- PE&RC (7)
- Laboratory of Entomology (2)
- Laboratory of Genetics (2)
- Resource Ecology (2)
- Rural and Environmental History (2)
- WASS (2)
- WIMEK (2)
- Wageningen University (2)
- Alterra - Animal ecology (1)
- Animal Ecology (1)
- Aquatic Ecology and Water Quality Management (1)
- Biometris (WU MAT) (1)
- CE - Molecular Ecology Ecotoxicology and Wildlife Management (1)
- Consumer Science & Intelligent Systems (1)
- Food Microbiology (1)
- Food Microbiology Laboratory (1)
- Laboratory of Virology (1)
- Mathematical and Statistical Methods - Biometris (1)
- PPO Bees (1)
- PRI BIOINT Entomology & Virology (1)
- Plant Production Systems (1)
- Rijksinstituut voor Natuurbeheer (1)
- Rural Development Sociology (1)
- VLAG (1)
- W. Beekman (1)
- Z.W. Beer de (1)
- J.C. Biesmeijer (1)
- T. Blacquière (1)
- E.P.J. Boer (1)
- J. Bogaert (1)
- R. Bommarco (1)
- J.J. Boomsma (2)
- W.J. Boot (1)
- T. Breeze (1)
- F. Buelens (1)
- R.W. Butler (1)
- T.X. Chinh (1)
- B. Cornelissen (1)
- J.N.L.C. Donders (1)
- C. Dooremalen van (1)
- H. Erens (1)
- H.H. Fine Licht de (2)
- E.H.P. Frankema (1)
- L.G.M. Gorris (1)
- S. Gyldenkaerne (1)
- I.M. Jones (1)
- I. Jongenburger (1)
- D. Kleijn (1)
- L. Kozak (1)
- M. Lürling (1)
- A. Mabelis (1)
- F. Mees (1)
- J. Mitchell (1)
- B.B. Mujinya (1)
- M. Ngongo (1)
- T. Petanidou (1)
- E. Ranst van (1)
- M.W. Reij (1)
- W. Roepke (1)
- V.I.D. Ros (1)
- C. Rouland-Lefevre (1)
- J.A. Scheper (1)
- N. Seraphides (1)
- B. Slippers (1)
- M.J. Sommeijer (1)
- P. Stratum van (1)
- B.E. Vaissiere (1)
- L.B. Venema (1)
- I. Vranken (1)
- J. Wilde de (1)
- R.C. Ydenberg (1)
- M.H. Zwietering (1)
Rural livelihoods and agricultural commercialization in colonial Uganda: conjunctures of external influences and local realities
Haas, Michiel A. de - \ 2017
Wageningen University. Promotor(en): E.H.P. Frankema, co-promotor(en): N.B.J. Koning. - Wageningen : Wageningen University - ISBN 9789463436281 - 250
cum laude - livelihoods - livelihood strategies - communities - rural areas - farmers - history - colonies - colonialism - income - gender - social inequalities - food crops - cash crops - uganda - east africa - middelen van bestaan - strategieën voor levensonderhoud - gemeenschappen - platteland - boeren - geschiedenis - kolonies - kolonialisme - inkomen - geslacht (gender) - sociale ongelijkheden - voedselgewassen - marktgewassen - uganda - oost-afrika
The economic history of Sub-Saharan Africa is characterized by geographically and temporally dispersed booms and busts. The export-led ‘cash-crop revolution’ in parts of Sub-Saharan Africa during the colonial era is a key example of an economic boom. This thesis examines how external influences and local realities shaped the nature, extent and impact of the ‘cash-crop revolution’ in colonial Uganda, a landlocked country in central east Africa, where cotton and coffee production for global markets took off following completion of a railway to the coast. The thesis consists of five targeted ‘interventions’ into contemporary debates of comparative African development. Each of these five interventions is grounded in the understanding that the ability of rural Africans to respond to and benefit from trade integration during the colonial era was mediated by colonial policies, resource endowments and local institutions.
