Performance and seasonal abundance of the neotropical brown stink bug, shape Euschistus heros nymphs and adults on a novel food plant (pigeonpea) and soybean

Pigeonpea, Cajanus cajan (L.) Millsp. (Leguminosae) was found as a novel food plant of the neotropical brown stink bug, Euschistus heros (F.), in Paraná State, Brazil. Laboratory studies indicated nymphs performing better when fed on immature pods of soybean, Glycine max (L.) Merrill (Leguminosae), than on immature pods of pigeonpea. Female nymphs required 1.7 d less to complete development and tended to have a lower mortality on soybean (17.5%) than on pigeonpea (25.0%). At emergence, fresh body weight was greater on soybean than on pigeonpea. Adult E. heros performed better on soybean than on pigeonpea. After 120 d, 35% of adults were alive on soybean and 30% on pigeonpea; 93.3% of females oviposited on soybean, and 73.3% on pigeonpea, with an oviposition delay of 17 days on pigeonpea compared to soybean. Fecundity was 63% greater on soybean than on pigeonpea, and adult body weight gain for females and males at different ages was 6–36% greater on soybean than on pigeonpea. E. heros colonized soybean during January–March, from the pod-setting and filling stages (R3–R6) to maturity (R7–R8), and pigeonpea during April–June. These results indicate that E. heros has expanded its host range to pigeonpea in Brazil; pods of this plant are suitable food, and can support the insect during autumn-early winter, after soybean harvest, and before it enters into partial hibernation.     

Contribution to the rotifer fauna of subarctic Greenland (Kangerlussuaq and Ammassalik area)

Six water bodies in the region of Kangerlussuaq, West Greenland (67° 30 N, 50° 46 W), and four near Ammassalik, East Greenland (65° 36 N, 37° 38 W) were sampled. Sixty-nine taxa (2 Bdelloidea, 67 Monogononta) are reported, forty-six of which represent new records for Greenland. Proales pejleri n. sp. is described.     

Lipid peroxidation as the mechanism of modification of brain 5′-nucleotidase activity in vitro

The effect of lipid peroxidation on the Mg²⁺-independent and Mg²⁺-dependent activity of brain cell membrane 5-nucleotidase was determined and the affinity of the active sites of Mg²⁺-dependent enzyme for 5-AMP (substrate) and Mg²⁺ (activator) was examined. Brain cell membranes were peroxidized at 37°C in the presence of 100 M ascorbate and 25 M FeCl₂ (resultant) for 10 min. The activity of 5-nucleotidase and lipid peroxidation products (thiobarbituric acid reactive substances) were determined. At 10 min, the level of lipid peroxidation products increased from 0.20±0.10 to 17.5±1.5 nmoles malonaldehyde/mg membrane protein. The activity of Mg²⁺-independent 5-nucleotidase increased from 0.201±0.020 in controls to 0.305±0.028 mol Pi/mg protein/hr in peroxidized membranes. In the presence of 10mM Mg²⁺, the activity increased by 5.8-fold in the peroxidized membrane preparation in comparison to 14-fold in control In peroxidized preparation, the affinity of active site of Mg²⁺-dependent 5-nucleotidase for 5-AMP tripled, as indicated by a significant decrease inK _m (K _m=95±2 M AMP for control;K _m=32±2 MAMP for peroxidized).V _max was significantly reduced from 3.35±0.16 in control to 1.70±.09 moles Pi/mg protein in peroxidized membranes. The affinity of the active site for Mg²⁺ significantly increased (K _m=6.17±0.37 mM Mg²⁺ for control;K _m=4.0±0.31 peroxidized). The data demonstrate that lipid peroxidation modifies the Mg²⁺-dependent 5-nucleotidase function by altering the active sites for both the substrate and the activator. The modification of the 5-nucleotidase activity and the loss of Mg²⁺-dependent activation observed in this in-vitro study are similar to the changes previously observed by us in the hypoxic brain in-vivo. This suggests that lipid peroxidation which specifically alters the active site may be the underlying mechanism of the modification of 5-nucleotidase during hypoxia.     

