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1.
Slugs feed on some plant species but not on others for reasons that are not yet fully understood. We re‐examined the two largest studies on the preference of Arion lusitanicus for different plant species. Briner & Frank (1998) measured the consumption index of slugs (CIB) based on the dry leaf mass eaten per day per gram of slug mass. Kozlowski & Kozlowska (2009) also measured a consumption index of slugs (CIK) but on the basis of the area eaten per day per gram of slug mass. The two indices showed a moderate positive rank correlation. Briner & Frank (1998) found that slugs preferred annual to perennial plants and crops rather than wild species. On the other hand, Kozlowski & Kozlowska (2009) found no statistically significant difference in slug preference for annuals, biennials or perennials. Using botanical databases we selected plant traits related to slug herbivory and analysed 141 species. We first analysed the two data sets separately and found that CIB was higher for seedlings with a higher relative growth rate although this result was only marginally statistically significant. In addition, we found that annuals were consumed more than perennials and that cultivated plants were consumed more than wild plants. This is in agreement with the conclusions of Briner & Frank (1998). For CIK slugs consumed less from plants with high dry matter content (DMC). The use of classification and regression tree models solves the problem of analysing datasets with missing values. Regarding CIB, the tree models indicated that life cycle was the major branch. Within perennials, cultivated/wild origin of plants was the most important predictor of slug feeding. Within wild perennials slugs ate more from plants with low specific leaf area (SLA), i.e. relatively thick leaves. Within annuals we found the unexpected result that slugs ate more from plant species with either alkaloids or glucosinolates than from species without one of these compounds. For CIK, the results of tree models showed that slugs preferred shade‐intolerant plants to shade‐tolerant plant species. Within the shade‐tolerant group slugs fed more on leaves with low DMC. We only partially understand which factors make plants acceptable to slugs. We discuss this issue along with the pros and cons of the two methods used to calculate CI. 相似文献
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Arion vulgaris (syn. A. lusitanicus) is the most destructive pest slug in Europe. The species has been regarded a classic case of an ongoing biological invasion with negative economic and ecological impact in many European countries, but this status has recently been contested. In this study, we assessed mitochondrial and autosomal genetic diversity in populations of A. vulgaris across the entire distribution range in order to characterize its evolutionary history. Mitochondrial diversity in A. vulgaris was strongly reduced compared with the closely related and largely codistributed noninvasive species A. rufus and A. ater, indicating a very rapid spread of A. vulgaris through Europe. Autosomal diversity assessed in 632 individuals from 32 populations decreased towards eastern and northern Europe which is consistent with the reported expansion of the species towards these regions in the last decades. Demographic simulations supported very recent population founding events in most of the European range. The short periods between the first detection of A. vulgaris in different countries and only a very weak association of genetic structuring among populations with geographical distances suggest a human contribution in the ongoing expansion of the slug. We propose that this contribution may ultimately prevent the exact localization of the debated region of origin of A. vulgaris. However, the reclassification of A. vulgaris as noninvasive would be premature. Without counter measures, the Eastern and Northern European countries can expect to see this biological invasion continued in the future. 相似文献
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The slug Arion lusitanicus is an invasive species which has recently become established in many European countries and is considered a serious pest, both in agriculture and private gardens. The effect of temperature on growth rate, survival, egg developmental time and hatchability of the slug are reported. The growth rate was positively correlated with temperatures up to 20°C and A. lusitanicus continued (on average) to grow until they die. A model describing how growth depends on temperature was developed, and a field survey found that the predicted growth matched the observed with reasonable accuracy. This study confirms the assumption that A. lusitanicus die after egg laying. Free‐ranging A. lusitanicus has an annual life cycle, but our data show that slugs also possess the ability to live for up to 3 years. The egg developmental time was, like growth, positively correlated with temperature and was shortest at 20°C, but the optimum temperature for egg development, when regarded as the temperature with highest hatchability was found to be 10°C. In conclusion, this study has shown that growth and the life‐history traits, egg developmental time and hatchability, of A. lusitanicus are highly influenced by temperature. However, data also show that temperatures within the range 2–20°C did not influence survival rates to any large degree, and that A. lusitanicus can quickly adjust to changes in temperature. The study provides a number of basic parameters which contribute to the understanding of the population dynamics of A. lusitanicus. 相似文献