The first chapter reconstructs welfare development of Ugandan cash-crop farmers. Recent scholarship on historical welfare development in Sub-Saharan Africa has uncovered long-term trends in standards of living. How the majority of rural dwellers fared, however, remains largely elusive. This chapter presents a new approach to reconstructing rural living standards in a historical context, building upon the well-established real wage literature, but moving beyond it to capture rural realities, employing sub-national rural survey, census, and price data. The approach is applied to colonial and early post-colonial Uganda (1915–70), and yields a number of findings. While an expanding smallholder-based cash-crop sector established itself as the backbone of Uganda’s colonial economy, farm characteristics remained largely stagnant after the initial adoption of cash crops. Smallholders maintained living standards well above subsistence level, and while the profitability of cash crops was low, their cultivation provided a reliable source of cash income. At the same time, there were pronounced limits to rural welfare expansion. Around the time of decolonization, unskilled wages rose rapidly while farm incomes lagged behind. As a result, an urban–rural income reversal took place. The study also reveals considerable differences within Uganda, which were mediated to an important extent by differential resource endowments. Smallholders in Uganda’s banana regions required fewer labour inputs to maintain a farm income than their grain-farming counterparts, creating opportunities for additional income generation and livelihood diversification.
The second chapter zooms in on labour migration which connected Belgian-controlled Ruanda-Urundi to British-controlled Buganda, the central province of Uganda on the shores of Lake Victoria. The emergence of new labour mobility patterns was a key aspect of economic change in colonial Africa. Under conditions of land abundance and labour scarcity, the supply of wage labour required either the ‘pull’ forces of attractive working conditions and high wages, or the ‘push’ forces of taxation and other deliberate colonial interventions. Building upon primary sources, I show that this case diverges from the ‘conventional’ narrative of labour scarcity in colonial Africa. I argue that Ruanda-Urundi should be regarded as labour abundant and that migrants were not primarily ‘pushed’ by colonial labour policies, but rather by poverty and limited access to agricultural resources. This explains why they were willing to work for low wages in Buganda. I show that African rural employers were the primary beneficiaries of migrant labour, while colonial governments on both sides of the border were unable to control the course of the flow. As in the first chapter, this chapter highlights that the effects of trade integration on African rural development were uneven, and mediated by differences in resource endowments, local institutions and colonial policies.
The third chapter zooms out of the rural economy, evaluating the broader opportunity structures faced by African men and women in Uganda, and discussing the interaction of local institutions and colonial policies as drivers of uneven educational and occupational opportunities. The chapter engages with a recent article by Meier zu Selhausen and Weisdorf (2016) to show how selection biases in, and Eurocentric interpretations of, parish registers have provoked an overly optimistic account of European influences on the educational and occupational opportunities of African men and women. We confront their dataset, drawn from the marriage registers of the Anglican Cathedral in Kampala, with Uganda’s 1991 census, and show that trends in literacy and numeracy of men and women born in Kampala lagged half a century behind those who wedded in Namirembe Cathedral. We run a regression analysis showing that access to schooling during the colonial era was unequal along lines of gender and ethnicity. We foreground the role of Africans in the spread of education, argue that European influences were not just diffusive but also divisive, and that gender inequality was reconfigured rather than eliminated under colonial rule. This chapter also makes a methodological contribution. The renaissance of African economic history in the past decade has opened up new research avenues to study the long-term social and economic development of Africa. We show that a sensitive treatment of African realities in the evaluation of European colonial legacies, and a critical stance towards the use of new sources and approaches, is crucial.
