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10-Methyldodecanal, a Novel Attractant Pheromone Produced by Males of the South American Cerambycid Beetle Eburodacrys vittata.
Full text linkWe report the identification, synthesis, and field bioassay of a novel attractant pheromone produced by males of Eburodacrys vittata (Blanchard), a South American cerambycid beetle in the subfamily Cerambycinae. Headspace volatiles from males contained a sex-specific compound, identified as 10-methyldodecanal. In a field bioassay conducted in Brazil, significant numbers of males and females were caught in traps baited with synthesized racemic 10-methyldodecanal, consistent with the aggregation-sex pheromones produced by males of many cerambycine species. This compound represents a new structural class of cerambycid pheromones, and it is the first pheromone identified for a species in the tribe Eburiini
(R)-Desmolactone is a sex pheromone or sex attractant for the endangered valley elderberry longhorn beetle Desmocerus californicus dimorphus and several congeners (Cerambycidae: Lepturinae).
Full text linkWe report here that (4R,9Z)-hexadec-9-en-4-olide [(R)-desmolactone] is a sex attractant or sex pheromone for multiple species and subspecies in the cerambycid genus Desmocerus. This compound was previously identified as a female-produced sex attractant pheromone of Desmocerus californicus californicus. Headspace volatiles from female Desmocerus aureipennis aureipennis contained (R)-desmolactone, and the antennae of adult males of two species responded strongly to synthetic (R)-desmolactone in coupled gas chromatography-electroantennogram analyses. In field bioassays in California, Oregon, and British Columbia, traps baited with synthetic (R)-desmolactone captured males of several Desmocerus species and subspecies. Only male beetles were captured, indicating that this compound acts as a sex-specific attractant, rather than as a signal for aggregation. In targeted field bioassays, males of the US federally threatened subspecies Desmocerus californicus dimorphus responded to the synthetic attractant in a dose dependent manner. Our results represent the first example of a "generic" sex pheromone used by multiple species in the subfamily Lepturinae, and demonstrate that pheromone-baited traps may be a sensitive and efficient method of monitoring the threatened species Desmocerus californicus dimorphus, commonly known as the valley elderberry longhorn beetle
Traits underlying community consequences of plant intra-specific diversity.
Full text linkA plant's performance and interactions with other trophic levels are recorgnized to be contingent upon plant diversity and underlying associational dynamics, but far less is known about the plant traits driving such phenomena. We manipulated diversity in plant traits using pairs of plant and a substitutive design to elucidate the mechanisms underlying diversity effects operating at a fine spatial scale. Specifically, we measured the effects of diversity in sex (sexual monocultures vs. male and female genotypes together) and growth rate (growth rate monocultures vs. fast- and slow-growing genotypes together) on growth of the shrub Baccharis salicifolia and on above- and belowground consumers associated with this plant. We compared effects on associate abundance (# associates per plant) vs. density (# associates per kg plant biomass) to elucidate the mechanisms underlying diversity effects; effects on abundance but not density suggest diversity effects are mediated by resource abundance (i.e. plant biomass) alone, whereas effects on density suggest diversity effects are mediated by plant-based heterogeneity or quality. Sexual diversity increased root growth but reduced the density (but not abundance) of the dietary generalist aphid Aphis gossypii and its associated aphid-tending ants, suggesting sex mixtures were of lower quality to this herbivore (e.g. via reduced plant quality), and that this effect indirectly influenced ants. Sexual diversity had no effect on the abundance or density of parasitoids attacking A. gossypii, the dietary specialist aphid Uroleucon macolai, or mycorrhizae. In contrast, growth rate diversity did not influence plant growth or any associates except for the dietary specialist aphid U. macolai, which increased in both abundance and density at high diversity, suggesting growth rate mixtures were of higher quality to this herbivore. These results highlight that plant associational and diversity effects on consumers are contingent upon the source of plant trait variation, and that the nature of such dynamics may vary both within and among trophic levels
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Improvement of biological control agents : laboratory selection for fast larval development in the convergent lady beetle, Hippodamia convergens guerin-Méneville (Coleoptera: Coccinellidae)
Full text linkHippodamia convergens Guerin-Meneville was selected for
rapid development through five generations at four constant
temperatures (18, 22, 26, and 30°C). Two levels of selection
were used: intense and moderate. Differences in developmental
rate, survivorship, live adult weight, aphid consumption,
adult longevity, and fecundity were measured for both groups
and an unselected line.
The two selected lines exhibited significant differences
in developmental rate after the first generation of selection.
The differences increased by the fifth generation of
selection. Average differences between selected lines at 18,
22, 26, and 30°C in development from egg to adult were 4.9,
3.0, 1.0, and 1.5 days, respectively. Individuals from the
intense selected line had a lower developmental threshold
(11.3°C) than the moderate selected line (12.0°C). Also,
degree-day requirements from egg to adult were lower in the
intense (266 DD°) than moderate (277 DD°) line. Wild type
beetles accumulated 231 degree-days above a threshold of
13.6°C.
Survivorship at cold temperatures significantly increased
with selection for fast development. In addition, no
significant differences occurred in either live adult weight,
total larval consumption of prey, fecundity, or adult
longevity. Larvae selected for fast growth consumed higher
numbers of aphids per day and were more efficient
metabolically in converting prey mass into body mass than slow
growing larvae.
Because of a lower developmental threshold and lower
degree-day requirements, for complete development, beetles
from the intense selected line may accumulate more degree-days
throughout a year compared to a moderate selected line.
Predictions of population growth, based on an equation for
intrinsic growth rate, showed that beetles from the intense
selected line would produce 1.6 and 1.4 times more individuals
in a 60-day period than beetles from the moderate selected and
unselected lines, respectively. The results suggest that
intense selected beetles would develop faster earlier in the
season and would produce higher population numbers under
optimum conditions. Thus, selection of H. convergens produced
superior beetles for future introductions in biological
control
Plant mediated interactions between herbivores from different feeding guilds (Myzus persicae and Leptinotarsa decemlineata) on potato (Solanum tuberosum
Full text linkHerbivory induces defense responses in plants that alter plant traits, affecting insect fitness and behavior. Herbivores that share a host-plant can interact indirectly even if spatially or temporally distant. Jasmonic (JA) and salicylic (SA) acid play a central role in regulating plant defenses. Induction of these pathways is closely associated with the feeding guild of the herbivore. This study investigated how the co-occurrence of herbivores from different feeding guilds, Myzus persicae (Sulzer) and Leptinotarsa decemlineata (Say), could lead to differential responses in plant phytochemistry and herbivore performance and host-plant preference when feeding on potato, Solanum tuberosum L. In laboratory bioassays M. persicae performed better when feeding alone, but the presence of M. persicae did not impact L. decemlineata performance. Interestingly, when given a choice, M. persicae preferred host-plants that were damaged by L. decemlineata, while L. decemlineata preferred undamaged plants. A field study was conducted to evaluate the consequences of induced defenses due to multi-herbivory on tuber yield and whether laboratory performance results were consistent in an agricultural setting. Compared to laboratory bioassays, herbivore interactions were diminished in the field with no observed effect on yield. Differences in volatile emissions, glycoalkaloid, and JA/SA content are also discussed for each trial. Further studies investigating the qualitative and quantitative strength of feeding guild-plant interactions could provide a more thorough understanding of resistant traits and improve pest management products and practices.Thesis (M.S.)--Michigan State University. Entomology, 2016Includes bibliographical references (pages 77-88
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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