Greatest Populations Research Articles

The Relationship between International Migration, Agricultural Employment, and Household Labor Force in Türkiye

There isn't much academic research on the impacts of immigration on the labor market and job structure at the national level, although Türkiye is one of the nation’s hosting the greatest populations of refugees. Because of the scarcity of information, a research gap exists. As a result, the study was carried out to determine the impact of international migration on agricultural employment and the changes in agricultural employment in Türkiye. Johansen Co-integration and Granger Causality analyses were performed on data from 1988 to 2018 to evaluate the change in the agricultural workforce in Türkiye and to demonstrate the temporal influence of immigration. According to the findings of the cointegration study, a rise in emigration has a negative impact on the agricultural areas and agricultural employment while having a good impact on agricultural GDP. Migration has long-term detrimental consequences. According to the causality study, there is a one-way link between migration and agricultural GDP. A panel data analysis was performed to establish the short-term detrimental impact of migration on agricultural employment, as well as how the structure of employment altered and developed during this process. The statistics provide temporal data from 2004 to 2020, and the individual's agricultural employment status, education, income, continuous employment, and extra work status are cross-sectional data. According to the Panel Logistic Regression Analysis results, while more educated and higher income individuals leave away from the agricultural sector, the desire to have a side job leads the individual to the agricultural sector. International migration has a detrimental impact on agricultural employment and its structure in this scenario. As a result, the sustainability of the working arrangements established by immigration regulations should be assured, and limits and constraints should be implemented, particularly in the agricultural sector. When agricultural employees transition to other industries, agricultural areas are being used in ways that were not planned. As a result, in the long run, the decline in output may have a negative impact on agricultural GDP. This condition has been the topic of several research and may serve as the foundation for new ones.

Roughage to Concentrate Ratio and Saccharomyces cerevisiae Inclusion Could Modulate Feed Digestion and In Vitro Ruminal Fermentation.

The objective of this research was to investigate the effect of the roughage-to-concentrate (R:C) ratio and the addition of live yeast (LY) on ruminal fermentation characteristics and methane (CH4) production. The experimental design was randomly allocated according to a completely randomized design in a 4 × 4 factorial arrangement. The first factor was four rations of R:C at 80:20, 60:40, 40:60, and 20:80, and the second factor was an additional four doses of Saccharomyces cerevisiae (live yeast; LY) at 0, 2.0 × 106, 4.0 × 106, and 6.0 × 106 colony-forming unit (cfu), respectively. For the in vitro method, during the incubation, the gas production was noted at 0, 1, 2, 4, 6, 8, 10, 12, 18, 24, 48, 72, and 96 h. The rumen solution mixture was collected at 0, 4, 8, 12, and 24 h of incubating after inoculation. Cumulative gas production at 96 h was highest in the R:C ratio, at 20:80, while the addition of LY improves the kinetics and accumulation of gas (p > 0.05). Maximum in vitro dry matter digestibility (IVDMD) and in vitro organic matter digestibility (IVOMD) at 24 h after incubation were achieved at the R:C ratio 20:80 and the addition of LY at 6 × 106 cfu, which were greater than the control by 13.7% and 12.4%, respectively. Ruminal pH at 8 h after incubation decreased with an increased proportion of concentrates in the diet, whereas it was lowest when the R:C ratio was at 20:80. Increasing the proportion of a concentrate diet increased total volatile fatty acid (TVFA) and propionic acid (C3), whereas the acetic acid (C2) and C2-to-C3 ratios decreased (p < 0.05). TVFA and C3 increased with the addition of LY at 6 × 106 cfu, which was greater than the control by 11.5% and 17.2%, respectively. No interaction effect was observed between the R:C ratio and LY on the CH4 concentration. The calculated ruminal CH4 production decreased with the increasing proportion of concentrates in the diet, particularly the R:C ratio at 20:80. The CH4 production for LY addition at 6 × 106 cfu was lower than the control treatment by 17.2%. Moreover, the greatest populations of bacteria, protozoa, and fungi at 8 h after incubation were found with the addition of LY at 6 × 106 cfu, which were higher than the control by 19.0%, 20.7%, and 40.4%, respectively. In conclusion, a high ratio of roughage and the concentrate and addition of LY at 6.0 × 106 cfu of the total dietary substrate could improve rumen fermentation, improve feed digestibility, and reduce the CH4 production.

