Plant-odour mediates parasitoid host handling and oviposition in an endophytic tritrophic system

Abstract

The final steps of a parasitoid host selection process, host handling and oviposition, might be affected by the habitat cues to which parasitoids are exposed, and not only by the host itself. The habitat-related factors promoting parasitoid host-handling and reproductive success were investigated in a laboratory colony of Hyssopus pallidus, a larval parasitoid of the codling moth, Cydia pomonella, an important pest of apple. Parasitoid host handling was addressed in computer-monitored behavioural bioassays during 8 h. Naive females showed more intensive host handling behaviour (frequent host examination) when offered host larvae in combination with apple fruits or in combination with an artificial diet devoid of fruit material than when offered host larvae alone. The exposure of parasitoids to fresh apple during host handling resulted in an enhanced behavioural response equivalent to that one obtained by giving an oviposition experience prior to the bioassay. The progeny produced by parasitoids exposed to plant cues for 8 h was almost double that of parasitoids exposed to artificial diet or no cues. Parasitoids exposed to no cues produced the same amount of progeny than parasitoids exposed to apple cues only with an increased time of exposure (32 h). The data demonstrate that the odour emitted by the host-food plant represent not only a habitat location signal, but triggers and enhances parasitoid host handling behaviour and reproductive success.

Effects of a biocontrol agent of apple powdery mildew (Podosphaera leucotricha) on the host plant and on non-target organisms: an insect pest (Cydia pomonella) and a pathogen (Venturia inaequalis)

“…Indeed as the insects were mass-reared under optimally controlled conditions, the change in climatic conditions could disturb their egg laying behaviour (Kuhrt, Samietz and Dorn 2006). Moreover, mass-reared insects are known to lose sensitivity to host cues (Mattiacci, Hutter, Schoch, Scascighini and Dorn 2000;Gandolfi, Mattiacci and Dorn 2003). Both of these factors, environmental change and lost of sensitivity could explain the low quantity of eggs laid per female.…”

Reproduction and immature development of Hyssopus pallidus (Hymenoptera: Eulophidae), an ectoparasitoid of the codling moth

“…Since the behaviour of a female parasitoid will not only be influenced by the host itself and by the host-foodplant (Mattiacci et al, 2000) but obviously also by the condition of her ovaries, it is important to know what changes occur in the ovaries with increased age and with different diets. This information is also important for the planning and evaluation of behavioral studies.…”

Disengtangling the evolution of weak warning signals: high detection risk and low production costs of chemical defences in gregarious pine sawfly larvae

“…Even though olfactory cues can be important in locating prey over large distances (Hedlund et al 1996;Powell et al 1998;Mattiacci et al 2000), many parasitoid wasps and flies are shown to use visual cues (Powell et al 1998;Fischer et al 2001) to locate their hosts, at least over short distances. In D. pini larvae, the overall defence capacity against parasitoids was low; pine sawfly larvae need a long time to produce a clearly visible encapsulation reaction compared to other species (e.g.…”