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The feeding deterrent effect of carvone on the slug Arion lusitanicus was investigated. Carvone, a natural compound from caraway seeds, was incorporated into mulch to reduce its inherent volatility. In a laboratory choice experiment, boxes were filled on one side with carvone‐treated mulch and on the other side with untreated mulch. At carvone concentrations ranging from 0.03–0.75 ml litre?1 mulch, slugs ate significantly more lettuce on the untreated side. In a laboratory based no‐choice experiment, carvone concentrations of 0.25 and 0.75 ml litre?1 mulch significantly reduced slug feeding in comparison with the untreated control. Moreover at the highest concentration of carvone (0.75 ml litre?1 mulch) 50% mortality was recorded over a period of 5 days, indicating a clear molluscicidal effect. Due to its volatility carvone did not decrease plant defoliation by A. lusitanicus when applied directly onto lettuce. Subsequent field evaluation showed 0.75 ml litre?1 mulch to partially reduce slug feeding damage. However, this effect was not sufficient to significantly increase lettuce yield. The incorporation of a higher carvone concentration into mulch is still to be tested to confirm whether carvone‐treated mulch can be recommended as an effective alternative approach to chemical slug control. 相似文献
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《Basic and Applied Ecology》2014,15(7):607-615
In demographic studies on Brassica cultivars and accessions we observed large genotypic variation in the ability of seedlings to establish. Here we quantify the role of slugs during establishment by including and excluding slug herbivory.Slug exclusion during the first 10 days after germination led to 26.5 times more surviving seedlings in modern canola varieties of Brassica napus, 4.3 times more in feral B. napus and 1.9 times more in wild Brassica rapa. While seed and seedlings of canola were low in aliphatic glucosinolates (AGS), feral B. napus and wild B. rapa had much higher AGS levels. Consequently, we find a positive correlation between the survival of young seedlings and AGS concentration. Concentrations of indole glucosinolates (IGS) in seeds were much lower than those of AGS and did not correlate significantly with survival. Subsequently, we exposed 10-day-old seedlings to herbivory. In the 4 days following exposure, slug herbivory was negatively correlated to AGS concentration but not to IGS.In choice experiments in the lab, the preference of the slug Arion lusitanicus also correlated negatively with AGS content. A. lusitanicus preferred to feed on B. napus rather than on wild B. rapa, but had no significant preference when presented with plants similar in AGS content.Slugs can be a limiting factor for seedling recruitment in populations of B. napus, especially for modern canola cultivars with a low AGS content. 相似文献
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Methanol extracts of the plants Geranium robertianum, Lepidium sativum, Origanum vulgare, Salvia officinalis, Salvia pratensis, Saponaha officinalis, Thymus vulgaris, Trifolium repens and Valerianella locusta were produced and applied to cotyledons of 6–8 days old rape seedlings to investigate whether they can influence the feeding of the slug Arion lusitanicus on young rape. All plant extracts appeared to reduce slug feeding on rape to some extent, but only the extracts of Saponaria officinalis and V. locusta significantly deterred A. lusitanicus from feeding. The small effects of some extracts may be due to a poor extraction efficiency or an insufficient feeding inhibition capacity of these extracts. 相似文献
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The daily activity of the slug Arion lusitanicus was studied using time‐lapse video analysis in the laboratory. Under constant temperature (18°C) and 16–h photoperiod, the activity of slugs was measured in half‐hourly periods as locomotor activity, feeding or resting. Track lengths were determined using image analysis. Locomotion of A. lusitanicus was greatest at 5:30, 1.5 h after sunrise, and at 20:30, 1 h after sunset; least locomotor activity occurred between 13:00 and 14:00. The mean distance travelled by A. lusitanicus in 24 h was 10.8 m. The largest slug was the most active and the smallest the least. Slugs spent 68% of 24 hours resting, mainly under artificial shelter traps, 27% in locomotion and 4% feeding. Feeding occurred mainly during the hours of dakness (76%). All categories of behaviour investigated varied greatly between individuals and also between times of day. Homing to artificial shelters and other roost sites was regularly observed within 24 h (41%), but decreased considerably thereafter. The behavioural patterns proved to be in agreement with those found in a previous field investigation and are therefore also discussed with a view to their importance in pest control. 相似文献
