No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Milkweed Control by Food Imprinted Rabbits
Abstract
Many species of invasive plants are spreading out rapidly in Europe. The common milkweed occupies increasingly more area. Being poisonous, most animals will not graze on it however rabbits would be an effective organism for the biological control of milkweed. Rabbit kittens can learn the maternal diet in various ways. They prefer aromatic foods which their mother had eaten during pregnancy or lactation period, -even if it is poisonous- but they can also learn the maternal diet from the fecal pellets deposited by the mother into the nest during the nursing events. The present study was aimed to investigate if rabbit kittens can learn that the common milkweed is a potential food also. In the first 10days of their lives kits got fecal pellets originating from individuals having fed on common milkweed previously. When weaned on day 28 postpartum, these pups preferred the milkweed in the 3-way food choice test, opposite to the control group. Most surprisingly in a second experiment it was also shown that the common milkweed was also preferred by the kittens if their mother ate it not during, but one month before pregnancy.
... A. syriaca reproducing both asexually by underground rhizome-like stems and sexually by flowers (Broyles, Vail, & Sherman-Broyles, 1996;Csontos, Bózsing, Cseresnyés, & Penksza, 2009;Züst et al., 2015). A milky white latex functions as mechanical defence against herbivores (Ducs, Kazi, Bilko, and Altbaecker, 2016). After the species was introduced for ornamental purposes in the early 18th century (Gaertner, 1979), A. syriaca invaded European ecosystems, mainly in Hungary, Romania and Poland (Botta-Dukát and Balogh, 2008;DAISIE, 2017;Rutkowski et al., 2016;Zimmermann, Loos, von Wehrden, and Fischer, 2015). ...
... Finally, most experts come to the conclusions, that it is more effective and cost efficient to combine mechanical control and selective chemical control measures (Ducs et al., 2016;Kelemen et al., 2016;LIFE06 NAT/H/000104, 2014). The integration of control and eradication measures are more likely to success if they are implemented in a long-term monitoring. ...
... A. syriaca is poisonous and contain cardiac glysosides, which are toxic and may cause death in mammalian herbivores and some generalist insect herbivores (Ducs et al., 2016). While A. syriaca has a poisonous milky sap, its toxic properties are destroyed by boiling and even used for pharmaceutical purposes. ...
https://circabc.europa.eu/sd/a/854cb8c6-fd41-4ce6-92ed-8c431fe1b959/TSSR-2016-003%20Asclepias%20syriaca.pdf
This technical note has been drafted by a team of experts under the supervision of IUCN within the framework of the contract No
07.0202/2016/739524/SER/ENV.D.2 “Technical and Scientific support in relation to the Implementation of Regulation 1143/2014 on Invasive Alien Species”.
The information and views set out in this note do not necessarily reflect the official opinion of the Commission. The Commission does not guarantee the
accuracy of the data included in this note. Neither the Commission nor any person acting on the Commission’s behalf may be held responsible for the use
which may be made of the information contained therein. Reproduction is authorised provided the source is acknowledged.
... Although the species is toxic for the majority of mammalian herbivores, it has been found that European rabbits are capable of digesting A. syriaca (Ducs et al. 2016). Due to the possibility of adapting food preferences according to the dietary traditions in a habitat, grazing by European rabbits may be considered for the control of A. syriaca (Ducs et al. 2016). ...
... Although the species is toxic for the majority of mammalian herbivores, it has been found that European rabbits are capable of digesting A. syriaca (Ducs et al. 2016). Due to the possibility of adapting food preferences according to the dietary traditions in a habitat, grazing by European rabbits may be considered for the control of A. syriaca (Ducs et al. 2016). Cultural control in the sense of the management of crop fields can also assist in managing A. syriaca when it invades agricultural land (Hartzler and Buhler 2000). ...
This work synthesizes all aspects of Asclepias syriaca L. (Apocynaceae) including the taxonomy, distribution, history of introduction and spread, ecology, biology, uses and benefits, impacts on biodiversity and agriculture, legislation, and management. Asclepias syriaca is a perennial broad-leaved species native to North America. Introduced for ornamental and various other purposes, such as a source of fibre and rubber, it has become established in many regions of Europe and it had increasingly spread in the last decades (>1980s). Its reproductive behavior is characterized by a high production of wind-dispersed seeds and by the propagation of creeping lateral rhizomes, which allows the species to proliferate rapidly. The species persists in a wide range of edaphic and climatic environments. It occurs particularly in anthropogenic and (semi-)natural habitats, such as roadsides, agricultural land, abandoned sites and grasslands, open shrubland, and forests, respectively. Studies have demonstrated negative impacts on the biodiversity and ecosystem processes in invaded regions, namely in open sand grasslands in Hungary. Asclepias syriaca occurs as a competitive weed in crop fields. Since 2017, the species is regulated by the European Union (EU) under the Regulation No. 1143/2014, which states that A. syriaca is subjected to restrictions such as a ban on importing, selling, breeding and that EU member states are required to place effective management measures. Awareness raising activities are important to inform the public, farmers and stakeholders about the risks of this invasive alien plant. Effective direct control options include mechanical control as well as herbicide application.
