Influence of various host plants on the consumption and utilization of food by Pieris brassicae (Linn.)

Pieris brassicae (Linn.) is a destructive cosmopolitan pest of cruciferous crops. It is present wherever its host plants occur, and it is considered to be one of the most widely distributed of all the Lepidoptera. We investigated the affect of various host plants on the food consumption and utilization by P. brassicae. We quantified consumption of food, larval duration, pupal duration and weight on cabbage (Brassica oleracea var. capitata), cauliflower (Brassica oleracea var. botrytis), radish (Raphanus sativus), broccoli (Brassica oleracea var. italica) and mustard (Brassica campestris) under laboratory conditions. Insect-host relationships can be better understood by knowing the rate of food consumption, its digestibility and conversion of food eaten to body tissue. The consumption of food generally increased with the advancement of larval age. In our study we found that consumption of food was highest on radish and lowest on broccoli. The highest consumption of a particular host does not always indicate greater suitability of that host, until and unless other factors like consumption index (CI), relative growth rate (RGR), efficiency of conversion of ingested food (ECI), approximate digestibility (AD) and efficiency of conversion of digested food (ECD) are also considered. In the current investigation, factors like CI, RGR, ECI and ECD were highest on cabbage. Low body weight of pupa is associated with rapid development. On cabbage, the weight of pupa of both sexes was found lowest. Thus, from the present study, it can be concluded that cabbage is a more suitable host for P. brassicae than other host plants evaluated. Hence, on cabbage, the values of Waldbauer indices were highest and P. brassicae developed with a faster rate.     

Alewife planktivory controls the abundance of two invasive predatory cladocerans in Lake Michigan

1. We sampled along a nearshore transect (10-m bathymetric contour) in Lake Michigan to determine diet, 24-h feeding periodicity, daily ration and food requirements of an invasive fish, the alewife, Alosa pseudoharengus , relative to zooplankton abundance and production. Our objective was to determine whether the alewife controls the abundance of two invasive, predatory cladocerans, Bythotrephes longimanus and Cercopagis pengoi .
2. Bosminidae was the most abundant prey taxon and Chydoridae, Leptodora , Chironomidae and Bythotrephes were the least abundant. Neither Bythotrephes nor Cercopagis were important prey for small alewives (≤100 mm). Bythotrephes was eaten by over 50% of large alewives (>100 mm) and accounted for 10–27% of the diet weight. Cercopagis was eaten by about 30% of the large alewives but only accounted 1% of the diet weight.
3. Food weight in stomachs was highest early in the night for small alewives and lowest at night for large alewives. Chironomidae and large Chydoridae were the preferred prey of small alewives. Bythotrephes and large Chydoridae were the preferred prey for large alewives.
4. Food requirements of alewife were much less than production for most prey taxa, although the consumption of Bythotrephes greatly exceeded production on both dates. Alewives consumed only 3% of Cercopagis production. High selectivity and food requirements of alewife for Bythotrephes , and low selectivity and food requirements for Cercopagis , probably explain the difference in abundance between these two invasive cladocerans at our nearshore site in Lake Michigan.     

Determinants of the dramatic seasonal changes in the intake of energy and protein by Japanese monkeys in a cool temperate forest

Daily intake of gross energy (DGEI) and protein (DGPI) of Japanese monkeys in a cool temperature forest were investigated in different four seasons. As a result, dramatic seasonal differences in DGEI and DGPI were found: DGEI and DGPI in winter were significantly lower than those in spring and autumn, being only about 17–42% of those in the two seasons. DGEI and DGPI in summer were also lower than those in autumn and spring, being only about 29–52% of those in the two latter seasons. Seasonal comparisons of some variables on food qualities revealed that much lower values of DGEI and DGPI in winter and summer were influenced srongly not so much by the lower calorie and protein content of food as by the lower speed of dry weight intake. Multiple regression analyses for each food item revealed that the unit weight was a more important factor in determining the speed of dry weight intake than was the speed of unit intake. In addition, the speed of dry weight intake contributed much more to the speed of calorie and protein intake than did the content of calorie and protein. Multiple regression analyses, employing DGEI and DGPI (as dependent variables) and daily mean values of some variables related to food quality (as independent variables), revealed that the mean values of speed of calorie and protein intake on food items eaten in a day could explain 79.0% and 85.9% of the variance in DGEI and DGPI, respectively. In addition, the mean value of the speed of dry weight intake of food items eaten in a day can be used to explain 74.3% and 52.8% of the variance in DGEI and DGPI, respectively. These findings suggested that not only nutritional content of food but also the speed of dry weight intake strongly determined the nutritional condition of nonhuman primates. Am. J. Primatol. 41:267–288, 1997. © 1997 Wiley-Liss, Inc.     