The fourth chapter singles out the role of resource endowments in explaining Uganda’s ‘cotton revolution’ in a comparative African perspective. Why did some African smallholders adopt cash crops on a considerable scale, while most others were hesitant to do so? The chapter sets out to explore the importance of factor endowments in shaping the degrees to which cash crops were adopted in colonial tropical Africa. We conduct an in-depth case study of the ‘cotton revolution’ in colonial Uganda to put the factor endowments perspective to the test. Our empirical findings, based on an annual panel data analysis at the district-level from 1925 until 1960, underscore the importance of Uganda’s equatorial bimodal rainfall distribution as an enabling factor for its ‘cotton revolution’. Evidence is provided at a unique spatial micro-level, capitalizing on detailed household surveys from the same period. We demonstrate that previous explanations associating the variegated responses of African farmers to cash crops with, either the role of colonial coercion, or the distinction between ‘forest/banana’ and ‘savannah/grain’ zones, cannot explain the widespread adoption of cotton in Uganda. We argue, instead, that the key to the cotton revolution were Uganda’s two rainy seasons, which enabled farmers to grow cotton while simultaneously pursuing food security. Our study highlights the importance of food security and labour seasonality as important determinants of uneven agricultural commercialization in colonial tropical Africa.
The fifth and final chapter further investigates the experience of African smallholders with cotton cultivation, providing a comparative explanatory analysis of variegated cotton outcomes, focusing in particular on the role of colonial and post-colonial policies. The chapter challenges the widely accepted view that (i) African colonial cotton projects consistently failed, that (ii) this failure should be attributed to conditions particular to Africa, which made export cotton inherently unviable and unprofitable to farmers, and that (iii) the repression and resistance often associated with cotton, all resulted from the stubborn and overbearing insistence of colonial governments on the crop per se. I argue along three lines. Firstly, to show that cotton outcomes were diverse, I compare cases of cotton production in Sub-Saharan Africa across time and space. Secondly, to refute the idea that cotton was a priori unattractive, I argue that the crop had substantial potential to connect farmers to markets and contribute to poverty alleviation, particularly in vulnerable, marginal and landlocked areas. Thirdly, to illustrate how an interaction between local conditions and government policies created conducive conditions for cotton adoption, I zoom in on the few yet significant ‘cotton success stories’ in twentieth century Africa. Smallholders in colonial Uganda adopted cotton because of favourable ecological and marketing conditions, and policies had an auxiliary positive effect. Smallholders in post-colonial Francophone West Africa faced much more challenging local conditions, but benefitted from effective external intervention and coordinated policy. On a more general level, this chapter demonstrates that, from a perspective of rural development, colonial policies should not only be seen as overbearing and interventionist, but also as inadequate, failing to aid rural Africans to benefit from new opportunities created by trade integration.
Agricultural policies exacerbate honeybee pollination service supply-demand mismatches across Europe
Breeze, T. ; Vaissiere, B.E. ; Bommarco, R. ; Petanidou, T. ; Seraphides, N. ; Kozak, L. ; Scheper, J.A. ; Biesmeijer, J.C. ; Kleijn, D. ; Gyldenkaerne, S. - \ 2014
PLoS ONE 9 (2014)1. - ISSN 1932-6203 - 8 p.
ecosystem services - fruit-set - sequential introduction - bee abundance - declines - crops - colonies - density - enhance - biodiversity
Declines in insect pollinators across Europe have raised concerns about the supply of pollination services to agriculture. Simultaneously, EU agricultural and biofuel policies have encouraged substantial growth in the cultivated area of insect pollinated crops across the continent. Using data from 41 European countries, this study demonstrates that the recommended number of honeybees required to provide crop pollination across Europe has risen 4.9 times as fast as honeybee stocks between 2005 and 2010. Consequently, honeybee stocks were insufficient to supply >90% of demands in 22 countries studied. These findings raise concerns about the capacity of many countries to cope with major losses of wild pollinators and highlight numerous critical gaps in current understanding of pollination service supplies and demands, pointing to a pressing need for further research into this issue.