... However, the longer-term impacts and required cutting intensity are unknown. Other solutions to be further investigated might include grazing, for example by native animals, as, for example European rabbits are capable of digesting Asclepias (Ducs et al., 2016, Follak et al., 2021. In general, multiple control strategies are often applied to invaded communities (e.g. ...
This study aimed to assess the impact of the invasion of Asclepias syriaca, a perennial non‐native herbaceous species, on basic soil attributes and vegetation composition, and to study the effect of mechanical control, namely cutting of Asclepias, on target and other plant species. Sandy region of Kiskunság National Park, Hungary, Central Europe. In ten old‐fields, four 4 m x 4 m plots were established (n=40), of which three were invaded by Asclepias, and one was uninvaded. The invaded plots were treated as: (1) all Asclepias shoots, (2) half of the Asclepias shoots removed, or (3) untreated. The treatment was conducted twice a year during summer in the 2019‐2021 period. Before the first treatment, soil and vegetation were sampled. Afterwards, vegetation monitoring was performed twice a year: the cover of each vascular plant species and the number of Asclepias shoots were recorded in each plot. There were no differences in the studied soil attributes between the uninvaded and invaded plots. However, there were differences in vegetation composition, namely, the cover of sand grassland specialists was higher in uninvaded plots. Short‐term cutting negatively affected Asclepias after two years. The cover of specialists did not change in response to treatments, but the cover of other neophyte plant species increased. Based on our results, the invasion of Asclepias changes the vegetation composition, but not the soil. Although short‐term mowing can reduce the cover of Asclepias, the grassland specialist plants do not regenerate; instead, secondary invasion occurs. We conclude that more time or additional treatment is required for native plant recovery.
... In previous studies, longterm sheep grazing reduced giant goldenrod populations and allowed native plant species to become established in meadows [203]. Ducs et al. [204] also recommended that rabbit grazing could be an effective method to facilitate the control of common milkweed. Zhang et al. [205] used a bioherbicide isolated from the fungal pathogen Athelia rolfsii (Curzi) C.C. Tu & Kimbr. ...
Improving ecological connectivity (EC) within landscapes by establishing corridors and ecological networks has been proposed to counteract the negative effects of habitat fragmentation and climate change on biodiversity. To be functional, ecological networks should be kept free of opportunistic invasive species that can disrupt EC between protected areas and cause biodiversity loss. The present study focused on perennial herbaceous species whose occurrence in the Adriatic-Ionian region has increased in the last two decades, namely common milkweed (Asclepias syriaca), Jerusalem artichoke (Helianthus tuberosus), Japanese knotweed (Reynoutria japonica), Bohemian knotweed (Reynoutria × bohemica), giant hogweed (Heracleum mantegazzianum), giant goldenrod (Solidago gigantea), Canadian goldenrod (Solidago canadensis), and Bermuda buttercup (Oxalis pes-caprae). All species have a high potential to spread in grasslands, abandoned agricultural fields, forest edges, and riparian areas and pose a significant threat to native plant communities and biodiversity. Restoring heavily infested sites is a major challenge because these perennial invaders are very persistent and tend to alter the soil environment in invaded habitats and prevent the recolonization of native plant communities. Therefore, early action should be taken to prevent the spread of these environmental weeds in ecological networks and protected areas with high conservation value.
... Milkweed was introduced into Europe in the 17th century (Gaertner, 1979;Bukovinszky et al., 2014) from eastern North America and into Hungary in the 18th century by beekeepers (Balogh et al., 2007;Csontos et al., 2009). Currently, A. syriaca endangers the seminatural and natural vegetation of sandy regions (Ducs et al., 2016), has become one of the most abundant invasive plant species in Hungarian lowland forest plantations, and represents a major problem in conservation areas (Szit ar et al., 2016). Its negative effects are, however, not always straightforward (Szit ar et al., 2016;Somogyi et al., 2017). ...
• Non‐native tree plantations constitute a large part of forestation worldwide. Plantations are prone to invasion by exotic herbaceous plant species due to habitat properties, including understory vegetation structure.
• We established 40 sampling sites in 10 plantation forests. Sites were selected according to tree species (native poplar forests and exotic pine plantations) and common milkweed (Asclepias syriaca) density (invaded and non‐invaded sites) in a full factorial design. We collected spiders with pitfall traps.
• We found a significant effect of A. syriaca invasion on spider functional diversity (Rao's quadratic entropy), with invaded sites having a lower functional diversity than non‐invaded sites. A larger effect of invasion with A. syriaca on the RaoQ of spiders was observed in pine compared to poplar plantations. Spider species were larger, and web‐building spiders were more frequent in poplar forests than in pine plantations. We found no effect of A. syriaca invasion on species richness or abundance of spiders.
• Species composition of spider assemblages in the two forest types was clearly separated according to non‐metric multidimensional scaling. We identified seven species associated with pine plantations and six species associated with poplar plantations.
• The similar species richness and the higher functional diversity of non‐invaded sites suggested that these trait states were less similar than invaded sites and that functionally different species were present. In contrast, the invaded sites had lower functional diversities and thus more uniform trait state compositions, suggesting that environmental filtering played an important role in species sorting, making invaded plantations low‐quality secondary habitats for the original spider fauna.
