The use of clip cages to restrain insects reduces leaf expansion systemically in Rumex obtusifolius

Abstract. 1. Clip cages have been used widely by experimental ecologists to contain insects on plants.
2. Under controlled conditions, the effect of applying clip cages alone and clip cages and the chrysomelid beetle Gastrophysa viridula on systemic leaf expansion of Rumex obtusifolius was investigated. Treatments were applied to the fully expanded fourth leaf and expansion of leaf 8 was measured over a period of 22 days.
3. The application of clip cages reduced the rate at which leaf area increased and led to reductions in final leaf areas.
4. Clip cages have systemic effects on plant development and these effects are sustained even after the clip cage is removed. Investigators should take this into account in designing experiments.     

Parasitoid behaviour: predicting field from laboratory

Abstract.  1. Most of what is known about parasitoid behaviour comes from laboratory observations: field quantitative observations on searching parasitoids are extremely difficult to do and are rare. The basic components of Aphytis melinus 's response to California red scale ( Aonidiella aurantii ) were studied in the laboratory: encounter, rejection, drumming, probing, oviposition, and host-feeding. It was then asked whether these observations provided a reliable guide to behaviour in the field in a situation that was very different from the laboratory.
2. Field observations were carried out on bark on the trunk and interior branches of trees where live scale density is extremely high in patches, dead scale make up 90% of all scale, and could be expected to interfere with Aphytis search.
3. The laboratory observations predicted well the time taken in the field for each basic event (drumming or probing) and average times spent on a scale. Also well predicted were the distributions of times spent on drumming, probing, and total time on a scale. Rejection rates were much higher in the field. Thus, the laboratory studies predicted foraging behaviour in the field with variable success; potential explanations for observed mismatch between laboratory and field and its possible larger implications are discussed.     

Cell envelope phospholipid changes in a moderate halophile during phenotypic adaptation to altered salinity and osmotic stress

Abstract The increased content of negatively-charged phospholipids in membranes of Vibrio costicola grown at high salinities is mediated by increased phospholipid synthesis of phosphatidylglycerol relative to phosphatidylethanolamine. This phenomenon provides a system for investigating the factors involved in triggering and controlling haloadaptation in this moderately halophilic bacterium. We review recent experiments, which show that when subjected to sudden increases in external salinity, V. costicola senses both the absolute NaCl concentration and the magnitude of the salt shift. We show that the latter is sensed at least in part via osmotic pressure effects, since shift-up into sucrose-containing media triggers comparable changes in growth and in phospholipid composition and synthesis.     

Non-reciprocal cross-incompatibility in Trichogramma deion

In non-reciprocal cross-incompatibility (NRCI), the crossing of a female of a strain A with a male of a strain B results in hybrid offspring, whereas the reciprocal cross produces few or no hybrids. Only females are of hybrid origin in Hymenoptera because they arise from fertilized eggs; males arise from unfertilized (haploid) eggs. Crosses between many strains of Trichogramma deion showed some degree of NRCI. Crosses between a T. deion culture collected in Seven Pines, California (SVP) with one from Marysville, California (MRY) showed an extreme form of NRCI in which practically no female offspring was produced when MRY females were crossed with SVP males. The reciprocal cross produced a close to normal proportion of female and male offspring. Detailed studied of this cross indicated that 1) the female offspring produced in the compatible interstrain cross were not the result of parthenogenesis but were true hybrids, 2) the incompatible interstrain cross did not produce female offspring because fertilized eggs died during development, 3) the death of these eggs could not be prevented by either antibiotic or temperature treatment, 4) cytoplasmically inherited factors causing NRCI could be discounted because backcrossed females with the genome of MRY and the cytoplasm of SVP, exhibit the NRCI relationship characteristic of their genome. Therefore the NRCI between these strains appears to be caused by a modification coded for by the nuclear genes of MRY that results in incompatibility when SVP sperm fertilizes MRY eggs. In addition the level of incompatibility in crosses between the SVP females and MRY males is temperature sensitive, the higher the rearing temperature the lower the level of compatibility.     

