Functional Biodiversity in Different Agricultural Systems: Methods and Techniques for Conservation and Enhancement of Ecosystem Services

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

Ground-dwelling arthropods as biodiversity indicators in maize agroecosystems of Northern Italy

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

Validation and Ecological Niche Investigation of a New Fungal Intraspecific Competitor as a Biocontrol Agent for the Sustainable Containment of Aflatoxins on Maize Fields

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

Sesamia su mais: al Nord aumentano le popolazioni

Sesamia cretica e piralide sono tra i principali insetti nocivi del mais. Le larve di questi insetti possono essere facilmente confuse vista la simile morfologia. Per impostare un efficace controllo di sesamia è fondamentale un accurato monitoraggio. La lotta biologica si è rivelata la soluzione migliore assieme alla distruzione dei residui coltural

Biology and conservation of Zerynthia cassandra (Lepidoptera, Papilionidae) in semi-natural environments and agricultural landscapes

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\u2019 survival in the long term

Long term changes in the communities of native ladybirds in Northern Italy: impact of the invasive species Harmonia axyridis (Pallas)

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\u20132016 with those sampled in 1995\u20131996, 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\u20132016. 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\u20131996 and 2015\u20132016. 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

A new PCR based molecular method for early and precise quantification of parasitization in the emerging olive pest Dasineura oleae

BACKGROUND: Dasineura oleae (Angelini 1831) (Diptera: Cecidomyiidae) was considered a minor pest in olive orchards, but in recent years severe outbreaks have been registered in several Mediterranean countries. Damage is caused by the feeding activity of larvae that induce gall formations and alters the physiological activity of the leaves. In Italy, this pest may be controlled by four Hymenoptera parasitoid species belonging to Platygaster and Mesopolobus genera such as Platygaster demades Walker 1835, Platygaster oleae Szelenyi 1940 (Hymenoptera: Platygastridae), Mesopolobus aspilus (Walker 1835) and Mesopolobus mediterraneus (Mayr 1903) (Hymenoptera: Pteromalidae), but parasitization becomes evident only after gall dissection. RESULTS: In this study, we aim to: (i) design a primer for the detection of specimens belonging to Platygaster and Mesopolobus genera; (ii) develop a multiplex quantitative polymerase chain reaction (qPCR) protocol combined to a fast samples DNA extraction method; (iii) apply the developed protocol to field‐collected specimens and compare this method with traditional techniques based on visual estimation of parasitism rate on larvae. Primers were designed to anneal with cytochrome oxidase subunit I (COI) sequences of Platygaster and Mesopolobus genera while protocols were developed to be fast and capable to process several samples at the same time. Molecular analyses demonstrated to provide almost double of the parasitism rate assessed by visual inspection. Furthermore, on second instar larvae the PCR‐based method was able to detect ten‐fold times the parasitization rate estimated by visual inspection. CONCLUSION: The application on a greater scale of this newly developed method could be fundamental in the determination of the biological control potential in olive orchards

Bactrocera oleae pupae predation by Ocypus olens detected by molecular gut content analysis

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

Influence of Cover Crop Termination on Ground Dwelling Arthropods in Organic Vegetable Systems

A key aspect in cover crop management is termination before the cash crop is planted. The aim of this study was to assess the effects of termination methods on ground-dwelling arthropods. The conventional mechanical termination method—i.e., green manuring by means of a disc harrow—was compared to flattening using a roller crimper. Two different crop systems were investigated for two growing seasons; cauliflower was grown in autumn after the termination of a mixture of cowpea, pearl millet, and radish, and tomato was cropped in spring and summer after the termination of a mixture of barley and vetch. Ground beetles (Coleoptera: Carabidae), rove beetles (Coleoptera: Staphylinidae), and spiders (Araneae) were sampled by means of standard pitfall traps throughout the growing season of both cash crops. The roller crimper increased the overall abundance of ground beetles in the first growing season of both cash crops, whereas in the second year, no significant effect could be detected. Rove beetles were more abundant in plots where the cover crops were terminated by the roller crimper. Finally, green manuring increased the abundance of spiders, especially on the first sampling date after cover crop termination. Albeit different taxa showed different responses, the termination of cover crops by a roller crimper generally increased the abundance of ground dwelling arthropods. Given that most of the sampled species were generalist predators, their increased abundance could possibly improve biological control

Influence of agro-ecological service crop termination and synthetic biodegradable film covering on Aphis gossypii Glover (Rhynchota: Aphididae) infestation and natural enemy dynamics

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