Use of actometry and electronic nose devices to assess locomotor activity of two

GUILLERMO HEIT, VALERIA MESSINA, GRACIELA MAREGGIANI , ROSA COHEN, AND PAOLA CARRIZO.

CIENCIA E INVESTIGACIóN AGRARIA

PONTIFICIA UNIVERSIDAD CATOLICA CHILE

Año: 2011 vol. 38 p. 265 - 275

0304-5609

The effect of odour signals on locomotor activity of Cycloneda sanguinea and Harmonia axyridis was evaluated through two different actometric devices, in order to differentiate between the responses of the coccinellids in direct contact with the substrates and those exposed only to volatiles, without contact. The odour profile of environmental volatiles (semiochemicals) implied in the bioassays was analyzed using an  Electronic nose (Modular Sensor System Moses II). Treatments included the use of volatiles emitted by pepper leaves (healthy or infested with Myzus persicae), M. persicae moults and honeydew, and healthy leaves treated with an artificial inductor of the systemic 25 acquired response to herbivory (AISAR). Our results suggest that a specific stimulus linked to aphid-host interaction would trigger a distinctive locomotor activity pattern in H. axyridis, with or without any contact with the aphids or the host plant. In contrast, C. sanguinea was no able to differentiate among volatiles from infested or uninfected pepper leaves and clean filter paper (control). Once C. sanguinea was in contact with aphid-infested pepper leaves (regardless of previous prey density), it moved slowly and scanned exhaustively the area. H. axyridis showed a significant reduced locomotor activity when it was in contact with aphid infested pepper leaves or aphid moults and honeydew as well, as reliable signals of a food source. Treatment with Actigard failed to evoke in both Coccinellidae, the same behavioural response than the treatment with aphid-infested pepper plants. In addition, we proved the E-Nose is capable to differentiate among blends of volatiles released from cut healthy or aphid-infested pepper leaves.Cycloneda sanguinea and Harmonia axyridis was evaluated through two different actometric devices, in order to differentiate between the responses of the coccinellids in direct contact with the substrates and those exposed only to volatiles, without contact. The odour profile of environmental volatiles (semiochemicals) implied in the bioassays was analyzed using an  Electronic nose (Modular Sensor System Moses II). Treatments included the use of volatiles emitted by pepper leaves (healthy or infested with Myzus persicae), M. persicae moults and honeydew, and healthy leaves treated with an artificial inductor of the systemic 25 acquired response to herbivory (AISAR). Our results suggest that a specific stimulus linked to aphid-host interaction would trigger a distinctive locomotor activity pattern in H. axyridis, with or without any contact with the aphids or the host plant. In contrast, C. sanguinea was no able to differentiate among volatiles from infested or uninfected pepper leaves and clean filter paper (control). Once C. sanguinea was in contact with aphid-infested pepper leaves (regardless of previous prey density), it moved slowly and scanned exhaustively the area. H. axyridis showed a significant reduced locomotor activity when it was in contact with aphid infested pepper leaves or aphid moults and honeydew as well, as reliable signals of a food source. Treatment with Actigard failed to evoke in both Coccinellidae, the same behavioural response than the treatment with aphid-infested pepper plants. In addition, we proved the E-Nose is capable to differentiate among blends of volatiles released from cut healthy or aphid-infested pepper leaves.