Impact of male mating history on the postmating resumption of sexual receptivity and lifetime reproductive success in Choristoneura rosaceana females

Abstract.  The first objective of the present study is to test the hypothesis that the decrease in the number of eupyrene spermatozoa in the spermatheca is directly associated with the resumption of sexual receptivity in female moths, an aspect that has not been examined in previous studies. The obliquebanded leafroller, Choristoneura rosaceana , is used and females mated with previously mated males have a shorter refractory period than those mated with virgins. This difference is associated with a faster rate of movement of sperm from the spermatheca. Overall, the length of the female refractory period coincides with the mean time required for the number of eupyrene sperm in the spermatheca to drop to approximately 3000, regardless of male mating history. Although such a decline in sperm numbers may be a factor responsible for the resumption of sexual receptivity, this is clearly not the only one because more than 40% of females remate even though sperm numbers in the spermatheca are well above this threshold. Virgin males do not vary the mass or the content of their ejaculate as a function of the female's reproductive status and this may increase the risk of sperm competition if the female is previously mated. The second objective of this study is to examine the effect of previous male mating history on female reproductive potential. Females mated with previously mated males have a significantly lower fecundity than those mated with virgin males. However, in all treatments, remating increases both female longevity and lifetime fecundity. There is also a significant effect of female mass on the length of the refractory period and on lifetime fecundity, with large females resuming sexual receptivity sooner and laying more eggs than small ones, regardless of male mating history.     

Tree heterogeneity,resource availability,and larger scale processes regulating arboreal ant species richness

Abstract Processes acting on different spatial and temporal scales may influence local species richness. Ant communities are usually described as interactive and therefore determined by local processes. In this paper we tested two hypotheses linked to the question of why there is local variation in arboreal ant species richness in the Brazilian savanna (‘cerrado’). The hypotheses are: (i) there is a positive relationship between ant species richness and tree species richness, used as a surrogate of heterogeneity; and (ii) there is a positive relationship between ant species richness and tree density, used as a surrogate of resource availability. Arboreal ants were sampled in two cerrado sites in Brazil using baited pitfall traps and manual sampling, in quadrats of 20 m × 50 m. Ant species richness in each quadrat was used as the response variable in regression tests, using tree species richness and tree density as explanatory variables. Ant species richness responded positively to tree species richness and density. Sampling site also influenced ant species richness, and the relationship between tree density and tree species richness was also positive and significant. Tree species richness may have influenced ant species richness through three processes: (i) increasing the variety of resources and allowing the existence of a higher number of specialist species; (ii) increasing the amount of resources to generalist species; and (iii) some other unmeasured factor may have influenced both ant and tree species richness. Tree density may also have influenced ant species richness through three processes: (i) increasing the amount of resources and allowing a higher ant species richness; (ii) changing habitat conditions and dominance hierarchies in ant communities; and (iii) increasing the area and causing a species–area pattern. Processes acting on larger scales, such as disturbance, altitude and evolutionary histories, as well as sampling effect may have caused the difference between sites.     

Life cycle assessment of biofuels from Jatropha curcas in West Africa: a field study

In recent years, liquid biofuels for transport have benefited from significant political support due to their potential role in curbing climate change and reducing our dependence on fossil fuels. They may also participate to rural development by providing new markets for agricultural production. However, the growth of energy crops has raised concerns due to their high consumption of conventional fuels, fertilizers and pesticides, their impacts on ecosystems and their competition for arable land with food crops. Low-input species such as Jatropha curcas , a perennial, inedible crop well adapted to semiarid regions, has received much interest as a new alternative for biofuel production, minimizing adverse effects on the environment and food supply. Here, we used life-cycle assessment to quantify the benefits of J. curcas biofuel production in West Africa in terms of greenhouse gas emissions and fossil energy use, compared with fossil diesel fuel and other biofuels. Biodiesel from J. curcas has a much higher performance than current biofuels, relative to oil-derived diesel fuels. Under West Africa conditions, J. curcas biodiesel allows a 72% saving in greenhouse gas emissions compared with conventional diesel fuel, and its energy yield (the ratio of biodiesel energy output to fossil energy input) is 4.7. J. curcas production studied is eco-compatible for the impacts under consideration and fits into the context of sustainable development.     

Regulation of mRNA Utilization and Degradation by Amino-acid Starvation

Amino-acid starvation of a stringent strain of E. coli relieves the polar effect on distal messenger RNA imposed by a nonsense mutation. There is no relief of polarity starvation of a relaxed strain. In fact, starvation of a relaxed (but not of a stringent) strain by itself causes an artificial polar effect on distal mRNA. These findings are consistent with a mechanism for polarity based on mRNA degradation.     

