Chemical Communication in Plant-Aphid Interactions

Mechanisms that maintain and separate pea aphid host races

Dr. Grit Kunert

The pea aphid, Acyrthosiphon pisum (Harris), is actually a complex of distinct races that each is specialized on a native host plant of the legume family [Peccoud, J., Ollivier, A. et al. (2009) and Peccoud, J. and J. C. Simon (2010)]. Some aphid races are able to survive on several plant species, while others only survive on just one or a few plant species. However, all pea aphid host races can develop on the universal host plant Vicia faba. This ecological specialization can be considered as one of the first steps towards sympatric speciation since the host fidelity of races leads to assortative mating which reduces gene flow between host-races. In our group we enter into the questions why some aphid races are able to feed on a certain legume plant whilst the same plant is unsuitable for another aphid race. What makes certain legume plants resistant to some aphid races? And what might aphid races force to feed on a certain legume plant?

Group members: Daniel Rosenberger (technician), Carlos Fernando Sánches Arcos (PhD student), Alexander Schwarzkopf (PhD student), Susanne Seyfarth (diploma student), Ilka Vosteen (PhD student)

Cooperation partner: Jean-Christophe Simon INRA, Université Rennes 1, Le Rheu Cedex, France

 

Characterizing feeding behaviour of Acyrthosiphon pisum clones on host and non-host plant species by the electrical penetration graph (EPG) technique

Alexander Schwarzkopf, Dr. Grit Kunert

Our study aims to localize plant factors which influence host fidelity and hence host race formation in A. pisum. We conducted a broad comparative study on several A. pisum clones collected from different legume host plants in France and the United Kingdom. Firstly, we characterized the performance of nine A. pisum clones on six legume plant species, and showed different degrees of specialization to potential host plant species. Secondly, we selected six aphid clones and monitored their feeding behavior on four plant species by the Electrical Penetration Graph (EPG) technique. With the differences in the feeding behavior we try to explain the different degrees of host plant specialization. Additionally, we localize plant factors influencing aphid feeding behavior in different plant tissues.

 

Legume chemistry and the specificity of pea aphid races

Carlos Fernando Sánchez Arcos, Dr. Grit Kunert

Each pea aphid host races is specialized on a native host plant of the legume family. The role of the host plant chemistry for this adaptation has not been studied in depth, so the main objective of this project will be the isolation, purification, identification, and evaluation of chemical compounds from Pisum sativum, Vicia faba, Medicago sativa and Trifolium pratense involved in aphid – host plant specialization.

The role of enemy free space for the maintenance of pea aphid races

Ilka Vosteen, Dr. Grit Kunert

The pea aphid complex consist of at least 11 genetically distinct host races which are adapted to their specific host plants, but can all develop on the universal host plant Vicia faba. Natural enemies might prefer some of the host plants for prey searching or oviposition, eventually creating an enemy free space for aphids on certain host plants. The existence of such an enemy free space may be one factor which helps to maintain the separated host races of the pea aphid complex. The attractiveness of a certain plant for natural enemies might depend on host plant architecture, volatile profile and chemical composition which may alter the nutritional value and / or toxin content of aphids, thereby influencing natural enemy performance. The aim of my PhD thesis is to test if the different host plants provide a predator free or reduced space for the aphid races specialized on them and to link predator preference with certain plant traits.

 

Former group members:

Dr. Eduardo Hatano: PhD thesis: Chemical communication in an aphid-natural enemy system: new mechanisms of aphid alarm signalling and wing induction. Supervised by Prof. Wolfgang Weisser

Carolina Reinhold: Diploma thesis: The influence of (E)-β-farnesene on the host choice of Myzus persicae