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PhD student, FRS-FNRS

phone: +32 (0)2 650 22 67

e-mail: sihellem@ulb.ac.be










Research interests



PhD research project

Modalities of Asexual Queen Succession in the neotropical humivorous termite Cavitermes tuberosus and implications of reproductive organisation on alate sex ratio


Supervisors: Yves Roisin and Denis Fournier


Unusual reproductive strategies, combining advantages of sexual and asexual reproduction, have recently been brought to light in social insects. In some termite species, the workforce and dispersing alates are produced sexually and the foundress queen eventually gets replaced by parthenogenetically-produced daughters: this atypical breeding system is termed Asexual Queen Succession (AQS). When AQS is followed by the replacement of the founder king, the foundress queen’s genome will be transmitted in higher proportion than the king’s. This will theoretically favour a female-biased investment in dispersing alates. AQS and its implications have first been discovered in some lower termites of the genus Reticulitermes.

AQS was recently demonstrated by our team in Cavitermes tuberosus, a Termitidae from French Guiana. Contrary to the other species in which it has been documented, AQS in C. tuberosus has several peculiarities: AQS occurs late in the colony’s life, parthenogenetically-produced replacement queens remain of small size and probably low fertility.

Our project focuses on the particularities of AQS in C. tuberosus and its ultimate consequences on alate sex ratio. In addition, we will focus on other promising species, study their breeding systems, evaluate to what extent AQS should favour a female-biased alate investment and whether theoretical predictions are fulfilled.




Educational background



  1. 2015 - today: PhD thesis in Evolutionary Biology (Université Libre de Bruxelles, Belgium)

  2. 2013 - 2015: Master in Organisms Biology and Ecology (Université Libre de Bruxelles, Belgium)

  3. 2010 - 2013: Bachelor in Biological Sciences (Université Libre de Bruxelles, Belgium)



Publications



Hellemans S, Bourguignon T, Kyjaková P, Hanus R, Roisin Y (2017) Mitochondrial and chemical profiles reveal a new genus and species of Neotropical termite with snapping soldiers, Palmitermes impostor (Termitidae : Termitinae). Invertebrate Systematics 31, 394-405.

Fournier D, Hellemans S, Hanus R, Roisin Y (2016) Facultative asexual reproduction and genetic diversity of populations in the humivorous termite Cavitermes tuberosus. Proceedings of the Royal Society B: Biological Sciences 283, 2016.0196.



Posters and oral communications



Hellemans S (2015) Reproductives strategies and sex ratio in the termite Cavitermes tuberosus. 22nd Benelux Congress of Zoology, Amsterdam (The Netherlands) - Invited speaker

Hellemans S, Hanus R, Roisin Y, Fournier D (2015) Particularities of Asexual Queen Succession in the soil-feeding termite Cavitermes tuberosus (Termitidae: Termitinae). 28ème Congrès de l'Union Internationale pour l'Etude des Insectes Sociaux - Section Française, Tours (France).

Hellemans S, Fournier D, Hanus R, Roisin Y (2015) Implications of Asexual Queen Succession in termites on population sex-ratio. 28ème Congrès de l'Union Internationale pour l'Etude des Insectes Sociaux - Section Française, Tours (France).

Hellemans S, Fournier D, Hanus R, Roisin Y (2016) Investigating key traits for AQS emergence in Termitinae. 6th European Meeting of the International Union for the Study of Social Insects, Helsinki (Finland).

Hellemans S, Kaczmarek N, Roisin Y, Fournier D (2017) Wolbachia: a puppet master in the parthenogenesis of the Neotropical termite Cavitermes tuberosus? European Conference of Tropical Ecology, Brussels (Belgium).

Hellemans S, Kaczmarek N, Roisin Y, Fournier D (2017) Symbiosis between Wolbachia and the Neotropical termite Cavitermes tuberosus. Interdisciplinary Scientific Seminars ULB, Brussels (Belgium).

Kaczmarek N, Hellemans S, Roisin Y, Fournier D (2016) Maternally inherited bacteria in the parthenogenetic termite Cavitermes tuberosus: master manipulator or obligate mutualist? Entomology in Belgium, Brussels (Belgium).

Kaczmarek N, Hellemans S, Roisin Y, Fournier D (2017) Sex or food, what matters the most in the intimate relationship between Wolbachia and the parthenogenetic termite Cavitermes tuberosus? 4th Young Natural History scientists' Meeting, Paris (France).

Roisin Y, Hanus R, Hellemans S, Fournier D (2015) Asexual Queen Succession in neotropical soil-feeding termites. III Simpósio Brasileiro de Termitologia, João Pessoa, Paraíba (Brazil).



Awards



  1. 2016: Adrien Bauchau Award
    scientific award for the best Master thesis in Biological sciences

  2. 2015: Jacques Kets Award
    scientific award for the best Belgian master thesis in Zoology, The Royal Zoological Society of Antwerp and the Royal Belgian Zoological Society

  3. 2015: Paul Brien Award
    scientific award for the best Master thesis of the Department of Organismic Biology, ULB







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