Observations on changes in the quality of food eaten by the wild rabbit*

The quality of the food eaten by rabbits can be predicted from the quality of the recently ingested food in the anterior portion of the stomach using the equation: crude protein in food (% dry weight) = 1.42 × crude protein in stomach (% dry weight). The relationship which food bears to the ecology of rabbits differs from population to population. In semi-arid north-western and mediterranean New South Wales changes in food quality are closely related to changes in climate and to various important aspects of rabbit biology. In southern Queensland and subalpine New South Wales, quality of food in the stomach is less significantly related to changes in climate and the biological parameters measured.     

Behavioral transitions and weight change patterns within the PREMIER trial

Little is known about the transition in behaviors from short-term weight loss to maintenance of weight loss. We wanted to determine how short-term and long-term weight loss and patterns of weight change were associated with intervention behavioral targets. This analysis includes overweight/obese participants in active treatment (n = 507) from the previously published PREMIER trial, an 18-month, multicomponent lifestyle intervention for blood pressure reduction, including 33 intervention sessions and recommendations to self-monitor food intake and physical activity daily. Associations between behaviors (attendance, recorded days/week of physical activity, food records/week) and weight loss of ≥5% at 6 and 18 months were examined using logistic regression. We characterized the sample using 5 weight change categories (weight gained, weight stable, weight loss then relapse, late weight loss, and weight loss then maintenance) and analyzed adherence to the behaviors for each category, comparing means with ANOVA. Participants lost an average of 5.3 ± 5.6 kg at 6 months and 4.0 ± 6.7 kg (4.96% of body weight) by 18 months. Higher levels of attendance, food record completion, and recorded days/week of physical activity were associated with increasing odds of achieving 5% weight loss. All weight change groups had declines in the behaviors over time; however, compared to the other four groups, the weight loss/maintenance group (n = 154) had statistically less significant decline in number of food records/week (48%), recorded days/week of physical activity (41.7%), and intervention sessions attended (12.8%) through 18 months. Behaviors associated with short-term weight loss continue to be associated with long-term weight loss, albeit at lower frequencies. Minimizing the decline in these behaviors may be important in achieving long-term weight loss.     

The Progressive Increase of Food Waste in America and Its Environmental Impact

Food waste contributes to excess consumption of freshwater and fossil fuels which, along with methane and CO₂ emissions from decomposing food, impacts global climate change. Here, we calculate the energy content of nationwide food waste from the difference between the US food supply and the food consumed by the population. The latter was estimated using a validated mathematical model of metabolism relating body weight to the amount of food eaten. We found that US per capita food waste has progressively increased by ∼50% since 1974 reaching more than 1400 kcal per person per day or 150 trillion kcal per year. Food waste now accounts for more than one quarter of the total freshwater consumption and ∼300 million barrels of oil per year.     

Suitability of Aerially Sown Artificial Baits as a Technique for Poisoning Feral Goats

The preferences of a captive herd of goats with feral ancestry were evaluated for 11 artificial pest control baits and commercial stock feed pellets. A commercial stock food pellet (based on barley, bran, and oats) was the most preferred basic bait. A mixture of 2% diced Griselinia littoralis (broadleaf) leaves (a preferred natural food plant) and 2% molasses (per weight of basic bait) increased palatability of this basic bait. The best lured bait was aerially sown at I kg ha(-1) in a 380 ha area with about 50 feral goats. Only 25% of the goats were shown by the biological tracer iophenoxic acid to have eaten baits after 8 days. We conclude that one-hit aerial poisoning of goats is unlikely to be effective as a control method because most goats are unlikely to eat food from off the ground.     