Maternal care in the European rabbit is limited to one brief nursing visit a day. To investigate the nature of this unusual mother- young relationship, four domestic does and their litters were kept separately except for the once-daily nursing, and the following parameters were recorded; from post-natal days 1 to 30, the duration of nursing bouts, daily milk yield, deposition of faecal pellets in the nest by does. daily weight gain of pups, eating of faecal pellets and nest material by pups, their water intake, and from post weaning days 31 to 44, their weight gain. Does were mated immediately after giving birth, and the measures for the first litters raised when does were pregnant were compared with the results for the second litters raised when does were not pregnant. Four control does and their litters were treated in the same way but without separating mothers and young. Pups progressed from drinking milk alone, to nibbling faecal pellets, to ingesting nest material, drinking water and finally to eating lab food. However, growth rates and the pattern of weaning depended on does' reproductive state. The first litters, raised by pregnant does, were significantly lighter and were weaned earlier than the second litters raised by the same does when not pregnant. The rabbit thus provides a particularly good opportunity to investigate the processes underlying the transition to independent feeding in a mammalian species.
The Bugac Juniper Forest consists of a mosaic of woods, shrubs and xeric grasslands lying on a sand dune system, and a part of the forest is a core area of the Man and Biosphere Program. Compared to the other sand dune areas of the Kiskunsag region, the Bugac Juniper Forest is composed of more differentiated patches interspersed with locally poorer vegetation. The succession of vegetation on drought-prone, sandy regions of the Carpathian Basin is less predictable than that on other soil types, but this difference from sites of the same climatic and edaphic conditions is probably mainly due to the high abundance of herbivores, particularly rabbits Oryctolagus cuniculus relative to the low productivity of the grassland. The present state of the forest is the result of secondary succession consequent on burning, heavy grazing and forestry intervention. Lack of an adequate species pool for this edaphic semi-desert might be also involved. -from Authors
2 Institute of Ecology and Botany of the Hungarian Academy of Sciences Abstract: In Hungary, large abandoned agricultural areas have been invaded by the non-indigenous common milkweed ( Asclepias syriaca L.). This species hinders the regeneration of sand y oldfields to open sand grassland (Pannonic sand steppes - Annex I 6260 habitat type). Glyphosate application is a cost-effect ive control method that helps avoid soil surface distur bance and subsequent germination of milkweed seeds in the soil. However, it affects non-target plant species negatively, as well. In our study we explored the e ffects of the treatment on the non-target vegetation. Glyphos ate spraying was applied to three oldfields in the Kiskunság National Park to control vigorous stands of A. syriaca in July 2006. Shoot number of A. syri aca and percentage cover of plant species were estimate d in 1m 2 permanent plots before and after treatment (June 2006 and June 2007). Elimination of common milkweed was successful in the short term. Multivariate analysis showed a general shift of species composit ion following herbicide spraying. The share of summer annual herbs and grasses increased significantly, w hile perennial grasses and herbs decreased in cover . A significant decrease in the average cover of sand g rassland specialist species were detected, while we edy species increased in their abundance. The revealed changes showed that it is an effective way to contr ol common milkweed in the short term. However, it disturbs the underlying vegetation so that it relapses succession back to an earlier stage, rich in annual species in the case of the open patch types, while helps to proceed succession when the vegetation has been closed by clonal grasses.
In the beginning of its intro- duction Common milkweed, Asclepias syriaca L. was used in Hungary as ornamental plant. After escaping from cultivation it has become wide spread during last decades of the 20th century. Nowadays, it covers large areas especially on san- dy soils, and its further appearance is expected on dry, deforested and degraded areas. Two neglected fields and one abandoned vineyard were selected. For sampling two quad- rates of size 4 m2 were used at each stand. The stands were characterized by the following vari- ables: density of stems, percentage of reproductive stems, average number of inflorescences, average number of fruits, fruits per all inflorescences on a stem, pods per fruited inflorescences on a stem, average number of seeds per fruit. In the same quadrates the soil seed bank was studied at two depths (0-5 cm and 5-10 cm). The results showed that the density of stand, percentage of reproductive specimens and aver- age number of fruits were significantly higher on the neglected fields than on the abandoned vineyard. In the neglected fields large number of seeds were detected in the upper soil-layer (2.7- 18.6 × 103 seeds m-2), but in the lower soil-layer much fewer seeds were found and only in one of the fields. Common milkweed seeds were almost completely missing from both soil layers of the abandoned vineyard. However, the seeds recov- ered from the soils practically did not germinat- ed, indicating that seeds of earlier years sets have lost viability, i.e. the studied stands of A. syriaca did not form a persistent soil seed bank. Never- theless, the fresh seed production of the neglected field populations, that can reach 7-10 thousands seeds m-2, may cause a very strong propagulum load not only in the site but also on the surround- ing areas.
