Molecular ecology of some Cecidophyopsis mites (Acari: Eriophyidae) on Ribes species and evidence for their natural cross colonisation of blackcurrant (R. nigrum)

Ribosomal DNA from Cecidophyopsis mites from different Ribes species was amplified using the polymerase chain reaction and the products digested using restriction enzymes. After separating the DNA fragments on gels, it was possible to identify specimens of mites obtained from field samples by comparing the profiles of their DNA banding patterns with those of known Cecidophyopsis species. Using this analysis, a non-gall forming mite found infesting blackcurrant buds in New Zealand was identified as the gooseberry mite (C. grossulariae). On wild red currant (Ribes spicatum) from Finland showing two sizes of galled buds, the red currant gall mite (C. selachodon) was identified in the larger galls located at the tips of branches and a distinct mite in the smaller galls located on the lower parts of the branches. A mite with a DNA banding profile indistinguishable from this latter mite from R. spicatum was also identified in galled buds of blackcurrant genotypes growing in Finland, including those containing the blackcurrant gall mite (C. n'ftw)-resistance genes P or Ce. The DNA banding profile of this mite resembled most closely that of C. ribis , but was distinct from it. The occurrence of C. grossulariae and this distinct Cecidophyopsis mite on blackcurrant has implications for the genetic control of Cecidophyopsis mites and possibly for the spread of the reversion disease agent in this crop.     

Lectin-mediated agglutination of plant protoplasts

Abstract The ability of concanavalin A, soybean agglutinin and lectins from Pisum sativum and Bandeiraea simplicifolia to mediate the agglutination of protoplasts prepared from Nicotiana glauca, Zea mays, and Lactuca sativa was assessed. Pea lectin failed to mediate agglutination; the other lectins agglutinated the three cell types tested. A microtiter assay was used to assess the activity of the lectins. The three active lectins had different activities against each of the protoplast types tested.     

Clonal composition of the peach-potato aphid Myzus persicae (Homoptera: Aphididae) in France and Scotland: Comparative analysis with IGS fingerprinting and microsatellite markers

Fourteen colonies of the peach‐potato aphid, Myzus persicae, were taken either from French peach trees or weeds in 2001. Thirty five apomictic parthenogenetic lineages (APLs) were established. Ribosomal DNA intergenic spacer (IGS) fingerprinting was used to characterise these and 28 fingerprints were duly obtained. Those lineages with different fingerprints were considered different genotypes and those with the same fingerprint as the same. The genetic identity of APLs was further tested using four microsatellite loci. APLs that differed by IGS fingerprint had distinct microsatellite allele combinations and those that had the same IGS fingerprint had the same microsatellite allele combinations. The results confirmed that IGS types corresponded to different aphid genotypes. Independent APLs with identical IGS and microsatellite genotype were therefore considered different representatives of the same clone. APLs from M. persicae found on Scottish crops in 1995, 1996 and 2001, as well as a long‐term laboratory line were also examined by the same methods. Their IGS fingerprints were similar or identical suggesting that they all belonged to the same clone. Microsatellite markers also suggested that these lineages were derived from a single clone. Some field lineages exhibited slight modifications to their IGS fingerprints confirming that the IGS evolves more rapidly than these microsatellite alleles. Thus, IGS will continue to provide a useful marker for aphid fieldwork.     

Foraging and habitat use by Nycteris grandis (Chiroptera: Nycteridae) in Zimbabwe

This study describes the foraging strategies, foraging areas, and roosts used by four female radio-tagged Nycteris grandis along the Zambezi River in Mana Pools National Park in Zimbabwe. The bats exhibited two foraging strategies, sometimes hunting from perches, other times flying continuously close to the ground. Some individuals used one strategy more than the other. During the study, the bats fed mainly on frogs, selecting only Ptychadena anchietae ; they also took crickets, moths and cicadas. Each bat usually consumed two frogs each night and patterns of occupation of feeding perches suggest that their foraging efficiency was between 21 and 36%. The marked bats roosted in an old water tower or in a hollow Acacia albida. Four of five marked females were nursing young during this study.     