Aspects of energetics of adult walleye pollock, Theragra chalcogramma (Pallas), from Alaska

Body energy partitioning was examined for field-caught, adult walleye pollock; additional laboratory studies were conducted on fish held under controlled temperature conditions at Seward, Alaska.
Average consumption for pollock feeding daily was 0.5% of body weight (3100 cal) at 5°C, resulting in an average growth of 0.12% body weight day⁻¹. These results suggest that large pollock grow at similar rates and have similar food conversion efficiencies to those of Atlantic cod held at similar temperatures.
Resting metabolic rates measured on adult fish were combined with similar data from juveniles to calculate a regression of specific metabolic rate against wet weight: y = 173x⁻⁰²⁶. Maintenance rations amounted to 4.8 cal g⁻¹ day⁻¹ at 5°C, very close to the 0.28% value for juveniles. Estimation of metabolic rate using maintenance ration data resulted in values that were 55% higher than those obtained from oxygen consumption data for unfed fish. Weight loss during starvation was 0.18% of body weight day⁻¹ at 5°C, corresponding roughly to a starvation metabolic rate 50% lower than the resting metabolic rate we report.
We estimate that an adult pollock will lose about 37% of its prespawning body weight and about 46% of its body energy during spawning. These losses result, primarily, from changes in the weight of gonad, liver and somatic tissues as opposed to changes in specific energy content of those tissues.     

Operation Everest. II: Nutrition and body composition

Progressive body weight loss occurs during high mountain expeditions, but whether it is due to hypoxia, inadequate diet, malabsorption, or the multiple stresses of the harsh environment is unknown. To determine whether hypoxia due to decompression causes weight loss, six men, provided with a palatable ad libitum diet, were studied during progressive decompression to 240 Torr over 40 days in a hypobaric chamber where hypoxia was the major environmental variable. Caloric intake decreased 43.0% from 3,136 to 1,789 kcal/day (P less than 0.001). The percent carbohydrate in the diet decreased from 62.1 to 53.2% (P less than 0.001). Over the 40 days of the study the subjects lost 7.4 +/- 2.2 (SD) kg and 1.6% (2.5 kg) of the total body weight as fat. Computerized tomographic scans indicated that most of the weight loss was derived from fat-free weight. The data indicated that prolonged exposure to the increasing hypoxia was associated with a reduction in carbohydrate preference and body weight despite access to ample varieties and quantities of food. This study suggested that hypoxia can be sufficient cause for the weight loss and decreased food consumption reported by mountain expeditions at high altitude.     

Diel feeding periodicity, daily ration and prey selection of a riverine population of juvenile chinook salmon, Oncorhynchus tshawytscha (Walbaum)

The diel feeding periodicity, daily ration and prey selection of juvenile chinook salmon, Oncorhynchus tshawytscha , were studied in relation to the available prey. Maximum dry weight of food intake occurred about dawn, when mayflies were the major prey, but the greatest number of freshly eaten prey occurred during the afternoon, when chironomids and terrestrial dipterans predominated. Feeding activity at night was low, with smaller mayflies comprising up to 50% of the prey. During the day the young salmon fed selectively on chironomids and the larger mayflies, while trichopterans and terrestrial taxa were under-represented in the diet. Food consumption over the 24-h period averaged 8.3% of the fish dry body weight. Prey abundance in the drift explained about 50% of the composition of the diet. Although the fish selected larger mayflies, size apparently was not a main criterion for selection because chironomids, although smaller than mayflies, were also frequently eaten. Previous dietary experience of the fish and the diel pattern of prey abundance appear to best explain the selective feeding of juvenile chinook salmon.     

Instar duration, adult consumption, oviposition and nitrogen utilization efficiencies of leafhoppers feeding on different quality food (Auchenorrhyncha: Homoptera)

Abstract. 1. Plant material of Holcus lanatus L. removed from an artificially fertilized trial was used to rear leafhoppers of three feeding types: Dicrano-tropis hamata Boheman and Ebmana sulphurella Zetterstedt, (phloem feeders), Eucelis incisus Kirschbaum (xylem feeder) and Zyginidia scutellaris Herrich-Schaeffer (mesophyll feeder).
2. In the laboratory, leafhopper instar durations, adult consumption rate, oviposition rate, and nitrogen utilization efficiency were influenced by the quality of the food consumed. Adult longevity was unaffected by the level of food quality normally found in plants.
3. Z.scutellanis consumed mesophyll contents equivalent to 72% of its body weight each day but only digested about 30% of its intake. Eincicus had a low dry weight consumption rate (12% body weight/day) but digested its food more efficiently (60%) than the other feeding types. The two phloem feeders consumed mounts equivalent to 25% of their body weight each day and digested 40–50% of their intake.
4. Each species reached maximum nitrogen utilization efficiencies at different plant nitrogen levels. This suggests that leafhopper species may be associated with a particular nitrogen concentration in the grasses.     

