Divergent, genetically based feeding behaviour of two sympatric Arctic charr, Salvelinus alpinus (L.), morphs

Abstract –  Arctic charr, Salvelinus alpinus (L.), is one of the several northern fishes that show resource polymorphisms in postglacial lakes. Two reproductively isolated morphs of Arctic charr coexist in distinct ecological niches in the subarctic lake Fjellfrøsvatn, North Norway. Offspring of the two morphs (termed littoral charr and profundal charr) were reared separately but under identical conditions. Their feeding behaviour was compared experimentally using different kinds of live prey. The fishes had no experience with natural prey before the experiments. The littoral morph were more effective in eating live plankton ( Daphnia ) and littoral benthos ( Gammarus ), and had a higher attack rate against pleuston (surface prey, Gerris ) compared with the profundal morph. The two morphs behaved in accordance with expectations from their in situ niche utilisation towards the three prey types. This indicates a case of incipient ecological speciation where divergence in resource utilisation in contrasting niches has evolved adaptations in feeding behaviour by natural selection.     

丝棉木金星尺蛾的发生及防治

丝棉木金星尺蛾 Abraxas susp ecta Warren在砖石瓦块下的土中越冬 ,主要危害大叶黄杨 Eu-onymus japonicus L.。文章记述了该虫主要形态特征、发生规律及防治方法     

杜鹃模拟鹰及杜鹃外形多态性的进化(英文)

很早人们就已发现一些寄生性繁殖的杜鹃,其外形与Accipiter属的鹰类非常相似。最近的实验表明,大杜鹃(Cuculus canorus)模拟鹰类有助于其接近宿主大苇莺(Acrocephalus scirpaceus)的巢。不过,大苇莺却能够通过公众信息传递来识别大杜鹃的这一计谋。反过来,这也导致了杜鹃外形多态性的进化,以避免宿主对杜鹃的识别。通过比较研究,我们发现在寄生性的杜鹃中,模拟鹰类外形(如虹膜黄色,胸腹部具斑纹,脚黄)的杜鹃种类具有明显的外形多态性(29%的种类),远高于不模拟鹰类外形的杜鹃(仅8%的种类具有多态性)。系统发生分析进一步证实了模拟鹰类外形与杜鹃多态性进化之间的相关性。我们认为,杜鹃对鹰类的动态模拟很可能促进了杜鹃外形多态性的进化,以避免宿主对杜鹃的识别。     

Hydroacoustic assessment of mono‐ and polymorphic Coregonus density and biomass in subarctic lakes

Density and biomass estimates of pelagic fish are essential to understand food web interactions and ecosystem functioning. We conducted surveys of six subarctic lakes for assessing both mono‐ and polymorphic whitefish Coregonus lavaretus (L.) populations. Monomorphic whitefish lakes were inhabited by a habitat and diet generalist, large sparsely rakered (LSR) morph, whereas polymorphic whitefish lakes had a littoral benthivorous LSR morph, a pelagic planktivorous densely rakered (DR) morph and in two cases a benthivorous small sparsely rakered (SSR) morph inhabiting the profundal zone. In addition, an introduced specialist zooplanktivore, vendace Coregonus albula (L.), inhabited one of the monomorphic lakes. Hydroacoustics was found to be an appropriate method for estimating coregonid densities and biomasses in large and deep polymorphic lakes occupied by the planktivorous DR morph or vendace, but only during dark nights in autumn. The suitability of hydroacoustic assessment for benthivorous LSR and SSR morphs was low, especially in polymorphic whitefish lakes due to their preference for near‐bottom habitat or shallow areas not sampled with hydroacoustics. The pelagic density of DR morph varied from 330 to 1780 fish·ha^?1 and biomass from 1.4 to 13.3 kg·ha^?1 in polymorphic whitefish lakes, whereas corresponding estimates for LSR morph were 10–320 fish·ha^?1 and 0.5–8.4 kg·ha^?1 in monomorphic whitefish lakes. In general, polymorphism tended to increase the density and biomass of whitefish in the pelagic area compared with monomorphic systems.     

有翅型与无翅型棉蚜发育及繁殖能力比较研究

在室内采用网罩盆栽苗研究有翅型与无翅型棉蚜若虫及成虫发育历期、繁殖能力、成虫寿命、产仔能力、体重.有翅型与无翅型棉蚜若虫发育历期之间无显著差异.二者成虫寿命、第一次产仔数量、平均每次产仔数差异不显著,而生殖前期、产仔次数、净增殖率与内禀增长率均存在极显著差异(P<0.01).有翅型棉蚜的产仔次数极显著小于无翅型,而有翅型棉蚜生殖前期显著长于无翅型棉蚜.无翅型棉蚜净增殖率显著大于有翅型棉蚜.无翅型棉蚜可能可以将用于翅发育和飞行的能量转而用于繁殖.     