This article reviews and summarizes data sets that attempt to compare performance, population dynamics, and herbivory of invasive plant species. Specifically, we review results from studies comparing (1) individual and population parameters of plant invaders in their native and exotic range, (2) herbivore pressure and natural enemy guilds associated with plant invaders in their native and exotic range, and (3) performance and defense levels of native and exotic populations of the invasive under standardized conditions and the performance of selected herbivores. We found a total of 39 published and 2 unpublished studies, investigating 40 plant species. The majority of studies within the first category showed that invaders form larger populations, grow denser, have higher reproductive output, larger seed banks, and higher regeneration rates in the exotic compared with the native range. In contrast, plant vigor was not always greater, presumably because of increased intraspecific competition. Nearly all studies within the second category showed that herbivory (percentage of attack, species number and load) was reduced and, if investigated, that the herbivore community shifted from specialists to generalists and from endophagous to exophagous species in the exotic compared with the native range. Under standardized conditions (category 3), an equal number of studies found increased vigor or no significant differences between plants from the exotic and native range. In a few cases, plants from the exotic range grew less vigorous. Specialist herbivores generally preferred or developed better on plants from exotic compared with native populations, which were also better defended. Studies comparing plant invaders at field sites in their native and exotic range or under standardized conditions can help identify factors facilitating successful invasions, which in turn can improve the selection and efficiency of biological control agents and the development of integrated management strategies. We therefore suggest to include comparative studies more frequently in biological control programs and to extend them to include manipulative experiments and comparisons of control agents. Additional index words: Biological weed control, comparative studies, enemy release hypothesis, evolution of increased competitive ability hypothesis. Abbreviations: EICA, evolution of increased competitive ability; ERH, enemy release hypothesis.
All terrestrial vascular plants probably invest in some form of toxic chemical defence that can be lethal to potential or actual herbivores. However, many insect herbivores are specialists that can handle these toxins with varying degrees of success (Bernays, 1988, 1989; Bernays & Graham, 1988) and some of the most specialized species store or sequester host plant-derived toxins and use them for their own chemical defences against natural enemies at the third trophic level (Rowell-Rahier & Pasteels, 1992). It is these sequestering specialists that pose a paradox for plants because greater investment in toxic chemical defences by a plant may lead to enhanced herbivore fitness and reduced plant fitness.
Choosing an appropriate diet raises special problems for generalist herbivores, especially in areas where most of the plant species are poisonous. This was the case in our study site, the Bugac Juniper Forest (Kiskunsag National Park, Hungary). The main herbivore of this forest, the wild rabbit (Oryctolagus cuniculus), can choose from about 70 plant species, but several of these are toxic or only of medicinal value. Moreover, even the nutritious species of the sparse vegetation are available only for short periods. The annual mortality rate is extremely high for the young, only those individuals survive that can find suitable places to hide and the least poisonous plants to eat. This selection pressure might force the pups to get information about the edible food types as early as possible, i.e. in the nest from their mother.
Development of semi-natural vegetation has recently been a primary concern of restoration efforts. A primary management question is whether active intervention is required or spontaneous secondary succession could suffice. We studied 54 old-fields in central Hungary, which differed in time since abandonment but which had similar environmental conditions and management histories. The sites were grouped into four age groups according to the time elapsed since cultivation abandonment: 1–5, 6–10, 11–23 and 24–33 yr. In each old-field we recorded the species and estimated their abundances. We grouped species in two ways: according to life form (annuals, biennials, perennials, woody plants) and according to coenological behaviour (weeds, sand and steppe generalists, specialists). We analysed the changes in species number and abundance in these categories as a function of site age.
Contrary to other successional studies, the total number of species did not change significantly among the four age groups. A significant change was detected between the first two age groups as to life-form composition. Species number and abundance of annuals decreased, while the perennials and woody plants increased. As to coenological behaviour, species number changed only in the first two age groups, while abundance changed in the first three. Weeds quickly disappeared and specialists established and spread, while the species number and abundance of generalists did not change significantly. We concluded that the basic shifts in species composition are almost completed within 10 yr. Most of the late successional species colonized and weeds disappeared. We conclude that there was no need for active intervention in this system: the spontaneous secondary succession leads to semi-natural vegetation.
Biological invasions in Hungary are causing severe problems as a result of recent introductions and rapid land use changes. Poorly managed agricultural and rural, disturbed areas, and aquatic ecosystems are the most prone to plant invasions. Dry grasslands and semi-natural forests are less prone to invasions. A few plant species have led to human health (allergenic) problems. Some insect species have caused economic problems to crop production. A number of monitoring networks and control measures are in place for selected plants and insects.
Following interaction with a “demonstrator” rat, an “observer” rat prefers that diet eaten by its demonstrator prior to their
interaction (Galef & Wigmore, 1983). The present series of studies demonstrates that such demonstrator influence on observer
diet preference can be found in: (1) first-generation laboratory bred wild rats as well as domesticated rats, (2) food-deprived
as well as nondeprived observers, (3) unfamiliar as well as familiar demonstrator-observer pairs, (4) both 21-day-old and
adult observers, and (5) rats selecting fluids as well as solids for ingestion. These data indicate that the social transmission
of information concerning distant diets is a general and robust phenomenon, observable under a wide variety of experimental
conditions.
This study determined whether experience with onion- or garlic-flavored milk affected intake of foods with those flavors. Orphaned lambs were exposed from 2 to 3 days of age for 50 days to either onion- or garlic-flavored milk at a 0.1% concentration. Lambs were then offered a choice of (1) onion- and garlic-flavored food; (2) onion-flavored and unflavored food; (3) garlic-flavored and unflavored food. Intake of foods offered in single choice tests with each flavor at concentrations of 2, 4, 6, 8, 10, 12, 14, and 16% was also measured. Although all lambs ingested more onion-flavored food than garlic-flavored food, they ate relatively more (P < 0.05) food with the flavor to which they were exposed in milk than did lambs exposed to the alternate flavor in milk. Lambs exposed to onion-flavored milk also ingested more (P < 0.05) onion-flavored food, when it was offered with unflavored food, than did lambs exposed to garlic-flavored milk. Experiences with flavors in milk did not affect (P > 0.05) intake of garlic-flavored food when offered with unflavored food. Regardless of which flavor they were exposed to in milk, intake of onion- and garlic-flavored food offered alone was similar (P > 0.05) at all flavor concentrations.