Spatial patterns and morphology of termite (Macrotermes falciger) mounds in the upper Katanga, D.R. Congo
Mujinya, B.B. ; Adam, M.Y.O. ; Mees, F. ; Bogaert, J. ; Vranken, I. ; Erens, H. ; Baert, G. ; Ngongo, M. ; Ranst, E. van - \ 2014
Catena 114 (2014). - ISSN 0341-8162 - p. 97 - 106.
bellicosus isoptera - lubumbashi area - central-africa - d.r. congo - michaelseni - geochemistry - evolution - abundance - colonies - soils
This study examines the spatial distribution patterns and morphological characteristics of Macrotermes falciger mounds in the peri-urban zone of Lubumbashi, D.R. Congo. Spatial patterns of mounds were assessed using high-resolution satellite images for 24 plots of variable size (3 to 27 ha). Soil morphological features were described for five termite-mound profiles of 5 to 9 m depth/height. A mean areal number density of 2.9 ± 0.4 mounds ha- 1 is estimated for the degraded miombo woodland of the study area. Spatial statistical analyses document that termite mounds are regularly distributed in all studied plots. The overall mean nearest-neighbour distance between termite mounds is 44.6 ± 0.6 m. The high relative number of inactive mounds in the region, with regular distribution patterns, suggests that current termite mound occurrences are largely relict features. There are no clear indications for an impact of the nature of the parent material on the spatial distribution of the mounds. One aspect of differences in morphology between the studied mounds is that the stone layer occurs at greater depth in topographic low areas than at crest and slope positions. This is interpreted as being mainly conditioned by erosion. Mn–Fe oxide concentrations occurring in all studied termite mound profiles reflect a seasonally high perched water table beneath the mound, which is more pronounced at lower landscape positions. In summary, mound positions in the habitat are consistent with intraspecific competition rather than soil and substrate characteristics as controlling factor, whereas variation in morphological characteristics between termite-mound profiles appears to be a function of the parent material.
Recent switch by the Great Blue Heron (Ardea herodias fannini) in the Pacific northwest to associative nesting with Bald Eagles (Haliaeetus leucocephalus) to gain predator protection
Jones, I.M. ; Butler, R.W. ; Ydenberg, R.C. - \ 2013
Canadian Journal of Zoology 91 (2013)7. - ISSN 0008-4301 - p. 489 - 495.
colonies - advantages - habitat - magpies
The Great Blue Heron (Ardea herodias fannini Chapman, 1901) in the Pacific northwest appears to have modified nesting behaviour in response to the strong recent recovery of the Bald Eagle (Haliaeetus leucocephalus (L., 1766)) population. Previously undescribed, herons now often nest in close association with some breeding eagles, even though eagles depredate heron nestlings, are implicated in the recent reproductive decline of herons, and may induce abandonment of heron breeding colonies. We tested the hypothesis that breeding herons gain protection from the territorial behaviour of eagles. Natural observations and simulated incursions showed that nesting eagles actively repel other eagles within at least 250 m around the nest site, thereby establishing a relatively safe place for herons to nest. Surveys showed that 70% of heron nests and 19% of heron colonies were located within 200 m of eagle nests with high reproductive success. These herons had greater reproductive success than those nesting far from eagle nests.
|Colonial Exploitation and Economic Development: The Belgian Congo and the Netherlands Indies Compared
Frankema, E.H.P. ; Buelens, F. - \ 2013
London : Routledge (Routledge explorations in economic history 64) - ISBN 9780415521741 - 292
kolonialisme - kolonies - kolonisatie - economische ontwikkeling - congo - democratische republiek kongo - belgië - nederlands indië - nederland - geschiedenis - colonialism - colonies - colonization - economic development - congo democratic republic - belgium - netherlands east indies - netherlands - history
This volume discusses the comparative legacy of colonial rule in the Netherlands Indies and Belgian Congo during the nineteenth and twentieth centuries. Whereas the Indonesian economy progressed rapidly during the last three decades of the twentieth century and became a self-reliant and assertive world power, the Congo regressed into a state of political chaos and endemic violence. To which extent do the different legacies of Dutch and Belgian rule explain these different development outcomes, if they do at all? By discussing the comparative features and development of Dutch and Belgian rule, the book aims to contribute to a deeper understanding of the role of colonial institutional legacies in long run patterns of economic divergence in the modern era and to add a comparative case-study to the strand of literature analyzing the marked differences in economic and political development in Asia and Africa during the postcolonial era.
