Hostplant,larval age,and feeding behavior influence midgut pH in the gypsy moth (Lymantria dispar)

Summary The midgut pH of late instar gypsy moth (Lymantria dispar L.) larvae is strongly alkaline, and varies with diet, larval stadium, and time since feeding. Midgut pH rises with time since feeding, and does so more quickly, reaching greater maximum values, on some diets than others. Leaf tissues of 23 tree species resist increases in alkalinity differentially; this trait and differing initial leaf pH may explain the impact of diet on gut pH. Third instar larvae may have gut conditions favorable for tannin-protein binding shortly after ingesting certain foods, but with time midgut alkalinity becomes great enough to dissociate tannin-protein complexes. Older instars rarely exhibit gut pHs low enough to permit tannin activity. Alkaline gut conditions may explain the gypsy moth's ability to feed on many tanniniferous plant species, especially in later instars. Consequences for pathogen effectiveness are discussed.     

The diet of the edible cockle Anadara antiquata L. (Bivalvia,Arcidae) in Dar es Salaam,Tanzania, during the northeast monsoons

The diet of the cockle Anadara antiquata L. was studied along Dar es Salaam coast during the N-E Monsoon season. No zooplankton were found in the 80 cockle guts examined. 27 phytoplankton genera were identified, an indication of wide phytophagy. Members of classes Bacillariophyceae, Chlorophyceae, Pyrophyceae and Prasnophyceae were very prevalent in the diet. Scenedesmus, Chlamydomonas, Palmeria, Exuviella, and Coscinodiscus showed the highest recurrence frequencies per gut.     

Reduced intestinal calcium and dietary calcium intake,increased aluminum absorption,and tissue concentration in the rat

To test the influence of calcium (Ca) on aluminum (Al) absorption, Ca was withheld from or added (1 mM) to the perfusate of thein situ rat gut. The rats had been maintained on Purina Rat Chow. Ca addition significantly decreased (to 70%) the rate of Al disappearance from the gut and decreased (to 55%) the area under the curve of Al appearance in portal blood. To test the influence of Ca deficiency on Al absorption, rats were maintained on a low-Ca (0.008%) or a Careplete (0.5%) diet for 1–4 wk. Thein situ gut was prepared, and a perfusate containing approximately 1 μM Ca was used. The rate of Al disappearance from the gut of low-Ca diet rats was significantly faster than from the gut of rats maintained on the Ca-replete diet, averaging 156% of the latter. Al appearance in portal blood was significantly greater (averaging 38%) in rats maintained on the low-Ca diet than in controls. To determine if Ca deficiency influences Al tissue distribution independent of gastrointestinal Al absorption, rats maintained on a low-Ca or a Ca-replete diet received 20 ip Al injections over 1 mo. Rats eating the low-Ca diet demonstrated enhanced tissue Al accumulation in all tissues studied, except for muscle and cerebral cortex. These results demonstrate enhanced Al absorption and tissue retention in the presence of reduced intestinal Ca concentration and reduced Ca intake.     

The gut morphology of the African ice rat,<Emphasis Type="Italic"> Otomys sloggetti robertsi</Emphasis>, shows adaptations to cold environments and sex-specific seasonal variation

We studied the gut morphology of the ice rat Otomys sloggetti robertsi, a non-hibernating murid rodent endemic to the sub-alpine and alpine regions of the southern African Drakensberg and Maluti mountains. The gut structure of O. s. robertsi is well adapted for a high fibre, herbivorous diet, as is the case with other members of its subfamily Otomyinae. Despite the broad similarity in gross gut morphology with mesic- and arid-occurring otomyines, O. s. robertsi has a larger small intestine, caecum, stomach volume and parts of the colon, which we suggest are adaptations for increased energy uptake and/or poor diet quality in alpine environments. However, O. s. robertsi has a smaller larger intestine than other otomyines, perhaps because it occupies a mesic habitat. Seasonal sexual differences occurred, with females increasing dimensions of the stomach, small intestine length, caecum, and large intestine in summer. Sexual asymmetry in gut morphology may be related to increased energy requirements of females during pregnancy and lactation, indicating phenotypic plasticity in response to poor quality vegetation and a shorter growing season in alpine habitats.Communicated by G. Heldmaier     