Characteristics of the butterflies on various forms of land uses

Abstract The purpose of the work was to identify the occurrence of butterflies depending on landform uses and human influence on the population domination structure. The research was conducted in the ‘Krzywda’ field-and-forest Site occupying 172 ha. The area consists of the land leaving in fallow, meadows and wasteland including about 68 ha of swamps that are strongly eutrophic due to human economic activity. The area is subjected to artificial succession inhibition processes in the form of mowing and cutting of trees and shrubs. 32 species of butterflies were recorded during the research, that is, 20% of all species within this group occurring in Poland. The research has approved the great spatial and quantitative diversification of the occurring area of butterflies depending on the form of the land uses. The greatest number of species and their greatest populations were found in the land laying in fallow without the removal of the biomass. The least number of species and their specimens were collected in the unmown laying fallow land. Lycaena virgaureae was the most numerous species collected. The correct domination structure characterized by a small number of numerous species and a large number of species consisting of a low number of specimens. Processes observed in the studied Site subjected to various types of land use influence the occurrence diversity of this group of insects.

环渤海沿海地区土地承载力时空分异特征

PDF HTML阅读 XML下载 导出引用 引用提醒 环渤海沿海地区土地承载力时空分异特征 DOI: 10.5846/stxb201311302853 作者: 作者单位: 辽宁师范大学海洋经济与可持续发展研究中心,辽宁师范大学海洋经济与可持续发展研究中心 作者简介: 通讯作者: 中图分类号: 基金项目: 教育部人文社会科学重点研究基地项目(12JJD790032) Land carrying capacity spatiotemporal differentiation in the Bohai Sea Coastal Areas Author: Affiliation: KRI-Center for Studies of Marine Economy and Sustainable Development，Liaoning Normal University,KRI-Center for Studies of Marine Economy and Sustainable Development，Liaoning Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:沿海地区是中国未来社会经济发展的重点区域,近年来沿海地区人地矛盾越来越突出,研究沿海地区土地承载力具有重要意义。针对以往评价中的不足,采用韦伯-费希纳定律确定指标评价标准;利用D-S证据理论进行主客观综合权重的计算,运用可变模糊集理论及模型对土地承载力进行综合评价,并以环渤海沿海地区进行实例分析。研究结果表明,2000-2011年,环渤海地区土地承载力整体呈持续上升趋势,但空间分布差异显著,天津、唐山、大连、盘锦、青岛、烟台、东营、威海土地承载力相对较高,锦州、营口、秦皇岛、滨州、潍坊、日照属于中等水平,沧州、丹东、葫芦岛四市土地承载力相对较低。可变模糊评价模型应用于土地承载力评价,计算简便,可操作性强,评价结果可信度高。 Abstract:The study of land carrying capacity is important for coordinating the development of resources, environment, and the economy. This carrying capacity is an important element in the study of regional sustainable development. Coastal areas have the greatest populations, highest population densities, rich resources, and convenient transportation. As in other coastal countries, the coastal area of China is the most developed part of the country. With the acceleration of urbanization, population and economic activity are strongly agglomerating in these coastal areas, resulting in a series of land use conflicts. With such tremendous growth of the economy and society, the conflict between supply and demand of land resources has become increasingly acute. Unreasonable and excessive use of land resources has caused serious damage to the ecological environment of coastal areas and a degradation of land resources. Study on the land carrying capacity of the Bohai Sea coastal areas has great significance for the sustainable development of the Bohai Sea economic circle. The land resource system is complex and has openness, dynamics, social and other characteristics. Therefore, it is difficult to accurately quantify the population, environment, and socioeconomic development. It is also difficult to quantify limits on the land carrying capacity. However, by constructing an indicator system, we can measure dynamic trends and relative land carrying capacity, thereby guiding land use activities. Land carrying capacity assessment is a comprehensive evaluation that involves multiple factors, including natural, social, economic, technological, and others. These factors are interconnected and place mutual restrictions on each other. Relationships between these factors are complex. There is vagueness and uncertainty, as well as dynamic variability under certain temporal and spatial conditions. To date, studies on land carrying capacity have mostly concentrated on inland and ecologically vulnerable areas. There is little research on land carrying capacity in coastal areas. Further, classification standards of assessment indexes in variable fuzzy assessment are mostly determined with reference to relevant statistical data and existing standards. There is a certain subjectivity and arbitrariness, along with inaccuracies. In view of the limitations of prior studies, this work applied the Weber-Fischna law to determine classification standards of assessment indexes. We also used D-S evidential theory to combine subjective factor weights and objective weights to make integrated weights more reliable and accurate. The variable fuzzy assessment method was used to assess comprehensive land carrying capacity in the Bohai Sea coastal areas. Results for those areas show that the land carrying capacity of seventeen cities from 2000 to 2011 had an upward trend on the whole, along with obvious spatial distribution differences. There were higher land carrying capacities at Tianjin, Tangshan, Dalian, Panjin, Qingdao, Dongying, Yantai, and Weihai. Those capacities at Jinzhou, Yingkou, Qinhuangdao, Binzhou, Weifang, and Rizhao were at a medium level, and those at Cangzhou, Dandong, and Huludao were relatively low. The economic development level had strong effects on land carrying capacity. An appropriate economic scale and structure is conducive to sustainable and intensive land use. Application of the variable fuzzy assessment model to land carrying capacity is characterized by simple calculation, ease of operation, and reliable results. 参考文献 相似文献 引证文献