Queen survival and oxalic acid residues in sugar stores after summer application against Varroa destructor in honey bees (Apis mellifera)
Cornelissen, B. ; Donders, J.N.L.C. ; Stratum, P. van; Blacquière, T. ; Dooremalen, C. van - \ 2012
Journal of Apicultural Research 51 (2012)3. - ISSN 0021-8839 - p. 271 - 276.
colonies - jacobsoni
Methods using oxalic acid (OA) to control Varroa destructor in honey bee (Apis mellifera) colonies are widely applied. In this study, the effects of an OA spray application in early summer on the survival of young and old queens, and on OA residues in sugar stores were investigated. A questionnaire among beekeepers was used to determine the ‘normal’ and ‘acceptable’ queen mortality as a result of beekeeper activities. ‘Acceptable’ queen mortality (4.1 ± 0.1% (n = 11)) did not differ from queen mortality after OA spray application (2.7% for old and 3.8% for young queens). ‘Normal’ queen mortality (1.1 ± 0.4% (n = 11) and 4.2 ± 0.1% (n = 11) for old and young queens, respectively) also did not differ from queen mortality after spraying OA. OA found in sugar stores of colonies sprayed with OA (94 ± 7 mg/kg (n = 8)) did not differ from control colonies (80 ± 4 mg/kg (n = 9)). Finding OA residues in both groups was probably due to bees foraging on chestnut (Castanea sativa) trees. We conclude that OA spray application in periods without brood during spring and summer poses little danger to honey bee queens and that in sugar stores harvested in summer, OA residues are within the limits of natural variability Supervivencia de las reinas y residuos de ácido oxálico en el azúcar almacenado en abejas (Apis mellifera) tras el tratamiento estival contra Varroa destructor. Resumen: Los métodos de control contra Varroa destructor en colonias de la abeja de la miel (Apis mellifera) usando ácido oxálico (AO) son ampliamente aplicados. En este estudio se ha investigado el efecto de la aplicación de un espray de AO a principios del verano sobre la supervivencia de las reinas tanto jóvenes como adultas, y los residuos del AO en el azúcar almacenado. Se pasó un cuestionario entre los apicultores para determinar cuál era la mortalidad “normal” y “aceptable” de la reina como consecuencia de las actividades apícolas. La mortalidad “aceptable” (4.1 ± 0.1% (n = 11)) no difirió de la mortalidad tras la aplicación del espray de AO (2.7% para reinas adultas y 3.8% para jóvenes). La mortalidad “normal” (1.1 ± 0.4 % (n = 11) y 4.2 ± 0.1% (n = 11) para reinas adultas y jóvenes, respectivamente) tampoco difirió de la mortalidad tras la aplicación del espray AO. El AO encontrado en las reservas de azúcar de las colonias tratadas con el espray (94 ± 7 mg/kg (n = 8)) no fue diferente de las colonias control (80 ± 4 mg/kg (n = 9)). El haber encontrado residuos de AO en ambos grupos fue probablemente debido al forrajeo de las abejas en los castaños (Castanea sativa), además de a la utilización de azúcares artificiales en la alimentación. Concluimos que la aplicación del espray de AO en periodos sin cría durante la primavera y el verano plantea pocos riesgos tanto para las reinas como para el azúcar almacenado. Los residuos de AO están dentro del límite de variabilidad natural
Factors influencing the accuracy of the plating method used to enumerate low numbers of viable micro-organisms in food
Jongenburger, I. ; Reij, M.W. ; Boer, E.P.J. ; Gorris, L.G.M. ; Zwietering, M.H. - \ 2010
International Journal of Food Microbiology 143 (2010)1-2. - ISSN 0168-1605 - p. 32 - 40.