Carnivorous bats?

Only large bats can take large prey but size alone does not identify 'carnivorous bats' (those including small terrestrial vertebrates in their diets). Morphological data, including body mass, aspect ratio and relative wing loading, along with information about orientation and foraging strategies can be used to characterize a suite of features which identifies carnivorous bats. We use the available data to make predictions about which large Microchiroptera will be found to be carnivorous. A combination of morphological features including body mass (^0.017 kg), low aspect ratio (<6.3), and low relative wing loading (<36) significantly identifies carnivorous species from among other animal-eating forms. Some carnivorous species use short, low intensity, high frequency, broadband echolocation cells but rely on prey generated cues to locate their targets. Other carnivorous species are facultative echolocators. The available data lead to the prediction that Phyllostomus hastatus and Hipposideros diadema are not regularly carnivorous, while Otonycteris hemprichi may be. Large species with echolocation calls adapted for flutter detection (rhinolophids and hipposiderids) or those with long narrowband calls and high aspect ratio wings with high relative wing loading (for example molossids, some emballonurids and some vespertilionids) chase airborne prey in the open; neither of these approaches involves prey other than arthropods.     

Stomatal Behaviour and Water Relations of Chilled Phaseolus vulgaris L. and Pisum sativum L.

Leaf diffusion resistance interpreted as stomatal resistance,leaf water potential (_w), solute potential (_s) and leaf turgorpotential (_p) of the chilling sensitive species Phaseolus vulgariswere determined during chilling at 4 °C in the light. Bothchill-hardened and non-hardened plants were used. For comparison,the chilling resistant species Pisum sativum was also used. The results for chilled P. sativum were similar to those obtainedfor chill-hardened P. vulgaris plants receiving a chilling treatment.In both cases a reduction in stomatal aperture and the maintenanceof a positive leaf turgor were the responses to chilling. Leavesof chilled but non-hardened P. vulgaris plants were found tomaintain open stomata throughout the chilling treatment despitea severe wilt developing after 7 h at 4 °C. This was incontrast to the chill-resistant P. sativum. which showed a rapidclosing and subsequent re-opening of the stomata to a new reducedaperture. During the first 12 h of chilling _wof P. vulgaris leaves changedfrom –0.47 MPa to –1.24 MPa. On more prolonged chilling_w tended to return to pre-chilling values. In addition. _p decreasedfrom 0.42 MPa to zero after only 9 h of chilling, and remainedat this value for the remainder of the chilling period, _s, changedrapidly from –0.89 MPa to –1.35 MPa in the first7.5 h, and after 9 h. _w and _s, were equal, i.e. zero _p. In contrast,the chilling resistant plant P. sativum maintained a positive_p throughout the chilling period, and there was little differencebetween values of _w, and _s in control and chilled leaves. Key words: Chilling, Stomata, ater relations, Phaseolus vulgaris, Pisum sativum     

Wounds and the origin of blood-feeding in bats

This new theory about the origin of blood-feeding in bats is based on four main premises: (1) that the diets and feeding behaviour of some bats have always varied; (2) that the Miocene mammal fauna of South America included many large (≥ 2 kg body mass) forms; (3) that wounds offered protovampaire bats the opportunity to feed on blood; and (4) that sharp, strong upper incisor teeth were a prerequisite to feeding at wounds. This theory proposes that variation in feeding behaviour led protovampire bats to feed on concentrations of insect larvae at wounds on large mammals, thence to insects and body fluids, and finally to blood. The chiropteran family Phyllostomidae is confined to the New World and its members frequently have robust upper incisor teeth and flexible foraging behaviour. Elsewhere in the world, bats with flexible foraging behaviour lack robust incisors, while those with robust incisors are more conservative in their foraging. The wound theory of the origin of blood-feeding in bats takes into account their anatomy and foraging behaviour as well as the availability of large prey. In contrast to earlier theories that blood-feeding in bats originated from fruit-eaters with robust incisors or through the gleaning of ectoparasites, the wound theory also explains why vampire bats occur only in the New World.