Janosch Dohrs

I am a doctoral candidate in biology at the Ruhr University Bochum (RUB) and my dissertation is on the perfume biology of orchid bees.

Orchid bees are a tribe of corbiculate bees found exclusively in the tropical regions of Central and South America. The male orchid bees exhibit a remarkable and, according to current knowledge, unique behaviour. They collect a wide range of different scents and use them to create a species-specific perfume, comparable to pheromones in terms of function. Their behaviour is the reason for the significant ecological role played by orchid bees in the tropical rainforest. This is because a wide variety of different plant species (in particular orchids) have developed a highly specific pollination system which makes them highly dependent on orchid bees.

The benefits for the plants in this system are largely self-explanatory, however there are still questions regarding the benefits to the male bees of the perfumes collected. Besides its function simply in terms of finding a mate, the perfume also has potential for the coding of further information.

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Male orchid bee resting in Senna blossom

The question relating to the additional coded information forms the key element of my doctoral thesis. Using this system, valuable insights can be provided regarding the processes of speciation and of mate selection in the animal world. The high ecological importance of the orchid bees in the tropics of the Americas means that an under-standing of the ecology may be helpful in developing concepts for protecting this ecosystem.

Regular stays abroad (Costa Rica, Mexico, USA) are necessary for conducting my field research. A large proportion of my field studies are being carried out in South Florida. This location was selected due to the high distribution of an orchid bee species, Euglossa dilemma, introduced by chance (the original range of this species extends from southern Mexico to northern Costa Rica) and due to the excellent infrastructure locally. As part of my doctoral thesis, numerous mating experiments will be conducted on the test organism E. dilemma. My second stay in Florida from the start of August to mid-November 2024 was funded by the Prof. Bingel scholarship from the DAAD-Stiftung. The aim of the stay was to carry out experiments on the function of orchid bee perfume for the purpose of mate selection in the context of species recognition.

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The international reasearch group working on FLREC Campus

I chose Ft. Lauderdale Research & Education Center (FLREC) as the host institution. There has been a cooperation in place here with Dr Chouvenc's research group for many years. Over the course of its existence, this cooperation has produced a range of findings relating to different aspects of orchid bee ecology (in particular in relation to social biology and function of perfume, see Henske et al., 2023; Saleh et al., 2021, 2022; Saleh & Ramírez, 2019).) The FLREC is located in Davie, in Broward County, and is part of the University of Florida's Institute of Food and Agricultural Sciences.

On the FLREC campus, a number of flight cages were set up by research groups from the RUB and from the University of California Davis for conducting cage experiments on orchid bees. The pre-existing cooperation with the host institution meant that the coordination and planning of the stay ran smoothly. However, unlike the previous year,   I was not able to live on the FLREC campus in 2024 and therefore had to live in rented accommodation a bit off campus in a suburb of Ft. Lauderdale. I shared a nice accommodation with a doctoral candidate from the University of California Davis with whom I had worked on last year's project.

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Cages set up for experiments on-campus

My working day on site began each morning (Monday to Sunday) at 7.30 am and started with observations in the flight cages. The purpose of the morning observations was to document behaviour, in particular the behaviour of the male orchid bees. Male orchid bees are generally most active from sunrise to late morning and for this reason mornings were devoted to observations. Because a large number of naive (i.e. freshly emerged) males and females were required, these were reared on the campus. Each day, after the observations, these young bees had to be examined for individuals which had freshly emerged from the pupa.

Following the observations, there was generally still work to do on a working day. While the mornings mostly followed the same pattern, the afternoons were more varied. Afternoons were used, on the one hand, for maintaining the flight cages, i.e. for removing weeds, tending to nectar and pollen producing plants, mending any holes and repairing the irrigation system; and on the other hand, there was often lab work and office work which had to be done.

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During field research

For the lab work, I had all the equipment in the host laboratory available to me and I had support from Dr Chouvenc and his staff – support which I needed. The lab work largely comprised preparations of the test bees and preparation of samples for subsequent analysis in Bochum. In addition to the laboratory equipment, I was also provided with a place in the office where, in the afternoons, I could complete office work and have the regular meetings with my supervisor. After work, I also attended the regular FLREC seminars where FLREC faculty members and associated researchers presented their work.

