Molar enamel thickness in European Miocene and extant hominoidea

Based on a roentgenographic analysis, the molar enamel of certain European Miocene dryopithecines is absolutely thick (r=1.03–1.30 mm in thickness); the molar enamel of certain European pliopithecines is thin (r=0.32–0.82 mm thick). The rank order for enamel thickness in extant hominoids (from thickest to thinnest) is confirmed to beHomo, Pongo, Gorilla, Pan, andHylobates. There is a great deal of enamel thickness variability within the great ape sample. Extant analogues suggest that dryopithecines were probably adapted to a frugivorous/gramnivorous dietary regimen, while pliopithecines were probably better suited to folivory.     

Ecology of gorillas and its relation to female transfer in mountain gorillas

Understanding the principles that underly primate social evolution depends on integrated analysis of data on behavioral ecology, demography, life history tactics, and social organization. In this paper, data on the behavioral ecology of gorillas are reviewed and comparisons made among the three subspecies. Gorillas are selective feeders; and, their patterns of food choice are consistent with models of feeding by large generalist herbivores. They rely heavily on terrestrial herbaceous vegetation, which provides an abundant supply of densely distributed food. Availability of this food varies little in space and time; and, gorilla foraging activity can maintain its productivity. The level of frugivory and the extent of seasonal variation in diet and habitat use vary among and within populations. Low variability in food distribution patterns makes cooperative defense of foraging areas not worthwhile; but, it also means that ecological costs associated with gregariousness are low. However, demographic and life history data on mountain gorillas show that these costs may be sufficient to reduce female reproductive success as group size increases. Advantages to being with high quality males apparently can outweigh these costs. The implications of these data for the evolution of the mountain gorilla social system, and the possible roles of male protection, predation, and female/female competition in this regard, are discussed.     

Alkaloid level in narrow-leafed lupin, Lupinus angustifolius, influences green peach aphid reproductive performance

Two viviparous parthenogenetic clones of the green peach aphid, Myzus persicae (Sulzer), one collected from Rydalmere, New South Wales (NSW), and the other from South Perth (SP), Western Australia, were reared on radish, Raphanus sativus L. cv. Scarlet Globe, under controlled conditions. The NSW clone was fed on simple artificial diets containing alkaloid extracted from narrow-leafed lupin, Lupinus angustifolius L. cv. Fest., and its reproductive performance monitored over 112 h. Forty (40) h into the experiment and thereafter, aphids on the control diet (sucrose solution) produced significantly more offspring (P<0.05) than those on diets containing alkaloid. In a separate experiment, apterae of each clone were caged on three lines (cv. Yorrel, cv. Danja and 84L:441) of narrow-leafed lupin, and allowed to reproduce. The first three offspring were retained, and all developed to 3rd or 4th instar stage. Two nymphs were removed, and the remaining nymph reared through. All three lines produced adults. The number of young produced were counted over 11 days. Fecundity of the SP clone was lower on line 84L:441, but there was no difference in the fecundity of the NSW clone. Phloem exudate and green tissue was concomitantly collected from all lines, and analysed by GC-MS for the alkaloids lupanine and 13-hydroxylupanine. Line 84L:441 contained the highest level of total alkaloids in both phloem and tissue. All experiments indicate that alkaloid level may suppress fecundity of green peach aphids.     

Effect of riparian land use on contributions of terrestrial invertebrates to streams

Since terrestrial invertebrates are often consumed by stream fishes, land-use practices that influence the input of terrestrial invertebrates to streams are predicted to have consequences for fish production. We studied the effect of riparian land-use regime on terrestrial invertebrate inputs by estimating the biomass, abundance and taxonomic richness of terrestrial invertebrate drift from 15 streams draining catchments with three different riparian land-use regimes and vegetation types: intensive grazing — exotic pasture grasses (4 streams), extensive grazing — native tussock grasses (6 streams), reserve — native forest (5 streams). Terrestrial invertebrate drift was sampled from replicated stream reaches enclosed by two 1 mm mesh drift nets that spanned the entire channel. The mean biomass of terrestrial invertebrates that entered tussock grassland (12 mg ash-free dry mass m^–2 d^–1) and forest streams (6 mg AFDM m^–2 d^–1) was not significantly different (p > 0.05). However, biomass estimated for tussock grassland and forest streams was significantly higher than biomass that entered pasture streams (1 mg AFDM m^–2 d^–1). Mean abundance and richness of drifting terrestrial invertebrates was not significantly different among land-use types. Winged insects contributed more biomass than wingless invertebrates to both pasture and tussock grassland streams. Winged and wingless invertebrates contributed equally to biomass entering forest streams. Land use was a useful variable explaining landscape-level patterns of terrestrial invertebrate input for New Zealand streams. Evidence from this study suggests that riparian land-use regime will have important influences on the availability of terrestrial invertebrates to stream fishes.     