The influence of growth stage of different cereal species on host susceptibility to Gaeumannomyces graminis var. tritici and on Pseudomonas populations in the rhizosphere

The dynamics of infection by Gaeumannomyces graminis var. tritici (Ggt), the soil-borne fungus causing the disease take-all, in wheat (Triticum aestivum L.), rye (Secale cereale L.), barley (Hordeum vulgare L.) and triticale (x Triticosecale Wittmack) was investigated at different growth stages of the cereal hosts. In the field, Ggt spreads along rows of plants from the inoculum sources. At harvest, Ggt DNA was detected up to 60 cm away from inoculum sources in all species except rye, although most of the take-all lesions occurred in roots less than 30 cm away in all species, with rye being the least affected. The greatest populations of fluorescent Pseudomonas sp-species were extracted from the rhizosphere of cereal roots sampled near the points of Ggt inoculation; were found prior to the booting growth stage in triticale and rye; and were not related to the concentration of Ggt in the roots. In pots in a glasshouse experiment, Ggt colonised seedling wheat roots to a concentration of 103 ng DNA/mg dried roots and caused 14 % take-all severity in roots during plant development. In rye, seedling roots contained Ggt DNA at 15 ng/mg dried root, which decreased to negligible concentrations until heading, then increased rapidly to 280 ng DNA/mg dried root at kernel development. Take-all root severity in rye increased from 1 to 50 % over that period. In a second glasshouse experiment, inoculation of roots of host plants at various growth stages with actively growing hyphae of Ggt showed that the pathogen was able to overcome resistance in rye plants after an establishment phase.

Attitudes of international music students from East Asia toward US higher education institutions

Nine National Association of Schools of Music (NASM) accredited universities in the United States (US) with the greatest populations of international students were surveyed to identify the status of East Asian international students’ attitudes toward their schools. Among East Asian international music students at US higher education institutions, the results indicated that the professor’s reputation, scholarships, and the program’s reputation were perceived as the most influential factors impacting the program choice; a good relationship with professors, good feedback from professors, and emotional stability were perceived as the most influential factors impacting academic success; and the professor’s teaching, the professor’s expertise, and the improvement of musical skills were perceived as the most influential factors impacting students’ satisfaction levels. The most problematic issues reported were the language barrier and the cultural differences between their host and home countries. In addition, many of the East Asian international music students in this study noted financial difficulties. Recommendation and conclusion are provided for US institutions and East Asian international students.

