Research   Theses  Publications  Presentations  Awards  help    to staff list 

Current Research (PhD Thesis):

My research is mainly focused on agricultural insect pests and insect-plant interactions. The aim of my PhD project is to investigate chemosensory organs of rhizophagous cockchafer larvae (Melolontha melolontha) and find chemical cues for their host plant location. The larvae have been described as polyphagous, and CO2 was the only identified attractant known. However, clear host plant preferences have been described, particularly for dandelion (Taraxacum officinale).
We found that larval attraction to undamaged dandelion roots is affected by plant age, substrate type, light regime and mycorrhizal symbionts. We analyzed volatile and water-soluble substances of dandelion root exudates from plants grown under different abiotic (e.g. light regime) and biotic factors (mycorrhizal symbionts). To identify which of the substances other than CO2 are involved in larval host plant finding, electrophysiological and behavioral analyses were conducted. We hypothesize that both, taste and olfactory cues are involved in orientation of larvae to host plant roots. Contact chemosensilla and olfactory sensilla were found on on larval antennae, labial and maxillary palps.

1. Root exudates:
We measure how exudation of undamaged Taraxacum officinale roots changes with abovementioned plant treatments in order to identify potential chemical cues for M. melolontha. Compounds of interest are volatiles (e.g. terpenoids) and sugars.
2. Ultrastructure and Electrophysiology:
We examine abundance and location of olfactory and gustatory receptors on antennae, maxillary and labial palps of M. melolontha by means of scanning and transmission electron microscopy. Detection of plant root derived compounds (see above) on larval head appendages is tested with electrophysiological recordings.
3. Larval orientation belowground:
Electrophysiogically active compounds are tested for behavioral responses. Furthermore, the question is addressed if growth conditions (light intensity, growth duration, substrate type, infection with mycorrhizal fungi) of host plants affect larval host plant finding.
last updated on 2012-07-29