The common milkweed causes considerable damages on the agricultural and nature conservation areas. The area occupied by this weed is continuously bigger. The common milkweed is spread over North-America between the 35th and 50th degree of western Latitude and 60th 103rd degree of longitude. Millions of hectares are polluted by this weed in the United States. Important is its spread also in Asia (Iraq), in Europe (Carpathian Basin, Poland, Bulgaria, Switzerland, France, Austria, Germany), as well as in the area of the former Soviet Union (Belorussia, The Baltic Countries, Caucasus, and the Ukraine). Though the basic biological characters of this plant are well known, still its control is a significant problem, the damages increase on the areas occupied by this weed. We collect seed samples from several Hungarian areas in 2007. After the sampling we determined the average sprout length and the number of follicle as well as the average seed numbers in the follicle. We determined also the weight of thousand seeds of the resultant seed samples. At natural circumstances the seedlings appear at a soil temperature of 15 degrees C during the end of April and first week of May. Under Laboratory circumstances the dormancy of the seeds ceases continuously from November on, germinate at a temperature of 20-30 degrees C, the maximum germination can be achieved in the first part of April. At January we started germination examinations with the seeds in Petri dish, among laboratory condition.
The impact of browsing on vegetation depends on the relative density and species composition of browsers. Herbivore density and plant damage can be either site-specific or change seasonally and spatially. For juniper (Juniperus communis) forests of a sand dune region in Hungary, it has been assumed that plant damage investigated at different temporal and spatial scales would reflect selective herbivory. The level of juniper damage was tested for a possible correlation with the concentration of plant secondary metabolites (PSMs) in plants and seasonal changes in browsing pressure. Heavily browsed and nonbrowsed junipers were also assumed to differ in their chemical composition, and the spatial distribution of browsing damage within each forest was analyzed to reveal the main browser. Long-term differences in local browsing pressure were also expected and would be reflected in site-specific age distributions of distant juniper populations. The concentrations of PSMs (essential oils) varied significantly among junipers and seasons. Heavily browsed shrubs contained the lowest oil yield; essential oils were highest in shrubs bearing no damage, indicating that PSMs might contribute to reduce browsing in undamaged shrubs. There was a seasonal fluctuation in the yield of essential oil that was lower in the summer period than in other seasons. Gas chromatography (GC) revealed differences in some essential oil components, suggesting that certain chemicals could have contributed to reduced consumption. The consequential long-term changes were reflected in differences in age distribution between distant juniper forests. These results confirm that both the concentration of PSMs and specific compounds of the essential oil may play a role in selective browsing damage by local herbivores.
Reported that 24 nursling rat pups poisoned following ingestion of 1/2-cc of milk from a female rat eating a diet different from that of their own mother showed an aversion to that female's diet during weaning. A 2nd experiment showed that pups fed 31/2-cc meals of milk from a female rat and which were not poisoned showed a slightly increased preference for that female's diet at weaning. Results are interpreted as offering additional evidence that (a) a mother's milk contains gustatory cues reflecting the flavor of her diet and (b) these cues are sufficient to influence dietary preference at weaning.
Studied feeding preferences of weaning rat pups in 4 experiments with 20 recently parturate female hooded rats and their litters (reduced to 8 or 12 pups per litter). Results show that cues associated with the diet eaten by a lactating female rat are transmitted to her young, probably via her milk, and are sufficient to markedly influence the food preferences of her young during weaning. For their 1st meals of solid food, the weanlings actively seek and preferentially ingest the diet their mother has been eating during the nursing period, even if that diet is relatively unpalatable. (15 ref.)
The importance of syntrophic relationships among microorganisms participating in biogas formation has been emphasized, and the regulatory role of in situ hydrogen production has been recognized. It was assumed that the availability of hydrogen may be a limiting factor for hydrogenotrophic methanogens. This hypothesis was tested under laboratory and field conditions by adding a mesophilic (Enterobacter cloacae) or thermophilic hydrogen-producing (Caldicellulosyruptor saccharolyticus) strain to natural biogas-producing consortia. The substrates were waste water sludge, dried plant biomass from Jerusalem artichoke, and pig manure. In all cases, a significant intensification of biogas production was observed. The composition of the generated biogas did not noticeably change. In addition to being a good hydrogen producer, C. saccharolyticus has cellulolytic activity; hence, it is particularly suitable when cellulose-containing biomass is fermented. The process was tested in a 5-m(3) thermophilic biogas digester using pig manure slurry as a substrate. Biogas formation increased at least 160-170% upon addition of the hydrogen-producing bacteria as compared to the biogas production of the spontaneously formed microbial consortium. Using the hydrogenase-minus control strain provided evidence that the observed enhancement was due to interspecies hydrogen transfer. The on-going presence of C. saccharolyticus was demonstrated after several months of semicontinuous operation.
