泽泻田优势天敌对莲纹夜蛾幼虫的捕食作用研究

通过开展几种优势天敌对莲纹夜蛾的捕食作用研究发现,在相同猎物密度下,拟水狼蛛雌成蛛的日捕食量〉草间小黑蛛雌成蛛的日捕食量,龟纹瓢虫雌成虫的日捕食量〉黑翅小花蝽雌成虫的日捕食量,说明拟水狼蛛和龟纹瓢虫对莲纹夜蛾1-2龄幼虫具有较强的控制能力.经拟合,它们各自的捕食功能反应均属HollingⅡ型反应,其圆盘方程分别为：Na=1.00260N/（1＋0.98404N）（草间小黑蛛雌成蛛）、Na=0.94118N/（1＋0.02804N）（拟水狼蛛雌成蛛）、Na=0.44238N/（1＋0.00375N）（龟纹瓢虫雌虫）、Na=0.50312N/（1＋0.01350N）（黑翅小花蝽雌成虫）.a/Th值的大小是反映天敌对猎物控制能力强弱的参数,供试的这4种天敌对莲纹夜蛾1-2龄幼虫控制作用效果的a/Th值大小依次为：龟纹瓢虫雌成虫的a/Th〉拟水狼蛛雌成蛛的a/Th〉黑翅小花蝽雌成虫的a/Th〉草间小黑蛛雌成蛛的a/Th.此外,研究结果还表明,天敌的捕食作用有较强的种内干扰效应,随着捕食者密度的增大,平均捕食量逐渐减少,捕食作用率也相应降低.     

Reproductive biology of the endangered wattled curassow (Crax globulosa; Galliformes: Cracidae) in the Juruá River Basin,Western Brazilian Amazonia

The reproductive biology of Crax globulosa is virtually unknown, this knowledge comprised of only a few anecdotal notes. We found nine nests of Crax globulosa in the middle section of the Juruá River, western Brazilian Amazon, during the dry season. Nests averaged 22.5 m from water and 13.3 m above the ground. We observed two nest types: five made of twigs, leaves and vines, and four within a bromeliad. All nests contained two eggs, but six (67%) were subsequently predated. A female tagged with a transmitter nested twice during the same breeding season. A chick was monitored together with its parents for > 10 months. In addition to hunting and habitat loss, nest predation could be another threat to this endangered species.     

农药作用下的食虫瘤胸蛛对黑尾叶蝉若虫捕食功能影响

以稀土元素铕为荧光示踪物质,以“水稻-黑尾叶蝉(Nephotettix.cincticeps)-食虫瘤胸蛛(Ummelita insec-ticeps)”这一食物链中的水稻和黑尾叶蝉作为铕的传递者,经萃取和反萃取等一系列化学分析方法,定量测定了在一定时间(5 d)和空间条件下黑尾叶蝉若虫对水稻的取食量以及不同施药浓度、不同蛛虫密度条件下食虫瘤胸蛛的摄食量.结果表明:在未施药状况下,食虫瘤胸蛛个体5 d共摄食黑尾叶蝉若虫3.4头;蛛、虫比例为1∶9时是最有利发挥食虫瘤胸蛛控虫能力的最佳比例;在施药状况下,无论施用农药雕螟何种浓度,食虫瘤胸蛛的摄食量均比对照组要低,且随着施药浓度的增加,食虫瘤胸蛛的捕食及控虫能力减弱.     

六斑月瓢虫对豆蚜捕食功能反应研究

研究了六斑月瓢虫各龄幼虫和成虫对豆蚜的捕食功能反应,并进行了Holling-Ⅱ型和Holling-Ⅲ型功能反应模型拟合,结果表明,六斑月瓢虫的捕食量随虫龄的增大而增加,其发现率和最大捕食量也增大,平均处理时间减少.     