Last year's project produced valuable results supporting the understanding of perfume as a prezygotic reproductive barrier (i.e. a reproductive barrier which takes effect before fertilization of the egg. This prevents costly hybrid matings as interspecific hybrids are frequently infertile or less fertile) which will form the basis of subsequent experiments next year in 2025. The preliminary results have already been presented at the annual meeting of the Entomological Society of America and in the context of public lecture in a German entomological association. The plan is for the data collected in 2024 to also be published in a specialist journal in 2025.

As this was my second stay with the host institution, I had already built up some good friendships in Florida before this year. However, during this year's stay, I was able to make new contacts and consolidate existing ones, in particular within the host research group but also outside this. Contacts within the host research group are of a professional but also personal nature. I think that, after successfully completing my doctorate, there will also be the opportunity for me to carry out potential future projects within this cooperation. I am also pleased to still be working with, and within, the host research group on joint projects.

However, beyond the professional level, I also made a large number of international friends and gained insights into a wide range of different cultures. My impressions were shaped, in particular, by the culinary specialities of the international student body. This meant that, on various occasions, I had the opportunity to try, for example, Mexican aguachile (a cold dish made with prawns or raw fish and with cucumber, lemon juice and chillies), Ecuadorian llapingachos (a fried potato pancake) and Nigerian chin chin (a fried dough-based snack). On a number of occasions, I enjoyed an evening meal with some of the students, including a Chinese hot pot and Korean BBQ.

At the start of November, a huge event took place in the centre of Ft. Lauderdale to celebrate the Day of the Dead (Día de Muertos). There were lots of stalls selling a variety of traditional Latin American dishes and a range of hand-crafted goods, all accompanied by live music. In the US, Thanksgiving is traditionally celebrated on the fourth Thursday of November. To mark this, I had been invited to join a member of staff from the host research group together with other students who either had not travelled home for the public holiday or who, as international students, did not celebrate Thanksgiving in their home countries.

The large proportion of Latin American students and staff at the FLREC meant I was also able to significantly improve my Spanish skills. South Florida has a strong Latin American (especially Cuban) influence. From this perspective, the chance to improve my Spanish skills was relevant to me personally but also professionally as a large part of my field research is carried out in rural regions of Spanish-speaking countries (Mexico and Costa Rica). It is particularly useful to have a command of Spanish here because, in these regions, people often only have very limited English language skills.

Since the project required observations to be carried out almost every day, leisure activities were largely confined to afternoons or evenings. Firstly, there were the regular board game evenings on the campus. These were organised by Dr Chouvenc. Besides well-known board games, such as Ticket to Ride, Dr Chouvenc's own creations were also frequently introduced and tested out. I also went to a few concerts during my stay. Two of these concerts took place at the Seminole Hard Rock Hotel & Casino Hollywood, also known colloquially as “The Guitar Hotel”. This is a casino and hotel in the shape of a guitar which, as a landmark, is prominently visible from the main road, “Florida’s Turnpike“, in Hollywood.

Although South Florida is heavily urbanized, there are still a number of opportunities here for nature lovers to get out into the countryside as much as they need. I spent many afternoons in the various country parks. Fern Forest Nature Center and Tree Tops Park are certainly worth mentioning. There is also a cooperative arrangement in place with these parks. We have deployed nesting boxes for orchid bees and therefore obtain from here a proportion of the freshly emerged bees. These parks have various “nature trails” which give an insight into Florida's nature, despite the surrounding roads. There is a cooperative arrangement in place with another park - Flamingo Gardens. This park combines a botanical garden, a zoo, a wildlife sanctuary and a museum. Flamingo Garden specialises, in particular, in native species in Florida. I generally combined visits to these parks with smaller project-related work. For this, I was able to use cars from the university's carpool.

For nature lovers, a visit to the Everglades National Park is essential. This is a national park covering an area of around 5,500 km² and characterised by wetlands. I hired a car together with other students for the visit. It is not possible to visit the National Park without a car as the individual trails can only be accessed via a long road. The highlights that can be seen here are Caribbean manatees, Mississippi alligators, American crocodiles and large number of different birds.

All in all, my stay in South Florida and at the FLREC was a really defining experience for me, both personally as well as professionally. I would like to thank the DAAD-Stiftung for making this experience possible.