measurement uncertainty - microbiology - colonies - plates
This study aims to assess several factors that influence the accuracy of the plate count technique to estimate low numbers of micro-organisms in liquid and solid food. Concentrations around 10 CFU/mL or 100 CFU/g in the original sample, which can still be enumerated with the plate count technique, are considered as low numbers. The impact of low plate counts, technical errors, heterogeneity of contamination and singular versus duplicate plating were studied. Batches of liquid and powdered milk were artificially contaminated with various amounts of Cronobacter sakazakii strain ATCC 29544 to create batches with accurately known levels of contamination. After thoroughly mixing, these batches were extensively sampled and plated in duplicate. The coefficient of variation (CV) was calculated for samples from both batches of liquid and powdered product as a measure of the dispersion within the samples. The impact of technical errors and low plate counts were determined theoretically, experimentally, as well as with Monte Carlo simulations. CV-values for samples of liquid milk batches were found to be similar to their theoretical CV-values established by assuming Poisson distribution of the plate counts. However, CV-values of samples of powdered milk batches were approximately five times higher than their theoretical CV-values. In particular, powdered milk samples with low numbers of Cronobacter spp. showed much more dispersion than expected which was likely due to heterogeneity. The impact of technical errors was found to be less prominent than that of low plate counts or of heterogeneity. Considering the impact of low plate counts on accuracy, it would be advisable to keep to a lower limit for plate counts of 25 colonies/plate rather than to the currently advocated 10 colonies/plate. For a powdered product with a heterogeneous contamination, it is more accurate to use 10 plates for 10 individual samples than to use the same 10 plates for 5 samples plated in duplicate
Patterns of interaction specificity of fungus-growing termites and Termitomyces symbionts in South Africa
Aanen, D.K. ; Ros, V.I.D. ; Fine Licht, H.H. de; Mitchell, J. ; Beer, Z.W. de; Slippers, B. ; Rouland-Lefevre, C. ; Boomsma, J.J. - \ 2007
BMC Evolutionary Biology 7 (2007). - ISSN 1471-2148 - 11 p.
multiple sequence alignment - phylogenetic-relationships - evolutionary history - ants - macrotermitinae - isoptera - colonies - models - trees - comb
Background Termites of the subfamily Macrotermitinae live in a mutualistic symbiosis with basidiomycete fungi of the genus Termitomyces. Here, we explored interaction specificity in fungus-growing termites using samples from 101 colonies in South-Africa and Senegal, belonging to eight species divided over three genera. Knowledge of interaction specificity is important to test the hypothesis that inhabitants (symbionts) are taxonomically less diverse than 'exhabitants' (hosts) and to test the hypothesis that transmission mode is an important determinant for interaction specificity. Results Analysis of Molecular Variance among symbiont ITS sequences across termite hosts at three hierarchical levels showed that 47 % of the variation occurred between genera, 18 % between species, and the remaining 35 % between colonies within species. Different patterns of specificity were evident. High mutual specificity was found for the single Macrotermes species studied, as M. natalensis was associated with a single unique fungal haplotype. The three species of the genus Odontotermes showed low symbiont specificity: they were all associated with a genetically diverse set of fungal symbionts, but their fungal symbionts showed some host specificity, as none of the fungal haplotypes were shared between the studied Odontotermes species. Finally, bilaterally low specificity was found for the four tentatively recognized species of the genus Microtermes, which shared and apparently freely exchanged a common pool of divergent fungal symbionts. Conclusion Interaction specificity was high at the genus level and generally much lower at the species level. A comparison of the observed diversity among fungal symbionts with the diversity among termite hosts, indicated that the fungal symbiont does not follow the general pattern of an endosymbiont, as we found either similar diversity at both sides or higher diversity in the symbiont. Our results further challenge the hypothesis that transmission-mode is a general key-determinant of interaction specificity in fungus-growing termites.
