence of undesired (nonseeded) species from the local propagule pool. To test effects of species seeding pattern on how grasslands develop spatially, we seeded 20—4 × 4–m bare soil plots with 16 tallgrass prairie species. Treatment plots were divided into 16—1 × 1–m subplots, 64—0.5 × 0.5–m subplots, 256—0.25 × 0.25–m subplots, or 1,024—0.125 × 0.125–m subplots. Each species was hand broadcast into separate subplots (1 m² total area/species) within each plot. An additional treatment included uniformly mixing and broadcasting all seeds across a plot. We recorded species cover at the 0.125 × 0.125–m scale within each plot at the beginning of the second and third growing seasons. While species persistence was greatest within plots seeded with larger subplots, plots with smaller subplots were more spatially diverse and less occupied by nonseeded species over time than larger subplot and mixed plots. As is common in reconstruction efforts, establishment was variable among species and seeding with monospecific subplots enhanced colonization of desired rhizomatous species (e.g., Heliopsis helianthoides, Monarda fistulosa, Elymus virginicus) into unoccupied locations at the expense of species from the local propagule pool. Results suggest that seeding species in smaller, monospecific patches could result in grasslands with a more balanced native species composition than those established with a seed mixture approach.     

Ilex sanqingshanensis sp. nov. (Aquifoliaceae) from Jiangxi Province,China

Ilex sanqingshanensis, a new species of Aquifoliaceae from Jiangxi, China, is described and illustrated with morphological characteristics and ultrastructure of pollen grains. The new species is easily distinguished from the most similar species I. wugongshanensis C. J. Tseng ex S. K. Chen et Y. X. Feng by having smaller leaves that are elliptic, ovate or elliptic‐ovate, with shorter (0.5–1.0 vs 2–3 mm) teeth on the leaf margin, longer pedicels of staminate flowers (2.0–3.5 vs 1.5 mm), smaller pyrenes (3.5–4.0 × 2.0–2.5 vs 4.5–5.0 × 3.0 mm), and woody pyrenes (vs stony pyrenes).     

Very low-angle light scattering. A characterization method for high-molecular-weight DNA

A very low-angle light-scattering photometer is described with respect to optical features, scattering cell, correction factors, and absolute calibration in the angular range 2°–35°. An improved microfiltration apparatus was used to obtain essentially dust-free aqueous solutions for very low-angle light scattering. The instrument was calibrated with silicotungstic acid, an absolute molecular-weight standard, and the calibration was confirmed with the use of several secondary standards. Very low-angle light-scattering measurements were made to determine the weight-average molecular weight M?_r and z-average radius of gyration R_g,z of a commerical preparation of calf-thymus DNA. Microfiltration of the solutions allowed measurements down to 6°. The value M?_r = 20.0 × 10⁶ obtained by extrapolating 6°–9° data to 0° is more than three times that from 30°–75° data (6.38 × 10⁶) but ～20% smaller than that from 10–35° data (23.7 × 10⁶). The experimental errors in M?_r and R_g,z are estimated to be ±8% and ±14%, respectively. Combined 6°–75° data from two photometers fit well a theoretical scattering curve for a model wormlike coil of the same M?_r as the DNA sample.     