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Dandelion is a common Asteraceae species that populates disturbed sites and gaps within swards where it becomes an important competitor of grasses. The natural control against dandelion includes seedling predation, with slugs, particularly Arion lusitanicus, being the most important in the Czech Republic. However, the study of slug seedling consumption is difficult because naturally established seedlings are not always available. Therefore, we developed a method of exposing laboratory‐grown seedlings as bait for slug predation. Dandelion seeds were sown in plastic cups containing a bottom layer of moist substrate. The emerged seedlings were thinned to 20 and displayed in an open area. During 2008–2010, the seedling baits were placed at 15 sites at 1 month intervals throughout the dandelion vegetative season, in parallel with plasticine baits that monitored slug feeding activity. For each 1 month interval, seedling survival was observed for a period of 8 days, and the estimated time to death was calculated; the percentage of surviving seedlings was then recorded. This method of seedling presentation demonstrated that local and temporal variation in seedling survival is correlated with slug feeding activity. The advantage of this technique is that the seedlings in baits may be presented at any place and time, as required by the experimental design; however, we found that the estimated time to seedling death was shorter for the exposed baits than for the naturally established seedlings. The method is suitable for the study of plant species other than dandelion, and also for aims other than the study of spatiotemporal trends in seedling consumption by slugs. 相似文献
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Each of 36 observer rats was: (1) exposed to a demonstrator rat that had eaten an unpalatable, cayenne-pepper-flavored diet (Diet Cay), then tested to determine its willingness to eat Diet Cay and (2) exposed to a demonstrator rat that had eaten a palatable diet (Diet NPT) to which the observer had previously learned an aversion, then tested to determine its willingness to eat Diet NPT. In both instances, some observers ate substantial amounts of the diet that their respective demonstrators had eaten, while other observers did not. No consistency was found across the two situations in the relative susceptibility of individual observer rats to social influences on their food choices. In a second experiment, observer rats interacted, at 3 day intervals, with demonstrator rats that had each eaten different diets. After each interaction, all observers were given a choice test to determine their preferences for the diet that their demonstrators had eaten. Again, there was no consistency in the relative strength of individual observer rats' socially induced preferences for diets fed to demonstrators. Stable individual differences in magnitude of susceptibility to social influence on food preference did not account for a detectable proportion of observed variance in diet selection. 相似文献
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Daily variation in the number of slugs under and around 25 cm × 25 cm pad‐traps was recorded in plots of crop cultures. Grey field slugs Deroceras reticulatum and garden slugs (Arion distinctus and Arion hortensis) left traps at dusk and came back at the end of the night. The time of day at which the number of trapped slugs was maximal did not occur in the middle of the day, when slugs were inactive, but in the early morning and in the evening, a few hours before dusk. This was due to a rise in temperature under the traps in the middle of the day. However, the grey field slugs stayed under traps throughout the morning, when temperatures under the traps reached values more favourable for rest. 相似文献
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Mari S. Golub Carl L. Keen Andrew G. Hendrickx M. Eric Gershwin 《Primates; journal of primatology》1991,32(1):49-59
Zinc deprivation has been shown to produce hypogeusia in rhesus monkeys but the possible consequences of altered taste sensitivity
for food preference and selection is not known. We studied 13 rhesus monkeys (2.5 to 3 years of age) for food preference in
a structured choice situation. These animals were fed two levels of dietary zinc: marginally zinc deprived (fed 4 μg zinc/g
diet from conception and throughout development;N=6), or control (fed a 100 μg zinc/g diet throughout the study;N=7). Preference for familiar vs unfamiliar food items, order of food preferences, persistence in retrieval of preferred and
nonpreferred foods, and preference under four deprivation periods were examined. Animals were offered a choice of two food
items, both containing minimal zinc levels, and food choice and latency of choice were measured. Results indicate that animals
fed the marginal zinc diets had reduced preference for unfamiliar foods relative to controls and different patterns of food
preference. These results may be relevant to maintenance of appropriate food selection in marginally zinc deprived populations. 相似文献
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１９８５年４月用标志重捕法观察了大仓鼠的活动范围;野外直接观察了鼠的活动及危害;室内直接观察了昼夜活动节律;在笼养状况下,观察了大仓鼠捕食黑线仓鼠和小白鼠的行为;室内观察了大仓鼠选食种子的行为。 相似文献
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In vivo effects of Manduca sexta allatostatin and allatotropin on larvae of the tomato moth, Lacanobia oleracea 总被引：1，自引：0，他引：1
Abstract. Injection of Manduca sexta allatotropin (Manse-AT) into fifth or sixth stadium larval Lacanobia oleracea had no significant effect on larval growth, development or food consumption, compared to control injected insects. In contrast, injection of M. sexta allatostatin (Manse-AS) into fifth stadium larvae resulted in a retardation of growth, reduction in feeding and increased mortality, compared to control injected insects, but had no effect on non-feeding (day 7) sixth instar larvae. Results suggest that Manse-AS is not acting on the corpora allata (CA) to inhibit Juvenile Hormone (JH) synthesis to produce the observed effects, but most likely by its myoinhibiting action on the foregut. Inhibition of foregut peristalsis by Manse-AS in vivo appears to suppress feeding, resulting in increased mortality. Foregut peristalsis may be inhibited by the intact peptide or a deletion peptide produced by cleavage of Manse-AS by haemolymph enzymes, because Manse-AS (5-15) also inhibits muscle contractions in the foregut in vitro . 相似文献
17.