Presumptive horizontal symbiont transmission in the fungus-growing termite Macrotermes natalensis
Fine Licht, H.H. de; Boomsma, J.J. ; Aanen, D.K. - \ 2006
Molecular Ecology 15 (2006)11. - ISSN 0962-1083 - p. 3131 - 3138.
odontotermes-formosanus - phylogenetic inference - population-genetics - isoptera - recombination - comb - sequences - colonies - basidiomycota - establishment
All colonies of the fungus-growing termite Macrotermes natalensis studied so far are associated with a single genetically variable lineage of Termitomyces symbionts. Such limited genetic variation of symbionts and the absence of sexual fruiting bodies (mushrooms) on M. natalensis mounds would be compatible with clonal vertical transmission, as is known to occur in Macrotermes bellicosus. We investigated this hypothesis by analysing DNA sequence polymorphisms as codominant SNP markers of four single-copy gene fragments of Termitomyces isolates from 31 colonies of M. natalensis. A signature of free recombination was found, indicative of frequent sexual horizontal transmission. First, all 31 strains had unique multilocus genotypes. Second, SNP markers (n = 55) were largely in Hardy-Weinberg equilibrium (90.9%) and almost all possible pairs of SNPs between genetically unlinked loci were in linkage equilibrium (96.7%). Finally, extensive intragenic recombination was found, especially in the EF1 alpha fragment. Substantial genetic variation and a freely recombining population structure can only be explained by frequent horizontal and sexual transmission of Termitomyces. The apparent variation in symbiont transmission mode among Macrotermes species implies that vertical symbiont transmission can evolve rapidly. The unexpected finding of horizontal transmission makes the apparent absence of Termitomyces mushrooms on M. natalensis mounds puzzling. To our knowledge, this is the first detailed study of the genetic population structure of a single lineage of Termitomyces.
Production of reproductives in the honey bee species Apis cerana in northern Vietnam
Chinh, T.X. ; Boot, W.J. ; Sommeijer, M.J. - \ 2005
Journal of Apicultural Research 44 (2005)2. - ISSN 0021-8839 - p. 41 - 48.
mellifera - colonies - behavior - africa - brood
In 20 colonies of Apis cerana in northern Vietnam, colony growth, production of drones and queens (sexuals), and swarming and supersedure were related to available flower forage and climate. Despite the tropical setting of the study with year-round forage, production of sexuals was restricted to two periods from March to July and from September to December. Most swarming occurred in May when forage was most abundant. Positive correlations between available forage, colony growth, and production of sexuals suggest that the synchronized production of drones and queens is defined by nutrient flow into the colony. If flow is high, the colony starts growing; when the colony is large enough drones and queens are produced, and eventually the colony swarms. Production of sexuals is synchronized because foraging conditions are sufficient to allow growth for only part of the year. Patterns in drone and queen rearing by A. cerana are similar to patterns found in Apis mellifera. Variation may reflect differences in environment and between species
Extractable substances (anionic surfactants) from membrane filters induce morphological changes in the green alga Scenedesmus Obliquus (Chlorophyceae)
Lürling, M. ; Beekman, W. - \ 2002
Environmental Toxicology and Chemistry 21 (2002)6. - ISSN 0730-7268 - p. 1213 - 1218.
toxiciteit - filters - scenedesmus - oppervlaktespanningsverlagende stoffen - oppervlaktewater - morfologie - kolonies - fytoplankton - aquatische ecosystemen - toxicity - surfactants - surface water - morphology - colonies - phytoplankton - aquatic ecosystems
The effect of filtration of medium through different kinds of filters (glass fiber, mixed esters of cellulose and nitrocellulose) on the morphology in the green alga Scenedesmus obliquus was examined. Several compounds potentially released from membrane filters were further investigated, and among them, two anionic surfactants were found to be morphologically active. Exposure to the anionic surfactants resulted within 2 d in the transformation of unicellular populations of Scenedesmus in populations dominated by colonies. Growth rates between control and surfactant-exposed populations were identical, and the morphological effect occurred at surfactant concentrations far below the reported no-observed-effect concentration for growth inhibition, stressing the need for inclusion of morphological appearance of Scenedesmus in algal toxicity testing to improve the assessment of ecological risks.