CHROMOSOME DIFFERENTIATION IN SEVERAL SPECIES OF MELILOTUS

Shastry , Sishta V. S., William K. Smith , and Delmer C. Cooper . (U. Wisconsin, Madison.) Chromosome differentiation in several species of Melilotus. Amer. Jour. Bot. 47(8) : 613–621. Illus. 1960.—Two species of the section Eumelilotus (M. alba and M. officinalis), 2 of Micromelilotus (M. messanensis and M. segetalis), 2 F₁ hybrids (M. officinalis × M. alba and M. messanensis × M. segetalis), 2 autotetraploids (M. alba and M. officinalis), and 1 allotetraploid (M. officinalis × M. alba), were utilized during the course of this investigation. The 4 species and F₁ hybrids have 16 somatic chromosomes and the tetraploids have twice that number (32). The 2 Eumelilotus species are completely isolated because of seed failure after cross pollination. The F₁ hybrid (M. officinalis × M. alba), obtained elsewhere by the use of embryo-culture techniques, was intermediate between the parents in certain morphological characters and was ca. 75% pollenfertile whereas the parents approached complete fertility. No structural differences between the chromosomes were evident at pachytene. Disturbances which led to the reduced fertility occurred at later stages of meiosis. The Micromelilotus species are cross compatible, but the F₁ hybrid (M. messanensis × M. segetalis) is highly sterile. Despite chromosome structural differences of various types evident at pachytene, bivalents regularly occur at metaphase I. Irregular distribution of the chromosomes at later stages of meiosis leads to high sterility. Species which readily cross but produce a hybrid of very low fertility are likely to compound chromosomal structural differences, because of abnormalities in meiosis, in contrast with species that are completely incompatible.     

Molecular fingerprinting of peppermint (Mentha piperita) and some Mentha hybrids by sequencing and RFLP analysis of the 5S rRNA Non-Transcribed Spacer (NTS) region

Hybridization of species belonging to the genus Mentha is quite common. However, the indicators of hybridity are many and make Mentha hybrids' identification difficult. By using the same molecular strategy that allowed us to unequivocally identify some Mentha species, we amplified the Not-Transcribed-Spacer (NTS) of the 5S-rRNA gene to characterize the industrial crop peppermint, M. × piperita and some important Mentha interspecific hybrids: M. × dalmatica, M. × dumetorum, M. × rotundifolia, M. × maximilianea, M. × smithiana, M. × verticillata, M. × villosa. DNA amplification, sequence and cluster analysis revealed differences in the 5S-rRNA NTS region of Mentha hybrids. Peppermint and all other hybrids were unequivocally discriminated by RFLP analysis by using TaqI restriction enzyme, while a further discrimination between M. × dumetorum and M. × verticillata was obtained by XhoI restriction enzyme. Essential oil composition showed clustering patterns similar to DNA fingerprint, with a clear discrimination between plants producing menthofuran (e.g. M. aquatica and its related hybrids, including peppermint) and those containing piperitenone oxide (M. longifolia and its related hybrids).     

Stromanthe bahiensis sp. nov. (Marantaceae), endemic to southern Bahia State,Brazil

Stromanthe bahiensis Yoshida‐Arns, Mayo & J. M. A. Braga sp. nov. (Marantaceae) is described as an endemic to the Atlantic Forest coast of southern Bahia State in Brazil. It is similar to S. hjalmarssonii (Körn.) Petersen, which is restricted to Central America, but differs from it by the following characteristics: petiole 14–70 cm long, leaf blade oblong‐ovate to ovate‐lanceolate, fertile bracts 18–30×2–4 mm, narrowly lanceolate to ovate‐lanceolate, sepals 4–6 mm long, corolla lobes 3.0–3.5 mm long, outer staminodes 2.0–3.5×1–2 mm, pale bluish or purplish, callose staminode 2–3×1–2 mm, cucullate staminode 2–3 mm long and ovary hirsute. The new species is described and illustrated with diagnostic characters, taxonomic comments and remarks on its conservation status.     

Coccidian Parasites (Apicomplexa: Eimeriidae) from Insectivores. II. Six New Species from Japanese Shrew Moles (Talpidae)1