Glyphosate in fisheries management

Glyphosate is the active ingredient of the broad-spectrum, translocated herbicide Roundup. Glyphosate is cleared for safe use in or near watercourses, being rated virtually non-toxic by the World Health Organisation. Trials in and alongside Irish fishery watercourses first commenced in 1989 and are continuing to date. The aim of this work is to evaluate the product's efficacy in clearing nuisance reed species in recreational fisheries. The longevity of control and impact on the habitat and its fauna is also investigated. Trials in canal fisheries have demonstrated the capacity of glyphosate to remove obstructive stands of reeds (mainly Schoenoplectus lacustris, Glyceria maxima, Phragmites australis, Sparganium erectum and Typha latifolia), so creating reed-free areas and swims for anglers. These swims remained open for three years following a single application. In 1992 a trial over a 3 km length of the River Boyne, a renowned salmonid fishery, was undertaken. The results clearly demonstrated the ability of glyphosate to provide long-term control of dense (354 shoots m^–2) Schoenoplectus infestations in a large watercourse. In the year following, less than one shoot per m² was present in the channel. In 1994 a small increase in density (7.6 shoots m^–2 was recorded, so enabling unobstructed angling in a stretch of river that had been virtually unfishable for years. Trout (Salmo trutta L.) and salmon (Salmo salar L.) also used the newly exposed gravels for spawning in the winter of 1993, thereby improving fish recruitment and production in the fishery.     

使用MUG培养基定量检测植物药中大肠杆菌时荧光猝灭现象的发生与克服方法

实验中观察到,用ＭＵＧ培养基对植物药中的大肠杆菌定量时多发生荧光猝灭现象,影响检测结果。本文对此现象产生的原因与克服方法进行了系统的考察,发现以一种简便的转接方法可排除植物药介质对菌检的干扰。该方法由两组检验系列构成,当怀疑正常稀释系列（第一系列）４０ｈ培养液的荧光结果可能因猝灭现象呈假阴性时,立即分别将该系列的１—３号管培养液以０．５ｍｌ的接种量转接入新鲜的ＭＵＧ培养基（第二系列）,重新培养２４ｈ,荧光猝灭现象即可克服。综合两系列的荧光、产气和吲哚三项生化特征得出检品中大肠杆菌含量。实际应用表明,此法能显著提高使用该培养基时菌检结果的可靠性。     

Detection and identification of ferricrocin produced by ectendomycorrhizal fungi in the genusWilcoxina

The ectendomycorrhizal fungiWilcoxina mikolae isolates CSY-14 and RMD-947 andW. rehmii isolate CSY-85 were grown in pure culture under iron-limiting conditions. All three isolates tested positive for siderophore formation using both the ferric perchlorate assay and a sensitive HPLC iron-binding assay. A peptide siderophore was isolated from the culture medium by HPLC and shown to contain the amino acids serine, glycine and ornithine in a 1:2:3 ratio. This siderophore was identified as ferricrocin on the basis of electrospray mass spectroscopy and its co-chromatography in two different HPLC systems with ferricrocin isolated fromAspergillus fumigatus. Ferricrocin was the only siderophore isolated from theseWilcoxina cultures. This is the first report of siderophore formation by ectendomycorrhizal fungi.     

Biology and life cycle ofAtelocauda koae,an unusual demicyclic rust

Atelocauda koae, a rust of the native HawaiianAcacia koa, is considered as a demicyclic species, having spermogonial, aecial, and telial states, but is unusual in production of aeciospores simultaneously with teliospores rather than consecutively. Host inoculation with spores of each state separately confirmed that the life cycle was perpetuated by the telial state, but the aeciospores, while capable of germination and stomal penetration, did not produce detectable infection. This rust therefore behaves as a microcyclic species, and appears to be in evolutionary transition toward this reduced state. Teliospores produced vestigial, permanently attached basidiosopores which germinated to produce infective hyphae. The hyphae entered the host either through stomata or penetrated the epidermis directly, with the latter method being more common. Unusual nuclear associated with teliospore germination, in which meiosis occurs in more than one diploid nucleus was observed, in confirmation of an earlier study.