Biochemistry of frog ribonucleases

Frogs have unique pyrimidine base-specific RNases, with structures similar to those of turtle, iguana and chicken RNases. Among the four frog RNases discussed here, three from Rana pipiens, R. catesbeiana and R. japonica oocyte cells show anti-tumour activity, and the latter two show lectin activity towards sialic acid-rich glycoproteins. In this review, (i) we compare their unique primary structures with respect to the locations of their disulphide bridges, three-dimensional structure, base specificity and heat stability as compared with RNase A, and (ii) we summarize current knowledge about the mode of action of lectin and the antitumour activities of the three frog RNases.     

Mixed‐species social aggregations in Madagascan tadpoles—determinants and species composition

The frequency, species composition, and determinants of mixed‐species tadpole aggregations were analysed under natural conditions in a dry forest of western Madagascar. Most aggregations (73%) were formed by more than one species, with up to four species per individual aggregation. Dyscophus insularis (Microhylidae) and Aglyptodactylus securifer (Mantellidae) were the most abundant species in these aggregations. Using a logistic regression model we analysed to what extent the presence and absence of aggregations in a pond can be predicted by its biotic and abiotic habitat variables. Aggregations are more likely in deep, clear ponds with little leaf litter cover on the bottom, while the overall density of invertebrate predators in the pond seems to play a minor role. Our observations suggest that the formation of mixed‐species aggregations in tadpoles of the Kirindy Forest in our system is primarily a reaction to vertebrate predators. Therefore, aggregation behaviour may play a key role in the ability of several anuran species to utilize these spawning waters that are unpredictable in regard to the presence of fish and other vertebrates.     

Seed predation heterogeneity in the loculate fruits of a Mediterranean bushy plant

The effects of the number of locules per fruit on seed predation in a Mediterranean woody plant (Cistus ladanifer) were analysed. Plants produced fruits with a similar number of locules (fruits with a small, intermediate or large number of locules). Nevertheless, there were no differences in the number of fruits produced or predated per plant. Different types of fruits did not differ in size, seed weight, fruit to wall ratio, insect predation rate or mean proportion of destroyed locules. They did differ, however, in the variation of the proportion of destroyed locules; fruits with few locules had a wider variation than fruits with a large number of locules. Our results suggest that phenotypic selection pressure on insect predation could give rise to more between‐fruit variation in the seed output saved from predation in those plants producing fruits with a small number of locules.     

Ecology and behaviour of the ‘road tarantulas’ Eupalaestrus weijenberghi and Acanthoscurria suina (Araneae,Theraphosidae) from Uruguay

Spatial distribution, burrow morphology, phenology, defensive displays and predation of two theraphosid spiders living in meadows were studied in Uruguay. Exhaustive field studies complemented with laboratory observations were carried out. Eupalaestrus weijenberghi occurred throughout the country while Acanthoscurria suina occurred only in the southern half. Both species seemed to be the most abundant theraphosid spiders in Uruguay as they live in the dominant landscape of the country. Burrows from both species showed a similar morphological pattern but a terminal narrow tube was found only in E. weijenberghi. We observed that A. suina always co‐occurred with E. weijenberghi but this species frequently occurred in the absence of the former. When co‐occurring A. suina showed an aggregated distribution while E. weijenberghi was randomly distributed. A restricted reproductive period was found for both species, mainly between March and April, evidenced by the massive presence of walking adult males and then confirmed by pit‐fall traps. Moulting, oviposition and longevity were also studied. Conspicuous species‐specific defensive behaviours were displayed by the tarantulas in all cases, when collected. These tarantulas showed spatial co‐occurrence and temporal coexistence with the beetle Diloboderus abderus, an important pest of grasslands. Tarantula predation on adult beetles was confirmed, these spiders being one of the few beetle predators. Their maximal efficiency in beetle predation could reach 65?000 prey captured per hectare by month. These polyphagous tarantulas seem to be potential agents for the biological control of beetle pests.     

具有Crowley-Martin型功能性反应的随机非自治捕食模型的持续与灭绝

主要研究了一类具有Crowley-Martin型功能性反应的随机非自治捕食模型的持续性与灭绝性.种群灭绝、平均意义下非持续以及平均意义下弱持续的充分性判据被建立.此外,利用数值模拟验证了所得理论结果的有效性.