ABSTRACT. Thirty-eight of 51 (74.5%) shrew moles collected in Japan were infected with from one to four species of Eimeria and/or Isospora including six of six Dymecodon pilirostris and 32 of 45 (71.1%) Urotrichus talpoides. Four eimerians and two isosporans were identified and all are described as new species. Sporulated oocysts of Eimeria amorphospora n. sp. were subspheroid/ellipsoid, 21.1 × 17.9(18-25 × 16-21) μm. Sporocysts were amorphous, gelatinoid envelopes 20.3 × 7.5 (17–24 × 7–9) μm. Sporozoites were enclosed together within a membrane in each sporocyst. This species was found in 9 of 45 (20%) U. talpoides. Sporulated oocysts of Eimeria gonocilia n. sp. were subspheroid/ellipsoid, 28.8 × 24.4 (25–30 × 21–28) μm; a highly ornate outer oocyst wall gave the appearance of a ciliated ball. Sporocysts ovoid, pointed at both ends, were 17.0 × 9.0 (15–19 × 7–11) μm; this species was found in 4 of 45 (8.9%) U. talpoides. Sporulated oocysts of Eimeria talpoidei n. sp. were asymmetrical ovoid, 20.6 × 13.3 (18–23 × 12–15) μm, with sporocysts lacrimiform, 12.0 × 5.8 (10–14 × 5–7) μm. This species was found in 7 of 45 (15.6%) U. talpoides. Sporulated oocysts of Eimeria honshuensis n. sp. were ellipsoid, 15.5 × 11.4 (13–18 × 10–13) μm, with sporocysts ovoid, 9.1 × 5.2 (8–10 × 4–6) μm. This species was found in 10 of 45 (22.2%) U. talpoides and in 5 of 6 (83.3%) D. pilirostris. Sporulated oocysts of Isospora dymecodi n. sp. were subspheroid/ellipsoid, 15.8 × 12.6 (13–17 × 11–13) μm, with sporocysts ellipsoid, 10.9 × 6.9 (10–13 × 6–8). This species was found in six of six D. pilirostris. Sporulated oocysts of Isospora urotrichi n. sp. were spheroid/subspheroid, 13.4 × 12.4 (11–16 × 9–14) μm, with sporocysts ovoid, 9.2 × 6.3 (8–11 × 5–7) μm. This species was found in 27 of 45 (60%) U. talpoides. Only 14 of 38 (36.8%) infected hosts (one D. pilirostris, 13 U. talpoides) were seen to be naturally infected with only one coccidian species when sampled.     

Hemiboea purpurea sp. nov. (Gesneriaceae) from a limestone area in Guangxi,China

Hemiboea purpurea Yan Liu & W. B. Xu, a new species of Gesneriaceae from Guangxi, China, is described and illustrated. The new species is similar to H. follicularis C. B. Clarke, but differs by smaller leaf blades, 3–10×2–5 cm, corolla purple, ca 2.0–2.5 cm long, exserted from the involucre, filaments glandular‐puberulent and staminodes 3. It is only known from one site in the Rongshui County.     

SEGREGATION IN NEW ALLOPOLYPLOIDS OF GOSSYPIUM. IV. SEGREGATION IN NEW WORLD × ASIATIC AND NEW WORLD × WILD AMERICAN HEXAPLOIDS

Phillips , Lyle L. (North Carolina State Coll., Raleigh.) Segregation in new allopolyploids of Gossypium. IV. Segregation in New World × Asiatic and New World × wild American hexaploids. Amer. Jour. Bot. 49(1): 51–57. 1962.—The New World tetraploid cottons, G. hirsutum and G. barbadense, are natural amphidiploids (genome formula, 2 [AD]) combining species of the cultivated Asiatic (2A) and wild American (2D) groups of diploid cottons. Genetic segregation for marker alleles in New World × Asiatic and New World × wild American synthetic hexaploids have been determined. Average segregation for several loci in New World × Asiatic hexaploids is close to the autoploid 5:1 ratio, ranging from 5.1 to 6.8:1. Average segregation for 3 loci (L, Rd, and R₁) common to a series of New World × wild American hexaploids is: New World × G. raimondii, 9.3:1;–× G. harknessii, 16.4:1;–× G. armourianum, 17.4:1;–× G. aridum, 20.3:1;–× G. lobatum, 21.4:1–× G. thurberi, 32.9:1;–× G. gossypioides, 66.5:1. These data are discussed, and the method by which they were derived is compared with other cytogenetical means of discerning phylelic interrelationships among Gossypium species.     

