Adult female and neonate larval plant preferences of the generalist herbivore, Epiphyas postvittana

The polyphagous leafroller moth, Epiphyas postvittana, is a pest of many fruit crops in New Zealand. Since the larva is highly mobile, host selection in this insect may involve both the adult female and the larva. In order to test the relative importance of the adult female and the neonate larva in the selection of host plants, the ovipositional preferences of females, and the preferences or acceptances of neonate larvae towards 26 plant species, consisting of 15 plants considered hosts and 11 not considered hosts, were investigated. In the ovipositional tests, the mean preferences of females for hosts and non-hosts were very similar. In contrast, larvae showed a significantly greater mean preference or acceptance towards hosts than to non-hosts, in both choice and no-choice bioassays, respectively. There were highly significant correlations between the preferences and acceptances of larvae for plants in the choice and no-choice tests. In the no-choice tests, there was a highly significant correlation between the acceptances of neonate larvae towards plants after one and three days (i.e., acceptances changed little over time). Moreover, in these no-choice tests, there was a significant negative correlation between larval acceptance at 1 day and larval mortality after 3 days; that is, the less acceptable a given plant at 1 day, the more likely larvae would fail to establish, feed, and survive on it by three days. Female and larval preferences towards the various plants were also negatively correlated. Together, these data suggest that the selection of a plant for the neonate larva to feed on is largely governed by the preferences of the larva, rather than by the preferences of the female. However, selection of a plant for oviposition by the female, may be important in host selection for reasons unrelated to larval preferences, for example, by encouraging dispersal, perhaps to other plant species, of the neonate larvae and thereby decreasing intersibling competition.     

Vive la variance: a functional oviposition theory for insect herbivores

We developed state-dependent life-history theory to explain the variance in clutch size decisions made by insect herbivores under a variety of ecological scenarios. An important aspect of our theory is explicit representation of the distribution of host quality and frequency of occurrence. Examination of the theory suggests that clutch size decisions can be highly non-linear with respect to host quality and variability. We then use our theory to explore the potential for bet-hedging strategies to evolve as a function of unpredictable catastrophic events that decimate entire clutches. Our analysis suggests that the benefits to employing such a strategy will frequently be outweighed by costs brought on by delayed oviposition.     

黑龙江嘉荫晚白垩世渔亮子组孢粉地层研究

黑龙江嘉荫县渔亮子组是我国最早发现爬行动物化石的层位,盛产鸭嘴龙等爬行类化石,前人认为,该组在层位上相当于北美晚白垩世马斯特里赫特期Ｅｄｍｏｎｔｏｎ群,ＨｅｌｌＣｒｅｅｋ和Ｌａｎｃｅ组,但孢粉化石资料提示,渔亮子组中的被子植物花粉尚未发展至上述群（组）的阶段,其层位应较之低,大致相当于北美的坎佩尼期ＢｅｌｌｙＲｉｖｅｒ群（组）或相当层位。     

RAPD技术与桂花品种分类和鉴定

简介了随机扩增多态ＤＮＡ（ＲＡＰＤ）技术的原理,及对桂花品种分类鉴定的必要性,并建议开展ＲＡＰＤ技术在桂花品种分类鉴定的应用研究。     

Embryo Sacs of Hevea brasiliensis and Carica papaya Isolated with Enzyme-Squash Technique

The enzyme-squash technique had been employed to study the development of megaspores and embryo sacs from tropical plants of Hevea brasiliensis Muel-Arg. and Carica papaya L. Ovules fixed with FAA or FPA were enzymatieally macerated in 3% pectinase cellulase solution or in 3–4% snailase solution for 4–6 h, at 28–30℃ to isolate the embryo sacs after being squashed. The whole structural images of megaspores and embryo sacs at different developmental stages were observed and identified without staining under Olympus BH-2 phase contrast microscope or light microscope after ron-aceto-carmine staining.     

