Boletín de la AeE

Nezara viñchila adults (Heteroptera: Pentatomidae), as in many Pentatomid species, have highly developed scent glandular system. Some of these gland secretions have been found to play a role in the process of host searching and recognition by the egg-parasitoid Trissolcus basalis (Hymenoptera: Scelionidae). In spite of these importan! results, the action of chemical cues at each level of the host location process is not well known. To better characterise the chemical ecology of this host-parasitoid relationship, we have analised parasitoid response to host odours in Y-olfactometer and in a circular arena with the aid of an automated image analysis system.

Tests conducted with these two experimental devices, both indicated that chemical cues from adult N. viridula males and females elicited different behavioural responses in the wasps.

Volatile chemicals from adult host males, attracted T. basalis females in the Y-olfactometer while those released by mated host females did not.

Chemical stimuli deposited by single adult host female or male allowed to walk in half of the circular arena resulted in parasitoid increased remaining in the affected área. In addition, parasitoids responded to host females cues strongly decreasing linear speed and distance moved in the entire arena converssely angular speed, number of stops and time spent motionless increased.

Those data strongly suggests that volatile cues from N. viridula adult males are used by T. basalis to lócate the potential host community. Once the host community is detected, contact cues from males provide additional information to the parasitoid aboutthe presence of the host. In contrast N. viridula females contact chemicals act as searching stimulants restricting parasitoid research to an área where the host is more likely to be located.

The role of host scent secretions in triggering these responses and in particular chemicals percived by contact has been investigated.