Properties of a new strain of tobacco streak virus from Clematis vitalba (Ranunculaceae)

A distinct strain of tobacco streak virus (TS V/Cle), isolated in Yugoslavia from wild Clematis vitalba showing chlorotic spots or yellow netting of the leaves and from many symptomless shrubs, is described. TSV/Cle was seed transmitted in C. vitalba (70%), and in the experimental hosts Chenopodium quinoa (80%), Nicotiana benthamiana and N. megalosiphon. It was also detected in the pollen of infected C. quinoa. Purified virus preparations mostly contained quasi-spherical particles measuring 24–26 × 28, 26–28 × 28–30 and 28–31 × 32–36 mn, and sedimented in sucrose density gradient and analytical centrifugation as three components with sedimentation coefficients of 76S, 87S and 98S. The virus contained a single polypeptide species of mol. wt of c. 25 000. Unfractionated TSV/Cle preparations contained four RNA species with mol. wts, estimated by gel electrophoresis in agarose, of 1.1 × 10⁶, 0.9 × 10⁶, 0.7 × 10⁶ and 0.3 × 10⁶. In comparative experiments, TSV/Cle differed from four reference strains of TSV (TSV/B, TSV/HF, TSV/RN, and TSV/Ro) in host range and in symptoms induced in some common hosts. In agar gel double diffusion tests it was more closely related to TSV/B and TSV/M (SDI = 5) than to TSV/HF (SDI = 7), TSV/RN (SDI = 7) or TSV/Ro (SDI = 5–8). Immunoelectrophoresis experiments clearly distinguished TSV/Cle from the reference strains. TSV/Cle strain was detected in C. vitalba plants from distant and climatically different regions in Yugoslavia.     

Coccidia of Brazilian Mammals: Eimeria corticulata N. Sp. (Apicomplexa: Eimeriidae) from the Anteater Tamandua tetradactyla (Xenarthra: Myrmecophagidae) and Eimeria zygodontomyis N. Sp. from the Cane Mouse Zygodontomys lasiurus (Rodentia: Cricetidae)

Feces from a specimen of Tamandua tetradactyla (Linn.) from Portel, Para State, north Brazil, contained two different coccidial oocysts; one identified as Eimeria tamanduae Lainson 1968, and the other as a new species, described here as Eimeria corticulata n. sp. Oocysts of E. corticulata are ellipsoidal, 37.4 × 30.4 (31.2–43.7 × 23.7–35.0) μm, shape index (length/width) 1.2 (1.0–1.5). Oocyst wall 2.5–3.7 μm thick and composed of two layers; an outer thick, brown-yellow one with radial striations, and a thin inner smooth one: no visible micropyle. Oocyst residuum a large globule of about 10.7 × 10.3 μm, usually accompanied by a number of smaller attached globules. Sporocysts ellipsoidal, 21.0 × 11.0 (20.0–22.5 × 10.0–12.5) μm, with a conspicuous Stieda body: shape index 1.9 (1.6–2.2). Sporocyst residuum a small number of scattered granules: sporozoites 18.7 × 5.0 μm, with a large posterior refractile body. Eimeria zygodontomyis n. sp. is described in feces from Zygodontomys lasiurus (Lund) from the Serra dos Carajas, Para. Oocysts ellipsoidal to cylindrical, 16.5 × 12.0 (13.7–18.7 × 11.2–12.3) μm, shape index 1.4 (1.2–1.5). Wall colorless, smooth, single-layered and about 0.6 μm thick: no micropyle. No oocyst residuum, but a polar granule of about 1.8 × 1.0 μm is sometimes present. Sporocysts ellipsoidal, 8.4 × 5.5(7.5–8.7 × 5.0–6.2) μm, shape index 1.5 (1.4–1.7), with a thin colorless wall and a delicate Stieda body. Sporozoites enclose a compact residuum of about 2.5 × 3.7 μm.     

