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11 pages, 1490 KB

Open AccessArticle

Seasonal Dynamics of Non-Biting Midges (Diptera: Chironomidae) and Relevant Environmental Factors

by Teng Lei, Jingjing Gu, Mengyao Zhao, Yuqiu Chen, Chao Song and Xin Qi

Insects 2024, 15(12), 921; https://doi.org/10.3390/insects15120921 - 25 Nov 2024

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The family Chironomidae is speciose and is present in almost all freshwater habitats. Adult non-biting midges emerge from waterbodies and swarm in high numbers, occasionally disrupting people’s outdoor activities. In order to understand the seasonal dynamics of species composition, a continuous observation of non-biting midge diversity was performed. Adult non-biting midges were collected using light traps from the autumn of 2022 to the summer of 2023 in an urban wetland park. Species were identified based on morphological characteristics and DNA barcodes. Alpha diversity was evaluated using Margalef, Pielou, and Shannon–Wiener indexes. Beta diversity was evaluated using unconstrained NMDS analysis and constrained CCA. The impacts of environmental factors, including barometric pressure, temperature, relative humidity, and wind speed, on the variation in species composition were estimated in the constrained analyses. A total of 42 species were identified, with 29 species belonging to Chironominae, 9 species belonging to Orthocladiinae, and 4 species belonging to Tanypodinae. The species composition varied across different seasons. Summer sites and autumn sites shared the highest similarity in diversity, and spring sites presented the lowest diversity. The variation was significantly correlated with environmental conditions. The results showed that seasonality is a factor influencing the diversity of adult non-biting midges. Full article

(This article belongs to the Section Insect Ecology, Diversity and Conservation)

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10 pages, 2092 KB

Open AccessArticle

Swarming Insects May Have Finely Tuned Characteristic Reynolds Numbers

by Andy Reynolds

Biomimetics 2024, 9(11), 660; https://doi.org/10.3390/biomimetics9110660 - 30 Oct 2024

Cited by 1 | Viewed by 1754

Abstract

Over the last few years, there has been much effort put into the development and validation of stochastic models of the trajectories of swarming insects. These models typically assume that the positions and velocities of swarming insects can be represented by continuous jointly Markovian processes. These models are first-order autoregressive processes. In more sophisticated models, second-order autoregressive processes, the positions, velocities, and accelerations of swarming insects are collectively Markovian. Although it is mathematically conceivable that this hierarchy of stochastic models could be extended to higher orders, here I show that such a procedure would not be well-based biologically because some terms in these models represent processes that have the potential to destabilize insect flight dynamics. This prediction is supported by an analysis of pre-existing data for laboratory swarms of the non-biting midge Chironomus riparius. I suggest that the Reynolds number is a finely tuned property of swarming, as swarms may disintegrate at both sufficiently low and sufficiently high Reynolds numbers. Full article

(This article belongs to the Special Issue Computational Biomechanics and Biomimetics in Flying and Swimming: 2nd Edition)

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15 pages, 1183 KB

Open AccessFeature PaperArticle

Adult Chironomid (Chironomidae: Diptera) Positive Phototactic Behaviour—A Cue for Adult Population Management and Impact on Insect Biodiversity at Lake Trasimeno, Central Italy

by Matteo Pallottini, Sarah Pagliarini, Marianna Catasti, Leonardo Giontella, Gianandrea La Porta, Roberta Selvaggi, Elda Gaino, Leonardo Spacone, Alessandro Maria Di Giulio, Arshad Ali and Enzo Goretti

Environments 2024, 11(1), 1; https://doi.org/10.3390/environments11010001 - 19 Dec 2023

Cited by 2 | Viewed by 4003

Abstract

The positive phototaxis showed by adults of some pestiferous chironomid species, annoying to waterfront residents and businesses, was investigated at Lake Trasimeno (Italy) to develop a strategy against their massive swarms. Two experimental devices (ChiroTraps), located at Passignano sul Trasimeno (PA) and at Sant’Arcangelo (SA), were employed in 2019 and 2020. The total biomass attracted by the traps amounted to 6498.78 g at PA and to 8597.05 g at SA. Chironomids biomass constituted 99.66% and 96.59% of the biomass in these sites, respectively. Only a few specimens of other fauna except chironomids were found at PA. In contrast, the values at SA were considerable, being 91- and 35-fold (number of taxa and weight, respectively) higher than in PA. These results demonstrated that exploiting the light attraction behaviour of adult chironomids is an efficient method for managing their pestiferous populations, thereby reducing the necessity of using insecticides. By comparing the biodiversity in the two sites, it was evident that the differences were linked primarily to the environmental conditions. Finally, it is suggested that light trapping systems should be located in urban centres or floated on the lake surface to maximise the efficiency of trapping chironomids and minimising the impact on biodiversity. Full article

