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Mr A.J. (Bram) Knegt MSc

PhD Candidate
Faculty of Science
Institute for Biodiversity and Ecosystem Dynamics
Photographer: FNWI

Visiting address
  • Science Park 904
  • Room number: C3.218
Postal address
  • Postbus 94240
    1090 GE Amsterdam
Contact details
  • Research

    I started my PhD in December 2012, supervised by dr. Martijn Egas. My research focuses on the plant-eating arthropod Tetranychus evansi - a spider mite. This spider mite species originated in South America but has recently become an invasive species in many parts of the world. The rapid spread of this species is of concern for agriculture, because it likes to eat many commercially grown crops, such as tomato, potato, aubergine and pepper. 

    One reason why T. evansi can so easily infest these plants is that it can suppress their defense. The exact mechanism behind this is unknown, but it causes the infested plants to be very edible compared to other plants. Upon infestation, the spider mites quickly multiply, and cover the plant with dense webbing. Within 2-3 weeks the plant dies, and the mites disperse to find new host plants.

    Suppression of plant defense is not new for science, but the extent to which T. evansi can suppress plant defense is unprecedented. Why is T. evansi so keen on suppressing plant defense? What evolutionary forces have driven this species to become such an aggressive suppressor? In my research I aim to find answers to these questions.

    Tetranychus evansi female (left) and male (right). Picture downloaded from

  • Contact

    A.J. (Bram) Knegt MS

    PhD Candidate

    Population Biology - Institute for Biodiversity and Ecosystem Dynamics

    University of Amsterdam


    Visiting address

    Science Park 904

    1098 XH Amsterdam

    Room C3.218



    a.j.knegt (at)

  • Publications




    • Kant, M. R., Jonckheere, W., Knegt, B., Lemos, F., Liu, J., Schimmel, B. C. J., ... Alba, J. M. (2015). Mechanisms and ecological consequences of plant defence induction and suppression in herbivore communities. Annals of Botany, 115(7), 1015-1051. DOI: 10.1093/aob/mcv054  [details] 


    • Knegt, B., Alba, J. M., Ataide, L. M. S., Barbosa, T. A., Bernardo, A. M. G., Chafi, R., ... Egas, M. (2017). Meta-analysis reveals intraspecific variation in herbivores for plant-mediated interactions. Poster session presented at Gordon Research Conference "Plant - Herbivore Interactions", Ventura, CA, USA, United States.
    This list of publications is extracted from the UvA-Current Research Information System. Questions? Ask the library  or the Pure staff  of your faculty / institute. Log in to Pure  to edit your publications. Log in to Personal Page Publication Selection tool  to manage the visibility of your publications on this list.
  • Ancillary activities
    No known ancillary activities