Food utilization and metabolic efficiency in larval and adult house crickets

The most rapid growth of the fat body, ovaries and residual body occurred only at the time of maximal feeding, which was the time of highest metabolic rate. Larvae ceased feeding before the next moult and lost weight. Adult females did not cease feeding and never lost weight. Mated females maintained a high feeding rate that corresponded to a constant oviposition rate with no gonotrophic cycles. Virgin females maintained a lower feeding rate and maintained fully mature eggs in a viable state for life.Growth during the last larval stadium was entirely somatic and characterized by a great accumulation of a lipid rich (65%) fat body. Net growth during the first 10 days of adult life was entirely gonodal, because the small amount of residual body growth was matched by the amount of fat body loss. However, since the residual body was 60% protein and the fat body was 60% lipid, some of the somatic protein growth had to come from the diet and some of the fat body lipid went for ovarial growth.The 20% dietary protein was more than sufficient for all somatic and ovarial growth, and some protein was catabolized for energy. The amount of uric acid in larval faeces accounted for almost all protein catabolism, but in adult females half of the catabolized protein nitrogen did not appear in the faeces. With only 5% dietary lipid both larvae and adults had to synthesize additional lipids from carbohydrates to supplement absorbed lipids for growth demands. Almost all absorbed and synthesized lipids were used for somatic growth in the larvae and for ovarial growth in the adults, because the per cent of food calories used for growth greatly exceeded the per cent dry weight of food used for growth. Based on the calories and dry weight of available fuel, almost all energy production was based on carbohydrate oxidation. Some carbohydrate was used for lipid synthesis but very little was used for growth.Probably the absorption efficiency (72%) and growth efficiency (28%) was the same for both the last instar larvae and virgin females because they ate exactly the same food. However, the larval metabolic efficiency (42%) was higher than that of females (37%), which indicated that more of the absorbed food was converted to tissue during larval growth (somatic) than during adult growth (ovarial).Of the dry weight of food eaten during the last larval stadium, 30% was egested, 32% was oxidized, 28% appeared as growth, and 10% was condensed to lipid and became part of the 28% growth. Of the dry weight of food eaten during the first 10 days of adult life, 27% was egested, 41% was oxidized, 25% appeared as growth, and 6% was condensed to lipid.     

FOOD SELECTION IN THE LAND SNAIL LIMICOLARIA FLAMMEA MULLER (PULMONATA: ACHATINIDAE)

Food consumption by juvenile and adult specimens Limicolariaflammea was measured as dry weight of food eaten. The snailwas fed weekly for 15 months on four types of food (lettuce,potato, apple and carrot) and chalk provided, hence an opportunityto select for food. Juvenile snails showed greater selectivitydepending on whether the food was needed for somatic growthor reproduction. On the other hand, when fed exclusively onone each of the same food items and given no opportunity tochoose, the snails grew better on the same food items they selectedin the choice experiment. The absorption efficiencies (AD) werehigh, the utilisation efficiency (ECI) was 1–13% and showeddistinct peaks corresponding to egg production. Values for ECDwere 1.25–15.5%. Variation in growth rates was due mainlyto utilisation efficiencies of the four foods tested. Largeamounts of chalk were eaten during the period of somatic growthand greatly reduced during the reproductive phase of L. flammea.The significance of these findings to the snails ecology isdiscussed. (Received 9 April 1991; accepted 11 June 1991)     

Compensatory feeding response of the slug Sarasinula plebeia to dietary dilution

Summary Like many polyphagous herbivores, individuals of Sarasinula plebeia (Fischer) (Soleolifera: Veronicellidae) consume a variety of plant species that may differ in nutritional content. In this study we determined the ability of these slugs to compensate for such variation in diet composition. Dilution with water of an agar-based diet containing commercial guinea pig food or carrot root to obtain dry weights (dw) of 90, 70, 40 and 10% of diet fresh weight (fw), caused immature slugs to consume increasingly more fresh weight of food [as much as 4.7-(guinea pig) to 6.1-fold (carrot) more]. Dry weight consumption and body mass-relative dry weight consumption rate also increased at intermediate dilutions, buth with further dilution, dry weight intake declined despite the greater fresh weight consumption. At each dilution level, slugs fed the guinea pig diet consumed from ca. 5-to 6.4-fold more fresh weight than the carrotfed slugs. The former grew substantially, with their final biomass and body mass-relative growth rate varying curvilinearly with diet % dw. If these slugs had not fed more but instead maintained the same fresh weight consumption as slugs in the 90% dw tretments, without altering food utilization efficiencies, then their biomass gain in the 70, 40 and 10% dw treatments would have been only about 62, 43, and 21%, respectively, of the values actually attained. In contrast, carrot-fed slugs did not grow and were only able to maintain their initial biomass. For each diet, slug tissue water (% fw) was highest in the most diluted treatment but did not differ significantly among the other dilution levels. Approximate digestibility of the carrot diet was highest at intermediate dilution levels (ca. 75% of ingested food was digested and absorbed); for the guinea pig diet, this efficiency declined linearly from about 66% to 59% with increased dilution. For slugs that grew (i.e., those fed the guinea pig diet), effeciences of converting digested (29–52%) and ingested (18–33%) food to dry biomass were both curvilinearly related to diet % dw. Thus, S. plebeia, like many other herbivores, has the capacity to increase food consumption substantially inresponse to reduced dietary nutrient level, allowing the slugs to cope with variable nutrient content in their food plants.     

