CHIRONOMUS Journal of Chironomidae Research , ces 365 derniers jours

Journal of Chironomidae research



jeudi 17 juin 2021

mardi 15 décembre 2020

  • Short comment on Chironomidae (Insecta: Diptera) from Brazil’s Federal District

    There is much left to learn about the diversity of Chironomidae in Brazil. To help to resolve this problem, a preliminary study of the Chironomidae present in a stream located in center of Brazil was proposed. The aim of this research was to provide a first record of the Chironomidae assemblage at Sarandi stream, in the Brazilian Cerrado. Samples were taken using a handheld D-net from the stream in October 2009. The samples were transported to the laboratory where the material was processed and the Chironomidae specimens were slide mounted, counted and identified to genera. Ninety individuals belonging to 15 genera were found, Chironomini was the richest tribe, with seven genera, while Tanytarsini showed the highest abundance of individuals (55.6%). Overall, Rheotanytarsus (20%), Tanytarsus ortoni-group (16.7%) and Lopescladius (14.4%) were the most abundant genera.


mardi 20 octobre 2020

  • Longevities of Adult Chironomidae (Diptera) from Two Streams in Iceland

    Mean annual air temperatures are predicted to increase by several degrees in the Arctic. This increase in temperature will likely impact organisms adapted to current conditions. Studies of longevities of winter-active Chironomidae from cold, groundwater-fed streams in Minnesota demonstrate that winter-emerging species are long-lived as adults when incubated at cold or sub-freezing air temperatures post emergence. It is unknown if this holds for species emerging in sub-arctic latitudes during warm months, or if warm air temperatures affect the adults of species emerging from cold and geothermally heated streams. The goal of this study was to determine the effects of exposure to air temperatures predicted by climate change models on the longevities of Chironomidae emerging from both cold and geothermally heated larval environments. Chironomidae were trapped at emergence from two groundwater-fed streams with contrasting (warm and cold) thermal regimes at the Hengladalir valleys in the Hengill alpine geothermal area in southwestern Iceland over 4 days in July 2018. Adults (N=102) were randomly divided into two treatments and incubated at either 20°C or 6°C for 28-32 days to determine influence of source stream and incubation temperature on adult longevity. These temperatures were selected to simulate current and predicted water and air temperatures that adult chironomids are likely to be exposed to with climate change. Adults incubated at 6°C survived longer than adults incubated at 20°C irrespective of source stream. All adults incubated at 20°C died within 1-5 days post-emergence. Longevities of taxa incubated at 6°C ranged from 13 to more than 32 days. Species of Diamesa exhibited the greatest longevities, with 41.7% surviving more than 28-32 days post-emergence at 6°C. We were unable to determine maximum longevity for Diamesa within the 6°C treatment because surviving adults had to be sacrificed at the termination of the experiment on day 32. However, the minimum longevity we report is similar to longevities determined for other Diamesa species and indicates that Diamesa species in Iceland are also long-lived under cold air temperatures. We suggest there may be a difference in longevity between sex, with females living longer than males at cold temperatures. By contrast, we found that both sexes of Diamesa and all other chironomid taxa that we tested are susceptible to warm air temperatures regardless of stream of origin. Therefore, warming climatic temperatures could potentially lead to shortened adult lifespans for these sub-arctic taxa.


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