饲料类型对茶尺蠖幼虫肠道细菌多样性及幼虫存活率的影响

【目的】茶尺蠖是茶园中的重要害虫。研究茶尺蠖寄主食物-肠道菌群-茶尺蠖生长发育三者之间的关系对于茶尺蠖的防治具有重要的理论指导价值。【方法】分析不添加茶叶因子的纯人工饲料和茶树鲜叶对茶尺蠖幼虫的存活影响;用高通量测序技术分析不同饲料饲喂的茶尺蠖幼虫的肠道菌群异同。【结果】取食人工饲料的幼虫死亡率远远高于取食茶树鲜叶的幼虫;取食人工饲料的幼虫肠道细菌多样性和丰富度高于取食茶树鲜叶的幼虫;茶尺蠖幼虫肠道中存在很多促进宿主生长的细菌。【结论】饲料类型影响茶尺蠖幼虫的存活;饲料类型影响茶尺蠖幼虫肠道菌群结构。     

The relationship between ontogeny, morphology, and diet in the Chinese hook snout carp (Opsariichthys bidens)

The relationship of changes of body and mouth shape with diet during ontogeny in the Chinese hook snout carp Opsariichthys bidens was examined. Shape changes were analyzed using geometric morphometrics. Body shape changed from a shallow body to a deep body as size increased. Similarly, the head of O. bidens changed from an upward-pointing direction to a downward-pointing directing as size increased. The position of the eye also changed during ontogeny, with large individuals having an eye situated higher on the head than small individuals. The conspicuous symphyseal knob on the lower jaw of O. bidens results in a typical zigzag pattern of the jaw. The zigzag pattern became more pronounced as fish grew larger. No difference in body shape or jaw shape was found between males and females. The shape changes were associated with changes in diet, suggesting that diet choice over the course of ontogeny has a strong impact on body shape. Benthic macroinvertebrates and zooplankton dominated the diet of small individuals, medium-size individuals specialized in benthic macroinvertebrates, and fish dominated the diet of large individuals.     

Ingestion of live filamentous diatoms by the Great Lakes amphipod,Diporeia sp.: a case study of the limited value of gut contents analysis

Individuals of the Great Lakes amphipod, Diporeia sp. (formerly named Pontoporeia hoyi) were collected from a 45-m deep station in southeastern Lake Michigan and isolated in small laboratory feeding vessels at 4 °C, after the animals had voided their guts over a 24-hour period. Over a 20-day period, following introduction of a single ration of live cells of the filamentous diatom, Melosira varians, 9 of 10 animals had ingested this material, and 7 of these 9 individuals had deposited fecal pellets. Subsequent examination of gut contents and fecal pellets showed that although animals had ingested whole algal cells/filaments, little of the material in gut contents or fecal pellets bore any identifiable structural similarity to cells/filaments prior to ingestion. The results suggest that earlier studies of pontoporeiid gut contents may seriously underestimate the importance of algal components in the amphipod's diet and imply that Diporeia sp. growth and production may be more closely linked to primary production than previously thought.     

Interactions between developmental processes,growth, and food selection in the larvae and juveniles of Rutilus rutilus (L.) (Cyprinidae)

Summary The aim of this study was to assess the effects of developmental events, occurring in fish during the first weeks after hatching, on the quantity and quality of the ingested food and on growth. The investigation was carried out with the larvae and juveniles of Rutilus rutilus, the single cyprinid species occurring in an oligotrophic subalpine lake in Tirol, Austria. Comparison between availability of prey in the water and gut contents suggests that the selection of food by the young fish is strongly influenced by developmental processes. For example, the prevalence of indigestible phytoplankton in the gut of young larvae can be taken as a sign of the not yet fully developed sensory and locomotory capacities of the young fish (El-Fiky et al. 1987). Furthermore, quantitative and qualitative changes in the gut contents correlate strongly with changes in the form and relative length of the gut, but reflect only weakly the availability of prey in the water. In the Seefelder See population of R. rutilus the switch from a phytoplankton to a cladoceran dominated diet is accompanied by an increase in relative growth rate by nearly one order of magnitude (Wieser et al. 1988).     

Bioevaluation of Subabul (Leucaena leucocephala) proteinase inhibitors on Helicoverpa armigera

Helicoverpa armigera, a highly polyphagous pest, has a broad host spectrum, causes significant levels of yield loss in many agriculturally important crops. Serine primarily responsible for most of the proteolytic activity in the larval gut of lepidopteron insects. Neonate larvae were reared on artificial diet and chickpea seeds smeared with Subabul Trypsin Inhibitor. Larvae fed with artificial diet showed reduction in larval weight up to 21% (HSTI) and 43% (LSTI). However, larvae fed on seeds showed significant reduction in weight, 52.4% (HSTI) and 60.3% (LSTI), suggesting that the diet also plays a vital role on the effectiveness of the inhibitors on larval growth and development. HSTI and LSTI inhibited the gut proteinases from larvae fed on artificial diet significantly (41.40% and 64.36%) compared to the gut proteinases (27.80% and 38.90%) from larvae fed on chickpea seeds. Seeds smeared with 10,000 TIU resulted in complete mortality of larvae while there was no mortality observed in artificial diet. The results reveal that LSTI is a stronger inhibitor of insect gut proteinases and for larvae fed with poor nutrition in the natural ecosystems, low level expression of inhibitor would be enough to affect the growth and development. Handling editor: Chen-Zhu Wang     

