Impact of agricultural practices on the quality of soil organic matter

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Spatio-temporal dynamics of Drosophila suzukii: A landscape perspective

La composizione del paesaggio svolge un ruolo fondamentale nel controllo delle dinamiche degli insetti. Gli habitat naturali e semi-naturali, nonostante siano fonte di importanti servizi ecosistemici, forniscono siti di svernamento ottimali nonché un'ampia gamma di piante ospiti per numerose specie dannose alle colture. In tal modo possono potenzialmente favorire un aumento delle densità di popolazione di queste specie, promuovendo la loro diffusione nel territorio. A questo proposito, il presente lavoro di tesi si propone di approfondire la relazione tra la distribuzione e il danno di una specie invasiva polifaga, Drosophila suzukii, e l'ambiente fisico circostante. D. suzukii è un insetto approdato di recente in Europa, provocando ingenti danni economici su diversi piccoli frutti di interesse commerciale. La gestione di questo carpofago è particolarmente complessa a causa del suo elevato potenziale dispersivo e della sua polifagia. Nei capitoli 2 e 3 si è studiato l'effetto della composizione del paesaggio sulla distribuzione di D. suzukii e sul danno provocato alle coltivazioni. Nel corso della stagione vegetativa, la marcata presenza di habitat semi-naturali ha fortemente influenzato la risposta del carpofago, con conseguente incremento della densità di popolazione. In particolare, i ceraseti situati in zone boschive sono risultati essere i più attaccati dall'insetto. Nel capitolo 4 è stato attuato un monitoraggio a grande scala geografica al fine di determinare le dinamiche temporali e la sincronizzazione dell'attività di D. suzukii lungo gradienti altitudinali in ambiente alpino. A causa dell'elevato potenziale di dispersione, la sincronizzazione dell’attività delle popolazioni dell'insetto è risultata essere estremamente elevata sia a grandi distanze che a quote molto diverse. Nel capitolo 5 è stato svolto un lavoro preliminare di meta-analisi atto a valutare la relazione tra gli insetti dannosi alle colture e la composizione del paesaggio. Coerentemente con quanto ottenuto dai precedenti studi su D. suzukii, si può osservare come un'alta presenza di habitat naturali e semi-naturali nel paesaggio comporti un aumento delle densità di popolazione di queste specie. Considerando i problemi emergenti legati al recente arrivo di D. suzukii ed altre specie invasive in zone temperate, questo lavoro sottolinea la necessità di approfondire lo studio dei potenziali effetti che la composizione paesaggistica può avere sulle dinamiche spazio-temporali delle popolazioni di insetti invasivi

Investigating beetle communities in and around entry points can improve surveillance at national and international scale

Beetles are commonly moved among continents with international trade. Baited traps set up in and around entry points are commonly used to increase chances of early-detection of incoming species and complement visual inspections. A still underestimated benefit of this surveillance approach is the high number and diversity of collected bycatch species. In this study, we exploited a multiyear surveillance program carried out with baited traps at five Spanish ports and their surrounding natural areas to investigate i) the importance of identifying bycatch to more promptly detect nonnative species belonging to non-target groups; ii) patterns of native and nonnative species richness and abundance inside the port areas vs. surrounding natural areas; iii) the occurrence of spillover events between natural areas surrounding ports and the port areas, and iv) whether the native species most commonly introduced into other countries are more abundant in port areas than in surrounding natural areas. A total of 23,538 individuals from 206 species representing 33 families were collected. The number and taxonomic diversity of the 26 bycatch nonnative beetle species testified that the identification of these unintentionally trapped species can provide additional information on ongoing invasions. Patterns of spillover and native species richness and abundance in port areas vs. surrounding natural areas highlighted a differential ability of different beetle families to colonize port areas. Finally, native species most commonly introduced into other countries were more abundant in port areas than in their surroundings, while the opposite trend occurred for native species that have not been introduced elsewhere. Our study highlighted that the use of traps baited with generic attractants can aid in early-detection of nonnative beetle species, and that the identification of native species can provide useful information on the risk of introduction in other countries.The study was funded by the Servei d’Ordenació i Gestió Forestal (Conselleria d’Agricultura, Desenvolupament Rural, Emergència Climàtica i Transició Ecològica) of Generalitat Valenciana. Davide Rassati was partially supported by the CRUI-CARE Agreement. 2019 STARS Grants programme (project: MOPI–Microorganisms as hidden players in insect invasions)

