1,720,997 research outputs found
L’occupazione del territorio da parte di Lymantria dispar (Linnaeus) (Lepidoptera Erebidae) come indice di previsione della probabilità di danno.
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Using verified citizen science as a tool for monitoring the European hornet (Vespa crabro) in the Island of Sardinia (Italy)
No full textThe European hornet, Vespa crabro L. (Hymenoptera: Vespidae), is a eusocial insect native to Eurasia that was accidentally introduced in the island of Sardinia (Italy) in 2010. This alien generalist predator could impact on native insect species through predation or competition by modifying interspecific relations in sensitive island ecosystems. As part of the Interreg project ALIEM, the present work regarded the first monitoring activity of the European hornet conducted in Sardinia by means of verified citizen science. The main goals of this study were to define the distribution area of the wasp in 2018 and evaluate the profile and the performance of citizen scientists. Our results showed that V. crabro is mainly located in north-eastern Sardinia and that the hotspot was probably the commercial port of Olbia. Furthermore, data provided by contributors were very accurate and none of the parameters considered to define the participants (age, gender, education level, job category) was a true predictor of a volunteer's ability to recognise the wasp. In conclusion, this small-scale study suggests that citizen scientists could be a valuable aid to monitor already-established alien species and could be part of a surveillance network for early detection of other potentially invasive alien species not yet introduced in Sardinia, such as the yellow-legged hornet, Vespa velutina, which is already present in northern Italy
A multidiversity approach to investigate the impact of mining exploitation on spider diversity in the abandoned mine district of Montevecchio-Ingurtosu (Sardinia, Italy)
No full textThe impact of mining activities on spider (Araneae) diversity and assemblages was studied in two abandoned mine sites in Sardinia (Italy), where mining activities started in the middle of the nineteenth century and closed down over a century later. Spider community composition was analysed in dumps, undisturbed forests and scrublands which represent the natural chronosequence following the abandonment of the mining district. The identification of spiders was performed at the lowest taxonomic level possible and differences in abundance, species richness (SR), and functional diversity (FD) were analysed. Nonmetric multidimensional scaling (NMDS) and a permutated multivariate analysis of variance (PERMANOVA) routine were conducted to evaluate the relationships of spider assemblages with land cover, and the indicator species analysis was performed to identify the typifying species. During the entire sampling period, 2312 spiders were captured, and approximately 80% of the total were identified at the species level (79 spider species belonging to 28 different families). No differences in abundance and SR were found, whereas FD, which showed the highest values in forests, significantly differed among sites. A distinct separation among assemblages and a significant effect of the land use on spider assemblages were found (PERMANOVA, R2 = 0.59, p < 0.001). Twelve species were selected as indicator species. Our results underlined the possibility to consider ground-dwelling spiders as a valuable target group for biomonitoring programmes supporting projects of near-natural restoration and/or technical reclamation of mining sites
Seasonal phenology of Tuta absoluta (Lepidoptera: Gelechiidae) in protected and open-field crops under Mediterranean climatic conditions
No full textThe population structure and dynamics of the tomato leafminer Tuta absoluta were investigated in a protected tomato crop and on potato and tomato crops and Solanum nigrum plants under open-field Mediterranean climatic conditions (Sardinia) by captures in pheromone-baited traps and visual inspection of host plants. In the greenhouse crop, male captures and leaf infestation were low in winter and increased steadily in spring up to 797.3 males/trap/week and 6.4 mines/leaf, respectively. Under open-field conditions, males were captured all year round with a peak in early September, concurrently with highest mean daily temperatures. Pest density in potato crops was very low (<0.3 mines/leaf), as well as on S. nigrum (0.16 mines/leaf). Conversely, high pest infestation was observed in tomato leaves (3.8 mines/leaf) and fruits (27% damaged fruits). Eggs, larvae and adults were detected over two consecutive winters, indicating that T. absoluta can develop continuously over the year under natural conditions. Parasitoids were recorded throughout the survey at low rates (≤16.1%). The most active beneficials were Necremnus tutae and Neochrysocharis formosa in protected and open-field crops, respectively. The tomato leafminer completed 6 generations in the greenhouse tomato crop during the winter-spring growing season, whereas in open-field crops the pest completed two generations on winter potato and 4-5 in spring-summer tomato. The degree-day model based on minimum and maximum temperatures reliably described the population dynamics in the protected crop, and estimated the completion of 7.4 generations per year under open-field Mediterranean conditions
Variability of beetle assemblages in Mediterranean cork oak woodlands: does the higher taxa approach reliably characterize a specific response to grazing?