强化玉米饮食对小鼠肠道菌群结构和功能的影响

【目的】采用高通量测序方法研究强化玉米饮食对小鼠肠道菌群结构的影响以及可提高宿主糖代谢相关菌群功能基因的分析。【方法】分别给予两组小鼠(各10只)常规饮食和强化玉米饮食(1/4的玉米粉加3/4的常规饮食成分),喂养10周,之后采集小鼠粪便样本,提取DNA,使用高通量测序仪进行宏基因组测序分析,比较两组小鼠肠道菌群和功能基因的差异。【结果】两组小鼠的终末体重没有明显差异。各样本DNA的测序有效率足够,肠道菌群的多样性存在一定差异。属放线菌门(Actinobacteria)的双歧杆菌(Bifidobacteriales)-B.pseudolongum分支和Coriobacteriia-Collinsella/Enterorhabdus分支的丰度在强化玉米饮食组的小鼠中显著升高,相应的宏基因组中涉及糖酵解和胆汁酸合成的一些酶和功能单元的含量也在强化玉米饮食组显著升高。【结论】强化玉米饮食可以提高肠道菌群中双歧杆菌等益生菌的丰度,增加宏基因组糖脂代谢相关基因和通路的含量,从而可能促进宿主的糖代谢功能。     

Rate of digesta passage in the Philippine flying lemur,Cynocephalus volans

The rate of digesta passage was measured in five captive Philippine flying lemurs (Cynocephalus volans). These animals were force fed capsules containing known quantities of either particulate or soluble markers. The volumes of the gastrointestinal tracts of three flying lemurs were determined based on the wet weight of the contents of each section of the gut. The mean rate of digesta passage was 14.37±3.31 h when determined using the particulate marker and 21.9±0.03 h when determined using the soluble marker. The values based on the particulate marker are between 2% and 10% of similar values for other arboreal folivores. The morphology of the gastrointestinal system of the Philippine flying lemur is similar to that of other hindgut fermenters. Flying lemurs have a simple stomach and a large caecum. The total gut capacity of the Philippine flying lemur is similar to that of other herbivores, but is slightly smaller than that of either the koala (Phascolarctos cinereus), a hindgut fermenter, or the three-toed sloth (Bradypus variegatus), a foregut fermenter. These data suggest that flying lemurs deal with the problems of a folivorous diet very differently than some other arboreal mammals. Phascolarctos cinereus and Bradypus variegatus may represent one extreme with Cynocephalus volans representing the other extreme along a continuum of foraging strategies that are compatible with the arboreal folivore lifestyle.Abbreviations bw body weight - EDTA ethylenediaminetetraaceticacid - MR metabolic rate - i mean rate of passage - t _exp expected time to appearance - t _o time to first appearance     

Digestive performance and selective digesta retention in the long-nosed bandicoot,Perameles nasuta,a small omnivorous marsupial

Bandicoots are opportunistic omnivores that feed on invertebrates, fungi and both epigeal and hypogeal plant parts. We examined the performance of the digestive tract of the long-nosed bandicoot (Perameles nasuta) in terms of intake and total digestibility, patterns of excretion of inert digesta markers, and likely sites of digesta retention, on two diets designed to mimic part of their natural plant and insect diets. On the insect diet (mealworm larvae), bandicoots virtually maintained body mass at a digestible energy intake of 511 kJ · kg^-0.75 · day^-1 and were in strongly positive nitrogen balance. In contrast, on the plant diet (shredded sweet potato), bandicoots ate only one-third as much digestible energy, lost 7% body mass, and were in negative nitrogen balance. Mean retention times of two particle markers on the plant diet (27.5 and 27.0 h) were more than double those on the insect diet (12.4 and 11.2 h), and on both diets the mean retention time of the fluid digesta marker was greater than those of the particle markers, indicating consistent selective retention of fluid digesta in the gut. It was seen radiographically than in mealwormfed bandicoots major sites of digesta retention were the distal colon and rectum, whereas in the sweet potato-fed animals the caecum and proximal colon were principal sites. It was concluded that retention of plant material in the caecum and proximal colon (the main sites of microbial digestion) and the preferential retention of fluid digesta (together with bacteria and small feed particles) in the caecum were important factors in the ability of bandicoots to switch between insect and plant foods, depending on relative availabilities, and thus to exploit nutritionally unpredictable environments.Abbreviations ADF acid-detergent fibre - bm body mass - Co-ED-TA cobalt-ethylenediaminetetra-acetic acid - CWC cell wall constituents - DE digestable energy - dm dry matter - EUN endogenous urinary nitrogen - ICP inductively-coupled plasma atomic emission spectroscopy - MFN metabolic faecal nitrogen - MRT mean retention time - NDF neutral-detergent fibre - ww wet weight     