Seasonal foods of European rabbits Oryctolagus cuniculus (Linnaeus, 1758) were studied by microhistological analysis of pellets in a protected area Bugac Juniper Forest, Hungary. Field experiments were also conducted to examine the role of rabbit foraging on common juniper Juniperus communis. The proportion of grasses, forbs and browses changed significantly throughout the seasons (p <0.0001). Spring diet was dominated by grasses (89%), summer diet by grasses (30%) and forbs (42%), whereareas in autumn grasses (60%) and browse (24%) were the main diet components. Juniper appeared only in winter diet (19%) together with other browse (60%). The high proportion of aromatic thyme Thymus glabrescens in summer diet (30%) and juniper in winter diet indicates that monoterpenoids of these plants did not keep rabbits from consumption even when other food sources were available. Planted juniper seedlings disappeared within weeks due to the browsing by rabbits.
Low nutritional quality and high levels of condensed tannins adversely affect voluntary intake of blackbrush (Coleogyne ramosissima Torr.) by goats. We studied: (1) how consumption of blackbrush or alfalfa pellets by young goats affected their consumption of those foods later in life, and (2) whether previous ingestion of blackbrush or alfalfa pellets affected the excretion of condensed tannins and total phenols from blackbrush in urine and feces, production of proline-rich proteins in saliva, excretion of nitrogen in feces, and mass of the liver, kidneys, parotid glands, and reticuloramen in goats. From 6 to 26 weeks of age, experienced goats were exposed to blackbrush, while inexperienced goats ate alfalfa pellets. Following exposure, both groups were offered older-growth blackbrush twigs (OG) or a choice between OG and current season's blackbrush twigs (CSG). A similar feeding trial was repeated nine months after exposure, and, in addition, both groups were offered a choice between OG ad libitum and alfalfa pellets at six levels of availability. Immediately after exposure, experienced goats ingested 95% more (P < 0.01) OG per unit of body weight than inexperienced goats, but both groups rejected CSG. Nine months after exposure, experienced goats ingested 27% more (P < 0.01) OG than inexperienced goats. Experienced goats ingested 30% more OG than inexperienced goats at every level of alfalfa pellet availability. The fate of condensed tannins and total phenols was similar for both groups, but experienced goats excreted 63% more (P < 0.05) uronic acids per unit of body weight. Neither experienced nor inexperienced goats produced proline-rich proteins in saliva. Experienced goats excreted 32% more (P < 0.01) nitrogen in feces per unit of nitrogen ingested than did inexperienced goats. The mass of the reticulorumen was 30% greater (P < 0.05) for experienced than for inexperienced goats one month after exposure, but did not differ 10 months after exposure. The mass of the liver, kidneys, and parotid glands did not differ between treatments. The results show that experience early in life can have profound and persistent effects on consumption of diets high in chemical defenses and low nutrional quality. The results also suggest that several physiological and morphological factors are involved.
The individuals in a flock of 12, 9-month-old Dorset Horn X Border Leicester X Merino sheep could be characterized according to the amount of independence they showed in terms of time spent “alone”. The frequency with which a sheep was first of a group to enter the paddock to graze was positively correlated with its initiation or “leadership” of activities in the paddock. There was a significant correlation between “leadership” in pair tests and in groups of six. The time spent alone by individuals in a group of six was positively correlated with a “leader”/follower ratio and negatively correlated with frequency of joining other sheep when grazing. The larger the leader/follower ratio, the less time a sheep spent with others when grazing in a group of 12.The observations suggest that “leadership” in activities is not a positive expression but a consequence of independence and being followed by other individuals.
In a series of four experiments, comparisons were made of the grazing preferences, food intake, live weight and wool production of sheep having experience of several contrasting nutritional environments. The environments ranged from semi-arid plant communities and sown pastures to hay fed in pens. The sheep were compared on sown pastures at Canberra, A.C.T., and at Bakers Hill, Western Australia.What appeared to be only small differences in experience resulted in marked differences in grazing preferences, which persisted for more than a year, despite attempts to remove them.Experience in different environments was also reflected in food intake. The differences in organic matter intake per kilogramme live weight were generally not as distinctive as differences in preferences.Seasonal patterns of live weight were significantly different in all experiments for sheep with different experience, and smaller differences were observed in wool production. An effect of previous nutritional experience of ewes on lamb birth weight and growth rates was evident. In general, sheep moved from pastoral areas to sown pastures took longer to adapt than did sheep moved from one type of sown pasture to another or from sown pastures to pastoral areas. Adult sheep took longer to adjust to a new environment than did lambs. Only in one experiment did there appear to be persistent effects of previous experience on production.
reviews the neural circuitry of the gustatory system in the omnivorous rat, and compares its anatomical and physiological features to that of the monkey / describe the overlapping central projections, and likely coprocessing, of viscerotopic and gustatory information at virtually all levels of the neural hierarchy (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Rat pups reared by mothers maintained on a diet inhibiting maternal pheromone production do not exhibit a tendency to approach the pheromone excreted by normally maintained lactating females. The results of the present experiments indicate that following exposure in isolation to the smell of maternal pheromone, rat pups reared by dams not producing maternal pheromone exhibit a strong preference for the odor of maternal pheromone. Furthermore, pups reared by non-pheromone producing dams, and exposed in isolation to an arbitrary odor, exhibit both a preference for that odor and a preference for a diet with which that odor is associated. These results are discussed as demonstrating the importance of stimulus familiarity, rather than association learning, in the development of pheromonal bonds and socially transmitted diet preferences.