Robin J. Blake Ben A. Woodcock Duncan B. Westbury Peter Sutton Simon G. Potts 《Agricultural and Forest Entomology》2013,15(1):77-85
- 1 Grass buffer strips have been widely sown to mitigate against intensive agricultural management practices that have negatively impacted on invertebrate and plant biodiversity in arable farming systems. Typically, such strips are floristically species poor and are dominated by grasses. In the present study, we developed management practices to enhance the floristic and structural diversity of these existing strips for the benefit of spiders, a key provider of natural pest control in crops.
- 2 Across three UK arable farms, we investigated the benefits of: (i) scarification to create germination niches into which wildflower seeds were sown and (ii) the effect of graminicide applications to suppress grass dominance. Spiders were sampled twice per year (July and September) during 2008 and 2009.
- 3 The combination of scarification with wildflower seeds, as well as graminicide, resulted in the greatest wildflower cover and lowest grass cover, with a general trend of increased abundance of adult and juvenile spiders. The abundance of Pachygnatha degeeri, Bathyphantes gracilis and juvenile wolf spiders of the genus Pardosa was positively correlated with wildflower cover, probably reflecting increased prey availability. Sward structure was negatively correlated with Erigone atra, Oedothorax fuscus and juvenile Pardosa abundance.
- 4 Management that utilizes existing commonly adopted agri‐environment options, such as grass buffer strips, represents a potentially important conservation tool for increasing the quantity and quality of invertebrate habitats. This can maximize opportunities for the provision of multiple ecosystem services, including pest regulation by predators such as spiders. These management practices have the potential to be incorporated into existing U.K. and European agri‐environment schemes.
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Summary Food preference, metal avoidance behaviour and desiccation tolerance were investigated for two collembolan species, Folsomia fimetarioides and Isotomiella minor, in order to test some hypotheses for their different distributions in relation to a heavy metal gradient. F. fimetarioides showed a higher preference for metal tolerant fungi than I. minor when they were offered fungi of different metal tolerance. When they could choose between polluted and unpolluted fungi and substrate, F. fimetarioides significantly avoided the polluted source while I. minor did not. Both species were negatively affected by drought. I. minor was more tolerant than F. fimetarioides when exposed to drought in combination with metal pollution. High supply of preferred fungal species and a better ability to avoid heavy metals favour F. fimetarioides and determine its dominance over I. minor in polluted soils. 相似文献
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THIERRY BACKELJAU CARLOS P. DE BRITO REGINA M. TRISTÃO DA CUNHA ANTONIO M. FRIAS MARTINS LUC DE BRUYN 《Biological journal of the Linnean Society. Linnean Society of London》1992,46(1-2):131-143
Thirty specimens of Arion intermedins from Flores (and Corvo) were electrophoretically (PAGE) assayed for 11 enzymes, yielding information about 14 putative loci in two colour morphs of this species. One of these colour variants was tentatively identified as A. pascalianus (P morph). Except for the Mdh locus, all loci in A. intermedins sensu lato from Flores were monomorphic. Mdh , however, was diallelic for Mdh100 and Mdh122 . This latter electromorph was absent in A. intermedins sensu stricto from Flores, but present in the P morph and A. intermedins from Belgium. As a consequence A. intermedins sensu lato from Flores consists of two genetic strains defined by the Mdh alleles. The genetic identity between these strains (7) is 0.929. The genetic identity between the P morph and A. intermedins sensu stricto in Flores is 0.951, while between the P morph and Belgian A. intermedins it is 0.973. These values suggest that the supposed A. pascalianus from Flores is only a colour morph of A. intermedins. This paper also provides the first published record of this species from the island of Corvo. 相似文献
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海南大田国家级自然保护区赤麂的食性 总被引：11，自引：0，他引：11
20 0 1年 1 0月至 2 0 0 2年 9月在海南大田国家级自然保护区 ,采用直接观察法和采食痕迹估计法对赤麂的食性进行了研究。共记录了赤麂 36 4群 ,群的平均大小为 1 32只。我们对这些赤麂利用的 5 2 3个取食地的植被进行了分析 ,并利用采食痕迹估计法确定了 2 94个取食地。赤麂取食的植物达到 2 1 5种 ,隶属 5 8科。其中木本植物 1 1 4种 (占 5 3 0 2 % ) ,草本植物 95种 (占 4 4 1 9% ) ,蕨类植物 6种 (占 2 79% )。取食频率超过 0 0 1 %的植物主要集中在 2 5个科 ,共计 5 5种 ,对这些种类的取食频率达到总取食频率的 89 2 3%。不同季节中赤麂取食的植物种类没有明显差异 ,但是在食物种类的选择方面存在季节性差异。赤麂对植物部位的选择性有季节性差异。从取食部位看 ,赤麂属于以嫩枝叶为主的精食者。无论旱季还是雨季 ,赤麂主要在有刺灌丛和灌丛草地生境类型中取食。野外见到赤麂以直接饮水的方式来补充对水分的需求 ,旱季表现得尤为明显 相似文献