Governing Change: The Metropolitan Revolution in Latin America

AbstractIn 21st‐century Latin America, cities are taking the lead. With the greatest populations and economic output concentrated in large‐scale metropolises, there is a real sense that the largest cities are outgrowing their national contexts. In many cases, power has been devolved at a municipal level. This has enabled mayors to implement infrastructural and transport projects. As Ricky Burdett and Adam Kaasa highlight in their discussion of two particular initiatives in São Paulo and Mexico City, it has also opened the way for innovative new community projects. Copyright © 2011 John Wiley &amp; Sons, Ltd.

A system dynamics model for the management of the gooseneck barnacle ( Pollicipes pollicipes) in the marine reserve of Gaztelugatxe (Northern Spain)

The gooseneck barnacle ( Pollicipes pollicipes) is a highly exploited species in Spain and Portugal due to the great commercial demand and the high prices in the market. Due to the inaccessibility of the Gaztelugatxe coastal area (Basque Country, Northern Spain), the gooseneck barnacle has maintained one of the greatest populations of the Basque coast in this area. Declared as a marine reserve by means of the 229/1998 (Basque Government) Decree, a 2 years moratorium in the gooseneck shellfishing was established. Facing the possibility of the gooseneck barnacle fishery opening in the area of the biotope, it was noticed the need for the development of a management tool, capable to think over the different management decisions: from the complete conservation of the system to the sustainable exploitation of the resource, joining together different social and biological factors, allowing the protection of the firsts (protection of the stock) and the development of the seconds (fishery activity). Based on the population dynamics of the gooseneck barnacle, a system dynamic model dominated by one positive and three negative loops was developed. The positive loop portrays the reproductive and maturation process, ultimately producing more adult gooseneck barnacles. The negative loops cause the stabilisation as the different stages of the population expire due by natural causes and exploitation of the resource. According to the model results, the best management decision is the maintenance of the moratorium. Taking into account the dispersion capability of larvae, other areas near the reserve, and subjected to commercial exploitation like Ogoño, Izaro and cape Villano, will benefit from the protection of Gaztelugatxe production. In the case of exploitation, the best management decision, which maximises captures and minimises the stock looses in a sustainable manner, is an alternate exploitation between Aketxe and Gaztelugatxe coastal areas of the marine reserve.

Neotermes platyfrons, a New Dampwood Termite (Isoptera, Kalotermitidae) from the Dominican Republic

Neotermes platyfrons n. sp. is described from the winged imago and the small and large soldier castes. This species is endemic to Hispaniola and surveys of the Dominican Republic indicate the greatest populations occur in the far-eastern coastal woodlands.

Temporary ponds and their invertebrate communities

1. Temporary waters are bodies of water that experience a recurrent dry phase of varying length that is sometimes predictable in its onset and duration. The maximum number of temporary and permanent ponds in England and Wales in 1880 is estimated to be >1 million. A 1920s survey showed lowest densities in mountainous areas (0.12 km−2) and highest densities in ancient woodland and ancient agriculture areas (115 km−2). 2. The most important physical and chemical influences on the biota of temporary ponds are the length of the aquatic phase, pattern of disappearance of the water, and whether the latter is predictable or unpredictable. Biological influences include the degree of inter/intraspecific competition and predation, and the seasonal influx of aerial colonizers. 3. Temporary ponds from Britain, northeastern North America and northwestern Australia are compared and, despite large differences in climate and zoogeography, considerable similarity is evident amongst their faunas. Snails, microcrustaceans, aquatic mites, springtails, odonates, chironomids, and a high diversity of Hemiptera and Coleoptera are characteristic of these habitats. British ponds share at least 33 genera and three species with their North American counterparts. The three main evolved strategies by which invertebrates survive in temporary ponds are physiological tolerance, life history modification, and migration. 4. The cyclical nature of the temporary pond environment creates a habitat that is distinctive enough to support species either not found in any other habitat type or that attain their greatest populations in these ponds. 5. Agricultural drainage and pond ‘improvement’ schemes are seen as distinct threats to the survival of temporary ponds and should be reviewed in the context that these water bodies are not ‘wasted’ areas of land but natural features of the environment. It is recommended that the management of wetlands in Britain should be directed towards maintaining a high diversity of natural water bodies, including a variety of temporary pond types. © 1997 John Wiley & Sons, Ltd.