Responses of Carnation Xylem Parenchyma Contact Cells to Incompatible and Compatible Fungal Vascular Parasites Introduced by Wounding

The evolution of contact cells in the stem xylem of carnationwas investigated after injury, infection with a non-pathogenicparasite (Verticillium dahliae), and infection with a specificpathogen (Phialophora cinerescens). Sampling was carried outfrom 6 h to 18 d at regular intervals and electron microscopefindings were related to a microcomputer search on the data.In controls (c), two types of contact-cells (C₁ and C₂) wereidentified along the vessels according to their ultrastructuralfeatures. All experimental stresses triggered ultrastructuralchanges leading to the appearance of new cell types in differentratios and after various times. The C₃ and C₄ types correspondedwith the initiation of secretory activity. This was found inall cases but more frequently with V. dahliae. The C₅ and C₆types were more or less morbid and were present only after infection.Moreover, C₆ were found with P. cinerescens only. Mitochondrialareas strikingly increased during the experiments but in a differentmode. The results reported here are in agreement with an early,intensive, organized but rapidly stabilized reaction in V. dahliae.Thus an efficient defence system is created. In contrast, adeficient defence was characterized by a delayed, excessiveand disorganized response towards the specific pathogenic agent. Carnation, contact cells, Dianthus caryophyllus L., Phialophora cinerescens (Wr.) van Beyma, vascular parasites, Verticillium dahliae Kleb., xylem     

Molecular and morphological boundaries of the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae)

Neoseiulus californicus (McGregor) is a natural enemy of pest mites used worldwide in many crops. Its correct identification is thus essential to ensure biological control success. The present study aimed to characterize molecular and morphological intraspecific variations for assisting in the diagnosis of the species and to build baseline information about expected variations within a commercially important phytoseiid species. Morphological and molecular [12S rRNA, cytochrome b mitochondrial (mt)DNA, and internal transcribed spacer] analyses were carried out on fourteen populations collected worldwide and on one mass‐reared strain. The genetic distances between the specimens of N. californicus and another related species were high and no overlap was observed, sustaining the reliability of such molecular methods for assisting a specific diagnosis. Furthermore, the genetic distances between populations of N. californicus were very low and overlap between intra‐ and interpopulations distances was observed, except for two populations collected in France (Marsillargues and Midi‐Pyrénées). The high mitochondrial differentiation between these two latter populations and the others questions their specific status: do they belong to the species N. californicus or to another cryptic species? However, using nuclear DNA marker analyses, no distinct differences were observed. Furthermore, even if significant morphological differences were observed between the populations, these differences were very small and the standard errors within each population were very low. We thus concluded that all the populations studied belong to the species N. californicus, despite unexpected high mitochondrial variations. The present study thus displays the importance of an integrative taxonomic approach for avoiding misidentifications. A discussion on morphological and mtDNA variations in relation to diagnostic reliability is developped. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 393–406.     

Development and characterization of microsatellite markers in Tectona grandis (Linn. f)

Teak (Tectona grandis Linn. f) is a hardwood species of worldwide reputation. It occurs naturally in India, Thailand, Myanmar and Laos. Fifteen highly polymorphic microsatellite loci were developed from a genomic library enriched for AG/TC repeats. Primers to amplify these loci were tested on 265 individual trees from different teak populations. An average of 14.7 alleles per locus were detected and expected heterozygosity ranged from 0.223 to 0.879. These loci constitute a powerful tool in investigating the mating system, gene flow, parentage analysis and population dynamics for use in sustainable management of teak forests and for in situ conservation purposes.     

DNA hybridizations on squash-blotted sandflies to identify both Phlebotomus papatasi and infecting Leishmania major

Epidemiological field studies on leishmaniasis have been hampered by the laborious, and often inefficient, methods used to assess the rates of infection of sandfly vectors (Diptera; Phlebotominae) by species of the causative disease organisms, protozoal parasites of the genus Leishmania (Kinetoplastida; Trypanosomatidae). We report the rapid and accurate identification of both sandfly vector (Phlebotomus (Phlebotomus) papatasi (Scopoli] and infecting Leishmania major Yakimov & Schokov by DNA hybridizations to squash-blotted sandflies. Large numbers of whole (infected) sandflies can be quickly squashed on to nylon hybridization filters and (following standard procedures) the filter-bound DNA can be hybridized sequentially to cloned, multicopy genomic sequences that are specific for species of Leishmania (kinetoplast DNA) or for the sandfly (ribosomal (r) DNA). Our sandfly probe consists of a 3.2 kb fragment of the intergenic 'non-transcribed' spacer of rDNA of P. papatasi that we have detected only in this species: it is present in all six geographically isolated populations tested (from Tunisia through to India) but cannot be detected in the morphologically similar P. (Phlebotomus) duboscqi Neveu-Lemaire, the vector of Leishmania major south of the Sahara; it also cannot be detected in Phlebotomus species of the subgenera Larroussius and Paraphlebotomus that together with P. papatasi are the dominant man-biting sandflies in north African foci of zoonotic cutaneous leishmaniasis, where (as in many arid regions of western Asia) P. papatasi is believed to be the sole vector of L. major.