Occurrence and performance of the aspen blotch miner,Phyllonorycter salicifoliella,on three host-tree species

Summary Larvae of the aspen blotch miner, Phyllonorycter salicifoliella Chambers (Lepidoptera: Gracillariidae), feed within leaves of three host-tree species in north-central Minnesota, USA. Far more individuals occur on Populus tremuloides than on P. balsamifera or P. grandidentata. We tested whether this pattern of host use reflected variable performance among alternative hosts by examining survivorship, sources of mortality, pupal mass, feeding efficiency, and development time of miners on each tree species. We also determined foliar water, nitrogen, condensed tannin, and phenolic glycoside content of host trees to test if host-tree chemical attributes were responsible for differences in performance. There was no significant difference in egg-to-adult survival among miners on different hosts, although dominant sources of mortality did vary. Miners on P. grandidentata suffered less parasitism and more predation than those on the other hosts, even though most parasitoid species attacked miners on all hosts. The other performance parameters varied among host species, but not in a consistent pattern. Pupal mass was greatest on P. tremuloides and P. balsamifera, the hosts with comparatively high foliar nitrogen and low phenolic glycoside concentrations. However, feeding efficiency was greatest and development time shortest for miners on P. grandidentata. Thus, pupal mass was the only index of performance maximized on P. tremuloides, the most commonly used host. Infrequent occurrence of Phyllonorycter salicifoliella on P. grandidentata results in part from phenological differences between this and the other host species. Low oviposition rates on P. balsamifera are correlated with low abundance of this host at the study site and a phenolic glycoside profile different from that of the other host species.     

Leaf production,reproductive patterns,field germination and seedling survival in Chamaedorea bartlingiana,a dioecious understory palm

Summary Chamaedorea bartlingiana is a dioecious palm that grows in the cloud forest understories of the Venezuelan Andes. Age and sexual differences in phenology and reproductive patterns were studied in labelled individuals of all age categories. This species has long-lived leaves and low leaf production, both characteristic of understory plants. Growth rates are lower in juveniles than in adults and in females than in males, as in other palms. Male and female individuals show different reproductive patterns. Male inflorescences are always produced at the same rate and the probability of surviving until anthesis is constant. Females produce reproductive buds at the same rate as males, but these buds have a 35% probability of becoming a ripe infrutescence if the plant has infrutescences already growing, and 70% if it does not. This pattern and the slow growth of inflorescences (1 year for males from bud to flowers, 2 years for females from bud to ripe fruits) cause a pluriannual reproductive pattern at the population level. Field germination does not follow this pattern, but shows one annual peak probably related to environmental conditions.     

Phenotypic variation in the breeding phenology of the woodlouse Armadillidium vulgare

Summary The breeding phenology of temperate wood-lice is strongly seasonal, the result of physiological constraints and precise environmental cues for reproduction. The adaptive value of such mechanisms is that the release of offspring coincides with favourable conditions for growth and survival (Willows 1984). We recorded the breeding phenology of Armadillidium vulgare (Latreille) on two grassland sites in Great Britain and found between-site and between-year variation in the onset of reproduction, the duration of reproductive activity, the release of offspring, the size of reproductive females and the number of broods per female. Between 82.7 and 97.7% of gravid females sampled were semelparous at 23 months, with the remainder iteroparous, producing a second brood after 35 months. On one site (Weeting Health) improved growth conditions during 1984 allowed some females (19.3% of gravid females sampled in that year) to produce a brood after 11 months. There was also an increase in the number of 3-year-old females found to be gravid. An experimental manipulation of the same habitat confirmed that such changes in life history tactics could be phenotypic responses. The observed phenotypic variation was sufficient to produce a range of life history tactics within a population. Mixtures of life history tactics within a population may be typical of invasive species and populations at the edge of the species range. Our results support the idea that phenotypic plasticity can be an appropriate tactic to maximise fitness in a fluctuating environment (Caswell 1983, 1989).     