英国 Hampsfell 蕨菜草地生态系统中枯叶分解作用的研究

 应用三种独立的方法估算蕨菜(Pteridium aquilinum )草地生态系统中蕨菜枯叶的分解速度。尽管所用的技术不同,但所有的估算量都属于同—幅度范围。 1．蕨菜枯叶的失重率在田间放置40周后为20一22%,由此应用枯叶的残留重量的自然对数与时间关系的指数回归,导出年腐解率为0.317一0.321克／克／年,即每年每克枯叶失去的重量。2．根据枯叶呼吸作用的测定所估算的氧的年总消耗量,指出21.04—24.38%的失重率是由枯叶上的微生物呼吸所造成。3．由枯叶的年输入量和地面积累的现存量计算而得的地表蕨菜枯叶的常数消失率为0.26。     

Food and water economy and its relation to growth in fifth-instar larvae of the tobacco hornworm, Manduca sexta

Fifth-instar larvae of Manduca sexta were reared on artificial diet at 25°C. Daily measurement of the wet and dry weights of insects, food eaten and faeces produced, allowed the construction of detailed budgets for food and water economy.Approximate digestibility (AD) was about 60% both in dry weight and energetic terms. This did not change significantly on successive days of the instar, despite the very considerable changes that occur in the size of the insect and the amount of food eaten during the same period. Two indices of conversion efficiency (ECI and ECD) also showed only insignificant changes during this time. ECI and ECD were both very high: at their maximal values, ECI was 43% (51% in energy terms) and ECD was 72% (81% in energy terms).Correction of the nutritional indices for the presence of food in the gut reduced their value slightly in all cases.Most of the water requirements of the larva were provided by the diet. The estimated gain from metabolic water was between 3.5 and 10% of the total water input. Faeces accounted for most of the water lost from the body; under our conditions transpirational losses were very small. Almost half of the water taken up with the food was retained in the body.The gut contents are more hydrated than the food. The faeces contain less water than the gut contents. It is suggested that the caterpillars recycle water by absorbing it from the faeces and returning it to the contents of the midgut. A quantitative model of such water movement within the body is presented. The data provide indirect evidence that caterpillars may optimise the retention time of food in the gut (and thus the AD) in order to maximise the absolute rate of nutrient uptake from it.     

Effects of naloxone on anti-conflict and hyperphagic actions of diazepam

Rats were treated with diazepam (DZP) with or without co-administration of naloxone (NLX). Animals were subsequently tested in two settings. Sated rats were tested for food consumption in their home cages for a 1 hr period following injection. Food was then removed and on the following day the fasted animals were placed in an open field for 15 min. A single food pellet (5–6 g) was secured in the center of the open field. Animals were observed and scored on frequency of rearing, grooming, urination, number of approaches to the food, amount of food eaten and x? g food eaten per approach to the food pedestal.DZP treatment increased food consumption by sated animals in their home cages. Naloxone blocked this effect. In the open field, DZP, reduced novelty induced grooming, increased the amount of food eaten and x? g food eaten per approach to the food pedestal. Co-administration of NLX had no affect on these parameters. The primary effect of NLX appears to be on consumatory behavior $\text{per se}$ and not on the anti-conflict properties of DZP.     