Investigating beetle communities in and around entry points can improve surveillance at national and international scale

Beetles are commonly moved among continents with international trade. Baited traps set up in and around entry points are commonly used to increase chances of early-detection of incoming species and complement visual inspections. A still underestimated benefit of this surveillance approach is the high number and diversity of collected bycatch species. In this study, we exploited a multiyear surveillance pro-gram carried out with baited traps at five Spanish ports and their surrounding natural areas to investigate i) the importance of identifying bycatch to more promptly detect nonnative species belonging to non-target groups; ii) patterns of native and nonnative species richness and abundance inside the port areas vs. surrounding natural areas; iii) the occurrence of spillover events between natural areas surrounding ports and the port areas, and iv) whether the native species most commonly introduced into other countries are more abundant in port areas than in surrounding natural areas. A total of 23,538 individuals from 206 species representing 33 families were collected. The number and taxonomic diversity of the 26 bycatch nonnative beetle species testified that the identification of these unintentionally trapped species can pro-vide additional information on ongoing invasions. Patterns of spillover and native species richness and abundance in port areas vs. surrounding natural areas highlighted a differential ability of different beetle families to colonize port areas. Finally, native species most commonly introduced into other countries were more abundant in port areas than in their surroundings, while the opposite trend occurred for native species that have not been introduced elsewhere. Our study highlighted that the use of traps baited with generic attractants can aid in early-detection of nonnative beetle species, and that the identification of native species can provide useful information on the risk of introduction in other countrie

Spatio-temporal dynamics of Drosophila suzukii: A landscape perspective

Landscape processes play a fundamental role in pest population dynamics. In particular, natural and semi-natural habitats, despite delivering important ecosystem services, can also support insect pest populations by providing refuge during pesticide applications, suitable overwintering sites and availability of alternative host plants. Against this background, my PhD thesis aimed at investigating the relationship between the distribution and damage of Drosophila suzukii, an invasive polyphagous pest, and landscape processes at multiple spatial scales. D. suzukii recently invaded Europe causing considerable economic damage on several thin-skinned fruits. The management of this pest is particularly complex due to its high dispersal potential, mobility and polyphagy. In Chapter 2 and 3 we studied the influence of landscape complexity on D. suzukii distribution and crop damage. During the growing season, semi-natural habitats enhanced population density and damage in cherry orchards. In particular, orchards within forested-dominated landscape appeared to be more susceptible to D. suzukii attacks. In Chapter 4 we examined at large geographical scale the temporal dynamics and synchronization of D. suzukii activity along steep elevational gradients in Alpine environments. Due to the high dispersal potential and mobility, the insect revealed an extremely high synchronization of population fluctuations across different locations and elevations. In Chapter 5 we introduced a preliminary meta-analysis work to evaluate how a large number of insect pests respond to landscape composition. Consistently with previous findings on D. suzukii, we found a positive relationship between pest density and landscape complexity. Considering the emerging problems linked to the invasion of D. suzukii and other invasive generalist pests across several temperate countries, our work emphasized the need to incorporate landscape processes to understand the spatio-temporal dynamics of pest populations across complex landscapes.La composizione del paesaggio svolge un ruolo fondamentale nel controllo delle dinamiche degli insetti. Gli habitat naturali e semi-naturali, nonostante siano fonte di importanti servizi ecosistemici, forniscono siti di svernamento ottimali nonché un'ampia gamma di piante ospiti per numerose specie dannose alle colture. In tal modo possono potenzialmente favorire un aumento delle densità di popolazione di queste specie, promuovendo la loro diffusione nel territorio. A questo proposito, il presente lavoro di tesi si propone di approfondire la relazione tra la distribuzione e il danno di una specie invasiva polifaga, Drosophila suzukii, e l'ambiente fisico circostante. D. suzukii è un insetto approdato di recente in Europa, provocando ingenti danni economici su diversi piccoli frutti di interesse commerciale. La gestione di questo carpofago è particolarmente complessa a causa del suo elevato potenziale dispersivo e della sua polifagia. Nei capitoli 2 e 3 si è studiato l'effetto della composizione del paesaggio sulla distribuzione di D. suzukii e sul danno provocato alle coltivazioni. Nel corso della stagione vegetativa, la marcata presenza di habitat semi-naturali ha fortemente influenzato la risposta del carpofago, con conseguente incremento della densità di popolazione. In particolare, i ceraseti situati in zone boschive sono risultati essere i più attaccati dall'insetto. Nel capitolo 4 è stato attuato un monitoraggio a grande scala geografica al fine di determinare le dinamiche temporali e la sincronizzazione dell'attività di D. suzukii lungo gradienti altitudinali in ambiente alpino. A causa dell'elevato potenziale di dispersione, la sincronizzazione dell’attività delle popolazioni dell'insetto è risultata essere estremamente elevata sia a grandi distanze che a quote molto diverse. Nel capitolo 5 è stato svolto un lavoro preliminare di meta-analisi atto a valutare la relazione tra gli insetti dannosi alle colture e la composizione del paesaggio. Coerentemente con quanto ottenuto dai precedenti studi su D. suzukii, si può osservare come un'alta presenza di habitat naturali e semi-naturali nel paesaggio comporti un aumento delle densità di popolazione di queste specie. Considerando i problemi emergenti legati al recente arrivo di D. suzukii ed altre specie invasive in zone temperate, questo lavoro sottolinea la necessità di approfondire lo studio dei potenziali effetti che la composizione paesaggistica può avere sulle dinamiche spazio-temporali delle popolazioni di insetti invasivi