Biomass production and energy balance of Miscanthus over a period of 11 years: A case study in a large‐scale farm in Poland

Giant miscanthus (Miscanthus × giganteus Greef and Deuter) and Amur silver grass (Miscanthus sacchariflorus Maxim./Hack) are rhizomatous grasses with a C4 photosynthetic pathway that are widely cultivated as energy crops. For those species to be successfully used in bioenergy generation, their yields have to be maintained at a high level in the long term. The biomass yield (fresh and dry matter [DM] yield) and energy efficiency (energy inputs, energy output, energy gain, and energy efficiency ratio) of giant miscanthus and Amur silver grass were compared in a field experiment conducted in 2007–2017 in North‐Eastern Poland. Both species were characterized by high above‐ground biomass yields, and the productive performance of M. × giganteus was higher in comparison with M. sacchariflorus (15.5 vs. 9.3 Mg DM ha^?1 year^?1 averaged for 1–11 years of growth). In the first year of the experiment, the energy inputs associated with the production of M. × giganteus and M. sacchariflorus were determined at 70.5 and 71.5 GJ/ha, respectively, and rhizomes accounted for around 78%–79% of total energy inputs. In the remaining years of cultivation, the total energy inputs associated with the production of both perennial rhizomatous grasses reached 13.6–15.7 (M. × giganteus) and 16.9–17.5 GJ ha^?1 year^?1 (M. sacchariflorus). Beginning from the second year of cultivation, mineral fertilizers were the predominant energy inputs in the production of M. × giganteus (78%–86%) and M. sacchariflorus (80%–82%). In years 2–11, the energy gain of M. × giganteus reached 50 (year 2) and 264–350 GJ ha^?1 year^?1 (years 3–11), and its energy efficiency ratio was determined at 4.7 (year 2) and 18.6–23.3 (years 3–11). The energy gain and the energy efficiency ratio of M. sacchariflorus biomass in the corresponding periods were determined at 87–234 GJ ha^?1 year^?1 and 6.1–14.3, respectively. Both grasses are significant and environmentally compatible sources of bioenergy, and they can be regarded as potential energy crops for Central‐Eastern Europe.     

Maclurochloa tonkinensis sp. nov. (Poaceae: Bambusoideae) from Vietnam

Maclurochloa K. M. Wong (Gramineae: Bambusoideae) is a genus of clambering bamboos with dry caryopses. It was thought to be monotypic in Peninsular Malaysia, but here we report one more species from Vietnam which is new to science: Maclurochloa tonkinensis H. N. Nguyen et V. T. Tran sp. nov. Maclurochloa tonkinensis is most similar to M. montana (Ridl.) K. M. Wong from which differs mainly by having internodes 50–58 × 3.0–3.5 cm and culm leaves with auriculate sheaths and erect blade.     

Genetic diversity of the genus Malus and implications for linkage mapping with SNPs

Knowledge about the sequence-based genetic diversity of a crop species is important in order to develop highly informative genotyping assays, which will eventually positively impact breeding practice. Diversity data were obtained from two pools of 185 and 75 accessions each, representing most of the species belonging to the genus Malus, by re-sequencing 27 gene-specific amplicons and by screening 237 Malus × domestica SNPs using the multiplex genotyping technology SNPlex™. Nucleotide diversity and insertion/deletion rates in M. × domestica were estimated as π = 0.0037 and 1/333 bp, respectively. The SNP frequency was estimated as 0.0194 (1 SNP/52 bp) while within a single apple cultivar an average of one SNP in every 455 bp was found. We also investigated transferability (T _SNP) of the heterozygous state of SNPs across the species M. × domestica and the genus Malus. Raw re-sequencing showed that 12–15% of M. × domestica SNPs are transferable to a second M. × domestica cultivar, however T _SNP rose to ∼41% with SNPs selected for high minor allele frequency. T _SNP of chosen SNPs averaged ∼27% in the two M. × domestica-related species, Malus sieversii and Malus sylvestris, but was much lower in more distantly related species. On the basis of T _SNP, simulations, and empirical results, we calculated that a close-design, multiplexed genotyping array with at least 2,000 SNPs is required for building a highly saturated linkage maps within any M. × domestica cross. The same array would gradually lose informativeness in increasingly phylogenetically distant Malus species.     

