1,721,082 research outputs found
Repellence and attractiveness: the double effect of essential oils on insect pests
Full text linkThe long-term use of synthetic insecticides has led to negative side effects on human health, environmental pollution, and to the development of resistance in treated pests. As an alternative, essential oils (EOs), complex mixtures of volatile compounds extracted from aromatic plants, have been largely investigated. EOs have a wide range of biological activities and are used for the protection of human, food, and crops from the attack of insects. Their activities against insect have been mainly reported as insecticide, antifeedant, or repellent. In particular, in the last 30 years, a large number of reports showed the repellent effect of the EOs extracted from plants of all continents and against most of the main insect pests. Nevertheless, on the contrary, there are also some reports that indicate the EOs can act as attractants to different insect species.
In this work, we assessed the attractiveness or repellence of EOs in relation to the EOs composition and dose, and to the insect species.
The results indicated that most of the EOs tested can exert both attractive and repellent activity depending on the dose. Since EOs contain volatile substances whose concentration varies in time after the application, the implication of these results will be discussed in relation to their possible use as insect repellents or as lures for trapping
Special Issue: Natural Substances against Insect Pests: Assets and Liabilities
No full textManyinsect pests directly compete with humans for food, damaging several crops
in the field and during the processing and storage. Every year, about 20% of the global
production of agricultural goods is lost due to more than 20,000 species of harmful in
sects. Moreover, some parasites can act as vectors of viruses and microorganisms, both
pathogenic to humans and other vertebrates. The control of those species is, therefore,
a crucial focus for the medical, veterinary, and agro-food chain operators. Scientific evi
dence revealed that the massive and continuous use of synthetic pesticides results in an
accumulation of residues in the environment (causing air, soil, and water pollution), and
have neurotoxic, carcinogenic, teratogenic, and mutagenic effects on human and non-target
animals. Furthermore, the insurgence of resistance to the more commonly used chemicals
in repeatedly treated pests is thoroughly stated in a multitude of scientific publications.
Despite all the drawbacks reported, insect pest control still mainly relies on synthetic
insecticides. Since the 1980s, research on natural products, also known as biopesticides, has
highlighted their numerous helpful effects against insect pests. To fully understand and
exploit the potential of natural substances, though, more improvement in the knowledge
of their vast and various bioactivities is essential. Biopesticides comprise a broad group of
different materials, which includes botanical products (e.g., volatile and fixed oils, vegetal
extracts, hydrolates), inert dust (e.g., diatomaceous earth, granite dust, kaolin), as well
as microorganisms (entomopathogenic bacteria, fungi). Because of their natural origin,
biopesticides are supposed to have fewer side effects than synthetic pesticides, although
they are not free from intrinsic limits. This “Natural Substances against Insect Pests: Assets
and Liabilities” Special Issue (SI) addresses current basic and applied research on the
isolation, chemical characterization, biochemistry, bioactivity, mode of action, benefits, and
risks related to the use of natural substances as insecticides
Insect Special Issue "Natural Substances against Insect Pests: Assets and Liabilities"
No full textAt present, insect pests are largely controlled by synthetic pesticides. Although these are effective, their wide and heavy use has caused the rise of pest-resistant strains and negative effects on human health and on the environment, and their public acceptance is currently low. Since the Middle Ages, natural compounds have been employed for bactericidal, virucidal, fungicidal, parasiticidal and insecticidal applications. After a period of synthetic insecticides’ dominancy, in the last two decades, renewed efforts have been made to investigate the bioactivity of new natural substances (NSs) against a wide range of insect pests and parasites. Many NSs have been recognised as excellent adulticidal, larvicidal, ovicidal, growth and/or reproduction inhibitors, repellents and oviposition deterrents. However, even if they still represent one of the most promising possibilities to explore new eco-friendly solutions against insect pests, some liabilities affect their use. In fact, their use has to face issues around production, formulation, stability and costs. Moreover, how they act in many cases needs to be elucidated, because many of them show the same mode of action as many neurotoxic insecticides, and consequently, attention need also be focused on induced resistance.
Based on the above, we would like to pursue these subjects through a Special Issue of the Insects journal under the title: “Natural Substances against Insect Pests: Assets and Liabilities”. In this regard, papers on the following indicative topics are more than welcome:
NSs isolation, chemical characterization and biochemistry;
NSs as insecticides, growth and/or reproduction inhibitors, repellents, oviposition deterrents, and attractives against harmful Insects;
NSs’ mode of action and induced resistance in insects;
Risks and benefits associated with the use of NSs;
Reviews, regulatory and legislation issues related to the use of NSs
Endemic Andean plants against food-stuff insect pest
No full textTropical Andes, because of the exceptional number of endemic plants, have been classified as a hyper-hot spot for biodiversity and they represent an extraordinary source of yet undiscovered bioactive compounds. In fact, many of these plants are used in the local traditional medicine by the population, as well as to control fastidious insects. The properties of many of these plants, as well as their smell, are due to their essential oils, volatile substances produced either as a protection against phytophagous insects and to attract pollinators. Several studies have reported the toxicity and repellent activity of Andean plants essential oils against insects. However, to our knowledge, no information is available about their attractiveness.
In this work, we analyzed the chemical composition and assessed the repellency and attractiveness of the essential oils of the Andean endemic plants Aloysia citrodora (Verbenaceae), Bursera graveolens (Bursedraceae), and Buddleja globosa (Scrophulariaceae) against the main food-stuff insect pests Rhizopertha dominica (Coleoptera: Bostrichidae) and Tribolium confusum (Coleoptera: Tenebrionidae) by area preference tests.
The results showed that the tested essential oils have high repellency rates at high concentrations whilst, on the contrary, they are attractive to the insects at the lowest concentrations. Such results, beside confirming that tropical Andes plants are a valuable unexploited source of bioactive substances, indicate that the use of essential oils as repellent for the protection of the food should be evaluated carefully, also taking into account that both i) concentration changes in time due to their volatility and ii) their compositional variation due to volatilization can cause dramatic changes of bioactivity of the essential oils against insect pests
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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