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The general aim of my PhD was focused on study the role of different agricultural systems in promoting functional biodiversity. In particular, the importance of habitat management techniques on natural enemy enhancement and conservation was considered at farm level with two-years samplings. Predation by polyphagous predators, which represents one of the most important ecosystem services in conservation biological control, was assessed using different approaches. In this context, molecular marker and artificial caterpillars (sentinel preys made by plasticine) were used to investigate the role of polyphagous predators in different cultivated systems. The hypothesis of my thesis is in agreement with the general assumption that diversified agro-ecosystems are more suitable for natural enemies than simplified ones. In vegetable system, natural enemies should be also favoured by the presence of Agro-ecological Service Crops by means of food supply, refuges and shelters. Moreover, we hypothesized that sustainable approaches such as green manure and roller crimper reduce soil disturbance and strengthen the ecosystem services, in comparison with conventional methods., Le attività di ricerca svolte durante il mio PhD sono state focalizzate allo studio dei metodi e delle tecniche per conservare e promuovere la biodiversità funzionale negli agro-ecosistemi. Campionamenti biennali, effettuati a livello di azienda, hanno permesso di valutare l’azione dei predatori polifagi nei confronti degli insetti dannosi utilizzando marker molecolari e bruchi artificiali di plastilina (dummy caterpillars). L’ipotesi della mia tesi è in accordo con il generale presupposto secondo cui i nemici naturali sono favoriti dai sistemi agricoli diversificati. A tal proposito, un punto chiave del dottorato ha riguardato l’influenza che le “Agro-ecological Service Crops (ASC)” hanno nei confronti degli insetti utili e dannosi in sistemi orticoli biologici. Difatti, è ben noto come le ASC avvantaggino i nemici naturali grazie a una maggiore disponibilità di cibo e di rifugi riducendo di conseguenza le infestazioni; sebbene tale affermazione debba essere valutata caso per caso. Inoltre, abbiamo ipotizzato che tecniche agronomiche quali il roller crimper e il sovescio riducano il disturbo del suolo rafforzando i servizi ecosistemici rispetto ai metodi convenzionali.

Reliable monitoring of arthropod diversity in a given agroecosystem is essential for the conservation of the related ecosystem services, such as biological control. The often daunting complexity of arthropod collection and identification, however, highlights the need for surrogate taxa that can be easily sampled and be representative of a number of other taxa in term of diversity, general community features and specific composition. In this study, we used pitfall traps to sample three ground-dwelling arthropod taxa important as biocontrol agents (ground beetles, rove beetles and spiders) in 9 conventionally managed maize agroecosystems of Northern Italy over the course of two years, with the goal of characterizing their assemblages and evaluating their reciprocal potential as indicators of activity density, species richness, community turnover and species co-occurrence. Although dominated by few generalist species, sampled arthropod communities were relatively species-rich, and included the first Italian record of the spider Zelotes metellus (Roewer) (Araneae: Gnaphosidae). Ground beetles as a group were confirmed as promising indicators for the species richness and community composition turnover of rove beetles and spiders. Additionally, several abundant arthropod species acted as indicators of the species richness of their respective groups, and the ground beetle Pterostichus macer (Marsham) also worked as an indicator of overall rove beetle activity density. While the co-occurrence of individual arthropod species was limited for the studied taxa, a few species such as the ground beetle Parophonus maculicornis (Duftschmid) did show promise as species-specific bioindicators. Our results could be useful in improving the monitoring and management of these important natural enemies in maize-growing regions.

Crop yield and plant products quality are directly or indirectly affected by climate alterations. Adverse climatic conditions often promote the occurrence of different abiotic stresses, which can reduce or enhance the susceptibility to pests or pathogens. Aflatoxin producing fungi, in particular, whose diffusion and deleterious consequences on cereals commodities have been demonstrated to highly depend on the temperature and humidity conditions that threaten increasingly larger areas. Biological methods using intraspecific competitors to prevent fungal development and/or toxin production at the pre-harvest level are particularly promising, even if their efficacy could be affected by the ecological interaction within the resident microbial population. A previously characterized Aspergillus flavus atoxigenic strain was applied in two maize fields to validate its effectiveness as a biocontrol agent against aflatoxin contamination. At one month post-application, at the harvest stage, its persistence within the A. flavus population colonizing the maize kernels in the treated area was assessed, and its efficacy was compared in vitro with a representation of the isolated atoxigenic population. Results proved that our fungal competitor contained the aflatoxin level on maize grains as successfully as a traditional chemical strategy, even if representing less than 30% of the atoxigenic strains re-isolated, and achieved the best performance (in terms of bio-competitive potential) concerning endogenous atoxigenic isolates.