Sympatric occurrence of three leaf beetle species of Macroplea Samouelle, 1819 (Coleoptera,Chrysomelidae, Donaciinae) in Finland with a key to species in Northern Europe

Macroplea Samouelle, 1819 is the only known fully aquatic leaf beetle genus with three European species that have earlier been classified by their assumed water salinity preferences. We studied the inter- and intraspecific variation of the specimens living in Northern Europe using both molecular (cytochrome c oxidase subunit I, COI) and morphological evidence. The variation in the COI sequences between M. mutica (Fabricius, 1792) and M. pubipennis (Reuter, 1875) was 8.4%–9%, M. mutica and M. appendiculata (Panzer, 1794) – 3.9%–4.9%, and M. appendiculata and M. pubipennis – 8.8%–9.2%. All three species were sampled together in the Bothnian Sea on the same water plants, showing that neither salinity nor plant species bear a decisive importance in their occurrence in the region. Phylogenetic results suggest the existence of two currently unknown Macroplea species that are evolutionarily close to M. appendiculata. A key to the Nordic species is provided.     

Effects of several establishment modes of Miscanthus × giganteus and Miscanthus sinensis on yields and yield trends

Miscanthus is a C4 perennial grass originating from East Asia, the yields of which progressively increase in the first years of growth. Several species for bioenergy have been studied since the mid‐1980s in Europe, in particular (Miscanthus × giganteus [M. × giganteus]), due to its high yields. M. × giganteus is mainly cultivated in France and established from rhizomes. Our study aimed to assess, in field conditions, alternative establishment methods combined with an alternative species, Miscanthus sinensis (M. sinensis). We set up a multi‐environment experimental network. On each trial, we tested two treatments with M. × giganteus, established from rhizomes (G_r‐sd) and from plantlets obtained from rhizomes (G_p‐sd), and two treatments with M. sinensis seedlings transplanted in single (S_p‐sd) and double density (S_p‐dd). ANOVA was performed to compare establishment and regrowth rates across treatments, as well as yields across treatments and site‐years. A logistic model was used to describe yield trends and to compare the maximum yield reached and the rate of yield increase of both species. Results showed that miscanthus establishment from plantlets resulted in higher establishment (between 87% and 92%) and regrowth (between 91% and 94%) rates compared to establishment from rhizomes. Treatments with M. × giganteus obtained higher average yields across site‐years than those with M. sinensis, but more variable yields across site‐years. We showed a strong species effect on yields, yield components (shoot weight, shoot density and shoot number per plant) and light interception (through leaf area index). Lastly, to use M. sinensis established from transplanted plantlets as an alternative to M. × giganteus, research would be required on the breeding of M. sinensis sterile seeds to avoid risks of invasiveness.     

Competition of Ethionine and Methionine for Aminoacyl-tRNA Formation in an In Vitro System from Ochromonas danica*

Aminoacyl-tRNA synthetase and tRNA were isolated from the chrysomonad Ochromonas danica. The mutual effect of methionine and ethionine, and the effect of other amino acids on methionyl- and ethionyl-tRNA formation, were tested in an in vitro system. The tRNA^Met had a similar accepting capacity for either methionine or ethionine. Ethionine and methionine, but none of the other amino acids tested, competed for the same aminoacyl-tRNA synthetase. The K_m of methionine was 0.88 × 10^–5 M, and that of ethionine 5 × 10^–4 M. Ethionine inhibited methionine binding; K_i 3.4 × 10^–4 M. The respective values in a similar system isolated from E. coli were 2.2 × 10^–5, 1.95 × 10^–3, and 1.95 × 10^–3.     