A Fluorescence Staining-Methyl Salicylate Clearing Technique for Demonstrating Pollen Nuclei

Recently several DNA-binding fluotochromes have been used for demonstrating pollennuclei. However, the autofluorescence of pollen wall often obscured the fluorescence of nuclei, thus limited the use of this method. Methyl salicylate (MS) as a clearing agent has shownexcellent effect for observing embryo sac in whole-mounted ovules. This aroused me to trya combination of fluorescent staining with MS clearing in orded to make a better demonstration of the pollen nuclei. Mature 2-celled or 3-celled pollen of several angiosperm species stained with Hoechst 33258(H33258) and cleared (via ethanol dehydration) with MS showed clearcut fluorescence oftheir generative or sperm nuclei and vegetative nucleus. MS greatly decreased the wall fluorescence and increased the transparency of the pollen contents, meanwhile maintained the H33258stained fluorescence, consequently made the nuclei brighter under a darkened background. For example, in sunflower pollen a pair of elongated and winding sperm nuclei whichcould not be identified after simple H33258 staining were quite visible after MS clearing, inartificially germinated pollen tubes, the locomotion of nuclei from pollen grain into the tube,the sequence of generative and vegetative nucle travelling along the tube and the division of generative nucleus into two sperm nuclei could be well followed by this method. The present technique may be adoptable for observations on the processes of microsporogenesis and male gametophyte development, and rogenesis in cultured anthers, and also possiblyfor tracing the nuclear events during pollination-fertilization.     

Adaptations of an Emergence Trap for Use in Tropical Streams

An emergence trap based on the MPI Schlitz model was designed for use in the tropics and it was tested over one year in Palawan, the Philippines. Instructions for construction and use are given here. Only commonly available materials were used, except for the collection assembly made of UV‐light permeable acrylic glass. Heavy and bulky assemblies were avoided to enable easy transportation in the field. A special modification allows a fast and easy replacement of the screen when damaged by flooding, as is often required when traps are used downstream of headwaters. This type of trap also allows sampling of a wide littoral strip. Problems concerning the use of emergence traps in the humid tropics are discussed based on experience at different longitudinal stream sections in Palawan. The results presented here suggest that this trap should be used especially for qualitative or semi‐quantitative approaches. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

在哈尔滨地区使用液体菌种栽培红平菇技术初探

从福建三明真菌研究所(福建省三明市375000)购入红平菇优良菌株,在哈尔滨地区对其进行了用液体菌种代替固体原料的栽培技术研究。包括一级种培养基的筛选、液体菌种培养基的筛选、栽培种制作与培养以及出菇管理技术。结果表明:对于一级种,红平菇在PDA和马铃薯半组合培养基上都生长良好,菌丝洁白、粗壮、浓密,7～8d长满斜面;红平菇在玉米粉葡萄糖蛋白胨和麦麸葡萄糖蛋白胨液体培养基上生长较好,7d时菌丝长满培养液,菌丝量较多;用与平菇相似的常规方法制作栽培种、养菌处理与出菇管理,红平菇的产量达100%～150%。由于采用了液体菌种的栽培模式,从制种到采收的整个过程共需要50～60d,比二级种为固体菌种的常规方法缩短26～31d,大大地缩短了生产周期,提高了经济效益。     

Random field models for fitness landscapes

 In many cases fitness landscapes are obtained as particular instances of random fields by randomly assigning a large number of parameters. Models of this type are often characterized reasonably well by their covariance matrices. We characterize isotropic random fields on finite graphs in terms of their Fourier series expansions and investigate the relation between the covariance matrix of the random field model and the correlation structure of the individual landscapes constructed from this random field. Correlation measures are a good characteristic of “rugged landscapes” models as they are closely related to quantities like the number of local optima or the length of adaptive walks. Our formalism suggests to approximate landscape with known autocorrelation function by a random field model that has the same correlation structure. Received: 10 November 1995 / Revised version: 19 February 1996