Insect Communities

Counting pollen tubes in Třeboň

Yannick behind a microscope looking at pollen tubes.

Recently, Yannick has spent a few days at the Botanical Institute of the Czech Academy of Science in Třeboň. There, together with Štěpán Janeček, he focused on pollen tubes of Hypoxis camerooniana, a common plant of montane grasslands of Mt. Cameroon. We selected this species as a model for our case study of the role of UV reflectance in pollination. The collected stigmas of specimens with manipulated UV patterns and control treatments were searched for germinating pollen grains to reveal whether they were effectively pollinated. Together with data on flower visitors, the pollen tubes will be analysed by Raissa, Štěpán’s Cameroonian PhD student.

New research: Fire, bombs and arthropods

For her Master thesis, Lucka will be sampling communities of arthropods at the relatively recently abandoned training bombing ranges in the Brdy Mts. Since 1930s the whole mountain range served as a military training area, especially target ranges for bombing created unique open heathlands. Lucka’s project will provide multitaxa data on the influence of such intensive disturbances to arthropod communities, which could potentially be highly useful for long term conservation of the unique habitats. On Friday, together with our close collaborator Ondra Sedlacek, we have visited Jordan and Tok bombing ranges to select individual study plots. The sampling will start a bit later in the Spring.

Recently burnt plots in the Jordan bombing range, Brdy Mts.

Back to Cameroon

Yesterday, a small part of our group has left to Cameroon again. Vincent, Sylvain and Pavel will spend two months in the field, presumably finishing our sampling of both butterflies and moths along the altitudinal gradient of Mt. Cameroon. During the last weeks of their expedition, they will also start with our research of influence of elephant disturbances on communities of both lepidopteran groups. Good luck!

Sylvain, Vincent and Pavel waiting for a connecting flight in Istanbul. Their last chance of connection, there is still no internet in the SW province in Cameroon.

New GAUK grant for our group

Recently our group, with Yannick as the principal investigator, has successfully applied for a student grant by the Grant Agency of the Charles University (GAUK).  The project is entitled “The importance of seasonality in shaping plant-pollinator networks in tropical montane forest” and will be focused on collecting data from more seasons in the montane forests around Mann’s Spring on Mt. Cameroon. We are very grateful to the Charles University for this opportunity to gain a better understanding of the influence of seasonality on pollination networks.

Our field camp in the Mann’s Spring area. © Francis Luma Ewome

Exploring floristic diversity in the Afrotropics

This week a new publication on the floristic diversity in the afrotropics, co-autored by Yannick, has been published in BMC Biology using the RAINBIO database. In this paper, spatial variation in floristic diversity and data collection is shown. Furthermore, it also shows the difficulties arising with quantifying diversity patterns using data gathered from different sources, with herbaria specimens being the main data source. More botanical exploration is needed to fill important gaps in our knowledge regarding afrotropical plant communities. However, the data presented already gives a good backbone for more sustainable management and improved conservation practices of Africa’s rich and unique flora. The paper has already received positive commentary in BMC Biology by one of the editorial board members (Magurran 2017) and has been the focus of a blogpost on the BMC Biology webpage.

The Afrotromontane forest canopy at Mann Spring, Mt. Cameroon. © Š. Janeček

Full citation: Sosef, M.S.M., Dauby, G., Blach-Overgaard, A., van der Burgt, X., Catarino, L., Damen, T., Deblauwe, V., Dessein, S., Dransfield, J., Droissart, V., Duarte, M.C., Engledow, H., Fadeur, G., Figueira, R., Gereau, R.E., Hardy, O.J., Harris, D.J., de Heij, J., Janssens, S., Klomberg, Y., Ley, A.C., Mackinder, B.A., Meerts, P., van de Poel, J.L., Sonké, B., Stévart, T., Stoffelen, P., Svenning, J-C., Sepulchre, P., Zaiss, R., Wieringa, J.J.,  and Couvreur, T.L.P. (2017) Exploring the floristic diversity of tropical Africa. BMC Biology 15:15

Back from another successful expedition

Rob, Jan, Yannick, Pavel and our close collaborator Štěpán Janeček have returned, mostly unscathed, from our dry season expedition on Mt. Cameroon. They continued with our research on pollination systems, as well as lepidopteran diversity in the three higher elevations of the mountain. One of our other collaborators, Szabolcs Sáfián, joined us for two weeks to help with the lepidopteran work.

Štěpán setting a camera in the canopy of Syzygium staudtii.

This expedition has provided enormous amounts of data, especially within our pollination research. Over 250 plants were filmed for ±24 hours in order to record their visitors. In the coming months both Jan and Yannick will try to process these recordings (from both last expeditions), but initial checks have already sparked their enthusiasm due to visitation from a wide range of species, e.g. bats, sunbirds, sphingids and rodents.

Just within a month another part of our group (Vincent, Sylvain and Pavel) will already return to finally finish the lepidopteran data collection.

New study on competition in pollination systems

For already a few years, our group collaborates in research of a pollination system of Hypoestes aristata plant in the Cameroonian Bamenda Highlands. We have already revealed the carpenter bee Xylocopa caffra to be its most frequent and efficient pollinator among the wide range of various flower-visiting species. Besides many different insect groups, the flowers are also visited by the northern double-collared sunbird (Cinnyris reichenowi) which does not contribute to the plant’s reproductive success. The sunbird significantly decreases the amount of nectar available for the real pollinators while depleting the nectar sources, and moreover it chases the carpenter bee of the flowering patches while defending the nectar sources. In the new publication, currently published in the prestigious Oecologia journal, we have compared daily energetic requirements of the mentioned frequent visitor species in relation to diurnal changes in the nectar quality and quantity. Our simplistic energetic model showed the smaller carpenter bee as competitively superior to the larger sunbird due to its smaller energy requirements. The larger sunbird seems to reduce this asymmetry in the exploitative competition by its use of the resources when the smaller competitor is inactive, its higher speed of the nectar consumption and the aggressive behaviour. Our study is one of the very few publications reporting the energetic point of view of competition among phylogenetically unrelated nectarivors.

Female (left) and male of Xylocopa caffra on flowers of Hypoestes aristata (© R. Tropek)

Citation: Padyšáková E., Okrouhlík J., Brown M., Bartoš M., Janeček Š. (in press) Asymmetric competition for nectar between a large nectar thief and a small pollinator: an energetic point of view. Oecologia.

New invasive crayfish for Czechia

During our long-term research of freshwater communities of lignite spoil heaps in Nortwestern Bohemia, we have also found several adult females of marbled crayfish (Procambarus fallax f. virginalis) in an artificial pool at the Radovesická spoil heap. Simultaneously, our colleagues led by Jiří Patoka have found another population inhabiting a public park in downtown Prague. Just recently, both our finds have been published by the Biologia journal. The marbled crayfish is an invasive species from Northern America with a strong impact on local communities of native crayfish, as well as the general freshwater biota. Unfortunately, it is a very common aquarium pet, the hobbyists are often responsible for its introduction to new localities. We hope that our new records will help to increase awareness amongst aquarists regarding the danger of spreading of unwanted non-native species. Simultaneously, we will try to initiate its eradication from both localities to avoid spreading to the common landscape.

Locality and picture of the marbled crayfish found in the Radovesická spoil heap. © V. Kolář (and Biologia).

Full citation: Patoka J., Buřič M., Kolář V., Bláha M., Petrtýl M., Franta P., Tropek R., Kalous L., Petrusek A., Kouba A. (2016) Predictions of marbled crayfish establishment in conurbations fulfilled: evidences from the Czech Republic. Biologia 71: 1380-1385.