High temperature induced diapause in the cotton bollworm shape Helicoverpa armigera

In laboratory studies, Helicoverpa armigera (Hübner) (Lep. Noctuidae) from Burkina Faso exhibited pupal dormancy induced by high temperatures. Exposure to 37 °C from the 3rd larval stage caused 94.7% of males to diapause but only 60.9% of females. No influence of daylength (12 and 16 h) was observed. Induction by high temperatures must begin during the larval stage to be effective. The pupal stage is not sensitive to induction. After storage at 37 °C for 60 days, 64.3% of dormant pupae survived and most of them resulted in adult emergence. After storage at 37 °C for 85 days, no dormant pupae survived. The development of dormant pupae is resumed after about 20 days at 21 °C whatever the duration of prior exposure to 37 °C (7, 14 or 30 days). There is no delay in non-dormant pupae kept at 21 °C. The possible role of this hot thermal diapause in the life history of H. armigera in Burkina Faso is discussed.     

Distribution of stream macroalgae in the northwest region of São Paulo State,southeastern Brazil

Forty-four stream segments were sampled from May to October in 1992 and 1993 in the northwest region of São Paulo State, southeastern Brazil (19°45–21°25S, 49°05–51°30S). Thirty-six macroalgal subgeneric taxa were found and Chlorophyta was the dominant algal group (47% species), followed by Cyanophyta (33.5%), Rhodophyta (14%) and Chrysophyta (5.5%). The most widespread species wereStigeoclonium helveticum (25% sites),Batrachospermum delicatulum andCompsopogon coeruleus (20.5%). Distribution was patchy, with species number per sampling site ranging from 0 to six (3.1 ± 1.7) and correlated positively with species abundance. Species cover ranged from 0 to 61% of the stream bottom (19.1 ± 19.7%). Most sites (57%) were dominated by one or two macroalgae species. No significant difference was found between the frequency distribution of variables measured for streams and for total macroalgae, but the most widespread species differed for most parameters and occurred over wider ranges of environmental conditions. Mean species number and abundance were close to values found in distinct regions or biomes of North America. Higher conductance and lower oxygen values, as well as rocky substrata, generally constituted the most favourable combination of conditions for the development of macroalgae in the region. The pattern of strong dominance of few species was considered to be typical for stream macroalgal communities in general.     

Diversity, geographical distribution, and conservation of Cactaceae in the Mier y Noriega region, Mexico

We carried out an inventory of the cactus species occurring in the Mier y Noriega region. The study was conducted in a square-shaped area of approximately 2845km², located in the southeastern segment of the Chihuahuan Desert region, between 23°00 – 23°30 lat. N and 100°00 – 100°30 long. W, including parts of the states of Nuevo León, Tamaulipas, and San Luis Potosí, Mexico. In order to know the cactus diversity, we developed an intensive method of botanical collecting; a total of 80 sites were sampled. With 54 species recorded, of which 28 were new area records and 14 new state records, the Mier y Noriega region is considered moderately rich in cactus species. Cactus diversity is distributed unevenly in the area, and the greatest species concentration occurs in its southwestern portion. The analysis of geographical distribution of individual species showed that the highest proportion (82%) are endemic to the Chihuahuan Desert Region, six of them having extremely narrow distributions. In addition, 19 species are considered endangered. With the aid of a complementarity analysis, we propose a strategy for the optimal conservation of the species and their habitats.     

The Atlantic forest in the Volta Velha Reserve: a tropical rain forest site outside the tropics

With its very broad latitudinal extension (from 5° to 30°S), Brazil's Atlantic Rain Forest includes sites that wouldnot be classified as tropical by commonly used climatic classificationsystems. This situation particularly holds for the sites nearthe southern limits of this ecosystem. The goal of this study was to assess forest floristic composition, physiognomic aspects (deciduousspecies, leaf types, leaf area index) and reproductive biology (monoecious/dioeciousspecies, pollination syndromes and dispersal syndromes) of the Atlantic forest in the Volta VelhaReserve, southern Brazil (26°04 S, 48°38 W Gr). The research focuses on theaffinities of this site, which lies outside generally accepted boundaries for tropical forest. Theresults demonstrate that Volta Velha has a typically tropical floristic composition, apparentlymaintained by local climatic conditions. The differences between the characteristics of the VoltaVelha forest and those of other tropical stands are within the range of differences observed amongclassically defined tropical sites.     