Arguments for the use of physiological criteria for improving the salt tolerance in crops

Efforts to develop new crop varieties with improved salt tolerance have been intensified over the past 15–20 years. Despite the existence of genetic variation for salt tolerance within species, and many methods available for expanding the source of genetic variation, there is only a limited number of varieties that have been developed with improved tolerance. These new varieties have all been based upon selection for agronomic characters such as yield or survival in saline conditions. That is, based upon characters that integrate the various physiological mechanisms responsible for tolerance. Yet over the same time period, knowledge of physiological salt responses has increased substantially.Selection and breeding to increase salt tolerance might be more successful if selection is based directly on the physiological mechanisms or characters conferring tolerance. Basic questions associated with using physiological selection criteria are discussed in the paper. These are centred around the need for genetic variation, the importance of the targeted mechanism, the ease of detection of the physiological mechanism (including the analytical requirements) and the breeding strategy. Many mechanisms, including ion exclusion, ion accumulation, compatible solute production and osmotic adjustment have been associated with genetic variation in salt tolerance. Yet their successful use in improving salt tolerance, via physiological selection criteria, is largely non-existent. Consideration is given to the role of physiological criteria in the short and long term in improving salt tolerance. In several glycophytic species, particularly legumes, physiological selection based on ion exclusion from the shoots shows promise. Recent results for white clover indicate the potential for using a broad physiological selection criterion of restricted Cl accumulation in the shoots, with scope for future refinement based upon the specific physiological characters that combined result in ion exclusion.     

Root biomass fraction as a function of growth degree days in wheat

Root, underground and above-ground biomass were measured on various wheat cultivars from 1986 to 1988 in the south-east of France. The results are expressed as root: total (f _r) or underground: total (f _u) biomass fractions. Observed f _r and f _u values are in good agreement with previous results. f _r and f _u decrease steadily from emergence to maturity, with an exponential tendency. When using cumulative growth degree days since emergence relative to cumulative growth degree days until ear emergence () as time scale, f _r and f _u can be expressed as simple functions of % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGceaqabeaacaWGMb% addaWgaaqaaiaadkhaaeqaamaabmaabaGccqaH4oqCdaahaaWcbeqa% aiaacQcaaaaamiaawIcacaGLPaaakiabg2da9iaaicdacaGGUaGaaG% imaiaaiwdacqGHRaWkcaaIWaGaaiOlaiaaiwdacaaI4aGaamyzamaa% CaaaleqabaGaeyOeI0IaaGymaiaac6cacaaI0aGaaGioaiabeI7aXn% aaCaaameqabaGaaiOkaaaaaaaakeaacaWGMbaddaWgaaqaaiaadwha% aeqaamaabmaabaGccqaH4oqCdaahaaWcbeqaaiaacQcaaaaamiaawI% cacaGLPaaakiabg2da9iaaicdacaGGUaGaaGymaiaaikdacqGHRaWk% caaIWaGaaiOlaiaaiIdacaaI4aGaamyzamaaCaaaleqabaGaeyOeI0% IaaGOmaiaac6cacaaIYaGaaGioaiabeI7aXnaaCaaameqabaGaaiOk% aaaaaaaaaaa!610D!\[\begin{gathered} f_r \left( {\theta ^* } \right) = 0.05 + 0.58e^{ - 1.48\theta ^* } \hfill \\ f_u \left( {\theta ^* } \right) = 0.12 + 0.88e^{ - 2.28\theta ^* } \hfill \\ \end{gathered} \]The incremental root biomass partitioning coefficient, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqySde2aaS% baaSqaaiaadkhaaeqaaOGaeyypa0JaaiikaiaadsgacaWGxbWaaSba% aSqaaiaadkhaaeqaaOGaai4laiaadsgacaWG0bGaaiykaiaac+caca% GGOaGaamizaiaadEfadaWgaaWcbaGaamiDaaqabaGccaGGVaGaamiz% aiaadshacaGGPaaaaa!4834!\[\alpha _r = (dW_r /dt)/(dW_t /dt)\], which describes the net increase in root biomass dW _r over time dt relative to the increase in total biomass (dW _r) over the same time period, has been derived from f and the relative growth rate. Its time course is accurately represented by% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqySdegdda% WgaaqaaiaadkhaaeqaamaabmaabaGccqaH4oqCdaahaaWcbeqaaiaa% cQcaaaaamiaawIcacaGLPaaakiabg2da9iabgkHiTiaaicdacaGGUa% GaaGymaiaaiwdacqGHRaWkcaaIWaGaaiOlaiaaiAdacaaIZaGaamyz% amaaCaaaleqabaGaeyOeI0IaaGimaiaac6cacaaI5aGaaGioaiabeI% 7aXnaaCaaameqabaGaaiOkaaaaaaaaaa!4D15!\[\alpha _r \left( {\theta ^* } \right) = - 0.15 + 0.63e^{ - 0.98\theta ^* } \]Under our experimental conditions, with no severe water stresses or nutrient deficiencies, and for our sampling frequency, around 2 weeks, the development scale , is the main factor governing the time courses of f _r, f _u and _r.     

