145 research outputs found

    Loss of ion homeostasis is not the cause of chill coma or impaired dispersal in false codling moth Thaumatotibia leucotreta (Lepidoptera: Tortricidae)

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    Dispersal is a central requirement of a successful sterile insect release programme, but field-released false codling moth (FCM) typically suffer from poor dispersal ability, especially at low ambient temperatures. Here we test the hypothesis that poor activity and dispersal in FCM is caused by delayed or perturbed recovery of ion and/or water homeostasis after chilling for handling and transport prior to field release. Hemolymph and flight muscle were collected from two treatment groups at three time points that targeted thermal conditions above and below the chill coma induction threshold of ~ 6 °C: 1) control moths kept at 25 °C, 2) moths exposed to 3 °C or 9 °C for 4 h, and 3) moths allowed to recover at 25 °C for 24 h after exposure to either 3 °C or 9 °C. We measured concentrations of Na+, K+ and Mg2+ in the hemolymph and muscle collected at each time point. Exposure to a chill-coma inducing temperature had little effect overall on ion balance in the hemolymph and flight muscle of false codling moth, but hemolymph [Na+] decreased from 10.4 ± 0.4 mM to 6.9 ± 0.7 mM as moths were chilled to 3 °C and then increased to 10.4 ± 0.9 mM after the 24 h recovery period. In the 9 °C cooling treatment, [K+] increased from 8.2 ± 0.5 mM during chilling to 14.1 ± 1.9 mM after the 24 h recovery period. No changes were seen in equilibrium potentials in either of the ions measured. Thus, we did not find evidence that water and ion homeostasis are lost by the moths in chill coma and conclude that reduced dispersal in field-released moths is not direct a consequence of the costs of re-establishment of homeostasis

    Three new Drosophilidae species records for South Africa

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    CITATION: De Araujo, L. I., Karsten, M. & Terblanche, J. S. 2020. Three new Drosophilidae species records for South Africa. Bothalia, 49(1), a2429, doi:10.4102/abc.v49i1.2429.The original publication is available at https://journals.abcjournal.aosis.co.za/index.php/abcBackground: Data on the current species diversity from the Drosophilidae family in South Africa is limited or outdated. Objectives: Using haphazard, limited trapping for a different study, we serendipitously report on and document Drosophilidae species in two distinct regions (representing a sub-tropical and a Mediterranean climate region) of South Africa. Method: Drosophilidae were trapped using mixed fruit and mushroom traps around urban areas in two climatically distinct regions of South Africa. The flies were identified using standard barcoding ( Cytochrome c Oxidase Subunit I [COI] gene sequence) and, in some cases, additional identification from a taxonomical expert using morphological traits. Species were checked against literature, online resources and a previously compiled library of South African Drosophilidae to determine whether they were new records. Results: Thirteen species were readily collected and identified. Of these, three species (Drosophila ananassae, Drosophila nasuta and Zaprionus taronus) have not been reported previously in South Africa. One of the species (Z. taronus) was captured in a home garden, while the other two species were captured in an urban-agricultural region with a sub-tropical climate. Conclusions: From our limited serendipitous sampling, three new species records have been found in sub-tropical climates in South Africa. With more comprehensive, systematic sampling, a better understanding of the South African Drosophilidae composition, and thus the detection of alien or invasive species, can be pursued. Baseline data for understanding spatio-temporal patterns of native biodiversity, or for informing management actions in the case of alien or invasive species, are currently inadequate for this group in the region.Publisher's versio

    Evaluation intégrée des mesures agro-environnementales territorialisées à enjeu "qualité des eaux" sur la période 2007 à 2011 : le projet MAEVEAU

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    The MAEVEAU project has developed an approach for an integrated assessment of effectiveness of regionalized Agro-Environmental Measures (MAET) intended to preserve water quality in relation to pesticides. This approach investigates the concept of efficiency through a triple analysis: the impact (net effects), the environmental cost-effectiveness and the role of organizational factors in the contracting process. The impact is assessed by a quasi-experimental approach by counterfactuals and examines adaptation of the matching method to the regionalized MAET. Cost-effectiveness analysis is based on integrated modeling spatially distributed coupling the agro-hydrological SWAT model, pesticides pressure indicators and a bio-economic model optimizing gross margin. The effectiveness of organizational factors focuses on transaction costs, the role of collective action and preferences for alternative contracts.La recherche conduite dans le projet MAEVEAU a développé une démarche d'évaluation intégrée de l'efficacité des Mesures Agro-Environnementales Territorialisées (MAET) à enjeu préservation de la qualité de l'eau vis-à-vis des pesticides sur la période 2007 à 2011. La question scientifique traite le concept d'efficacité de la politique en s'appuyant sur une triangulation des approches: une évaluation de l'impact (c'est-à-dire des effets propres de la politique), une évaluation coût-efficacité environnementale et une évaluation du rôle des facteurs organisationnels dans le processus d'adhésion. L'impact est évalué par une approche quasi-expérimentale par contrefactuel et questionne l'adaptation de la méthode du matching à la territorialisation des MAET. L'analyse coût-efficacité s'appuie sur une modélisation intégrée spatialisée couplant modèle agro-hydrologique, indicateurs pesticides spatialisés et optimisation économique des marges brutes. L'efficacité des facteurs organisationnels s'est intéressée aux coûts de transaction, au rôle de l'action collective et aux préférences pour des contrats alternatifs
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