Responsiveness of Amaranthus retroflexus seeds to ethephon, 1-aminocyclopropane 1-carboxylic acid and gibberellic acid in relation to temperature and dormancy

Dormant Amaranthus retroflexus seeds do not germinate in the dark at temperatures below 35°C. Fully dormant seeds germinate only at 35–40°C whereas non-dormant ones germinate within a wider range of temperatures (15 to 40°C). Germination of non-dormant seeds requires at least 10% oxygen, but the sensitivity of seeds to oxygen deprivation increases with increasing depth of dormancy. 10^–6 to 10^–4 M ethephon, 10^–3 M 1-aminocyclopropane 1-carboxylic acid (ACC) and 10^–3 M gibberellic acid (GA₃) break this dormancy. In the presence of 10^–3 M GA₃ dormant seeds are able to germinate in the same range of temperatures as non-dormant seeds. The stimulatory effect of GA₃ is less dependent on temperature than that of ethephon, while ACC stimulates germination only at relatively high temperatures (25–30°C). The results obtained are discussed in relation to the possible involvement of endogenous ethylene in the regulation of germination of A. retroflexus seeds.Abbreviations ACC 1-aminocyclopropane 1-carboxylic acid - GA₃ gibberellic acid - SD standard deviation     

A phytosociological analysis of woody species in forest communities of a part of Kumaun Himalaya

This paper reports on a detailed phytosociological analysis of forests in the NW catchment of the Gola River in Kumaun Himalaya, 29°19–29°27N and 79°32–79°42E. Fourteen sites and 56 stands at elevations ranging from 1200 to 2523 m and covering the following five forest types were investigated: Pinus roxburghii, mixed, Quercus leucotrichophora, Q. lanuginosa, and Q. floribunda. The basal cover of the forests differed according to slope position and aspect. The three oak forests had more basal cover than the other two, and Q. lanuginosa had the most. The performance of individual tree and shrub species and the number of saplings and seedlings differed according to slope position and aspect. The mixed forest had the greatest tree diversity, and among the others diversity increased with increasing basal cover. The diversity of trees, saplings, and herb layer was greatest on aspects with intermediate temperature and moisture conditions; whereas that of shrubs and seedlings increased towards the cooler (and wetter) and warmer (and drier) exposures. There was a positive relation between the diversity of shrubs plus seedlings and trees plus saplings in P. roxburghii and mixed forests; whereas this relationship was inverse in the three oak forests. In general, the dominance-diversity curves for the tree layer followed a geometric series conforming to the niche pre-emption situation in communities of low diversity. Among the forests, the regeneration was best in Q. lanuginosa and worst in Q. leucotrichophora.Nomenclature follows: Osmaston (1926).Finacial support from the Council of Scientific and Industrial Research, New Delhi and the Indian Space Research Organisation, Banglore is gratefully acknowledged.     

Determination of internal dynamics of deoxyriboses in the DNA hexamer d(CGTACG)2 by 1H NMR

The conformations and internal dynamics of the deoxyriboses of d(CGTACG)₂ have been determined by NMR measurements at 15°C. The conformations of the sugars were determined using coupling constants and time-dependent NOE measurements. The J-splitting patterns of the H1, H2 and H2 resonances show that the sugars exist as mixtures of conformations near C2 endo (south) and C3 endo (north). The population of the south conformation was larger for the purines than for the pyrimidines. The overall tumbling time of the molecule in ²H₂O was determined from measurements of the cross relaxation rate constant for the H6-H5 vectors of the two cytosine residues. Order parameters were determined for the H1-H2, H2-H2 and H2-H3 vectors from measurements of cross relaxation rate constants, making use of multi-spin analysis of the NOE build up rates. These order parameters are weakly dependent of the base sequence, and except for the terminal Cyt 1 residue, the H2-H2 and H2-H3 vectors are near unity, indicating the absence of rapid pseudorotation on the nanosecond time scale. However, the order parameter for the H1-H2 vector is significantly smaller than expected for rapid pseudorotation indicating the presence of other motions of the sugars. This motion must be about an effective axis parallel to the H2-H vector, and to occur with an angular fluctuation of about 30°.The results show that to obtain highly refined structures for nucleic acids by NMR the effects of spin diffusion and motional averaging cannot be ignored.Some of this work was presented as a poster at the 30^th Experimental NMR Conference at Asilomar, California 1989     

