1,721,075 research outputs found
Bactrocera oleae-induced olive VOCs routing mate searching in Psyttalia concolor males: Impact of associative learning
No full textOlfaction is a key sense routing foraging behaviour in parasitoids. Preferences for food, mate and host stimuli can be innate in parasitic wasps. Alternatively, learning-mediated mechanisms play a crucial role. Females of the braconid parasitoid Psyttalia concolor exploit olfactory cues arising from tephritid hosts and related microhabitats. However, little is known on the olfactory stimuli routing males searching for mates. In this study, we focused on the attractiveness of Bactrocera oleae-induced olive volatiles towards P. concolor males. Furthermore, we evaluated learning occurrence in virgin males, when trained for selected unattractive volatile organic compounds (VOCs) associated with mate rewards. (E)-β-Ocimene, α-pinene and limonene attracted virgin males in Y-tube bioassays. Unattractive VOCs evoked positive chemotaxis after associative learning training. P. concolor males exposed to VOCs during a successful or unsuccessful mating, showed short-term preference for these VOCs (<1 h). However, memory consolidation was strictly dependent on reward value. Indeed, males experiencing a successful mating showed a fast consolidation into protein dependent long-term memory, appearing after 24 h. On the other hand, males experiencing a less valuable training experience (i.e. unsuccessful courtship), did not show consolidated memory after 24 h. Overall, our findings suggest that P. concolor virgin males may exploit VOCs from the host microhabitat to boost their mate searching activity, thus their reproductive success. However, since learning is a costly process, P. concolor males retained durable memories just in presence of a valuable reward, thus avoiding maladaptive behaviours
Domenico Maffei, Il giovane Machiavelle banchiere con Berto Berli a Roma. Firenze, Giunti G. Barbera.
No full textGiordanengo Gérard. Domenico Maffei, Il giovane Machiavelle banchiere con Berto Berli a Roma. Firenze, Giunti G. Barbera.. In: Bibliothèque de l'école des chartes. 1974, tome 132, livraison 2. pp. 377-378
Sexual communication in Tephritidae: a focus on species infesting soft fruits
No full textTephritidae, also known as the true fruit flies, comprise a huge number of key agricultural pests, causing both quantitative and qualitative crop losses. Investigating mating sequences of these flies could help to unveil mate choice dynamics, adding information to improve behaviour-based control tools. Here we critically review knowledge about sexual communication and related behaviours in Tephritidae, with a special focus on agricultural pests of soft fruits. We examine features and the role of male-male combat in lek sites, cues affecting mating dynamics, and some fitness-promoting female behaviours [mainly female-female aggressive interactions on fruits and oviposition marking pheromones (OMPs)] that occur at oviposition sites. We outline future perspectives arising from knowledge about sexual communication for Integrated Pest Management programs for Tephritidae pests infesting soft fruits. Sexually selected traits are frequently good indicators of male fitness and knowledge of sexual selection processes may contribute to the improvement of Sterile Insect Technique (SIT) programs. Furthermore, males’ exposure to parapheromones can enhance the mating success of sterile flies used in SIT programs. Lastly, the development of IPM strategies based on OMP application could help to improve eco-friendly control approaches against Tephritidae infesting soft fruits
Advanced theory of mind uniquely contributes to children's multiple-text comprehension
No full textThis study examined the contribution of advanced theory of mind (AToM), operationalized as second- or higher-order recursive mentalistic reasoning, to multiple-text comprehension in fourth and fifth graders (N = 184). The role of AToM was analyzed by taking into account children's individual characteristics (i.e., age, gender, prior topic knowledge, word reading fluency, vocabulary knowledge, and single-text comprehension) and task features (i.e., contrast between positions on the topic of two sets of texts). Mixed models analysis revealed that AToM uniquely contributed to comprehension of multiple texts over and above the individual and task variables. In addition, the contribution of AToM to the comprehension of multiple texts did not significantly differ for the two tasks despite differences in contrast between positions on the topic. Results indicate that children's ability to consider different perspectives and mental states is a relevant unique predictor of multiple-text comprehension. (C) 2019 Elsevier Inc. All rights reserved
Essential oil-based nano-emulsions: Effect of different surfactants, sonication and plant species on physicochemical characteristics
No full textEssential oils (EOs) are promising active ingredients for biopesticides, although their use under field conditions is limited by several criticisms concerning their high volatility and degradability. To overcome these negative qualities, EOs can be encapsulated inside nanostructures (i.e. nanoparticles and nano-emulsions), which can guarantee the preservation of the insecticidal properties. In the current study, oil in water (O/W) nano-emulsions of seven commercial EOs (15 % w/w of anise, artemisia, fennel, lavender, peppermint, rosemary, sage) were developed using different non-ionic surfactants and formulation processes, to identify the best possible surfactant/process to produce stable nano-formulations. The EOs were firstly examined by gas-chromatography analyses to identify their chemical constituents. Sage, rosemary, peppermint, lavender and artemisia EOs were characterized by high percentage (up to 50 % of the detected compounds) of oxygenated monoterpenes, while fennel and anise EOs were mainly constituted by phenylpropenes (e.g. anethol). Then, nano-emulsions were developed via the self-emulsifying process alone or in combination with sonication, using four surfactants with different Hydrophilic Lipophilic Balance (HLB) index (5 % w/w of Tween 20, Tween 80, Span 20 or Span 80). The physical characteristics (droplet size and surface charge) of nano-emulsions were analyzed using the dynamic light-scattering technique. Sonicated nano-formulations presented smaller and more homogeneous size of the micelles than the non-sonicated ones, resulting in more stable nano-emulsions. Furthermore, usually emulsions produced using Tween 80 as surfactant gave the best results in terms of droplet size and polydispersity index (PDI) values. Therefore, Tween 80 sonicated nano-emulsions were examined during a storage period of 28 weeks to determine their stability over time and possible alteration of their physical characteristics. Results suggest that these nano-formulations had a good stability over time, since relatively small increases in PDI and size values were recorded. Formulation stability is a key issue to consider when proposing botanical biopesticides for agricultural applications. Our study reports the first step in the introduction of EO-based nano-emulsions into practical application
VOC emissions influence intra- and interspecific interactions among stored-product Coleoptera in paddy rice
No full textChemical properties and efficacy of Sweet orange essential oil nanoemulsion applied as cold aerosol against two stored product beetles
No full textCommon control strategies to manage stored product pests are mainly based on the use of synthetic insecticides and fumigants. Consumer’s demand for pesticide-free food, and the increasing resistance of pests to traditional insecticides, dictate the need to evaluate alternative control methods. For this purpose, many sustainable techniques have been tested for the control of stored product pests. Among them, Citrus essential oils can represent a valid alternative to synthetic insecticides. The effects of Sweet Orange essential oil (EO) nanoemulsion applied as cold aerosol were evaluated against adults of Tribolium confusum du Val (Coleoptera: Tenebrionidae) and Cryptolestes ferrugineus Stephens (Coleoptera: Cucujidae). Both chemical and physical characterization of the EO-based formulation was carried out. The developed formulation had an average size belonging to the nanometer scale and a low polydispersity index. The relatively high zeta potential value confirms the stability over time of the developed formulation. The efficacy of the tested formulation showed a dose-dependent response and the cumulated mortality of the exposed insects increaseduntil 24h of exposure for C. ferrugineus and until 120h for T. confusum. The tested formulation was more effective against T. confusum adults (LD50= 86.30 ppm) than C. ferrugineus ones (LD50= 36.79 ppm). The results of this study coupled with the large availability at reasonable costs of Sweet orange EO, are promising for the potential development of new tools against stored product pests
Essential Oils in Stored Product Insect Pest Control
No full textAmong botanical extracts used as insecticides, essential oils (EOs) are promising alternatives to chemical insecticides. EOs are synthesized by plants, and they play a key role in plant signaling processes including also attractiveness toward pollinators and beneficial insects. Plant species producing essential oils (over 17,000 species) are called aromatic plants and are distributed worldwide. Our review aims to evaluate research studies published in the last 15 years concerning the use of EOs in stored product protection. More than 50% of the retrieved manuscripts have been published by authors from Eastern countries (Iran, China, India, and Pakistan), investigating different aspects related to insect pest management (exposure route, effect on the target pest, and mode of action). Coleoptera was the most studied insect order (85.41%) followed by Lepidoptera (11.49%), whereas few studies targeted new emerging pests (e.g., Psocoptera). Almost all the trials were carried out under laboratory conditions, while no experiments were conducted under real operating conditions. Future research studies concerning the use of EOs as insecticides should focus on the development of insecticide formulations which could be successfully applied to different production realities
Volatile infochemicals from Rhyzopertha dominica larvae and larval feces involved in Theocolax elegans host habitat location
No full textThe development of biologically based approaches for stored product pest control is needed to reduce chemical inputs. Bioassays were performed to investigate host habitat location in the trophic interaction durum wheat/Rhyzopertha dominica/Theocolax elegans. GC-MS analyses were carried out to identify some chemical compounds produced by the host-related substrates. Choice and no-choice experiments demonstrated that female parasitoids were poorly attracted to intact kernels with respect to the infested substrates. Furthermore, T. elegans females performed longer residence time on infested wheat, and they generally displayed a short-term like fidelity for this cue, remaining on it during the whole observation. Infested wheat emitted one chemical (fenchone), which is possibly linked to host larvae presence, while the feces produced by host larvae emitted some other characteristic compounds. Results demonstrated that the presence of host larvae is a key factor for T. elegans host habitat location, considering that the attractiveness of the undamaged wheat is irrelevant. Furthermore, parasitoid females tended to stay on attractive cues, limiting the risk of contamination of other commodities. Biological control tools may be useful to improve the efficiency of pest management programs, but their application should be carefully evaluated
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