We studied the impact that two agro-ecological service crops or ASC, (vetch and barley), and two different ASC termination techniques (using a roller crimper or green manure) had on predation pressure in an organic vegetable system. We compared these two ASC termination techniques with a biodegradable plastic mulch, commonly used to control weeds in vegetable organic systems, over two consecutive growing seasons (2014–2015). Predation pressure was evaluated by means of artificial caterpillars made of green plasticine. Attack marks left on them were assigned to predators including chewing insects, birds and mammals. The frequencies of attack were significantly correlated with the activity density of carabids. In both experiments, carabid activity density was higher in ASC terminations than in the biodegradable plastic mulch control. Predation rate was significantly higher in the field with vetch flattened by roller crimper, while no significant difference was detected between termination techniques or in comparison with the control when barley was used as an ASC. The rate of ASC decomposition was higher in vetch than in barley and this could be the reason for the higher activity density of springtails in vetch. Carabid activity density was also positively correlated with springtail abundance. In conclusion, our field experiments showed that artificial caterpillars could represent a good standardized method to assess predation pressure in different habitats.

The Southern festoon, Zerynthia polyxena, is a south-European butterfly listed in Annex IV of the Habitats Directive (92/43/EEC). Populations from most of the Italian territory have been recently recognized as belonging to a separate species, endemic to Italy: Zerynthia cassandra. In the province of Bologna (northern Italy), Z. cassandra is quite common. The territory of the province is densely inhabited and modified by man. Semi-natural environments are found almost exclusively in the hills, while the plain is almost entirely built-upon or cultivated. This study was based on data collected in the field in the province of Bologna, and aimed to investigate some biological and ecological aspects of Z. cassandra, with the purpose of identifying the factors that favour its presence and the most relevant issues for its conservation. In the area of study, the hostplant of Z. cassandra is Aristolochia rotunda, which is common in the plain, along the edges of drainage canals, where it supports a large Z. cassandra population. In the hills, A. rotunda is scarcer, and Z. cassandra is present in small separated nodes. Human activities such as mowing and canal maintenance are potentially damaging to Z. cassandra, particularly if carried out when eggs and larvae are present. However, if correctly timed and executed, such maintenance can preserve grassy areas that would otherwise be colonized by bushes and trees, and in which A. rotunda finds a suitable environment. Some level of disturbance can be beneficial for Z. cassandra habitats, favouring the species’ survival in the long term.

Humankind draws important benefits from large-scale ecological processes termed ecosystem services, yet the status of several of them is declining. Reliable monitoring methods are essential for tracking the status of ecosystem services. Predation is the mainstay of natural pest control, a key ecosystem service. We used green plasticine caterpillars to monitor predation pressure, and to obtain baseline data on predator activity in transgenic Bt versus non-Bt maize fields in Old and New World countries. Predation pressure was measured at ground and canopy levels using an identical, small-plot experimental design in four European countries (Denmark, Slovakia, Romania and Italy) and Argentina. Total predation rate in maize was 11.7%d −1 (min. 7.2%d −1 in Argentina, max. 29.0%d −1 in Romania). Artificial caterpillars were attacked both by invertebrates (mostly chewing insects with 42.0% of the attack marks, and ants with 7.1%, but also predatory and parasitoid wasps, spiders and slugs), and vertebrates (small mammals 25.5%, and birds 20.2%). Total predation at ground level (15.7%d −1 ) was significantly higher than in maize canopies (6.0%d −1 ) in all countries, except Argentina. We found no significant differences between predator pressure in Bt versus non-Bt maize plots. The artificial caterpillar method provided comparable, quantitative data on predation intensity, and proved to be suitable for monitoring natural pest control. This method usefully expands the existing toolkit by directly measuring ecological function rather than structure.