Detecting successional changes in long-term empirical data from subalpine conifer forests

The gap dynamics of two Nothofagus pumilio (lenga) stands have been investigated. We evaluated and compared tree diameter distributions, spatial patterns, tree fall and gap characteristics and regeneration responses in gaps in two old-growth forests of Nothofagus pumilio in Southern Chile (Shangri-La: 36°60 S, 71°30 W; Reserva Coyhaique: 45°52 S, 72°00 W). In addition, we describe relationships between gap size and regeneration characteristics. We detected some differences in tree and sapling densities between sites. The causes of gap formation and the gap size distribution, mean gap area, and gap fraction were similar, but gap abundance was different at the two sites. The Reserva Coyhaique site had 15 gaps/ha compared to 10 gaps/ha for Shangri-La. Sizes of clumps of trees were within the range of sizes of canopy gaps at both sites. The density of saplings was higher in gaps than under closed forest at R. Coyhaique, but not at Shangri-La. We found that sapling densities were unrelated to gap size in both sites. The lower sapling density in gaps at Shangri-La might be explained by the presence of Chusquea quila, a competitive pioneer bamboo species. The height increment was related to gap size at Shangri-La, but not at R. Coyhaique. Gap size itself does not account for all the variation in recruitment performance in these Southern beech stands.     

Stable sulfur isotopic biogeochemistry of the Hubbard Brook Experimental Forest, New Hampshire

In natural ecosystems, differences often exist in the relative abundanceof stable S isotopes (°³⁴S) that can provide clues as tothe source, nature, and cycling of S. Values of °³⁴S inprecipitation, throughfall, soils, soil solution, and stream waters weremeasured at the Hubbard Brook Experimental Forest (HBEF), New Hampshire.Values of °³⁴S in precipitation and throughfall weresimilar to each other but differed seasonally. Precipitation°³⁴S values were higher in the dormant season[°³⁴S = 5.9±0.6 (17)][Mean + SE(N)]than in the growing season [°³⁴S = 5.0±0.6(40)] but throughfall growing-season values were higher[°³⁴S = 5.6±0.6(68)] than for the dormantseason [°³⁴S = 4.9±0.7 (9)]. Different treespecies did not affect throughfall °³⁴S values. In soilsolution, °³⁴S values were higher in the growing season(°³⁴S = 8.9±2.8; 8.8±1.7;and 4.0±0.6 for Oa, Bh, and Bs horizons, respectively) thanin the dormant season (°³⁴S = 5.6±1.5;3.7±2.4; and 3.4±1.2 for Oa, Bh, and Bshorizons, respectively). These seasonal differences in°³⁴S were probably caused by biological isotopicfractionation. The °³⁴S values in streams were generally2 lower and more variable than those in precipitation andthroughfall, suggesting fractionation and/or different isotopic sources inthe soil.     

Genetic evidence for the nature, and excision repair, of DNA lesions resulting from incorporation of 5-bromouracil

Summary Escherichia coli mutants defective in DNA uracil N-glycosidase (ung ^–) or endonuclease VI active against apurinic/apyrimidinic sites in DNA (xthA^–) exhibit enhanced sensitivity towards 5-bromodeoxyuridine relative to the wild type strain, pointing to involvement of these enzymes in repair of bromouracil-induced lesions in DNA.Mutants defective in DNA polymerase I, either in polymerizing activity (polAl^–) or (53)-exonuclease activity (polA107^–) exhibit unusually high sensitivity (including marked lethality) in the presence of 5-bromodeoxyuridine. The results indicate that DNA polymerase I, and its associated (5–3)-exonuclease activity, are involved in repair of bromouracil-induced lesions and are not readily replaced, if at all, by DNA polymerases II and III.Thermosensitive mutant in DNA ligase gene (lig ts7) shows high sensitivity towards 5-bromodeoxyuridine at 42°C indicating the role of the enzyme in repair of bromouracil-induced lesions in DNA.Involvement of DNA uracil N-glycosidase, and endonuclease active against apurinic/apyrimidinic sites in recognition and repair of 5-bromouracil-induced damage permits of some inferences regarding the nature of this damage (lesions), in particular dehalogenation of incorporated bromouracil to uracil residues.     