抗生素和肠道细菌对小菜蛾适合度的影响

【目的】小菜蛾是危害十字花科蔬菜的世界性重要害虫。通过分析抗生素对小菜蛾的毒性效应,了解肠道细菌对小菜蛾适合度的影响,有助于更好地阐明小菜蛾肠道细菌的功能。【方法】利用抗生素处理含有高丰度肠道细菌的萝卜苗饲养品系(FZss)小菜蛾幼虫,同时利用抗生素处理饲料饲养的无肠道细菌(SLss)小菜蛾幼虫,分析抗生素及肠道细菌对小菜蛾适合度的影响。【结果】抗生素处理FZss品系小菜蛾导致了小菜蛾发育历期延长,虫重、蛹重、化蛹率、产卵量和成虫寿命降低。利用抗生素处理无肠道菌的SLss品系小菜蛾幼虫,小菜蛾化蛹率和单雌产卵量均显著降低,而对发育历期、虫重和蛹重则无影响。【结论】综合两个研究的结果发现抗生素处理后宿主适合度的降低一方面是由于抗生素的毒性效应导致,另一方面是由于小菜蛾肠道细菌的缺失引起。抗生素的毒性效应主要表现为对化蛹率和单雌产卵量的影响,而肠道细菌则对小菜蛾的发育历期、虫重、蛹重以及成虫寿命具有重要的促进作用。     

葛仙米多糖对高脂小鼠血脂和肠道微生物的影响

[目的]研究葛仙米多糖对高脂饲料喂养小鼠血脂和肠道微生物的影响.[方法]将健康的8周龄雄性小鼠分成5组,每组10只:正常组C57/6CNC小鼠(N:灌胃生理盐水,喂饲标准饲料),对照组ApoE-/-小鼠(C:灌胃生理盐水,喂饲标准饲料),模型组ApoE-/-小鼠(M:灌胃生理盐水,喂饲高脂高胆固醇饲料),葛仙米多糖低剂...     

Feeding,Diet, and Jaw Form in West African Colobus and Procolobus

The functional link between mandibular morphology and masticatory stress has been documented by both experimental and comparative investigation. Somewhat more tenuous is the purported connection between dietary variation and the form of the jaws in primates. Several factors complicate the inference of such a connection, including anecdotal or incomplete dietary data from field studies and allometric effects on skeletal form that may have little to do with diet per se. We compared the jaws of sympatric colobines from West Africa to test the effect of diet on mandibular form. Procolobus badius and Colobus polykomos occupy the same habitat yet differ in diet primarily due to the exploitation of hard seeds by C. polykomos. The fact that the two taxa are comparable in body size also obviates the need for allometric qualifications. Colobus polykomos is expected to possess more robust mandibular corpora than Procolobus badius. In fact, the jaws of Colobus polykomos do not differ consistently from those of Procolobus badius in terms of biomechanical function. This apparent failure of mandibular morphology to reflect differences in diet and feeding behavior may be due to a variety of factors. We suspect that functional demands related to canine tooth support are contributing to obliteration of the expected biomechanical signal. Successful prediction of dietary effects on mandibular form requires consideration of competing structural and functional demands. The influence of diet on mandibular corporeal morphology is not equivalent across different primate species.     

Effects of protease inhibitors and dietary protein level on the black field cricket Teleogryllus commodus

Growth and survival responses were determined for black field crickets Teleogryllus commodus (Walker) (Orthoptera: Gryllidae) on artificial diets containing a range of levels of dietary protein, and protease inhibitors (PI's) at 0.33% (weight volume, w:v). The effect on cricket gut enzyme activities of adding PI's to a high protein diet was measured. All PI's which had in vitro binding activity against either trypsin or elastase (the two major cricket gut endopeptidases) reduced growth, but those which bound to both enzymes had the greatest effect. None of the PI's acted as a source of nutritional protein. Cricket growth rate increased with the addition of casein up to 3% w:v, but not with a similar addition of wheatgerm. The impact of PI's on growth was greatest on a 1.5% casein diet. On a high protein (3% casein) diet, the gut activity of trypsin was increased by potato proteinase inhibitors 1 and 2 while the activity of elastase and leucine amino peptidase were increased by soybean trypsin inhibitor and potato proteinase inhibitor 2. Increasing dietary casein up to 3.3% improved cricket survival. The potential of PI's as plant resistance factors against crickets was confirmed.     

