Assessment of Beetles in the Kafa Biosphere Reserve with Notes on Other Insects
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NABU - Biodiversity Assessment in Kafa, Ethiopia Schöller: beetles (& butterflies by Wiersborsky) Assessment of beetles in the Kafa Biosphere Reserve with notes on other insects Matthias Schöller, contribution on butterflies by Daniel Wiersborski 1 HIGHLIGHTS For the first time a comprehensive assessment of beetles at Kafa Biosphere Reserve has been conducted and reported, covering a wide range of habitats and altitudinal gradients. The various sampling and trapping methods applied proved to be effective. 400 beetle species belonging to 79 families / subfamilies were recorded, almost every major beetle family occurred in the sampled sites. Within 10 sampling days and despite collecting during an unfavourable season, 164 Staphilinidae species were recorded, out of ca. 530 known for Ethiopia (30%). Several species are new to science, e.g. in the genus Tachinoplesius. To date material determinations indicates that 35 species are new to science; however, this number could increase as far determinations are completed. In the bamboo forests, phytotelmata, yet unknown for Ethiopia, were discovered, hidden in freshwater habitats . Wetland habitats like the Shoriri wetlands are in good condition, more research in these areas is needed. Species diversity in PFM forest sites benefits when the moisture in the ground layer is kept by e.g. presence of large trees or microstructures like climbing plants, tree holes, or diversity in shrubs and herbs. Leaf beetles in the genus Altica could be good indicators of the status of conservation of the wetlands. NABU - Biodiversity Assessment in Kafa, Ethiopia Schöller: beetles (& butterflies by Wiersborsky) 2 INTRODUCTION Information on the insect fauna of Ethiopia was never reviewed, i.e. no check-list for the insects of Ethiopia is available. For few taxa only, this information can be quickly extracted from existing catalogues or keys (e.g. for the dragonflies). No national insect collection, which would allow comparison with earlier collections, exists. Moreover, comparatively few museum specimens are available in European museums. Existing information (Biondi et al., 2015; Borowiec, 1994; Medvedev, 2000; Selman, 1973) suggests that the insect fauna of Ethiopia differs considerably from that of the neighbouring countries Sudan, South Sudan, Somalia and Kenya. However, only the latter was comparatively well studied concerning the insect fauna. Consequently, information has to be compiled from scattered original publications, typically revisions of insect taxa on the genus or species-group level. This cannot be provided even for the beetles during this rapid assessment, it will be a long-term project, ideally coordinated by an Ethiopian institution. Such a checklist will give information on a large scale only, because many of the descriptions from the 19th and early 20th Century do not give the collection sites in detail (e.g. “Abyssinia”). An example for such a check-list, compiled by the author, is given in the appendix 2. On the species level, the beetle fauna of Ethiopia is composed of Afrotropical and Palaearctic elements. The study of museum specimens of leaf beetles, Chrysomelidae, by the author suggests the presence of only few Palaearctic elements. Generally, higher species diversity was expected in lowland ecosystems compared to montane forests. An influence of seasonality was expected because most Ethiopian beetles traced in museum collections were collected in April and March. The impact of settlements and habitat fragmentation on beetle species composition cannot be predicted so far, because the ecological demands of the different species are not yet known The beetles were sorted to the family level. The analysis resulting ideally in determination to species level, accompanied by information on status (taxa new to Ethiopia, new to science), will take on average at least one year. 3 MATERIALS AND METHODS 3.1 Study area The study sites are listed in Table 1. The study sites visited during the 10 working days included coffee forests (montane forests), bamboo forest, secondary forest, river banks, and wetlands. Table 1: Study sites and characteristics No Code Area Woreda Habitat Sites Bamboo forest / Riverine 1 BA BONGA Adiyo Bamboo forest vegetation 2 BK BONGA Adiyo Montane forests Boka forests 3 KO BONGA Gimbo Montane forests Komba forests Awurada valley Montane forests / Riverine 4 AW BONGA Decha (Gummi River, PFM vegetation sites) 5 AG BONGA Gimbo Wetland Alem Gono 6 SHO BONGA Gimbo Wetland Shoriri NABU - Biodiversity Assessment in Kafa, Ethiopia Schöller: beetles (& butterflies by Wiersborsky) 7 MA BONGA Decha Montane forests Mankira forests 8 GO-wet BOGINDA Gawata Wetland Gojeb wetland 9 GO-riv BOGINDA Gawata/Gimbo river/floodplain forests