Correlations between phytoplankton,organic detritus and carbon in North Sea waters during the Fladenground Experiment (FLEX' 76)

Quantitative analysis of phytoplankton, organic detritus and dissolved organic carbon was carried out, during the spring bloom, in a specific North Sea area (58° 55 N, O° 32 E) in the course of an international and multidisciplinary marine investigation (FLEX' 76). An attempt was made to correlate the fluctuations of these variables; the analysis, however, was complicated by massive water movements. A maximum of the phytoplankton bloom coincided with a maximum of organic detritus, while both variables turned out to be inversely correlated with the dissolved organic carbon content. The initial, high amount of dissolved organic carbon declined at a daily rate of ca. 13% during a period of non-interference by water movements. Two thirds of the dissolved organic carbon content are assumed to be transformed into particulate organic matter whilst the rest disappears through still unknown channels.     

Summer dormancy as a refuge from mortality in the freshwater bryozoan Plumatella emarginata

In expanding populations, individuals that produce dormant offspring when conditions are otherwise suitable for growth and reproduction incur a cost, since the dormant life stage delays reproduction. These individuals are at a disadvantage unless (1) there is not enough time for reproduction to occur before the environment degrades, or (2) the probability of death in the non-dormant state is high. Here we investigate resting stages of the freshwater bryozoan Plumatella emarginata to test the prediction that delayed emergence from dormancy can be related to seasonal fluctuations in mortality. Our results show that emergence in late spring and summer occurs at much lower frequencies than in early spring and is strongly associated with high mortality, at least in part due to predation. We document significant reductions in the growth and survival of plumatellid colonies during the summer in the presence of the crayfish Orconectes limosus. Thus summer dormancy provides a significant refuge from predation. Dormant resting stages during the winter also experience significant mortality. Our results are consistent with the general notions that (1) the proportion of colonies emerging from dormancy reflects tradeoffs in the relative risks of mortality in dormant versus non-dormant states, and (2) temporal shifts in the risk of mortality influence the timing of life-cycle transitions.     

Diversity of forest tree species in Yanbaru,the northern part of Okinawa Island

The natural forests of Yanbaru, in the northern part of Okinawa Island, harbor many endemic and endangered birds and mammals, and are dominated by an evergreen oak, Castanopsis sieboldii. The Simpson diversity (D) and equitability index (J) were calculated using survey data on number of stems ( 4.5 cm DBH) of each species found in sample plots.Near-climax old forests (age 50 yr, without pine trees) showed high species diversity of trees, 0.92 ± 0.01 in D and 0.83 ± 0.05 in J for trees of which DBH 4.5 cm, and 0.81 ± 0.04 in D and 0.75 ± 0.05 in J for trees of DBH 10 cm.These high values are comparable to those of tropical rain forests. Although even young forests showed high species diversity, diversity indices tended to increase with forest age.The U.S. Marine Corps leases the eastern half of Yanbaru which contains most of these near-climax forests. Conservation of natural forests in this area is recommended.     

