Biology subjects

Bollazzi, M.

Publications and source records attributed to Bollazzi, M..

4 recordsLinked to original sources

bioRxiv2026

Increasing threat: Rhynchophorus ferrugineus invaded mainland America through Uruguay.

Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) is one of the most dangerous palm pests worldwide. Here we report the invasion process of R. ferrugineus in Uruguay. Beyond morphological and molecular identification, we infer the geographic origin of the invasive population, describe the succession of introduced and native palms attacked, provide an easy-to-use key to differentiate the invader R. ferrugineus from the native Rhynchophorus palmarum, and model the ecological niche of R. ferrugineus in Uruguay and neighboring countries. First detected in 2022, the Uruguayan population of the weevil is the first to establish on mainland America, following the earlier island records from Curacao and Aruba. Phylogenetic analysis showed that the Uruguayan R. ferrugineus sequences clustered within a single clade, most closely related to sequences from southern China, and clearly distinct from the sequences of Curacao and Aruba, indicating at least two independent introduction events into the Americas from different source regions. After four years, R. ferrugineus has spread across an area of nearly 80,000 square kilometers and in January 2026 it reached Argentina, invading two points near the border with Uruguay. Over the first two years after the invasion, attacks focused on Phoenix canariensis, yet the three most common native palms in Uruguay, Butia odorata, Butia yatay, and Syagrus romanzoffiana, are currently being attacked. The diagnostic key to differentiate the pair R. palmarum / R. ferrugineus is based on three characters: the tip of the rostrum, the tegminal plate, and the ratio between the interocular space and the width of the rostrum at the base. Niche models showed that Uruguay and the neighboring areas of Argentina and Brazil are suitable for R. ferrugineus, and these are precisely the areas where both the highly susceptible P. canariensis and the native B. odorata, B. yatay, and S. romanzoffiana are present. Neighboring countries should therefore be prepared for the expansion of R. ferrugineus in the short term.

zoology↗

bioRxiv2026

Atta Leafcutter Ants are Fine-Scale Bioindicators of Geographic and Seasonal Climate Changes Across the Americas

AimWe develop Atta leafcutter-ants as bioindicators that respond at fine scales to geographic and seasonal climate changes in the Americas, thereby addressing the paucity of versatile insect bioindicator systems capable of monitoring climate in both Southern and Northern Hemispheres. LocationAmerican tropics and sub-tropics from latitudes S33.6{degrees} to N33.2{degrees}, with case studies from Colombia, Mexico, and southern USA. Time Period2012-2024. Taxon StudiedAtta leafcutter-ants. MethodsWe elucidate biogeographic patterns of mating-flight phenology of Atta leafcutter-ants across the entire Atta range from Uruguay/Argentina to the USA, using 2335 records of Atta reproductives from the community database iNaturalist, then ground-truth these patterns by comparison with (i) mating-flight records (n=806) from the Atta literature; and (ii) mating-flight observations (n=836) accumulated by a consortium of experts who have researched Atta for a combined 1000+ work-years. Onset of mating flights can be timed with great precision in Atta populations because mass-mating flights are synchronized and triggered by the first major rainfall of a rainy season. ResultsBiogeographic patterns in climate-dependent mating-flight phenologies recorded at iNaturalist are corroborated by observations accumulated in the literature and by Atta experts. Analyses reveal so-far unknown gradients in mating-flight phenology (e.g., Colombia to USA) that are correlated to geographic climate gradients, and season switches of mating flights from early to late in the year between proximate Atta populations (e.g., 200 kilometers apart), for example in the climatically complex Andean regions of Colombia. Regional differences in Atta mating-flight phenology correspond to temporal differences in rainfall between ecoregions of Colombia. Main ConclusionsAtta ants are tractable insect bioindicators to monitor climate impacts with detailed spatial and temporal resolution across a 9200-kilometer trans-equatorial transect in the Americas. We outline future research directions to explore climate-dependent biology using the continuously growing, and now ground-truthed, information at iNaturalist on Atta mating behavior.

ecology↗

bioRxiv2021

Recurring adaptive introgression of a supergene that determines social organization

Introgression has been proposed as an essential source of adaptive genetic variation. However, a key barrier to adaptive introgression is that recombination can break down combinations of alleles that underpin many traits. This barrier might be overcome in supergene regions, where suppressed recombination leads to joint inheritance across many loci. Here, we study the evolution of a large supergene region that determines a major social and ecological trait in Solenopsis fire ants: whether colonies have one queen or multiple queens. Using coalescent-based phylogenies built from the genomes of 365 haploid fire ant males, we show that the supergene variant responsible for multiple-queen colonies evolved in one species and repeatedly spread to other species through introgressive hybridization. This finding highlights how supergene architecture can enable a complex adaptive phenotype to recurrently permeate species boundaries.

evolutionary biology↗

bioRxiv2018

Landscape genomics of an obligate mutualism: discordant population structures between a leafcutter-ant and its fungal cultivars

To explore landscape genomics at the range limit of an obligate mutualism, we used genotyping-by-sequencing (ddRADseq) to quantify population structure and the effect of hostsymbiont interactions between the northernmost fungus-farming leafcutter ant Atta texana and its two main types of cultivated fungus. At local scales, genome-wide differentiation between ants associated with either of the two fungal types is greater than the differentiation associated with the abiotic factors temperature and precipitation, suggesting that specific ant-fungus genome-genome combinations may have been favored by selection. For the ant hosts, we found a broad cline of genetic structure across the range, and a reduction of genetic diversity along the axis of range expansion towards the range margin. In contrast, genetic structure was patchy in the cultivated fungi, with no consistent reduction of fungal genetic diversity at the range margins. This discordance in population-genetic structure between ant hosts and fungal symbionts is surprising because the ant farmers co-disperse with their vertically-transmitted fungal symbionts, but apparently the fungi disperse occasionally also through between-nest horizontal transfer or other unknown dispersal mechanisms. The discordance in populationgenetic structure indicates that genetic drift and gene flow differ in magnitude between each partner in this leafcutter mutualism. Together, these findings imply that variation in the strength of drift and gene flow experienced by each mutualistic partner affects adaptation to environmental stress at the range margin, and genome-genome interactions between host and symbiont influences adaptive genetic differentiation of the host during range evolution in this obligate mutualism.

evolutionary biology↗