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19 pages, 1672 KB

Open AccessArticle

Scale-Free Chaos in the 2D Harmonically Confined Vicsek Model

by Rafael González-Albaladejo and Luis L. Bonilla

Entropy 2023, 25(12), 1644; https://doi.org/10.3390/e25121644 - 11 Dec 2023

Cited by 3 | Viewed by 2856

Abstract

Animal motion and flocking are ubiquitous nonequilibrium phenomena that are often studied within active matter. In examples such as insect swarms, macroscopic quantities exhibit power laws with measurable critical exponents and ideas from phase transitions and statistical mechanics have been explored to explain them. The widely used Vicsek model with periodic boundary conditions has an ordering phase transition but the corresponding homogeneous ordered or disordered phases are different from observations of natural swarms. If a harmonic potential (instead of a periodic box) is used to confine particles, then the numerical simulations of the Vicsek model display periodic, quasiperiodic, and chaotic attractors. The latter are scale-free on critical curves that produce power laws and critical exponents. Here, we investigate the scale-free chaos phase transition in two space dimensions. We show that the shape of the chaotic swarm on the critical curve reflects the split between the core and the vapor of insects observed in midge swarms and that the dynamic correlation function collapses only for a finite interval of small scaled times. We explain the algorithms used to calculate the largest Lyapunov exponents, the static and dynamic critical exponents, and compare them to those of the three-dimensional model. Full article

(This article belongs to the Section Statistical Physics)

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12 pages, 3251 KB

Open AccessFeature PaperArticle

Role of Chironomus plumosus (Diptera, Chironomidae) Population in the Central Zone of the Shallow Lake Trasimeno (Italy)

by Matteo Pallottini, Sarah Pagliarini, Marianna Catasti, Gianandrea La Porta, Roberta Selvaggi, Elda Gaino, Leonardo Spacone, Alessandro Maria Di Giulio, Arshad Ali and Enzo Goretti

Sustainability 2023, 15(6), 5540; https://doi.org/10.3390/su15065540 - 21 Mar 2023

Cited by 4 | Viewed by 3629

Abstract

Adult swarms of non-biting pestiferous midges (Chironomidae: Diptera), primarily Chironomus plumosus, prevail over and around Lake Trasimeno (Italy) during the summer season. The current field survey (2018–2021, 33 sampling occasions) was carried out in the central area of the lake. It revealed a macrobenthic community consisting of Chironomidae (40.72%) and Oligochaeta (59.23%). Chironomus plumosus was the dominant chironomid species (98.84%). A previous survey (2000–2002, 11 sampling occasions) had highlighted a similar community, although C. plumosus had a lower density, comprising a maximum of 295.0 ind. m⁻². This density was five times lower than the maximum densities of 2018–2021. A survey (2018–2021, 58 sampling occasions) conducted in the littoral zone revealed much greater chironomid biodiversity, with C. plumosus abundance of only 24.35% among all chironomids. This species showed an average density (88.1 ind. m⁻²) five times lower than its density (467.9 ind. m⁻²) in the central zone (2018–2021). Therefore, the central area of the lake, constituting about 90% of its total surface area, is the main region for the origin of C. plumosus adults and, consequently, during the summer months, it is the primary source of the annoying swarms that affect residents and tourists of the lake vicinity. Full article

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15 pages, 2271 KB

Open AccessArticle

Population Dynamics and Seasonal Patterns of Chironomus plumosus (Diptera, Chironomidae) in the Shallow Lake Trasimeno, Central Italy

Sustainability 2023, 15(1), 851; https://doi.org/10.3390/su15010851 - 3 Jan 2023

Cited by 7 | Viewed by 4003

Abstract

Field sampling of littoral macrobenthos of the shallow Lake Trasimeno was conducted along 17 years (2005–2021) on 129 different occasions. This long-term field study deepens the knowledge concerning the life cycle of Chironomus plumosus (Diptera), the main responsible for summer chironomid swarms that adversely affect human littoral activities, providing useful information for its management. About 108,000 macrobenthic specimens were collected, belonging to Oligochaeta (Naididae) (62%), Diptera (Chironomidae) (37%), and only 1.5% to other invertebrate taxa. Eighteen chironomid taxa were found. The trend of chironomid density was not affected by C. plumosus, which showed a maximum increase in September. This peak is justified by the presence of large swarms of C. plumosus in late August in which the populations of the central area of Lake Trasimeno consistently participate. The larval density of this species did not increase over the 17 years. A detailed analysis of the sampled larvae and adult biomass catches from 2017 to 2020 reveals that four annual swarmings occurred: in April, July, August, and September–October. The water temperature remains higher than 20 °C during the night hours from the end of May to mid-September, strengthening the hypothesis of the three midge swarming cycles in the summer period until early autumn. Full article

(This article belongs to the Section Environmental Sustainability and Applications)

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