Three‐dimensional (3‐D) fluorescence spectroscopy analysis of the fluorescent dissolved organic matter released by the marine toxic dinoflagellate Alexandrium catenella exposed to metal stress by zinc or lead

We investigated the effects of zinc or lead on growth and on exudation of fluorescent dissolved organic matter (FDOM) by the marine toxic dinoflagellate Alexandrium catenella (Whedon & Kofoid) Balech. The species was exposed to increasing free zinc (1.34 × 10^?7 M–3.98 × 10^?6 M) or lead (5.13 × 10^?9 M–1.82 × 10^?7 M) concentra‐tions. Low metal levels ([Zn²⁺] = 1.34 × 10^?7 M; [Pb²⁺] = 5.13 × 10^?9 M) had no effect on cell growth. Toxic effects were observed from higher metal contamination ([Zn²⁺] = 3.98 × 10^?6 M; [Pb²⁺] = 6.54 × 10^?8 M), as a conversion of vegetative cells into cysts. Analysis of the released FDOM by three‐dimensional (3‐D) fluorescence spectroscopy was achieved, using the parallel factor analysis (PARAFAC). The PARAFAC modeling revealed four components associated with two contributions: one related to the biological activity; the other linked to the organic matter decomposition in the culture medium. The C1 component combined a tryptophan peak and characteristics of humic substances, whereas the C2 component was considered as a tryptophan protein fluorophore. The two others C3 and C4 components were associated with marine organic matter production. Relea‐sed fluorescent substances were induced by low ([Zn²⁺]= 1.34 × 10^?7 M; [Pb²⁺] = 5.13 × 10^?9 M) and moderate ([Zn²⁺] = 6.21 × 10^?7 M; [Pb²⁺] = 2.64× 10^?9 M) metal concentrations, suggesting the activation of cellular mechanisms in response to metal stress, to exudate FDOM that could complex metal cations and reduce their toxicity toward A. catenella cells.     

The effect of simulated seasonal temperatures on Metarhizium brunneum-associated mortality in Agriotes spp. click beetles,and a degree-day infection model

Entomopathogens tend to have a slow speed of kill when used for targeting agricultural insect pests. Relating temperature as a driver of this speed is important to predict pest mortality, and extending this to a degree-day infection model has rarely been studied. Many species of wireworms (Coleoptera: Elateridae), the larvae of click beetles, are subterranean and generalist agricultural pests that can be difficult to control with pesticides. Targeting adult beetles, however, may be an effective method to reduce larval recruitment. Metarhizium brunneum Petch (Hypocreales), an entomopathogenic fungus, kills click beetles but the mortality rate and speed of kill are expected to vary according to temperature. Using a thermal gradient plate to simulate daily oscillating temperatures in Agassiz, British Columbia, Canada, for April, May, and June, the effectiveness of M. brunneum strains LRC112 and F52 in causing mortality to Agriotes obscurus (L.) and Agriotes lineatus (L.) click beetles was studied in the laboratory. Mortality was fastest in beetles exposed to June temperatures and slowest in those exposed to April temperatures, with differences among beetle species × M. brunneum strain combinations. Higher temperatures resulted in more rapid mycelial outgrowth and conidiation in beetle cadavers, with only A. obscurus infected with M. brunneum LRC112 attaining near 100% conidiation. The number of degree days required to kill 50% of the beetles (LDD₅₀) was least for A. obscurus infected with M. brunneum LRC112 (176) followed by A. obscurus × M. brunneum F52 (212), A. lineatus × M. brunneum LRC112 (215), and A. lineatus × M. brunneum F52 (292). Hypothetical calculations showed that M. brunneum exposure earlier in the season resulted in a longer time to kill 50% of the beetles (LT₅₀) but the earliest LT₅₀ calendar date. Later M. brunneum exposure dates resulted in lower LT₅₀'s, but later LT₅₀ dates. This conceptual work demonstrates that daily temperature oscillations, seasonality, and degree days must be considered to predict the efficacy and speed of kill of different fungal entomopathogen strains when targeting different click beetle species.