Cox proportional-hazards model: evaluation of Popillia japonica survival after insecticide treatments

Survival analysis is frequently used to assess the effectiveness of insecticide trials on insect survival. The target organism of this study isPopillia japonica, a pestcurrently causing considerable damage tovariousplant species in Northern Italy.Here, the effects of differentinsecticides,evaluatedon insectsby field trialsina peach orchard,wereexplored through non-parametric tests and semi-parametric marginal Cox proportional-hazard models. Adultinsects were confined on peach plants in net cages containing 25 individuals each. Five insecticides(Abamectin, Acetamiprid, Deltamethrin, Phosmet and Sulfoxaflor)plus untreated control were tested with four net cages per treatment, following a completely randomized design.The non-parametric tests, performed both for right-and interval-censored data, and the marginal Cox model led to the same inferential conclusions. All the insecticides, in particular Abamectin, Acetamiprid, Deltamethrin andPhosmet,resulted to be effective in killing insects if compared to the untreated control

Spatio-temporal dynamics of Drosophila suzukii: A landscape perspective

Landscape processes play a fundamental role in pest population dynamics. In particular, natural and semi-natural habitats, despite delivering important ecosystem services, can also support insect pest populations by providing refuge during pesticide applications, suitable overwintering sites and availability of alternative host plants. Against this background, my PhD thesis aimed at investigating the relationship between the distribution and damage of Drosophila suzukii, an invasive polyphagous pest, and landscape processes at multiple spatial scales. D. suzukii recently invaded Europe causing considerable economic damage on several thin-skinned fruits. The management of this pest is particularly complex due to its high dispersal potential, mobility and polyphagy. In Chapter 2 and 3 we studied the influence of landscape complexity on D. suzukii distribution and crop damage. During the growing season, semi-natural habitats enhanced population density and damage in cherry orchards. In particular, orchards within forested-dominated landscape appeared to be more susceptible to D. suzukii attacks. In Chapter 4 we examined at large geographical scale the temporal dynamics and synchronization of D. suzukii activity along steep elevational gradients in Alpine environments. Due to the high dispersal potential and mobility, the insect revealed an extremely high synchronization of population fluctuations across different locations and elevations. In Chapter 5 we introduced a preliminary meta-analysis work to evaluate how a large number of insect pests respond to landscape composition. Consistently with previous findings on D. suzukii, we found a positive relationship between pest density and landscape complexity. Considering the emerging problems linked to the invasion of D. suzukii and other invasive generalist pests across several temperate countries, our work emphasized the need to incorporate landscape processes to understand the spatio-temporal dynamics of pest populations across complex landscapes