Development of an efficient method for screening microorganisms by using symbiotic association between <Emphasis Type="Italic">Nasutitermes takasagoensis</Emphasis> and intestinal microorganisms

Screening method of microorganisms that utilized the symbiotic association between insect (Nasutitermes takasagoensis: Nt) and intestinal microorganisms was developed. The existence of desired microorganisms that grew by degrading difficult-to-degrade materials in the gut was detected using survivability of Nt as an indicator. The desired microorganisms were isolated from the survived Nt. It was thought that guts of Nt behave as continuous culture systems whereby microorganisms that cannot degrade diet components are washed out, whereas those that can degrade it are retained and concentrated in the gut. About 60% of Nt fed with phenol artificial diet (PAD) died within 7 days, while 4% of termites survived for 9 days. The structure of intestinal microorganisms of the survived Nt fed with PAD differed from the bacterial communities obtained from enrichment culture (which contained phenol) of wood-feeding Nt. Relatively high colonies (650-times) were detected in the gut of Nt fed on phenol artificial diet compared with those obtained when Nt was fed on wood. Seven denaturing gradient gel electrophoresis (DGGE) bands were detected from gut of wood-feeding Nt, whereas 11 DGGE-bands were detected from that of phenol-feeding Nt. Out of 11 DGGE-bands, 5 of them were sequenced, and bacterial species including phenol-degrading bacteria were identified.     

Measurement of amphipod body length using a digitizer

A digitizer/camera lucida method was developed to measure total body length and gut contents of an amphipod Pontoporeia hoyi. The method was more accurate and precise than two conventional methods (the forceps/ocular micrometer method, and the map wheel/camera lucida method). The digitizer/camera lucida method also provided rapid and direct transfer of body and gut length values to a computer file for subsequent analysis.     

Predation in a temporary pond with special attention to the trophic role of Triops cancriformis (Crustacea: Branchiopoda: Notostraca)

Temporary ponds are described as environments with a low predation pressure. Notostracans inhabit these types of ponds, and some populations acquire a high proportion of larger individuals, whose feeding behaviour is mainly predatory. The predation nature of Triops cancriformis is not widely accepted, because its diet is still partly controversial. We analysed the diet of one population of T. cancriformis in a Mediterranean temporary pond (Espolla pond, NE Iberian peninsula) to evaluate its predation behaviour. The gut content of the individuals bigger than 10 mm is mainly composed of detritus, plant fibres and microcrustaceans (cladocerans, ostracods and copepods). The prey number increases with the body size of individual T. cancriformis as previously described. Sex-biased predation was observed for one copepod prey, but not for the other. Predation pressure in that community was monitored along six hydroperiods as the percentage of predator biomass (not only T. cancriformis) in relation to the non-predator biomass. The proportion of predator biomass is high, and this contrasts with the low predation pressure expected for a temporary system with short hydroperiods.     

Diet quality does not affect resting metabolic rate or body temperatures selected by an herbivorous lizard

Diet quality can influence many aspects of digestion, but the links between diet quality and resting metabolism are poorly understood. In nature, it might be beneficial to reduce energy expenditure when only poor quality diets are available. Alternatively, animals might increase the processing capacity of the gut to more thoroughly extract energy. If maintaining the processing capacity of the gut is energetically expensive, then increasing gut size or function might result in higher resting metabolism. In ectotherms, most digestive functions are temperature dependent, thus another strategy to maintain energy balance might be to alter selected body temperatures. We tested whether differing concentrations of dietary fiber affected the resting metabolic rate or body temperatures selected by chuckwallas (Sauromalus obesus) – lizards that naturally experience marked variation in dietary fiber. Resting metabolic rates measured at two temperatures and over three time intervals did not differ between groups of lizards force-fed low- (30% neutral-detergent fiber; NDF) and high-fiber (45% NDF) diets, nor did these diet differences influence body temperatures selected in a thermal gradient. We conclude that ecologically relevant differences in diet quality may have negligible effects on resting metabolic rates and body temperatures selected by chuckwallas. Accepted: 5 January 1998