Diets of Two Lemur Species in Different Microhabitats in Beza Mahafaly Special Reserve,Madagascar

Studies of primate diets usually focus on differences that distinguish species or populations. However, variation in diet can occur at a more local level of groups within a population, especially in a non-homogeneous habitat. I compared dietary variation in food composition and toughness across groups of 2 lemur species in Beza Mahafaly special reserve, Madagascar. Beza Mahafaly contains an 80-ha reserve (Parcel 1) that, while small, hosts a dense population of Lemur catta (ring-tailed lemurs) and Propithecus verreauxi verreauxi (sifakas). Microhabitats in the eastern vs. western sides of the parcel are structurally and floristically distinct. Sifakas in this parcel have small, discrete home ranges and are morphological folivores. For these reasons, I expected that the 6 groups studied would eat a different menu of food plants but with similar toughness values. Ring-tailed lemurs have comparatively large, overlapping home ranges, and I expected that the 5 study groups would eat similar foods. Despite living in different microhabitats across the parcel, sifakas exhibit high dietary uniformity both in dietary plant species composition and the toughness of the foods. Food selection in sifakas operates on two distinct levels. Sifaka groups share many key food species that appear independent of local abundances, but the ranking of the foods within each group appears related to availability. Ring-tailed lemur groups are more heterogeneous in the composition of their diets relative to sifakas, though the time spent feeding on individual foods reveals a marked preference for the fruits of Tamarindus indica by all groups. Food toughness is consistent across the parcel with the exception of the most western group. Ring-tailed lemurs are highly specific feeders, but indiscriminate nibblers. Sifakas are targeted, balanced feeders. There does not appear to be a consistent microhabitat effect operating across species. Differences within sifaka and ring-tailed lemur populations in food composition and toughness, however, correspond to an east-west microhabitat gradient. Measures of dietary flexibility must take into account not only the plant species consumed and the different parts eaten but also their associated food properties and proportion of time spent feeding on them.     

It’s Tough Out There: Variation in the Toughness of Ingested Leaves and Feeding Behavior Among Four Colobinae in Vietnam

Colobines are similar in their exploitation of a high percentage of leaf matter. However, this observation obfuscates interesting differences among genera of Southeast Asian colobines in morphology and behavior that may be reflected in the degree to which they rely on mastication or gut volume and gut retention time when ingesting and digesting leaves. We detail the use of a laboratory-based method to measure the mechanical properties of foods selected and processed by 4 captive species of Southeast Asian Colobinae —Pygathrix nemaeus, Pygathrix cinerea, Trachypithecus delacouri, and Trachypithecus laotum hatinhensis— at the Endangered Primate Rescue Center (EPRC), Vietnam. We also detail a field method that quantifies chewing rates and chewing behavior via a consumer-grade video camera and laptop computer. Observations in the captive setting permit a degree of experimental control that is not possible in the wild, and the location of the EPRC in the primates’ habitat country permitted us to provide leaves that they encounter and eat in the wild. We collected toughness data with a portable tester designed by Lucas et al. The average toughness of selected leaves does not differ among the taxa, nor does the length of time spent chewing foods. However, there are differences in feeding rate, with Trachypithecus spp. chewing foods twice as fast as Pygathrix spp. Our findings suggest that Trachypithecus spp. emphasize comminution of food by mastication, while Pygathrix spp. emphasize the comminution of leaf matter in the stomach. The hypothesis is supported by data on molar size, gut mass, and gut morphology. We provide new insights into dietary variation among primate species and detail methods that are typically conducted only in a laboratory setting. We augment the findings with additional data on activity, feeding rates, and tooth morphology.     