Colletotrichum species causing anthracnose on avocado fruit in Mexico: Current status

Colletotrichum species cause anthracnose disease in tropical and subtropical fruit crops worldwide. Mexico is the main producer and exporter of avocado (Persea americana) globally and has yearly outbreaks of anthracnose on this crop. However, which specific Colletotrichum spp. cause these outbreaks in avocado-producing regions remain uncertain; thus, the objective of the present study was to identify the species responsible. A survey performed in six production regions of Mexico yielded 232 isolates, from which a subset of 104 strains was selected based on morphological characteristics and origin. This subset was sequenced and haplotypes were analysed in the gapdh partial gene. Finally, 31 strains were identified through multilocus phylogenetic analyses using the sequences of the internal transcribed spacer region and six loci. This study revealed the presence of two species previously reported in Mexico (C. karsti and C. godetiae), three novel records in Mexico (C. siamense, C. fioriniae, and C. cigarro), four novel records on avocado (C. chrysophilum, C. jiangxiense, C. tropicale, and C. nymphaeae), and two novel lineages (Colletotrichum sp. 1 and Colletotrichum sp. 2). C. siamense was the most prevalent, while the species reported for the first time on avocado, including the novel lineages, were the least prevalent. C. karsti was the most widespread (four regions), followed by C. siamense, C. jiangxiense, and C. chrysophilum (three regions). Pathogenicity tests showed that all species caused anthracnose on avocado fruit. These findings will be useful for improving the management of avocado anthracnose outbreaks in Mexico.     

中国梨木虱翅型变化及其影响因素初探

对中国梨木虱不同月份和不同光周期下的翅型变化进行研究.结果表明,梨木虱翅型随月份发生明显变化,5—9月为短翅型,10月至次年4月为长翅型.恒温20℃条件下,短光周期(9 h光/15 h暗、8 h光/16 h暗)可诱导产生长翅型,而长光周期(12 h光/12 h暗,10 h光/14 h暗)可诱导产生短翅型.短光周期下长翅...     

不同受害油松对油松毛虫幼虫生长发育的影响

该文利用不同受害程度的油松针叶饲养油松毛虫幼虫,研究其对幼虫生长发育的影响.结果表明:油松毛虫取食受害松针后,营养指数都有所下降,尤其是取食受害50％的松针对幼虫影响最大,其取食量、排粪量最小,对食物的消化和利用指数较低,幼虫发育缓慢,死亡率增大,蛹重减轻,从而影响了油松毛虫的种群动态;取食受害25％和受害75％松针的幼虫的营养指数比较接近.同时深色型幼虫的营养指数较浅色型的高,死亡率较低,但在取食受害50％的松针后期,深色型幼虫的一些营养指数反而比浅色型的低.      

玉米果穗图像单一特征的品种鉴别力评价

寻找新的果穗性状并评价它们单独鉴别品种的能力,是玉米新品种特异性、一致性和稳定性（DUS）测试研究的重要内容。采集了4个品种各50个果穗的RGB图像,用图像处理法提取了4大类形态特征共计145个性状,逐一性状对品种进行判别分析,以性状的品种识别率表示性状鉴别品种的能力大小。单一性状的品种识别率变化在0.244～0.634之间,在前17个高鉴别力性状中,果穗长宽比等具有与指南性状同等的甚至更高的品种区分能力。单一性状的广义遗传力一般都小于0.66,且与鉴别力高度一致（y = 0.29 + 0.44x, r=0.897, P<0.01）。总体上,四大属性的鉴别力从大到小依次为形状类>纹理类>颜色类>大小类。从受试的145个特征中筛选出许多具有较高品种鉴别能力的性状,可望应用于玉米新品种DUS测试工作。     

阿维菌素亚致死剂量下2种色型豌豆蚜解毒酶活力的研究

采用室内培养方法研究了阿维菌素亚致死剂量分别处理红色和绿色型豌豆蚜后,其乙酰胆碱酯酶(AChE)、谷胱甘肽S-转移酶(GSTs)和多功能氧化酶(MFO)比活力在不同时间内的变化。结果表明,亚致死剂量LC20、LC10和LC5分别处理2种色型豌豆蚜24 h后,3种酶比活力均高于对照,且GSTs和MFO比活力均随亚致死剂量升高而增大,但AChE比活力表现为2种色型均在LC10处理后达到最大值,分别为13.93 nmol·min-1·mg-1(pro)和53.93nmol·min-1·mg-1(pro)。各处理表现为AChE比活力绿色型大于红色型,GSTs比活力与前者相反,而MFO比活力红、绿色型间无明显规律。随着处理后取样时间的变化,对红、绿色型豌豆蚜AChE、GSTs和MFO比活力的影响均表现为诱导或抑制作用,其中,GSTs比活力绿色型在0 h均达到最大值[nmol·min-1·mg-1(pro)]且显著高于其余时间,分别为49.84(CK)、48.87(LC5)、42.74(LC10)和45.35(LC20)。2种色型豌豆蚜体内AChE、GSTs和MFO比活力变化不但受阿维菌素不同亚致死剂量的影响,还表现出明显的时间效应。