Impact of the Arundo scale Rhizaspidiotus donacis (Hemiptera: Diaspididae) on the weight of Arundo donax (Poaceae: Arundinoideae) rhizomes in Languedoc southern France and Mediterranean Spain

Arundo donax L. (Poaceae) is native to Mediterranean Europe and invasive in the Rio Grande Basin of North America. Rhizomes from nine sites in France and Spain infested with a candidate control agent, the armoured scale Rhizaspidiotus donacis (Hemiptera: Diaspididae) weighed 50% less than those from nine sites without scale.     

Genetic variability in mitochondrial DNA in a regional population of the great tit (Parus major)

Genetic variation of mitochondrial DNA (mtDNA) in 18 great tits (Parus major) from three neighboring localities in Sweden was investigated with eight tetranucleotide restriction endonucleases. The 18 individuals could be separated into 13 different maternal lineages. The high number of female lineages present in this regional population contrasts with a low level of sequence divergence between the different mtDNA clones, with a mean of 0.19% sequence divergence between all individuals. There was no obvious spatial structuring of mtDNA clones among the three localities. The presence of a high number of different clones with a low degree of sequence divergence could be explained by the effects of a large long-term effective population size, with the mtDNA clones having diverged about 25,000–200,000 years ago.This study was supported by the Swedish Natural Science Research Council, the Erik Philip-Sörensen Foundation, and the Nilsson-Ehle Foundation.     

Salt tolerance of the reed plant Phragmites communis

Reed plants ( Phragmites communis Trinius) were grown at NaCl concentrations up to 500 m M and their growth, mineral contents and leaf blade osmotic potential were determined. Addition of NaCl up to 300 m M did not affect growth significantly. Sucrose, Cl^-and Na⁺ concentrations in the shoots increased with the salinity of the medium and the shoot water content decreased. K⁺ always contributed most to the leaf osmotic potential. Even in the presence of 250 m M NaCl in the rooting medium, the leaf blade contained only 50 mM Na⁺, suggesting that the plants have an efficient mechanism for Na⁺ exclusion. ²²Na⁺ uptake experiments suggested that the retranslo-cation of absorbed Na⁺ from shoots to the rooting medium lowered the uptake of Na⁺.     

Rhizome dynamics and resource storage in Phragmites australis

Seasonal changes in rhizome concentrations of total nonstructural carbohydrates (TNC), water soluble carbohydrates (WSC), and mineral nutrients (N, P and K) were monitored in two Phragmites australis stands in southern Sweden. Rhizome biomass, rhizome length per unit ground area, and specific weight (weight/ length ratio) of the rhizomes were monitored in one of the stands.Rhizome biomass decreased during spring, increased during summer and decreased during winter. However, changes in spring and summer were small (< 500 g DW m-2) compared to the mean rhizome biomass (approximately 3000 g DW m^–2). Winter losses were larger, approximately 1000 g DW m-2, and to a substantial extent involved structural biomass, indicating rhizome mortality. Seasonal changes in rhizome length per unit ground area revealed a rhizome mortality of about 30% during the winter period, and also indicated that an intensive period of formation of new rhizomes occurred in June.Rhizome concentrations of TNC and WSC decreased during the spring, when carbohydrates were translocated to support shoot growth. However, rhizome standing stock of TNC remained large (> 1000 g m^–2). Concentrations and standing stocks of mineral nutrients decreased during spring/ early summer and increased during summer/ fall. Only N, however, showed a pattern consistent with a spring depletion caused by translocation to shoots. This pattern indicates sufficient root uptake of P and K to support spring growth, and supports other evidence that N is generally the limiting mineral nutrient for Phragmites.The biomass data, as well as increased rhizome specific weight and TNC concentrations, clearly suggests that reloading of rhizomes with energy reserves starts in June, not towards the end of the growing season as has been suggested previously. This resource allocation strategy of Phragmites has consequences for vegetation management.Our data indicate that carbohydrate reserves are much larger than needed to support spring growth. We propose that large stores are needed to ensure establishment of spring shoots when deep water or stochastic environmental events, such as high rhizome mortality in winter or loss of spring shoots due to late season frost, increase the demand for reserves.     

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.     

Noninvasive semen collection from an adult orangutan

Preservation of the genetic diversity of the captive orangutan, especially the wild-caught founders, is critical in maintaining a long-term population in zoological parks. One solution to the problem of maintaining maximum genetic diversity would be to initiate a program of artificial insemination for genetically underrepresented individuals through the banking and interinstitutional use of cryopreserved semen. However, little is known about basic orangutan semen characteristics, and current methodology is inadequate to support such a program. In this paper, we report the results of semen collection from an adult Sumatran orangutan (Pongo pygmaeus abelli), using an artificial vagina without anesthesia or electrical stimulation. A total of 27 ejaculates were evaluated during a 1-year period. The total and liquid volumes of the ejaculates at 1 h following collection were 6.1 ± 0.6 ml and 2.6 ± 0.4 ml, respectively (mean ± SEM). The liquid portion continued to exude semen for 2 h; however, 90% of the motile sperm was exuded within the first 30 min. The total number of sperm in the ejaculate was 164 ± 10⁶ ± 16.5, and the percentage of motile cells was 60 ± 2.7%. We conclude that the artificial vagina provides a promising technique for semen collection in the orangutan, and view these results as an initial step in developing methods for in vitro sperm capacitation, sperm cryopreservation, and artificial insemination. © 1993 Wiley-Liss, Inc.     

日本大萝卜引种栽培研究

本文报道日本大萝卜引种栽培的试验结果,并为推广这一蔬菜新品种提供了有效的栽培技术措施。     

Begging, food provisioning, and nestling competition in great tit broods infested with ectoparasites

Ectoparasites are a ubiquitous environmental component of breedingbirds, and it has repeatedly been shown that hematoph-agousectoparasites such as fleas and mites reduce the quality andnumber of offspring of bird hosts, thereby lowering the valueof a current brood. Selection acting on the hosts will favorphysiological and behavioral responses that will reduce theparasites' impact. However, the results of the few bird studiesthat addressed the question of whether parasitism leads to ahigher rate of food provisioning are equivocal, and the beggingresponse to infestation has rarely been quantified. A changein begging activity and parental rate of food provisioning couldbe predicted in either direction: parents could reduce theirinvestment in the brood in order to invest more in future broods,or they could increase their investment in order to compensatefor the parasites' effect on the current brood. Since the nestlingsare weakened by the ectoparasites they may beg less, but onthe other hand they may beg more in order to obtain more food.In this study we show experimentally that (1) hen fleas (Ceratophyllusgallinae) reduce the body mass and size of great tit (Parusmajor) nestlings, (2) nestlings of parasitized broods more thandouble their begging rate, (3) the male parents increase thefrequency of feeding trips by over 50%, (4) the females do notadjust feeding rate to the lowered nutritional state of nestlings,and (5) food competition among siblings of parasitized broodsis increased. Ultimately the difference in the parental feedingresponse may be understood as the result of a sex-related differencein the trade-off of i0vesting in current versus future broods.