The ecology and behaviour of the parasitoid Ibalia leucospoides: lessons for biological control of forest pests

CORLEY JUAN; JOFRE NELIDA; FISCHBEIN DEBORAH; VILLACIDE JOSE

Simposio; 4th International Symposium on Biological Control of Arthropods; 2013

What attributes of parasitoid biology are especially relevant to host regulation and limitation in classical biological control, are a matter of much research and yet little consensus.  For invasive forest pests, classical biological control is a vital tool in management practices largely because of the broad time and spatial scales usually involved. The parasitoid wasp Ibalia leucospoides (Hochenwarth) (Hymenoptera: Ibalidae) is well known because of its role as one of several biological control agents of Sirex noctilio Fabricius (Hymenoptera: Siricidae). The woodwasp S. noctilio is probably the most damaging insect pest of cultivated pines throughout the Southern Hemisphere (Villacide & Corley 2012).  While biological control success of this forest insect has been attributed largely to the effects of the introduced parasitic nematode Deladenus siricidicola Bedding (Tylenchida: Neotylenchidae) on wasp reproduction, the contribution of parasitoid species to woodwasp population suppression is less clear. Ibalia leucospoides is a solitary parasitoid that is present in all pine plantations established in Patagonia, having spread together with Sirex noctilio. Parasitism levels have been estimated to reach approximately 40% locally, but it has been observed that these levels vary strongly both spatially and temporally. Also, pest population outbreaks have been experienced, even when the parasitoid was present. Our aim is, in continuation of recent work (Corley 2011), to present those ecological features of this parasitoid that may be involved in its success as a natural enemy of S. noctilio. By looking first into the pest’s ecology, we then focus on three major aspects: host searching (Fischbein et al 2012a; Pietrantuonno et al 2012), dispersal and life history (Corley & Bruzzone 2009; Fischbein et al 2012b).  Together, we expected through the analysis of recent data on these aspects, to contribute to more accurately establish our expectations on the role played by this parasitoid in regulating woodwasp populations affecting pine forestation worldwide.