Search results for "Dragonfly"
showing 7 items of 17 documents
The macrophyte, Stratiotes aloides, protects larvae of dragonfly Aeshna viridis against fish predation
2004
Predation could be one force determining which contemporary species occupy a certain habitat. Aeshna viridis is an endangered dragonfly species with a larval distribution strongly associated with lakes where the water plant, water soldier, Stratiotes aloides, occurs. In this study, the larvae were almost exclusively found in patches of S. aloides. To study larval association with S. aloides further, we conducted a series of laboratory experiments. Behavioural experiments indicated that larvae preferred S. aloides. Aeshna viridis larvae were nocturnal and rather inactive. Larvae on S. aloides were less susceptible to predation by the perch, Perca fluviatilis, than larvae on another water pla…
Influence of temperature and photoperiod on embryonic development in the dragonflySympetrum striolatum(Odonata: Libellulidae)
2015
Temperature and photoperiod play major roles in insect ecology. Many insect species have fixed degree-days for embryogenesis, with minimum and maximum temperature thresholds for egg and larval development and hatching. Often, photoperiodic changes trigger the transfer into the next life-cycle stadium. However, it is not known whether this distinct pattern also exist in a species with a high level of phenotypic plasticity in life-history traits. In the present study, eggs of the dragonfly Sympetrum striolatum Charpentier (Odonata: Libellulidae) are reared under different constant and fluctuating temperatures and photoperiodic conditions in several laboratory and field experiments. In general…
Resolving Bio-Nano Interactions of E.coli Bacteria-Dragonfly Wing Interface with Helium Ion and 3D-Structured Illumination Microscopy to Understand B…
2020
Obtaining a comprehensive understanding of the bactericidal mechanisms of natural nanotextured surfaces is crucial for the development of fabricated nanotextured surfaces with efficient bactericidal activity. However, the scale, nature, and speed of bacteria-nanotextured surface interactions make the characterization of the interaction a challenging task. There are currently several different opinions regarding the possible mechanisms by which bacterial membrane damage occurs upon interacting with nanotextured surfaces. Advanced imaging methods could clarify this by enabling visualization of the interaction. Charged particle microscopes can achieve the required nanoscale resolution but are …
Why are wasps so intimidating: field experiments on hunting dragonflies (Odonata: Aeshna grandis)
2003
Abstract The mechanisms of aposematism (unprofitability of prey combined with a conspicuous signal) have mainly been studied with reference to vertebrate predators, especially birds. We investigated whether dragonflies, Aeshna grandis, avoid attacking wasps, Vespula norwegica, which are an unprofitable group of prey for most predators. As a control we used flies that were painted either black or with yellow and black stripes. The dragonflies showed greater aversion to wasps than to flies. Black-and-yellow-striped flies were avoided more than black ones, suggesting that aposematic coloration on a harmless fly provides a selective advantage against invertebrate predators. There was no signifi…
Risk of Local Extinction of Odonata Freshwater Habitat Generalists and Specialists
2014
Understanding the risk of a local extinction in a single population relative to the habitat requirements of a species is important in both theoretical and applied ecology. Local extinction risk depends on several factors, such as habitat requirements, range size of species, and habitat quality. We studied the local extinctions among 31 dragonfly and damselfly species from 1930 to 1975 and from 1995 to 2003 in Central Finland. We tested whether habitat specialists had a higher local extinction rate than generalist species. Approximately 30% of the local dragonfly and damselfly populations were extirpated during the 2 study periods. The size of the geographical range of the species was negati…
Regional variations in occupancy frequency distributions patterns between odonate assemblages in Fennoscandia
2018
Odonate (damselfly and dragonfly) species richness and species occupancy frequency distributions (SOFD) were analysed in relation to geographical location in standing waters (lakes and ponds) in Fennoscandia, from southern Sweden to central Finland. In total, 46 dragonfly and damselfly species were recorded from 292 waterbodies. Species richness decreased to the north and increased with waterbody area in central Finland, but not in southern Finland or in Sweden. Species occupancy ranged from 1 up to 209 lakes and ponds. Over 50% of the species occurred in less than 10% of the waterbodies, although this proportion decreased to the north. In the southern lakes and ponds, none of the species o…