Diet composition influences the fitness of the herbivorous crab Grapsus albolineatus

The tropical rocky shore crab Grapsus albolineatus feeds primarily on filamentous algae but eats animal matter whenever it is available. During the summer the crab's diet switches to encrusting algae due to a die-off of filamentous algae. As a result of the switch the nutrients in the diet of the crab vary seasonally and may influence the fitness of the crab. Maintenance, growth, reproductive performance and nutrient storage of crabs were examined under four dietary regimes of increasing nutritional value ranging from low organic to high protein content. The nutritional quality of these diets significantly affected crab survival and moulting. Crabs fed on the nutritionally superior diet of algae and meat exhibited enhanced growth, higher levels of energy in the reproductive organs and stored more energy in the hepatopancreas than did individuals on the shore and crabs fed only on algal diets in the laboratory. Filamentous algae were a better food source than other algae, resulting in fewer deaths and superior levels of maintenance and growth. Growth and maintenance can occur on a pure algal diet, but reproductive performance and nutrient storage require some degree of added nutrients in the form of animal matter in the diet. Crabs fed coralline or foliose algae had higher mortality and fewer successful moults than crabs fed the other two diets. The fitness of G. albolineatus appears to be limited by the amount of extra nutrients obtained from animal matter. The opportunistic consumption of animal material in the form of carrion, or of animals associated with dietary algae, could be a key factor in the reproductive success of this crab.     

羊狂蝇化蛹、羽化的生物学研究

本文揭示羊狂蝇羽化与环境因素的相关性,幼虫在土壤栖息定位,蛹态,蛹与幼虫大小的相关性,成蝇活动行为和寿命,雌雄蝇比率等生物学特性,为羊狂蝇应用研究提供具有指导意义的基础资料。     

Behavioral strategies of aphid hyperparasitoids to escape aggression by honeydew-collecting ants

We analyzed the behavioral interactions between two species of honeydew-collecting ants (Lasius niger, Myrmica laevinodis) and foraging females of four species of aphid hyperparasitoids (Aphidencyrtus aphidivorus, Dendrocerus carpenteri, Pachyneuron aphidis, Asaphes vulgaris) usingAphis fabae ssp.cirsiiacanthoidis andLysiphlebus cardui on thistles as aphid and primary parasitoid, respectively. The observed interaction patterns and foraging parameters varied within hyperparasitoid species and revealed different strategies based upon behavioral and morphological constraints.D. carpenteri generally tried to avoid ant encounters. This avoidance strategy was successful in interactions withM. laevinodis but failed when encountering the more aggressiveL. niger, which caused about 26% adult mortality. In contrast,A. aphidivorus, P. aphidis, andA. vulgaris possess jumping ability and were hardly exposed to mortality risks. The escape reaction jump off was used as soon as ants made physical contact with foraging females. While the flight strategy ofP. aphidis is connected with cryptic movement patterns without avoidance behavior,A. aphidivorus first avoided ants and jumped off only as a last resort. Similar patterns, but less expressive, are displayed byA. vulgaris. We suggest that these different strategies are responsible for different foraging success in ant-attended resources in field.     

温度对黄粉虫成虫繁殖的影响

黄粉虫是多种小型经济动物的常用优良饵料,本试验在20.1℃,24.0℃、28.5℃、31.7℃和36.5五种恒温下饲养该成虫结果,成虫寿命平均分别为63.0、54.2、38.8、38.0和26.1天;每雌平均产卵量则分别为200.3、207.3、122.3、115.8和81.2粒,成虫平均生产1g卵消耗麸皮量分别为2.66、2.00、2.19、2.14和4.15g。结果说明人工繁殖黄粉虫的成虫期温度以24℃为最适宜。     

Aortic aneurysm in a Cebus apella monkey with experimentally induced atherosclerosis

The sudden death of a Cebus apella female (>19 years old) on an experimental hyperlipidic diet during three years is described. The gross lesions were hemothorax, atherosclerotic plaques in the aortic curve, and an aneurysm in the ascending aorta. Histologically, an enlargement of the intima in the ascending aorta with hyalinization and a thrombus were observed. The media was thinned and showed sclerosis and hemorrhage extending to the tunica adventicia.