Temporary ponds and their invertebrate communities

1. Temporary waters are bodies of water that experience a recurrent dry phase of varying length that is sometimes predictable in its onset and duration. The maximum number of temporary and permanent ponds in England and Wales in 1880 is estimated to be >1 million. A 1920s survey showed lowest densities in mountainous areas (0.12 km−2) and highest densities in ancient woodland and ancient agriculture areas (115 km−2). 2. The most important physical and chemical influences on the biota of temporary ponds are the length of the aquatic phase, pattern of disappearance of the water, and whether the latter is predictable or unpredictable. Biological influences include the degree of inter/intraspecific competition and predation, and the seasonal influx of aerial colonizers. 3. Temporary ponds from Britain, northeastern North America and northwestern Australia are compared and, despite large differences in climate and zoogeography, considerable similarity is evident amongst their faunas. Snails, microcrustaceans, aquatic mites, springtails, odonates, chironomids, and a high diversity of Hemiptera and Coleoptera are characteristic of these habitats. British ponds share at least 33 genera and three species with their North American counterparts. The three main evolved strategies by which invertebrates survive in temporary ponds are physiological tolerance, life history modification, and migration. 4. The cyclical nature of the temporary pond environment creates a habitat that is distinctive enough to support species either not found in any other habitat type or that attain their greatest populations in these ponds. 5. Agricultural drainage and pond ‘improvement’ schemes are seen as distinct threats to the survival of temporary ponds and should be reviewed in the context that these water bodies are not ‘wasted’ areas of land but natural features of the environment. It is recommended that the management of wetlands in Britain should be directed towards maintaining a high diversity of natural water bodies, including a variety of temporary pond types. © 1997 John Wiley & Sons, Ltd.

Stabilization of a type VI turn in a family of linear peptides in water solution

The sources of the stability of a type VI turn formed with high population in the cis isomeric form of an unblocked six residue peptide. Ser 1-Tyr 2-Pro 3-Tyr 4-Asp 5-Val 6 (SYPYDV), were investigated by making extensive amino acid substitutions at residues 2, 4 and 5. Several NMR parameters indicate the presence of the turn, including significant upfield shifts of the proton resonances of the cis proline, a small 3 J HN α coupling constant for residue 2, a cross-turn d αN ( i, i + 2) NOE from residue 2 to residue 4 and an increased mole fraction of the cis form in the conformational ensemble. By these criteria, a number of peptides were found to contain significant populations of type VI turn conformers in the cis form of the peptide. The NMR parameters are highly dependent on the sequence of the peptide, and are strongly correlated with each other and with the population of type VI turn. The greatest populations of turn conformations were observed for peptides of the general form AA-Ar-Pro-Ar-Hp, where AA represents any amino aicd. Ar an aromatic residue and Hp a small hydrophilic residue. Three is no evidence in the form of lowered amide proton temperature coefficients for direct hydrogen bonding as a primary source of turn stability. Instead, the major stabilizing factor, indicated by the strong dependence of the turn populatioin on the presence of aromatic (not hydrophobic) residues at positioins 2 and 4, is the stacking of the aromatic and proline rings. A measurable preference for deprotonated aspartate at position 5, which fis not part of the turn itself, and the destabilization of the turn at high and low pH, indicate that electrostatic interactions between the unblocked N termininus and the aspartate carboxyl group also act to stabilize the turn conformation when the Ar-Pro-Ar sequence is present. Implications for stabilization of local elements of secondary structure during the earliest events in protein folding are discussed.