Dormancy in Cereal Seeds: II. THE NATURE OF THE GASEOUS EXCHANGE IN IMBIBED BARLEY AND RICE SEEDS

When barley seeds imbibe water, the O₂ uptake of non-dormantseeds is considerably less than that of dormant seeds for atleast the first 6 h, irrespective of the rate at which the seedshad previously lost dormancy. During the initial 6 h of imbibition, the CO₂ output of dormantbarley seeds is usually only slightly greater than and sometimesno different from that of nondormant seeds. The CO₂ output ofdormant seeds is reduced by about 66 percent by millimolar KCN,whereas that of non-dormant seeds is decreased by about 12–13per cent only. The CO₂ output of dormant barley in nitrogenis considerably less than the CO₂ output of non-dormant seedsunder the same conditions. Dormant rice seeds also show a higher initial O₂ uptake thannon-dormant seeds, though this is not generally as marked asin barley. Similarly, the initial CO₂ output of dormant seedsis distinctly greater than that of non-dormant seeds, but inmillimolar KCN it is depressed to a greater extent than in non-dormantseeds. In nitrogen, the CO₂ outputs of dormant and non-dormantseeds were found to be the same. Consequently, unlike barley,dormant rice seeds appear to be as capable of carrying out alcoholicfermentation under anaerobic conditions as nondormant seeds. In barley, increasing the O₂ tension from 21 per cent to 100per cent increased the oxygen uptake of dormant seeds more thanthat of non-dormant seeds (an increase of 53 per cent as against20–23 Per cent). In dormant seeds there was a concomitantincrease in CO₂ output (about 50 per cent), but the CO₂ outputof non-dormant seeds was hardly affected. High concentrations of CO₂ are inhibitory to the germinationof both dormant and non-dormant barley seeds. At a concentrationof 10 per cent, however, CO₂ is inhibitory only to dormant seeds,although at 2.5–5 per cent it is sometimes stimulatoryto the germination of dormant seeds. A 24–h treatmentwith appropriate concentrations of ethanol, lactic acid, oracetaldehyde is also stimulatory to the germination of dormantbarley seeds. Histochemical investigations in barley indicated the presenceof peroxidase, cytochrome oxidase, and -glycero-phosphate dehydrogenasein the embryo, aleurone layer, and in a layer associated withthe testa. A number of other redox enzymes were detected inthe embryo and aleurone layer only. No differences in distributionor intensity of activity were detected between dormant and nondormantseeds.     

Reproductive isolation between the two forms ofPanonychus akitanus Ehara (Acarina: Tetranychidae)

Crossing experiments were carried out between the stiped-egg form collected from Sapporo (43°04N) and Machida (35°33N), and the stipeless-egg form ofPanonychus akitanus Ehara from Tomakomai (42°37N) and Imagane (42°34N). Intra-form crosses gave a high proportion of female progeny, but inter-form crosses only male progeny, suggesting that fertilization did not take place. The number of eggs laid during the first 10 days of the oviposition period was greater in intra-form crosses than in inter-form crosses (P<0.001). The latter, except for the cross between the Sapporo and the Imagane populations, had similar egg production to virgin females (P<0.05).Mated females showed a greater daily oviposition rate than virgin females. However, the latter drastically increased their oviposition rate after mating with their sons. The two forms are thus reproductively isolated.     

Fish populations in the Paraná River: Lentic environments of Diamante and San Pedro Areas (Argentine Republic)

Data on the fish populations of lentic water bodies of the Lower Paraná River in the Diamante and San Pedro areas (33°40–31°55 S, 59°40'–60°40 W), sampled during 1971 are given. Limnological characteristics such as surface area and depth of ponds, water turbidity, and plant cover are included. Differences in fish population size, structure, specific diversity, dominance, and biomass of particular species are established between two areas in a dry season.     

Seasonal phase shift and the duration of activity time in the Burbot,Lota lota (L.) (Pisces,Gadidae)

Summary The locomotor activity of the Burbot (Lota lota L.) performs a phase-shift of 180 ° towards the Zeitgeber (natural light-dark-cycle) twice a year at high northern latitudes (Messaure, Swedish-Lapland, 66 ° 42 N, 20 ° 25 E). The duration of activity in 24 hours never exceeds 11 hours. Maximum values are achieved just before the phase-shift in September/October and in February respectively. It is suggested that this fish species, frequently spread in North-European waters, has a maximum limit in its daily activity time (10 to 11 hours) controlled by phase-shift when the length of day (during day-activity) or night (during night-activity) becomes too long. In the course of the year the Burbot places the position of its activity on the shorter part of the light-dark-cycle.Supported by Swedish Natural Science Research Council and Max-Planck-Gesellschaft zur Förderung der Wissenschaften.