Biology subjects

Cerretti, P.

Publications and source records attributed to Cerretti, P..

6 recordsLinked to original sources

bioRxiv2025

Two forms, two functions: functional strategies of parasitoid bristle flies and their larvae

Species with complete metamorphosis undergo substantial changes in ecological functions, especially parasitoid insects with parasitic larvae and free-living adults. While parasitoids play essential ecosystem roles, limited knowledge is available about their shifting functional strategies. Here we focus on parasitoid bristle flies (Diptera: Tachinidae) to investigate the relationship between larval vs adult functional strategies. We retrieved trait data for 767 European species and defined functional trait spaces for larvae and adults. We then measured both functional distinctiveness (rarity in functional trait combination) and specialisation (variety of resources consumed). We found little correspondence in the functional distinctiveness of adults and larvae, with highly distinct larvae generating either functionally distinct or functionally common adults. In contrast, only specialised larvae (attacking a limited number of hosts) give origin to specialised adults (feeding on a limited number of flowers). This suggests selective pressure towards specialisation might act synergistically across life stages, if trophic resources are restricted in space for both the larva (e.g. caterpillar host) and adult (e.g. flowers). Global change can generate complex patterns of functional homogenisation in parasitoids, which can occur at different (or both) life stages and lead to ecosystem-wide consequences: from the outbreak of herbivore insects to the loss of pollination capacity.

ecology↗

bioRxiv2025

Spatial instability affects Key Biodiversity Areas scoping for bumblebees across three decades

Identifying potential Key Biodiversity Areas (KBAs) using species occurrence records is crucial for integrating hyperdiverse taxa, such as insects, into the KBA network. To ensure the KBA network supports effective conservation decision-making, established KBAs need to be reassessed every 8 to 12 years. Realistically, reassessments for very high numbers of species will be based also on opportunistic occurrence points. However, how changes in species distribution data availability and completeness in different time periods influence the spatial stability of potential KBAs over time has not been investigated in any taxa yet. We performed potential KBA assessments for 28 species and subspecies of bumblebees in Italy using an expert-validated dataset of distribution data collected between 1990 and 2023, using 10-year cumulative and progressive time series. Our findings reveal that KBA scoping for species with distributional knowledge gaps does not ensure stability and reliability over time. Potential KBA turnover percentages between different time periods can be high ([~=]133%). While only seven species/subspecies could trigger potential KBAs, their turnover percentage ranged between 28.5% and 50%. We highlight the need for standardized and strategic monitoring of established KBAs and species distributions between reassessments. We also discuss strategies to optimize monitoring plans under resource constraints.

ecology↗

bioRxiv2024

Neglected predatory insects trigger potential Key Biodiversity Areas in threatened coastal habitats

Key Biodiversity Areas (KBAs) are poised to become a powerful tool for identifying regions that host unique biodiversity. With their great diversity, insects hold significant potential as indicators for global KBA mapping, even in highly specialized and narrowly distributed habitats. For instance, species adapted to fragmented ecosystems like coastal sand dunes--among the most heavily impacted habitats worldwide--can serve as critical indicators to trigger KBAs in these fragile environments. Despite their relevance as indicators, the inclusion of insects in KBA assessments remains limited, especially for neglected insect species such as antlions. We tested selected KBA criteria on 26 antlion and owlfly species (Neuroptera: Myrmeleontidae) in Italy, including dunes specialists, and performed COI based genetic analysis to identify potential weaknesses of the assessment. Several endemic and dune specialist species trigger potential KBAs, showing limited (< 20% of their extent) overlap with the current protected area network, confirming the great value of these taxa in narrowly distributed habitats. Genetic data provides evidence of misidentification for widely distributed species. We advise for the integration of both spatial and genetic data to increase reliability of potential KBA assessments using neglected insect taxa.

ecology↗

bioRxiv2024

Glacier retreat decreases plant-pollinator network robustness over space-time

Glaciers are retreating worldwide at an ever-increasing rate, exposing new ice-free areas to ecological succession. This process leads to changes in biodiversity and potentially to species interactions. However, we still have a limited understanding of how glacier retreat influences species interaction networks, particularly the structure and robustness of mutualistic networks. After reconstructing plant-pollinator networks along a glacier foreland, we address the effects of glacier retreat on pollination network structure and robustness. Our results show that the prevalence of different network motifs changes over space-time. With glacier retreat, pollination networks shift from being highly connected with specialist interactions to loosely connected with generalist interactions. Furthermore, network robustness decreased with glacier retreat. Despite the turnover of plant species, we find that structural roles played by different plant species stay constant over space-time. Our findings suggest that glacier retreat pushes pollination networks towards a loss of specialist interactions and low robustness, leading to increased fragility in the long term. Monitoring network motifs may provide valuable insights into the ability of novel pollination networks to withstand disturbances and preserve functionality in the face of glacier extinction.

ecology↗

bioRxiv2021

DiversityScanner: Robotic discovery of small invertebrates with machine learning methods

Invertebrate biodiversity remains poorly explored although it comprises much of the terrestrial animal biomass, more than 90% of the species-level diversity and supplies many ecosystem services. The main obstacle is specimen- and species-rich samples. Traditional sorting techniques require manual handling and are slow while molecular techniques based on metabarcoding struggle with obtaining reliable abundance information. Here we present a fully automated sorting robot, which detects each specimen, images and measures it before moving it from a mixed invertebrate sample to the well of a 96-well microplate in preparation for DNA barcoding. The images are then used by a newly trained convolutional neural network (CNN) to assign the specimens to 14 particularly common, usually family-level "classes" of insects in Malaise trap samples and an "other-class" (N=15). The average assignment precision for the classes is 91.4% (75-100%). In order to obtain biomass information, the specimen images are also used to measure specimen length and estimate body volume. We outline how the DiversityScanner robot can be a key component for tackling and monitoring invertebrate diversity. The robot generates large numbers of images that become training sets for CNNs once the images are labelled with identifications based on DNA barcodes. In addition, the robot allows for taxon-specific subsampling of large invertebrate samples by only removing the specimens that belong to one of the 14 classes. We conclude that a combination of automation, machine learning, and DNA barcoding has the potential to tackle invertebrate diversity at an unprecedented scale.

zoology↗

bioRxiv2017

Facilitation between plants shapes pollination networks

SignificanceAlthough it is known that plant-plant and plant-pollinator interactions can strongly influence biodiversity and its effects on ecosystem functioning, the details of how competition and facili-tation among plants scale up to mutualistic interactions with pollinators and thus affect pollina-tion networks are poorly understood. We introduce a simple experimental system in which we control local plant interactions, measure pollinator responses and characterize plant-pollinator networks. We find that facilitation among plants produces synergistic and antagonistic effects on the pollinator community affecting the architecture and robustness of plant-pollinator net-works. Our results provide evidence for bottom-up non-additive effects of plant interactions on pollination networks and have implications for the way we study and manage ecosystems.

ecology↗