Wood ant wars : The relationship between aggression and predation in the red wood ant (Formica polyctena Foerst.)
Mabelis, A. - \ 1979
Leiden : Brill - 170
kolonies - Formicidae - kuddes (herds) - sociaal gedrag - colonies - herds - social behaviour
The Wolof of Saloum : social structure and rural development in Senegal
Venema, L.B. - \ 1978
Landbouwhogeschool Wageningen. Promotor(en): R.A.J. van Lier. - Wageningen : Pudoc - ISBN 9789022005835 - 228
landbouw - etnografie - antropologie - sociale wetenschappen - theorie - methodologie - sociaal beleid - plattelandsplanning - plattelandsontwikkeling - sociale economie - overheidsbeleid - landbouwbeleid - agrarisch recht - nederzetting - politiek - kolonisatie - kolonialisme - regering - kolonies - senegal - frankrijk - volkscultuur - gebruiken - volkenkunde - sociale kwesties - sociale problemen - economische planning - agriculture - ethnography - anthropology - social sciences - theory - methodology - social policy - rural planning - rural development - socioeconomics - government policy - agricultural policy - agricultural law - settlement - politics - colonization - colonialism - government - colonies - senegal - france - folk culture - customs - ethnology - social issues - social problems - economic planning
The study refers to the Wolof of Saloum, Senegal. Its aim was to examine which factors had induced change in rural stratification, co-operation and cohesion. Their significance for administration of rural development was studied. Views of historians and anthropologists are discussed. Literature was examined to determine the processes which had undermined the traditional Wolof states. In this manner, rural development administration was also studied since the colonial period. Fieldwork lasted one and a half years; for one year, a community-study was conducted, the other months were spent on completing questionnaires in the Arrondissement Medinah Sabach.The Islam reform movement had already undermined the power of the Wolof rulers before the spread of groundnut as a cashcrop and the consequent establishment of French colonial rule. This movement did not alter the differences in status and in influence between freeborn villagers and their slaves. In Saloum, the slaves founded independent farms after the 1st World War. Wealth, acquired by cultivating groundnuts and performing commercial sideactivities, has also become important to obtain influence. In the village studied, some descendents of slaves had become rich and a few were members of the councils of the village cooperative and party-branch. Agricultural co-operation was partly an expression of local stratification. Aid in labour was also given to in-laws, friends and the poor. Although wage labour had increased, co-operation had not been decreased by incorporation in the moneyeconomy. This incorporation and the application of Islam law had disintegrated the compound into households and the households into individual farms. In this process, other factors were probably important too. The government organizations concerned with the increase in agricultural production had insufficient knowledge of fragmentation of the domestic units, hierarchy in local power networks and the aristocratic culture pattern. It is likely that the propagated innovations did not decrease indebtedness and the difference in wealth between villagers.
|Het evenwicht in de natuur
Wilde, J. de - \ 1968
s.l. : [s.n.] (Heterosiscursus 1968-1969, les 3) - 2
dieren - biocenose - biogeochemie - biologische bestrijding - kolonies - kringlopen - ecosystemen - kuddes (herds) - mortaliteit - gewasbescherming - populatiedichtheid - populatie-ecologie - populatiegroei - sociaal gedrag - synecologie - animals - biocoenosis - biogeochemistry - biological control - colonies - cycling - ecosystems - herds - mortality - plant protection - population density - population ecology - population growth - social behaviour - synecology
Het boschonderzoek in Nederlandsch-Indië
Beekman, H.A.J.M. - \ 1921
Wageningen : Veenman - 22
bosbouw - nederland - kolonies - onderzoek - nederlands indië - forestry - netherlands - colonies - research - netherlands east indies
Over selectie van meerderjarige cultuurgewassen in tropisch Nederland
Roepke, W. - \ 1920
Wageningen : Veenman - 24
tropische gewassen - tropen - landbouw - kolonies - coffea - cacao - selectie - plantenveredeling - tropical crops - tropics - agriculture - colonies - cocoa - selection - plant breeding