No full textStudying macroarthropod community responses to different land uses is particularly interesting in agroforestry for the conservation of Mediterranean landscapes, which need to be managed in terms of ecological and functional sustainability. Because of the sensitivity of many taxa to human impacts, we assessed the response of beetle assemblages at low taxonomic resolution (i.e. family level) to grazing in Mediterranean cork oak woodlands in northern Sardinia (Italy). Scarab assemblages were also analysed at the species level because of their ecological role in grazed areas. Cork oak woodland descriptors were also recorded in order to relate beetle assemblages to the forest structure. Over the entire sampling period, 4550 beetles belonging to 47 families were captured using pitfall traps. Multivariate analyses performed on ground-dwelling beetle data showed a distinct separation in terms of assemblages between grazed and ungrazed sites. The average diameter of cork oak trees and the degree of shrub cover were significantly linked to the beetle family assemblages. Constrained multivariate analyses indicated the significance of grazing, by both large and small domestic herbivores, and altitude, as variables determining the pattern of scarab beetle assemblages. Mantel test showed a significant correlation between the beetle and scarab dissimilarity matrices indicating a similar pattern for the two levels of identification. Our results show the predictive power of beetles at the family taxonomic level, as well as scarab beetles at the species level. These turned out to be valuable indicators in biomonitoring programmes in Mediterranean cork oak woodlands in order to increase the resilience of cork oak agroforestry systems under future global change scenarios
Comparative laboratory and field study of biorational insecticides for Culicoides biting midge management in larval developmental sites
No full textAn appropriate management strategy of bluetongue vectors should include larvicidal treatments in their larval development sites utilizing active substances with low environmental impact. A selection of biorational insecticides with potential against dipteran larvae was assayed in the laboratory against field collected Culicoides larvae including C. cataneii, C. circumscriptus, and C. imicola, determining their median lethal concentrations in water and mud/water substrate. The efficacy of formulations containing the insect growth regulators pyriproxyfen and cyromazine, the botanical insecticide azadirachtin, and the entomopathogenic bacteria Bacillus thuringiensis israelensis and Brevibacillus laterosporus, was also assessed in field conditions in a comparative study conducted in sheep farm larval development sites, including treatments with the organophosphate temephos. Significant larvicidal properties were associated with the various insecticides evaluated in the laboratory assays and in field trials, although with different levels of effectiveness. While temephos was confirmed to be an effective broad spectrum larvicidal substance, B. laterosporus appeared to be the most effective among entomopathogens, while insect growth regulators combined a good efficacy to a long-lasting residual effect in the field. Everything considered, the use of these biorational insecticides alone or in combination with larval habitat manipulation techniques appears to be a promising method to complement integrated biting midge management programs
Enhancing insecticide activity using a physical mixture with cyclodextrin: a witch’s cauldron or an opportunity?
No full textCyclodextrins have many advantages when used in the agricultural field as complexes with agrochemicals. However, they interact with molecules and biological systems at different levels and an enhancement of agrochemical effectiveness even as a physical mixture cannot be ruled out. This was verified for the first time by a simple experimental system with mealworm larvae (Tenebrio molitor L.) as the pest, the inhibitor of chitin synthesis diflubenzuron as the insecticide, and β-cyclodextrin as the adjuvant. Under laboratory conditions, mealworm mortality was recorded under the following three treatments: (i) neat diflubenzuron, (ii) diflubenzuron/β-cyclodextrin physical mixture, and (iii) commercial formulation Dimilin WP25. The physical mixture with β-cyclodextrin significantly increased the mortality by enhancing the effectiveness of diflubenzuron. A significant dose effect was also found. Considering the application protocol, this result may be more likely due to the bioavailability enhancement of diflubenzuron by β-cyclodextrin. On the basis of the current knowledge and available literature, we assume that these results could be explained by the interactions between CDs and biological membranes and the associated increase in their permeability. The use of β-cyclodextrin in physical mixtures with insecticides could be of interest in the development of more effective agrochemicals through simpler and less costly research processes
When a threatened species becomes a threat: a key to reading the Habitats Directive based on occurrence and distribution of Cerambyx cerdo L. in Mediterranean urban and peri-urban areas
No full textCerambyx cerdo is a large saproxylic species included in the Annex IV of the European Habitats Directive as a ‘priority species’. Although C. cerdo populations have shown a significant decline in size and distribution in central and northern European forests, in the Mediterranean basin it is often considered as a pest in urban and peri-urban areas. Based on European legislations currently in use, we propose a simplified decision-making flowchart that should be followed regarding the adoption of different control measures against severe C. cerdo infestations
Development of Enumerative and Binomial Sequential Sampling Plans for Monitoring Lymantria dispar (L.) (Lepidoptera Erebidae) in Mediterranean Oak Forests
No full textLymantria dispar is the main threat to Mediterranean forests. Sampling methods used for monitoring the pest population density are generally very time-consuming for practical purposes, such as the delimitation of infested areas for control programs. Enumerative and binomial sequential sampling plans were developed using data collected in cork oak forests in Sardinia (Italy). The Taylor's power law (TPL) was used to evaluate the degree of aggregation of L. dispar egg masses among trees and to develop enumerative sampling plans at precision levels of 0.10 and 0.25 using the Green's method. Furthermore, binomial plans were computed by Wald's sequential probability ratio test. Lymantria dispar egg masses on trees were significantly aggregated and the degree of aggregation was similar in all population development phases. Overall, only 31 cork oak trees are to be monitored at the economic damage threshold of 2.5 egg masses/tree with a precision level of 0.25. Binomial sequential sampling plans also required lower sampling sizes (26.9-31.4 trees) than conventional sampling plans. Enumerative and binomial sampling plans could represent suitable methods for sampling L. dispar egg masses in Mediterranean forests, with the practical advantage of lower cost and time consumption than standard sampling plans
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