Herbicide-resistant Indica rice plants from IRRI breeding line IR72 after PEG-mediated transformation of protoplasts

The commercially important Indica rice cultivar Oryza sativa cv. IR72 has been transformed using direct gene transfer to protoplasts. PEG-mediated transformation was done with two plasmid constructs containing either a CaMV 35S promoter/HPH chimaeric gene conferring resistance to hygromycin (Hg) or a CaMV 35S promoter/BAR chimaeric gene conferring resistance to a commercial herbicide (Basta) containing phosphinothricin (PPT). We have obtained so far 92 Hg^r and 170 PPT^r IR72 plants from protoplasts through selection. 31 Hg^r and 70 PPT^r plants are being grown in the greenhouse to maturity. Data from Southern analysis and enzyme assays proved that the transgene was stably integrated into the host genome and expressed. Transgenic plants showed complete resistance to high doses of the commercial formulations of PPT.     

The assessment of two barley starch mutants as potential parents in a malting quality breeding programme

Grain and malt quality parameters were assessed in the barley starch mutants Waxy Hector, characterised by high levels of amylopectin, and Chalky Glenn, which has lines of cleavage across the large starch granules. Results were compared with those of their parental cultivars and suggested differences in the contribution of endosperm cell walls to milling energy. Although hot water extracts were not improved, other components, especially those associated with the fractured starch mutant, could be used in breeding programmes to improve aspects of quality, if they could be disassociated from deleterious effects of the starch mutation, e.g. poor grain filling.     

What are the consequences of being a downy oak (quercus pubescens) or a holm oak (Q. ilex) for breeding blue tits (Parus caeruleus)?

By comparison with deciduous oaks, the lower yearly production of new leaves in sclerophyllous oaks is hypothesized to have several consequences on animal communities. In particular, the production of arthropod communities that feed upon the leaves should be lower in sclerophyllous than in deciduous oaks, this causing changes in breeding patterns and the demographic balance in insectivorous birds. Studies in both deciduous and sclerophyllous habitats in southern France have shown that: 1) the spring development of new leaves occurs later and more slowly in sclerophyllous than in deciduous oaks, 2) the biomass of caterpillars is much lower in sclerophyllous oak forests, and 3) there is a large variation in life history traits of the Blue Tit depending in which type of habitat they breed. Laying date occurs later and clutch size is lower in sclerophyllous habitats than in deciduous habitats. The evolution of life history traits is discussed according to whether poor sclerophyllous habitats are isolated (e.g. on Corsica) or are parts of landscapes including both habitat types.     

The phenology ofProcladius crassinervis (Zett),Procladius signatus (Zett) andProcladius choreus (Mg) (Diptera,Chironomidae) at Lake Hald,Denmark

In an investigation of the phenology of the chironomid species of Lake Hald, Denmark, a very late flight activity (September–November) of the univoltine speciesProcladius choreus (Mg.) was observed. Among observations of the phenological patterns of univoltine chironomids inhabiting lakes of the Baltic type in Denmark, the phenological pattern ofProcladius choreus stands alone (JÓNSSON, 1987; LARSEN, 1991). Further two species of the genusProcladius Skuse,viz. Procladius crassinervis (Zett) andProcladius signatus (Zett), were found in the investigation and the phenological pattern of the three congeneric species was clearly allochronic, withProcladius crassinervis flying in spring,Procladius signatus flying in summer andProcladius choreus flying in autumn.     

Ecological aspects of Sargassum muticum (Fucales,Phaeophyta) in Baja California,Mexico: reproductive phenology and epiphytes

The reproductive phenology and epiphytic macroalgae of Sargassum muticum were studied through an annual cycle (September 1987 to November 1988) at two sites on the northwestern coast of Baja California, Mexico, which were subjected to different degrees of wave exposure. Sargassum muticum is a brown alga of Japanese origin, now considered a permanent member of the marine flora of Baja California. A similar reproductive development was observed at both sites, with a maximum percentage of reproductive plants from May to July (spring–summer) and minimum from December to March (winter). Reproductive plants were found throughout the year. A total of 48 species of epiphytes were identified and seasonal variation in their diversity was observed. The greatest diversity was found at the more protected site.