Density‐mediated indirect interactions alter host foraging behaviour of parasitoids without altering foraging efficiency

Abstract

Abstract. 1. Foraging decisions of parasitoids are influenced by host density via density-mediated indirect interactions. However, in the parasitoid's environment, non-suitable herbivores are also present. These non-hosts also occur in different densities, which can affect a parasitoid's foraging behaviour.2. The influence of non-host densities can be expressed during the first phase of the foraging process, when parasitoids use plant volatiles to locate plants infested by their host. They may also play a role during the second phase, when parasitoids use infochemicals from the host and plant to locate, recognise and accept the host.3. By using laboratory and field setups, it was studied whether the density of non-host herbivores influences these two phases of the foraging behaviour of the parasitoid Cotesia glomerata as well as the parasitoid's efficiency to find its host, Pieris brassicae caterpillars.4. The findings show that a high non-host density, regardless of the species used, negatively affected parasitoid preference for host-infested plants, but that the behaviour on the plant and the total host-finding efficiency of the parasitoids were not influenced by non-host density.5. These results are discussed in the context of density-mediated indirect interactions.

Costs of Persisting Unreliable Memory: Reduced Foraging Efficiency for Free-Flying Parasitic Wasps in a Wind Tunnel

“…This memory guides C. glomerata to subsequent host patches, but due to the high similarity of HIPV of host and non-host species, these wasps are often unable to discriminate between them (Geervliet et al, 1996;Vos et al, 2001;Bukovinszky et al, 2012), even after oviposition experience (Vosteen et al, manuscript in preparation). The presence of non-host on host plant species has been found to lead to reduced foraging efficiency (Vos et al, 2001;Bukovinszky et al, 2012;De Rijk et al, 2016b;Desurmont et al, 2018;Vosteen et al, manuscript in preparation).…”

Getting confused: learning reduces parasitoid foraging efficiency in some environments with non-host-infested plants

“…In two-choice assays C. glomerata often preferred dual infested plants that contained host plus non-host herbivores over non-host-infested plants (Shiojiri et al 2000 ; Bukovinszky et al 2012 ; De Rijk et al 2016a , b , c ). Similarly, foraging efficiency was not influenced by non-host-infested plants if the hosts were feeding on a dual infested plant (De Rijk et al 2016b , c ; but see Bukovinszky et al 2012 ). These studies suggest that C. glomerata is adapted to forage in the presence of non-host-infested plants if the hosts feed together with non-hosts on the same plant.…”

Effects of quantitative and qualitative differences in volatiles from host‐ and non‐host‐infested maize on the attraction of the larval parasitoid Cotesia kariyai

“…However, the emission of attractive volatiles is not limited to the infested stem part but systemically occurs throughout the plant, even in undamaged leaves (Potting et al., ). In the host location process, the density and feeding position of non‐hosts on a plant negatively affect the first phase (locating host habitat) of the foraging process of Cotesia glomerata (L.), but the second phase (finding a host on the plant) and the overall foraging efficiency of the parasitoid had no influence (de Rijk et al., ,b). Furthermore, we found that a large number of non‐host‐infested plants can affect the host‐searching efficiency of C. kariyai during the first phase, but we were unable to draw conclusions about the second phase yet.…”