Population Levels and Parasitism of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) on Peanut Cultivars

Sweetpotato whitefly, Bemisia tabaci (Gennadius), has recently become a pest of peanut in the southern United States. Limited observations in grower fields had identified differences in infestation among cultivars. We wished to determine whether selected cultivars grown commercially in this region resisted whitefly infestation and whether parasitism by aphelinid parasitoids differed among cultivars. Five cultivars were evaluated in summer 1992 and six in summer 1993. In 1992, ‘Florunner’ supported the greatest populations of red-eye nymphs and ‘Southern Runner’ supported the lowest populations. Encarsia nigricephala Dozier was the most common parasitoid (53.0% of all parasitoids reared), followed by Encarsia transvena (Timberlake) (25.6%), and Encarsia pergandiella Howard (18.3%). Parasitism was uniformly high and species composition on the five cultivars did not differ. In 1993, ‘Southern Runner’ supported the greatest populations of all immature whitefly stages except red-eye nymphs. ‘Marc I’ supported the lowest levels of whitefly infestation. E. nigricephala was extremely abundant in 1993 (85.3% of all parasitoids reared), followed by E. pergandiella (9.8%), and E. transvena (4.7%). Eretmocerus nr. californicus was found in low numbers in both years. Again, in 1993, parasitism was high on all cultivars (up to 100% by the end of September), and no differences were noted in the parasitoid composition among the six cultivars. Whitefly infestation was light in these noninsecticide-treated peanut plots, most likely because of natural control by native aphelinid parasitoids, and other beneficial insects.

Agronomic management of potato/sugarcane intercropping and its economic implications

Thirteen experiment-station and farmer experiments to determine the agronomic and economic benefits related to the intercropping of potato with sugarcane were run from 1982 to 1987 under rainfed conditions in Bangladesh. Cane yield was enhanced when intercropped with potato, and the benefit was related to the use of residual P and K, and to a lesser extent N. In all experiments, net returns from cane intercropped with potato were greater than from sole cane, and were further increased by the use of mulch. Potato yield increased to the maximum population tested as an intercrop (10 plants m −2), but maximum net economic benefits were not always derived from the greatest populations. Changing the traditional single-row planting system of sugarcane for a double-row system, in which more space was available for the intercrop, did not reduce cane yield but facilitated the planting of high potato plant populations. It is concluded that the practice of intercropping potato with sugarcane exploits the temporal complementarity between crops to the benefit of the farmer.

Quantitative studies of onchocerciasis transmission by Simulium yahense and Simulium sanctipauli in the Firestone Rubber Plantation at Harbel, Liberia.

Black fly vectors of onchocerciasis from three ecologically different Simuliid breeding habitats in the Firestone Rubber Plantation at Harbel, Liberia, were surveyed by human-biting collections conducted at weekly intervals over a 13-month period. Black flies were identified morphologically and the monthly and seasonal contribution of different vector species to the transmission of Onchocerca volvulus at each site was determined. Simulium yahense was identified as the predominant vector species at each site. Greatest populations of this species occurred during wet season (May-Oct), but its impact on transmission of onchocerciasis was most profound during dry season (Nov-Apr) when parity, infection, and infectivity were high. S. sanctipauli was the only other vector species captured, but biting populations of this species were small, and during wet season confined primarily to the vicinity of its breeding site in the Farmington River. Dry season populations of S. sanctipauli were also characterized by lower human-biting rates, and by higher rates of parity, infection, and infectivity. Monthly transmission potentials at each site were attributed primarily to S. yahense, with peak monthly transmission occurring during the dry season months of January-April. Against the WHO standard of 100 as a "tolerable" annual level of onchocerciasis transmission, annual transmission potentials for the three sampling sites were 94, 1,877, and 4,900, with highest values being calculated for S. yahense breeding sites.