Gojeb river 10 BO BOGINDA Gawata Montane forests Boginda forests KDA Guest House + 11 BG BONGA Guesthouse anthropogen settlement environment 3.2 Sampling methods A variety of sampling methods and trap types were used. These are presented in the following sections: 3.2.1 Collection methods Beating umbrella With the help of a beating umbrella, insects found on foliage can be caught. The umbrella is held beneath the foliage while the collector strikes it with a stick, and insects fall into the umbrella. It is especially effective with tough and scrubby or spiny plants. A disadvantage is its openness, some active insects can escape. A special umbrella for insects (Fig 1) can be obtained commercially in Europe, but common umbrellas can be also used. In the latter case, they should be unicolour, so insects can be readily perceived. An aspirator is used to collect the insects from the umbrella. Sifter With the help of a sifter (Fig.2), accumulations of organic material like leaf litter, and / or the top layer of soil is sampled. All typical arthropods of the top layer of soil are covered by this collection method. Some very small arthropods may be missed. In forest habitats, one square meter of leaf litter, and the top layer of soil was sampled. This was repeated three times, i.e. a total of three square meters were sampled. In every forest, the following sieving sites were chosen: a relatively open site, a site close to the buttress root of a tree, and a site close to decaying wood, respectively. Additional special microhabitats like organic material in tree hollows or on aerial roots, bark and fungi were sampled when possible. Sweeping net A sweeping net is used e.g. to catch insects present on herbs, grasses or flowers. A solid cloth or gauze is mounted on a metal frame held by a pole (Fig 3 and Fig 4). Aerial insect car net Many beetles fly from one place to another. Those beetles can be caught by aerial nets. In Kafa, an aerial insect car net mounted on a four wheel drive jeep was used (Fig. 5) The net was constructed by the author, as such nets are not commercially available. The length of the net was 2 m, the opening measured 0.5 m2, and the net was attenuate towards the end. A removable collecting bag was attached to the end of the net. The nylon material had a mesh width of 0.2 mm x 0.25 mm. The time and speed of collecting were standardised: one hour between 17:30 and 18:30 with a constant speed of 30 km /h, i.e. a distance of 30 km. GPS-data and altitude was recorded for the start and the end of the distance driven. NABU - Biodiversity Assessment in Kafa, Ethiopia Schöller: beetles (& butterflies by Wiersborsky) 3.2.2 Traps Barber pitfall trap The Barber pitfall trap is a tool for the quantitative assessment of terrestrial arthropods. Primarily nocturnal insects fall into it. Barber traps were positioned in three forest sites and at the Bonga Guest House for a period of six days. A plastic cup was placed in another plastic cup with a hole in the bottom to prevent drowning up the trap during rain (Fig 6). The outer cup was filled up to ¼ with a mixture of two parts ethanol (75%) and one part glycerine. The cup was buried in the ground, the upper rim of the cup carefully positioned on one level with the soil surface, so that it did not present a barrier to walking arthropods. A second Barber trap type with a funnel placed above the collection vial was tested, too. This trap prevents vertebrates from falling into the trap. Barber traps could only be placed in three sites (Guest House, Mankira forest, Komba forest) because the time did not allow visiting more places twice to collect the traps. Flight intercept trap Flight intercept traps are used to catch flying insects. They hit the glass-window of the trap and fall through the funnel into a cup filled with the liquid killing agent, i.e. one part glycerine and two parts 75% ethanol (Fig 7). Generally flying insects are randomly caught. In Kafa, a small type was used, as it can be transported more easily. It was modified with a moth- funnel trap used for forest- and stored-product moths by the author. Two forest sites and the area around the Guest House were sampled. The traps were used continuously for a period of six days. Flight intercept traps could only be placed in three sites because the time did not allow visiting more places twice to collect the traps. Light trap Many, but not all insects are attracted by light. When conditions are ideal, large numbers of insects can be caught. Ideal conditions are temperatures above 18°C, little or no moonlight, and little wind. A variety of light sources can be used, such as white light or black light (ultraviolet light). In Kafa, a light trap was provided by the Ethiopian insect team (Fig 8). A generator was used to power white light bulbs, set in front of a white sheet and a gauze light tower brought from Germany.