Agro-ecological service crops (ASC) can increase the vegetation complexity of agroecosystems leading to a positive impact on natural enemies of arthropod pests and on weed control. In this study, two ASC terminations (green manure and roller crimper) and a Mater-Bi-mulched control (MB) were compared in order to describe the effects on pests and beneficial dynamics in an organic vegetable system. The trials were conducted over two consecutive growing seasons in 2014 and 2015. Zucchini were grown as cash crop and barley as ASC. Pests and natural enemies were monitored fortnightly by visual samplings along the whole zucchini-growing season. Zucchini plants showed a faster vegetative growth in MB treatment than in ASC terminations. In both years, MB plots were characterized by higher soil temperature and higher leaf nitrogen concentration resulting in plants more susceptible to Aphis gossypii infestations. In all the experimental plots, natural enemies controlled aphid infestations and no insecticide and sprays were necessary. In conclusion, the tested ASC techniques have been suggested as a tool to mitigate aphid infestation.

The pupae of Bactrocera oleae (Diptera: Tephritidae) complete their development during autumn and winter in the soil, rather than in the drupe, resulting susceptible to edaphic predators. Environmentally friendly methods to control this olive pest involve the identification of its natural enemies. This study evaluated the role of Ocypus olens (Coleoptera: Staphylinidae) in the predation of B. oleae pupae, by means of molecular gut content analysis. Modified dry pitfall traps were used to collect live specimens from low-input olive orchards in Tuscany (Italy). Sampling was fine-tuned with a degree-day model estimating the presence of pest pupae in the soil. PCR analyses carried out on field-collected specimens demonstrated that O. olens is a predator of B. oleae, at least during autumn. These results are consistent with predictions of the degree-day model. Knowledge on species composition, traits and complementarity of the natural enemies of B. oleae pupae needs further investigation to advance conservation biological control strategies.

Since the mid-2000s, the exotic coccinellid species Harmonia axyridis (Pallas) has established itself in Northern Italy, raising serious concerns about possible repercussions on native ladybirds. In this study we compared the ladybird assemblages in 2015–2016 with those sampled in 1995–1996, before the arrival of H. axyridis. Surveys were carried out in the same sites and with the same methods for both periods. Aphidophagous ladybirds were sampled in hedgerows and herbaceous habitats at field margins by mechanical knockdown and sweeping net, respectively. The changes in the structure of ladybird communities after the arrival of H. axyridis were significantly different between arboreal and herbaceous habitats. Harmonia axyridis is currently the dominant species in shrubs and trees, and all the native ladybird species taken together account for only approximately one third of the total individuals sampled in 2015–2016. On the other hand, the relative abundance of the exotic species in herbaceous habitats was low, and it has had a negligible relevance on the structure of ladybird communities on grasslands. Among native species, Adalia bipunctata (L.), whose ecological niche largely overlaps with that of H. axyridis, suffered the largest decline between 1995–1996 and 2015–2016. The co-occurrence of H. axyridis invasion and the regression of A. bipunctata suggest a direct impact of the exotic species, because no other major modifications occurred in the studied areas between sampling periods.

Lepidoptera are the phytophagous group most at risk of impact by insect-resistant genetically modified (GM) plants since most of these crops have been developed to express toxins to specifically target lepidopteran pests. In the case of Bt-maize cultivation, pollen grains released by GM plants could dust larval host plants growing inside or nearby maize fields, thus leading to the exposure of caterpillars to the Cry toxins. This way of exposure has been studied mainly for butterflies, whereas moths, in spite of their great diversity and abundance, were rarely considered. To evaluate the potential exposure of moth species to maize pollen in absence of Cry-expressing plants, macro-moths were sampled by means of light traps in three protected areas of Northern, Central and Southern Italy where conventional maize is among the main crops. Light traps were activated in two consecutive years (2010- 11) from the beginning of June to the end of July, a period that encompasses the anthesis of most maize cultivars grown in Italy. Overall, 11446 individuals belonging to 201 species and nine families were collected. Given that larvae of several sampled species are likely to match the criteria of potential exposure to maize pollen and susceptibility to Cry toxins, macro-moths might be considered among the potential assessment endpoints for environmental risk assessment of GM plants, especially in the vicinity of protected areas.