Community ecology theory can be used to understand biological invasions by applying recent niche concepts to alien species and the communities that they invade. These ideas lead to the concept of ‘niche opportunity’, which defines conditions that promote invasions in terms of resources, natural enemies, the physical environment, interactions between these factors, and the manner in which they vary in time and space. Niche opportunities vary naturally between communities but might be greatly increased by disruption of communities, especially if the original community members are less well adapted to the new conditions. Recent niche theory clarifies the prediction that low niche opportunities (invasion resistance) result from high species diversity. Conflicting empirical patterns of invasion resistance are potentially explained by covarying external factors. These various ideas derived from community ecology provide a predictive framework for invasion ecology.
To curb the future economic and environmental impacts of invasive exotic species, we need to understand the mechanisms behind exotic invasions. One commonly accepted mechanism for exotic plant invasions is the enemy release hypothesis (ERH), which states that plant species, on introduction to an exotic region, experience a decrease in regulation by herbivores and other natural enemies, resulting in a rapid increase in distribution and abundance. The success of classical biological control has been used as support for ERH, but this observational evidence does not directly test ERH, and the more experimental evidence is equivocal. Competitive release through greater generalist enemy impact on natives seems to be an important but understudied mechanism of enemy release, but there is a serious need for experiments involving exclusion of natural enemies in invaded plant communities. With a clearer understanding of the role of enemy release in exotic plant invasions, we can begin to build a comprehensive predictive model of exotic plant invasions.
Anthropogenic introduction of species is homogenizing the earth's biota. Consequences of introductions are sometimes great, and are directly related to global climate change, biodiversity AND release of genetically engineered organisms. Progress in invasion studies hinges on the following research trends: realization that species' ranges are naturally dynamic; recognition that colonist species and target communities cannot be studied independently, but that species-community interactions determine invasion success; increasingly quantitative tests of how species and habitat characteristics relate to invasibility and impact; recognition from paleobiological, experimental and modeling studies that history, chance and determinism together shape community invasibility.
Elimination of plant toxicants via milk by lactating animals is considered a minor route of excretion; however, it may be important when the health of the neonate or food safety in humans is considered. Among plant toxicants excreted in milk is tremetol or tremetone, the toxin in white snakeroot (Eupatorium rugosum) and rayless goldenrod (Haplopappus heterophyllus). These plants have been responsible for intoxication of cows and their suckling calves and for many human poisonings. Other plant toxins excreted through the milk that pose a toxicity hazard include pyrrolizidine alkaloids in Senecio, Crotalaria, Heliotropium, Echium, Amsinckia, Symphytum (comfrey), Cynoglossum (hounds tongue) and Festuca (tall fescue); piperidine alkaloids in Conium, tobacco and others; quinolizidine alkaloids in Lupinus; sesquiterpene lactones of bitterweed and rubber weed; and glucosinolates in Amoracia (horseradish), Brassica (cabbage, broccoli, etc.), Limnanthes (meadowfoam), Nasturtium (watercress), Raphanus (radish) and Thlaspi (stinkweed). Many plants such as Astragalus, Oonopsis, Stanleya, Xylorrhiza, Aster, Atriplex, Sideranthus and Machaeranthera accumulate selenium and may cause intoxication when grazed. Selenium is found in the milk at concentrations relative to the amounts ingested by the lactating animal. Excretion of selenium via the milk is important in the deficiency state, but when in excess it may cause toxicity to offspring.
We investigated the influence of age of exposure to a specific forage on its consumption by young sheep both during and after that exposure. Prior exposure to the shrub Cercocarpus montanus enhanced subsequent consumption (P less than or equal to .05) of that shrub by lambs and yearlings during two experiments in consecutive years. Effects of prior exposure persisted as long as 9 mo without intervening exposure. Age of exposure influenced consumption in lambs both during the period of exposure (P less than or equal to .0001) and during feeding trials following exposure (P less than or equal to .07) in Exp. 1. Lambs exposed at 1 to 5 wk of age, when they are nonruminant and normally are dependent on the dam, browsed less of the time while at the shrub (P less than or equal to .02) and consumed less of the shrub (P less than .02) at a slower rate (P less than or equal to .03) than did lambs exposed at older ages. Lambs exposed at 4 to 8 wk of age, a period corresponding to the transition from nonruminant to ruminant digestion, consumed more shrub following exposure than did lambs exposed at younger or older ages (P less than equal to .05, unprotected least significant differences test). In Exp. 2, which compared naive yearlings with the experienced yearlings exposed as lambs in Exp. 1 the previous year, age of exposure did not influence consumption by yearling sheep following exposure; however, the number of months that had elapsed from the period of exposure varied from 0 to 13 among experimental groups and may have confounded results. Learning of forages appeared poor among nonruminant lambs; data were inconclusive concerning the efficiency of learning of lambs in the transition to ruminant digestion.
Many mandibulate insects that feed on milkweeds, or other latex-producing plants, cut leaf veins before feeding distal to
the cuts. Vein cutting blocks latex flow to intended feeding sites and can be viewed as an insect counteradaptation to the
plant's defensive secretion. Experimental vein severance renders milkweed leaves edible to generalist herbivores that do not
show vein-cutting behaviors and ordinarily ignore milkweeds in nature.
