The role of contact chemoreception in the host location process of an egg parasitoid
Iacovone, Alessia ; French, Alice Sarah ; Tellier, Frédérique ; Cusumano, Antonino ; Clément, Gilles ; Gaertner, Cyril ; Conti, Eric ; Salerno, Gianandrea ; Marion-Poll, Frédéric - \ 2016
Journal of Insect Physiology 91-92 (2016). - ISSN 0022-1910 - p. 63 - 75.
Behaviour - Electrophysiology - Gustation - Kairomone - Platygastridae - Sensilla chaetica - 016-3962
Taste allows insects to detect palatable or toxic foods, identify a mate, and select appropriate oviposition sites. The gustatory system strongly contributes to the survival and reproductive success of many species, yet it is rarely studied in insect parasitoids. In order to locate and assess a host in which they will lay their eggs, female wasps actively search for chemical cues using their sensory organs present mainly on the antennae. In this paper, we studied the role of antennal taste sensilla chaetica in the perception of contact semiochemicals in Trissolcus brochymenae (Hymenoptera: Platygastridae), an egg parasitoid of the brassicaceae pest Murgantia histrionica (Heteroptera: Pentatomidae). Methanolic extracts obtained from male and female hosts elicited action potentials in taste neurons housed in antennal sensilla chaetica, indicating that these sensilla are involved in the perception of non volatile host kairomones. In behavioural assays, wasp females displayed an intense searching behaviour in open arenas treated with host extracts, thus confirming that these kairomones are soluble in polar solvents. We further investigated the extracts by Gas Chromatography-Mass Spectrometry (GC-MS) and found that they contain several compounds which are good candidates for these contact kairomones. This study contributes to better understanding contact chemoreception in egg parasitoids and identifying gustatory receptor neurons involved in the host location process.
Dynamics of directional selectivity in MT receptive field centre and surround
Perge, János A. ; Borghuis, Bart G. ; Bours, Roger J.E. ; Lankheet, Martin J.M. ; Wezel, Richard J.A. Van - \ 2005
European Journal of Neuroscience 22 (2005)8. - ISSN 0953-816X - p. 2049 - 2058.
Electrophysiology - Extrastriate cortex - Macaque monkey - Middle temporal area - Motion perception
We studied receptive field organization of motion-sensitive neurons in macaque middle temporal cortical area (MT), by mapping direction selectivity in space and in time. Stimuli consisted of pseudorandom sequences of single motion steps presented simultaneously at many different receptive field locations. Spatio-temporal receptive field profiles were constructed by cross-correlating stimuli and spikes. The resulting spike-triggered averages revealed centre-surround organization. The temporal dynamics of the receptive fields were generally biphasic with increased probability for the preferred direction at short latency (50-70 ms) and decreased probability at longer latency (80-100 ms). The response latency of the receptive field surround was on average 16 ms longer than that of the centre. Our results show that surround input and biphasic behaviour reflect two different mechanisms, which make MT cells specifically sensitive to motion contrast in space and time.