POSSIBLE CLUES TO IMPROVED POND CULTURE OF PENAEID SHRIMP

ABSTRACTThis study was stimulated by the variability in results of United States shrimp culture in ponds, and the need for improved methods of estimating shrimp populations in ponds prior to harvest.Brown shrimp (Penaeus aztecus) were cultured in six 0.1 ha earthen ponds receiving thermal effluent from a steam electric generating station near Galveston Bay, Texas, for a 70–71 day culture period between April and July 1978. Two ponds were stocked with 3,500 shrimp each and four with 2,500 shrimp. Only shrimp in two ponds stocked at the lower density did not receive supplemental food. Each pond was treated weekly with 4.5 kg of 45‐0‐0 fertilizer to promote plankton blooms. Survival ranged from 79 to 91%; feeding treatment seemed to correlate with survival as two of the three ponds with 79% survival contained the unfed shrimp. Size of shrimp at harvest and daily growth rates were not correlated with stocking density or feeding treatment. Growth was positively correlated with increasing pond bottom softness.Based on seine sample data, wind direction strongly affected the distribution of brown shrimp. The greatest populations were usually found near the downwind shore of ponds; this relationship was strongest in ponds containing fed shrimp. The efficiency of seine samples was also affected by the time of day. Samples completed between 1800 and 0600 h caught more shrimp and were less variable than samples taken between 0900 and 1430 h. For improved population estimation, night sampling along downwind shores of culture ponds is recommended.

Lucerne aphid effects on 18 pasture legumes in southern Queensland: a glasshouse study

The suitability of 18 naturalized or commercial pasture legumes as hosts of the spotted alfalfa aphid (SAA) (Therioaphis trifolii f, maculata (Monell)) and the blue-green aphid (BGA) (Acyrthosiphon kondoi Shinji) and the effects of the aphids on the growth of these legumes were investigated in uncaged pots in a glasshouse trial. The species and cultivars tested were: Medicago sativa cv. Hunter River, M. truncatula var. truncatula cv. Jemalong, M. truncatula var. truncatula cv. Cyprus, M. scutellata cv. Robinson, M. littoralis cv. Harbinger, M. polymorpha, M. minima, M, lupulina, Trifolium repens cv. Ladino, T. repens cv. Grasslands Huia, T, semipilosum var. glabrescens cv. Safari, T, pratense cv. Grasslands Turoa, T, subterraneum cv. Woogenellup, T, glomeratum, Astragalus hamosus cv. loman, Vicia dasycarpa cv. Namoi, Ornithopus compressus cv. Pitman, Macroptilium atropurpureum cv. Siratro. Medicago spp. and Trifolium spp. supported the greatest populations of SAA and BGA, respectively, although high populations of the latter were supported on most legumes. M. scutellata cv. Robinson and M. truncatula cvv. Jemalong and Cyprus supported a low population of SAA while T. semipilosum cv. Safari was the only Trifolium sp. host. BGA developed on all legumes with lowest populations on O. compressus cv. Pitman, M. atropurpureum cv. Siratro and Vicia dasycarpa cv. Namoi. SAA reduced yields of all Medicago spp, except cvv. Jemalong, Cyprus and Robinson ; all M. littoralis cv. Harbinger and most M. polymorpha plants died. BGA reduced yields of all legumes except cv. Robinson, cv. Namoi, cv. Pitman and cv. Siratro; all cv. loman plants died. Treatment with both aphids reduced yields of all legumes except cv. Namoi, cv. Pitman and cv. Siratro and killed all plants of cv. Harbinger, M. polymorpha and cv, loman. Of the legumes examined, V. dasycarpa cv. Namoi, O. compressus cv. Pitman, M. atropurpureum cv. Siratro and perhaps M. scutellata cv. Robinson are the only cultivars of species which may be expected to produce reasonable yields under combined attack