Rabbit pups do not need to learn postnatally the pheromonal cues releasing nipple-search behavior. Pups delivered by caesarean section were able to attach to nipples as quickly as normally delivered controls in their first encounter with a lactating doe (Experiment I), and pups hand raised to Day 5 without postnatal experience of the nipple-search pheromone even showed an improvement in their reactivity to it similar to normally raised controls (Experiment II). However, 1-day-old pups could be conditioned during the first nursing episode to respond with nipple-search behavior to artificial odors painted on the mother's ventrum (Experiment III). Finally, pups conditioned on Day 1 but subsequently raised by hand or normally nursed showed retention of the conditioned responsiveness when tested on Day 5 (Experiment IV). These experiments suggest that although rabbit pups are capable of rapidly associating odors with suckling, they do not appear to depend on this ability under normal nursing conditions.
The odorant allyl sulfide (essence of garlic) dissolved in a corn oil vehicle was injected into rats to induce a conditioned aversion. In subsequent two-choice drinking tests, rats injected with odorant and lithium chloride, and rats injected with odorant and saline avoided drinking from a water bottle paired with the odorant. Because allyl sulfide and saline injections produced symptoms of malaise, we suspect that the odorant served as its own unconditioned stimulus. Rats injected with vehicle and saline showed no differential behavior. In a second experiment, gas chromatography indicated that allyl sulfide was present on the rat's breath within 3 minutes of injection, and was detectable for up to 5 hours post-injection. We conclude that conditioned aversions can be obtained to an intravascular odorant and that one route by which such odorants reach the nose is the breath.
Rabbit pups raised by mothers fed different diets during pregnancy and lactation show a clear preference for the diet of their mother at weaning. By supplementing does' lab chow diet with aromatic juniper berries, the present study aimed to investigate the relative importance of 1) fecal pellets deposited by the mother in the nest, 2) prenatal experience in utero, and 3) contact with the mother during nursing in determining pups' later food preference. The three means of transmission were found to be equally effective. Thus, pups from normally fed does raised with fecal pellets from juniper-fed mothers, pups from juniper-fed mothers cross-fostered to normally fed does immediately after birth, and pups of normally fed mothers nursed by juniper-fed does all showed as strong a preference for juniper as pups raised by juniper-fed mothers exclusively. Such apparent redundancy may not only help insure that less aromatic substances or substances transmitted differentially by these routes are learned, but also that pups can acquire a preference for a variety of foods eaten by their mother at different times.
Invading exotic plants are thought to succeed primarily because they have escaped their natural enemies, not because of novel interactions with their new neighbors. However, we find that Centaurea diffusa, a noxious weed in North America, has much stronger negative effects on grass species from North America than on closely related grass species from communities to which Centaurea is native. Centaurea's advantage against North American species appears to be due to differences in the effects of its root exudates and how these root exudates affect competition for resources. Our results may help to explain why some exotic species so successfully invade natural plant communities.
Expression of c-Fos was examined in the olfactory bulbs of 3-day-old rabbits after they had been presented with the odour of garlic as a novel stimulus, as a learned odour, or during conditioning, and this expression compared with baseline levels in non-stimulated controls. Exposure to garlic odour resulted in substantial and widespread increases in c-Fos expression in the olfactory bulbs of all animals. However, although conditioned pups showed a specific behavioural response to the learned garlic odour, neither the amount nor pattern of c-Fos expression differed compared to pups exposed to garlic as a novel odour. The odour-induced expression of c-Fos was not well localised, although there was a significant increase in the number of granule cells expressing c-Fos in the ventrolateral region of the bulb. These results support previous reports that the response to odours in the olfactory bulb of new-born animals is not as spatially distinct as that in adults. Nevertheless, the immature olfactory system of these young animals is clearly capable of very specific odour learning.
Here we present evidence that Centaurea maculosa (spotted knapweed), an invasive species in the western United States, displaces native plant species by exuding the phytotoxin
(–)-catechin from its roots. Our results show inhibition of native species' growth and germination in field soils at natural
concentrations of (–)-catechin. In susceptible species such as Arabidopsis thaliana, the allelochemical triggers a wave of reactive oxygen species (ROS) initiated at the root meristem, which leads to a Ca2+ signaling cascade triggering genome-wide changes in gene expression and, ultimately, death of the root system. Our results
support a “novel weapons hypothesis” for invasive success.
Social Learning in Food Preference Transmission in Wild and Domestic Rabbits
- Á Bilkó
Bilkó, Á., 1994. Social Learning in Food Preference Transmission in Wild and
Domestic Rabbits (in Hungarian with English Abstract). Eötvös Loránd
University, Budapest.
William's Obstetrics
- N J Eastman
- L M Hillman
Eastman, N.J., Hillman, L.M., 1961. William's Obstetrics. Appleton-Century., New
York.
Successfully Controlling Noxious Weeds with Goats, 21. National Coalition Against the Misuse of Pesticides
- L Lamming
Lamming, L., 2001. Successfully Controlling Noxious Weeds with Goats, 21.
National Coalition Against the Misuse of Pesticides, pp. 4.