I investigated mechanisms of parasitoid coexistence in a spatially structured host–multiparasitoid community (harlequin bugs [Murgantia histrionica] and two specialist parasitoids [Trissolcus murgantiae and Ooencyrtus johnsonii ]). I tested both local and metapopulation hypotheses. The local hypothesis, intraguild predation, predicts coexistence if the inferior larval competitor is superior at ...

The parasitoid wasp, Eretmocerus delhiensis (Hymenoptera, Aphelinidae) is a thelytokous and syn-ovigenic parasitoid. To evaluate E. delhiensis as a biocontrol agent in greenhouse, the killing efficiency of this parasitoid by parasitism and host-feeding, were studied. Killing efficiency can be compared by estimation of functional response parameters. Laboratory experiments were performed in cont...

Environmental variation is classically expected to affect negatively population growth and to increase extinction risk, and it has been identified as a major determinant of establishment failures in the field. Yet, recent theoretical investigations have shown that the structure of environmental variation and more precisely the presence of positive temporal autocorrelation might alter this predi...

Laboratory assays show that parasites often have lower heat tolerance than their hosts. But how physiological tolerances and behavioral responses of hosts combine to affect ecological interactions in heterogeneous field environments is largely unknown. We addressed this challenge using the model insect system braconid wasp parasitoid, Cotesia congregata, its caterpillar host, Manduca sexta. use...

A discrete-time host-parasitoid model including host-density dependence and a generalized Thompson escape function is analyzed. This model assumes that parasitoids are egg-limited but not search-limited, and is proven to exhibit five types of dynamics: host failure in which the host goes extinct in the parasitoid's presence or absence, unconditional parasitoid failure in which the parasitoid al...

Abstract Host-parasitoid interactions are complex. A parasitoid can change its host’s behavior by direct infection or simply presence in the shared environment. In red imported fire ant (RIFA, Solenopsis invicta ), workers display defensive postures to avoid potential parasitism when decapitating flies ( Pseudacteon spp.) hover above them. addition changes of individual ants, RIFA colonies limi...

Models of parasitoid-host dynamics are analyzed that include direct density dependence in the host population and either parasitoid- or host-density-dependent variation in parasitoid recruitment per parasitized host (parasitoid "yield"). The principal question addressed is how these forms of density dependence in parasitoid dynamics combine with aggregated parasitism to affect the stability of ...

The light brown apple moth, Epiphyas postvittana is a key pest of wine grapes in Australia. Two parasitoids, Dolichogenidea tasmanica and Therophilus unimaculatus, attack the larval stage of this pest. D. tasmanica is dominant in vineyards, whereas T. unimaculatus is mainly active in native vegetation. We sought to understand why they differ in their use of habitats. Plants are a major componen...