Grain aphids in New Brunswick. IV. Effects of malathion and 2,4-D amine on aphid populations and on yields of oats and barley

Aphid populations on oats (Fundy and Stormont) and barley (Charlottetown 80) were studied in the field and yields of these grains examined under the different levels of aphid infestation resulting from applications of malathion and 2,4-D amine to the crop.Two species of aphid, Rhopalosiphum padi (L.) and Macrosiphum avenae (Fab.), occurred on the grains, and the greatest populations developed on barley. In all cases highest numbers were associated with applications of 2,4-D amine. Applications of this herbicide to similar aphids under laboratory conditions showed that the species differed in their responses as measured by reproduction and longevity.One malathion treatment, applied when aphids were dispersing into the field, reduced ensuing aphid numbers on oats by 29% and on barley by 64%. Yields of oats were increased by 47% and of barley 32% when malathion alone was used. When malathion and 2,4-D amine were applied together, aphid results and yield results were confusing.In all treatments, aphid populations collapsed abruptly once the grain panicle emerged, and in no case did aphids persist more than 10 weeks on either grain.

Temperature Regulation of Mexican Free-Tailed Bats in Cave Habitats

The Mexican free-tailed bat, Tadarida brasiliensis mexicana , was noted in environments of 8° to 43°C and relative humidities of 10 to 100%. Large populations of bats usually occurred between 15° and 38°C and 65 to 95% relative humidity. Greatest populations were noted at 25° to 38°C. The temperatures of some Texas caves seem to be influenced by the heat given off by the bats as well as by the outside temperatures. Apparently migration is not directly related to cave temperature. Examination of body temperatures of roosting adult bats throughout the year in ambient temperatures of 12° to 36°C indicated that the subspecies usually regulates its body temperature at high levels in the wild and appears more temperature stable than many Microchiroptera that have been studied. Body temperatures of young bats (from birth until capable of flight) were well above environmental temperatures. Young bats had higher body temperatures as they became older and were at higher ambient temperatures. Regulation of the body temperature at high levels in low environmental temperatures seems to occur by increased heat production, although heat loss is apparently retarded by clustering behavior. Body temperature regulation at high cave temperatures appears to occur in the following ways: The body temperature of the bats remains below that of the deep cluster temperature by virtue of heat loss to the rocks and air which are at lower temperatures. Bats possibly move to cooler sites in the cave in times of heat stress and may separate from one another on the cave ceiling to increase heat loss. By flying and thus greatly increasing the surface area for heat loss the bats seem able to reduce their body temperatures.

THE EFFECT OF FOREST SUCCESSION UPON THE QUANTITY AND UPON THE NUTRITIVE VALUES OF WOODY PLANTS USED AS FOOD BY MOOSE

The moose, Alces americana, in British Columbia reaches its greatest populations in the young second growth forest areas. Numbers decrease as the forest approaches its climax stage. The decline in population is known to be mainly the result of malnutrition.The present study of three stages in forest succession growing under virtually identical conditions of soil and climate has concerned itself with quantity of available palatable browse; carotene and ascorbic acid content of available palatable and unpalatable trees and shrubs; and with determination of values for moisture, protein, carbohydrate, ether extractives, and total mineral content. Most of the analyses are confined to the winter dormant period.It is determined that the forest changes studied involve a reduction in quantity of palatable browse to about one-third; that there is an increase of carotene values and possibly of total mineral content in the vegetation on more advanced forest areas, but that in ascorbic acid content, ether extractives, total carbohydrates, and proteins the vegetation upon the younger forest areas is superior to that on the older areas.It is concluded, therefore, that the declining carrying capacity noted in a forest approaching its climax stage results from decreases in both the quantity and quality of food produced.It is further concluded that the most desirable winter range for moose is one upon which there is a variety of palatable species, predominantly in an early stage of growth, but with an intermixture of older forest stands bearing palatable coniferous trees.