The effect of feeding frequency on consumption of food,absorption efficiency,and gonad production in the sea urchin Lytechinus variegatus

The frequency of feeding in the field is variable in sea urchins, ranging from nearly continuous to diel or intermittent. It is essential to know the effect of feeding interval on physiological and metabolic processes to understand the basis for production. Lytechinus variegatus (50 mm horizontal diameter) were collected in January 1999 and held in closed-circuit aquaria at 25 degrees C and 35 per thousand salinity. After 9 days without food, individuals were fed one of three treatments: food available ad libitum, food available for 1 day every 2 days or food available for 1 day every 4 days for 28 days. The rate of food consumption per day of all individuals was high the first week of feeding. It then decreased to a lower, constant rate in those fed ad libitum but remained high in those fed one day every 2 or 4 days. The total amount eaten was directly related to frequency of feeding. The apparent dry matter digestibility (absorption efficiency) did not vary with frequency of feeding. As the total amount of energy absorbed was directly related to the frequency of feeding, the increase in the rate of food consumption does not compensate for a decrease in frequency of feeding. Gonad production efficiency was directly related to frequency of feeding. Gonad gross production (assimilation) efficiencies were 8.4, 3.9 and 3.4% for individuals fed every day, or fed one day every 2 and 4 days, respectively. The corresponding gonad net assimilation efficiencies were 12.5, 5.5, and 4.8%. A decrease in frequency of food availability results in use of a greater proportion of the food consumed for maintenance and less for gonad production.     

Dietary generalists and nutritional specialists: Feeding strategies of adult female blue monkeys (Cercopithecus mitis) in the Kakamega Forest,Kenya

Generalist primates eat many food types and shift their diet with changes in food availability. Variation in foods eaten may not, however, match variation in nutrient intake. We examined dietary variation in a generalist‐feeder, the blue monkey (Cercopithecus mitis), to see how dietary food intake related to variation in available food and nutrient intake. We used 371 all‐day focal follows from 24 adult females (three groups) in a wild rainforest population to quantify daily diet over 9 months. We measured food availability using vegetation surveys and phenology monitoring. We analyzed >700 food and fecal samples for macronutrient content. Subjects included 445 food items (species‐specific plant parts and insect morphotypes) in their diet. Variation in fruit consumption (percentage of diet and total kcal) tracked variation in availability, suggesting fruit was a preferred food type. Fruits also constituted the majority of the diet (by calories) and some fruit species were eaten more than expected based on relative availability. In contrast, few species of young leaves were eaten more than expected. Also, subjects ate fewer young leaves (based on calories consumed) when fruit or young leaves were more available, suggesting that young leaves served as fallback foods. Despite the broad range of foods in the diet, group differences in fiber digestibility, and variation that reflected food availability, subjects and groups converged on similar nutrient intakes (grand mean ± SD: 637.1 ± 104.7 kcal overall energy intake, 293.3 ± 46.9 kcal nonstructural carbohydrate, 147.8 ± 72.4 kcal lipid, 107.8 ± 12.9 kcal available protein, and 88.1 ± 17.5 kcal structural carbohydrate; N = 24 subjects). Thus, blue monkeys appear to be food composition generalists and nutrient intake specialists, using flexible feeding strategies to regulate nutrient intake. Findings highlight the importance of simultaneously examining dietary composition at both levels of foods and nutrients to understand primate feeding ecology.     

A bioeconomic study on a provisioned troop of Japanese monkeys (Macaca fuscata fuscata) at koshima islet,Miyazaki

The natural and provisioned (wheat) food intake of the Japanese monkeys on Koshima was measured by direct observation. It was found that the portion of wheat consumed reflects such social structures in Japanese monkeys as (a) the structure of cocentric circles composed of several classes, (b) female ranking orders, (c) social strictness in breeding or non-breeding seasons. The natural food intake forIcho (2–3 years old female) was estimated for three seasons (April, September and December) during 1971. Her daily caloric intake was estimated from a quantitative list of natural foods eaten and the quantity of wheat eaten by multiplying the appropriate caloric values, and digestibility of 70%. The kcal day per values were 411 in spring, 522 in summer and 559 in winter. Her daily energy consumption (DEC) was estimated to be 398, 423, and 447 kcal/day in the respective seasons derived from the equation DEC =153W^2/3 which was obtained from data on activity telemetry and basal metabolic rates. The two spring values are in agreement. The summer and winter values show considerable differences. The dependency on wheat was calculated for individuals of various ages and sexes. The dependency of juveniles (60%) is about double that of ordinary females (25%). The Koshima troop is largely dependent on the evergreen broad leaves through all seasons. The increase of the number of females was cumulatively simulated assuming constant age-specific fecundity and mortality. There appeared one stagnated period of increase during the years 1961–1964 due to external factors. It will be a future problem to relate the quality of nutrition to reproductive performance.