Effect of long-term water immersion on the fracture toughness of denture base and reline resins

doi: 10.1111/j.1741‐2358.2011.00573.x
Effect of long‐term water immersion on the fracture toughness of denture base and reline resins purpose: This study evaluated the fracture toughness (FT) of one denture base (Lucitone 550 – L) and four hard reline resins [Ufi Gel Hard (UH), Tokuyama Rebase II (TR), New Truliner (NT) and Kooliner (K)], and the effect of long‐term water storage on this property. Materials and methods: Forty specimens (40 × 8 × 4 mm) of each material were made, and FT was assessed after polymerisation (control of reliners), after 48 ± 2 h in water at 37°C (control of denture base resin) and after storage in water at 37°C for 7, 90 or 180 days (all materials). Data (MPa.m^1/2) were analysed by two‐way anova and Games–Howell test (p = 0.05). Results: Resin L exhibited the highest FT mean values. After 180 days of storage, FT mean values of L (3.37), UH (1.53) and K (1.20) were higher than those of the other periods. FT mean values of NT decreased from control (1.63) to 7 days (1.30) and then remained constant. FT mean values of TR (1.13) were similar in all periods of analysis. Conclusion: The denture base resin L showed higher FT mean values than the reline resins. Long‐term water storage increased the FT of L, UH and K, reduced the FT of NT and did not influence the FT of TR.     

粘虫高龄幼虫对转Bt基因玉米的消化和利用

在室内用重量法研究了粘虫Mythimna separata (Walker)高龄幼虫对转Bt基因玉米MON810和Bt11叶片的消化和利用,以明确Bt玉米对暴食期幼虫取食的影响。结果表明,在连续测定的5天中,取食MON810和Bt11两种Bt玉米叶片时,幼虫存活率和取食量均显著低于各自的对照组幼虫,取食Bt玉米叶片的幼虫体重呈下降趋势,第3 天时分别比第2 天减少12.2 mg 和7.4 mg,而取食对照玉米叶片时的幼虫日增重显著的高于处理组的幼虫,第3 天的日增重分别为100.4 mg 和119.9 mg。取食Bt玉米叶片的幼虫对食物的转化率(ECI和ECD)均为负值,在最初4 天的ECI和ECD都显著低于对照组幼虫,但取食两种非Bt玉米叶片的幼虫的近似消化率(AD) 随取食时间的延长而逐渐下降,取食第5 天分别为20.6 %和15.1 %;而取食MON810和Bt11叶片时幼虫的AD均显著地高于对照组幼虫。     

The effect of food composition on ingestion,development, and survival of a harpacticoid copepod, Tisbe cucumariae Humes

Feeding experiments were carried out on the benthic harpacticoid copepod Tisbe cucumariae Humes, using seven different diets of various dried and ground macroalgae and marsh grass, algal Aufwuchs, diatoms, polychaete meat, and cereal. In short-term experiments (1 h), ¹⁴C-labelled foods were used to measure ingestion rate of non-ovigerous adult females (individual dry wt = 5.57 ± 2.49 μg). No significant difference was found among the rates at which all foods, except polychaete meat, were ingested (12.7 to 17.3 × 10^?2μg dry wt· ind^?1· h^?1). Polychaete meat was consumed faster (23.9 × 10^?2μg dry wt·ind ^?1· h^?1). The nutritional value of the foods was estimated in long-term experiments (22 days) by measuring development time and survival of T. cucumariae. Both these variables were significantly correlated with the nitrogen, protein content, and C:N ratio of the foods. No relation was found, however, with the amount of carbon, calories and available calories in the diets. Thus, nitrogen (protein) content of the food was the factor limiting secondary production of the copepods.     

Effects of black howler monkey (Alouatta caraya) seed ingestion on insect larvae

Fig (Ficus monckii) and laurel (Ocotea puberula) seeds were obtained from Alouatta caraya feces (ingested seeds) and from trees (noningested) in northeastern Argentina. Seeds were examined to detect the presence (infested) or absence (noninfested) of larvae. Sixty percent (N = 315) of noningested fig seeds were galls with insect larvae inside, while 23% (N = 331) were encountered in the ingested group. Eighty-two percent (N = 28) of noningested laurel seeds were infested, and only 19% (N = 63) of ingested seeds were infested. According to the present data, the insects' larvae are digested by howlers intaking animal protein, but the laurel seeds were not destroyed. Am. J. Primatol. 45:411–415, 1998. © 1998 Wiley-Liss, Inc.