Ubiquitous but Ignored? A Case of Water Beetle in Southeastern Europe

Although freshwater habitats, especially springs, are widely recognized as top-priority habitats for monitoring and conservation procedures, their fauna, especially water beetles, are still poorly studied in the southeastern part of Europe. Thus, the dominant water beetle in these habitats, E. bosnica (Zaitzev, 1908) (Insecta: Coleoptera: Elmidae), has been completely ignored and misidentified. This study represents the first review of its taxonomy and its population and ecological traits. Both published and unpublished data are presented and discussed, as well as the results of field sampling in 46 springs and other waterbodies conducted in this region from 2004 to 2019. The identification characters of the male genitalia and the first DNA barcode of the species are presented. The results confirm the close phylogenetic relationship of E. bosnica with E. aenea (Müller, 1806) and E. rioloides (Kuwert, 1890). The species proved to be a useful environmental descriptor and can easily be used as a biological indicator due to its easy identification. The species shows remarkable sensitivity to environmental conditions and inhabits sites that are potentially under increased anthropogenic pressure and could disappear at an alarming rate. Thus, karstic habitats should be included in future conservation and monitoring procedures in this part of Europe.

Water Beetles: Species Diversity and Response to Physico-Chemical Parameters in Different Freshwater Habitats in Samtse, Bhutan

Bhutan is located between the two zoogeographic regions which are assumed to be rich in diversity of water beetles. The study aimed to determine the diversity and distribution pattern of water beetles in different freshwater habitats in Namgaychholing under Samtse district, Bhutan. The study also analysed the association of water beetles with the physico-chemical parameters. The data were collected from four different habitats with sample plot of 3 m × 1 m for a standard time of 1 hour in every plot. A total of 30 species belonging to 7 families were recorded of which Dytiscidae (n=626, RA=51) was the most abundant family and Lacconectus basalis (n=416, RA=34.13) was the most abundant species. The overall Shannon diversity index of the study area was H ′=2.48. Amongst the different habitats, marshy area had the highest Shannon diversity index (H ′=2.45) and stream had the lowest (H ′=1.82). A Kruskal Wallis test on diversity among different habitats showed no significant difference (p<.05). Through a cluster analysis, the species composition between the river and waterlogged showed 100% similarity index. Canonical correspondence analysis showed temperature as a main determining factor affecting the distribution of water beetles. With broad families encompassing the water beetles, similar study on water beetles in different regions of the country is recommended with particular emphasis on different families. Moreover, Bhutan falls in junction of Palearctic and Oriental Zoogeographic regions, which are known to be rich in diversity of water beetles. Hence, study in high-altitude lakes, which are assumed to be rich in diversity of water beetles are recommended despite social beliefs to keep lakes isolated and undisturbed.

Taxonomy of water beetles in the genus Hydrochus Leach, 1817, from Bolivia, Brazil and Paraguay (Coleoptera: Hydrochidae)

The taxonomy of Bolivian, Brazilian and Paraguayan water beetles in the genus Hydrochus Leach, 1817 is presented. The known fauna now consists of 77 species, 37 of which are described as new species. The new species are diagnosed, and high-resolution images of the habitus and male genitalia of each species are given, as are distribution maps. The following new species of Hydrochus are described: H. accinctus n. sp., H. amazonicus n. sp., H. ampliarmus n. sp., H. argutulus n. sp., H. artus n. sp., H. austrinus n. sp., H. canalis n. sp., H. casuarius n. sp., H. clandestinus n. sp., H. colossus n. sp., H. compactus n. sp., H. constrictus n. sp., H. curvus n. sp., H. diffusus n. sp., H. distinctulus n. sp., H. distinctus n. sp., H. diversus n. sp., H. forcipuloides n. sp., H. forcipulus n. sp., H. fritillus n. sp., H. irregularis n. sp., H. liquidus n. sp., H. longissimus n. sp., H. membraneus n. sp., H. personatus n. sp., H. potenspiculatus n. sp., H. pronotulus n. sp., H. quinarius n. sp., H. rectus n. sp., H. reticulatus n. sp., H. robustus n. sp., H. sculptissimus n. sp., H. triangularis n. sp., H. trituberculatus n. sp., H. usualis n. sp., H. velatus n. sp., H. xingu n. sp. New locality data are provided for the following species: H. alternatus Perkins, H. argutus Knisch, H. astrictus Perkins, H. baloghi Makhan, H. basilaris Perkins, H. bicarinatus Perkins, H. bisinuatus Perkins, H. bituberculatus Perkins, H. choennii Makhan, H. coeneni Makhan, H. collaris Perkins, H. cracentis Perkins, H. denarius Perkins, H. drakei Knisch, H. drechseli Makhan, H. ducalis Knisch, H. elsjeae Makhan, H. formosus Perkins, H. hellmani Perkins, H. iduae Makhan, H. jenniferiduae Makhan, H. kellymilleri Perkins, H. leei Perkins, H. lobatus Perkins, H. lobissimus Perkins, H. merkli Makhan, H. obscurus Sharp, H. pietersenae Makhan, H. piroei Makhan, H. pumilio Knisch, H. pupillus Orchymont, H. purpureus Knisch, H. radhakishunae Makhan, H. richteri Bruch, H. secretus Knisch, H. shorti Perkins, H. soekhnandanae Makhan, H. spanglerorum Perkins, H. tarsalis Chevrolet, H. variabilis Knisch, H. zicsii Makhan.

Beaver creates early successional hotspots for water beetles

Beavers (Castor spp.) are ecosystem engineers that induce local disturbance and ecological succession, which turns terrestrial into aquatic ecosystems and creates habitat heterogeneity in a landscape. Beavers have been proposed as a tool for biodiversity conservation and ecosystem restoration. So far, most research has compared biodiversity in beaver wetlands and non-beaver wetlands, but few studies have explored how beaver-created succession affects specific taxa. In this study, we investigated how water beetles responded to different successional stages of wetlands in a beaver-disturbed landscape at Evo in southern Finland. We sampled water beetles with 1-L activity traps in 20 ponds, including: 5 new beaver ponds, 5 old beaver ponds, 5 former beaver ponds, and 5 never engineered ponds. We found that beaver wetlands had higher species richness and abundance than non-beaver wetlands, and that new beaver wetlands could support higher species richness (321%) and abundance (671%) of water beetles compared to old beaver wetlands. We think that higher water beetle diversity in new beaver ponds has resulted from habitat amelioration (available lentic water, shallow shores, aquatic vegetation, and low fish abundance) and food source enhancement (an increase of both dead and live prey) created by beaver dams and floods. We conclude that using beavers as a tool, or imitating their way of flooding, can be beneficial in wetland restoration if beaver population densities are monitored to ensure the availability of newly colonizable sites.

Taxonomy of Central American water beetles in the genus Hydrochus Leach, 1817 (Coleoptera: Hydrochidae)

The taxonomy of Central American water beetles in the genus Hydrochus Leach, 1817 is presented, including the Mexican fauna. The known fauna now consists of 26 species, nine of which are described as new species. The new species are diagnosed, and high-resolution images of the habitus and male genitalia of each species, and detailed descriptions of the male genitalia are given. Geographical distribution maps are given for all species. The following new species are described: H. aeruginosus n. sp. (Mexico), H. argutoides n. sp. (Costa Rica), H. biexcavatus n. sp. (Belize, Costa Rica, Honduras, Mexico, Nicaragua), H. laevigatus n. sp. (Mexico), H. lubricus n. sp. (Mexico), H. mesoamericanus n. sp. (Belize, Mexico), H. nayaritensis n. sp. (Mexico), H. panamensis n. sp. (Panama), and H. perpunctatus n. sp. (Mexico), Images of the habitus and male genitalia, and detailed descriptions of the male genitalia are also provided for the following previously described species: H. beeneni Makhan 1992, H. bernardi Makhan 1994, H. brianbrowni Makhan 2005, H. elineae Makhan 1994, H. foveatus Haldeman 1852, H. vagus LeConte 1852, H. vanvondeli Makhan 1994, and H. variolatus LeConte 1852. New locality data are provided for 17 species: H. beeneni Makhan 1992, H. bernardi Makhan 1994, H. brianbrowni Makhan 2005, H. debilis Sharp 1882, H. directus Perkins 2020, H. elineae Makhan 1994, H. foveatus Haldeman 1852, H. leei Perkins 2019, H. obscurus Sharp 1882, H. pertuberculatus Perkins 2020, H. piroei Makhan 1992, H. sagittarius Perkins 2019c, H. soekhnandanae Makhan 1992, H. steineri Perkins 2020, H. vagus LeConte 1852, H. vanvondeli Makhan 1994, and H. variolatus LeConte 1852. Lectotypes are designated for H. vagus LeConte 1852. H. otvosi Makhan 1993 is a new synonym of H. variolatus LeConte 1852.

Cultural Significance of Beetles in Sub-Saharan Africa

An overview is given of how beetles are utilised, perceived, and experienced in daily life across sub-Saharan Africa. More than 300 people from 27 countries were interviewed and the results were compared with literature findings. Both the adults and larvae of many beetle species are eaten, mainly from the families Curculionidae, Buprestidae, Cerambycidae, Dytiscidae and Scarabaeidae. Some beetle species are used for medicinal purposes. The use of breast-shaped water beetles by adolescent girls to stimulate breast growth could be due to superstition or the effect of the defensive secretion containing steroid hormones. Blister beetles contain cantharidin, which influences the urinary tract, and is therefore used as an aphrodisiac and for treating venereal disease. Throughout Africa children play with beetles by letting them fly on a string. In the Sahel, the hard work of dung beetles is an inspiration for stories. Fireflies are generally associated with ghosts and witches, likely because the glowing of the beetles is interpreted as magical. Many beetle groups are brightly and attractively coloured and are therefore used in ceremonies and commerce. This type of indigenous knowledge, revealed in stories provided by older people, is rapidly disappearing due to urbanisation.

Cuticle Hydrocarbons Show Plastic Variation under Desiccation in Saline Aquatic Beetles

In the context of aridification in Mediterranean regions, desiccation resistance and physiological plasticity will be key traits for the persistence of aquatic insects exposed to increasing desiccation stress. Control of cuticular transpiration through changes in the quantity and composition of epicuticular hydrocarbons (CHCs) is one of the main mechanisms of desiccation resistance in insects, but it remains largely unexplored in aquatic ones. We studied acclimation responses to desiccation in adults of two endemic water beetles from distant lineages living in Mediterranean intermittent saline streams: Enochrus jesusarribasi (Hydrophilidae) and Nebrioporus baeticus (Dytiscidae). Cuticular water loss and CHC composition were measured in specimens exposed to a prior non-lethal desiccation stress, allowed to recover and exposed to a subsequent desiccation treatment. E. jesusarribasi showed a beneficial acclimation response to desiccation: pre-desiccated individuals reduced cuticular water loss rate in a subsequent exposure by increasing the relative abundance of cuticular methyl-branched compounds, longer chain alkanes and branched alkanes. In contrast, N. baeticus lacked acclimation capacity for controlling water loss and therefore may have a lower physiological capacity to cope with increasing aridity. These results are relevant to understanding biochemical adaptations to drought stress in inland waters in an evolutionary and ecological context.