A maternal influence on the conditioning to plant cues of Aphidius colemani Viereck, parasitizing the aphid Myzus persicae Sulzer

Abstract

Abstract. The offspring of parasitoids, Aphidius colemani Viereck, reared on Brussels sprouts and emerging from Myzus persicae Sulzer on a fully defined artificial diet, show no preferences in a four‐way olfactometer, either for the odour of the diet, the odour of Brussels sprouts, or the odour of two other crucifers (cabbage and Chinese cabbage). A similar lack of odour preferences is shown when the host aphids are exposed for parasitization (for 48 h) on cabbage, Chinese cabbage or wheat. However, if parasitization occurs on Brussels sprouts, a weak but statistically highly significant response to Brussels sprout odour is observed. Although as many as 30–35% of the parasitoids show no response to any odour, another 35% respond positively to the odour of Brussels sprout compared with responses to the odours of cabbage, Chinese cabbage or wheat of only approximately 10%. An analagous result is obtained when the parent parasitoids are reared on cabbage. In this case, significant positive responses of their offspring to cabbage odour occur only if the 48‐h parasitization has occurred also on cabbage. However, with parasitoids from Brussels sprouts parasitizing the aphids for 48 h also on Brussels sprouts, the offspring subsequently emerging from pupae excised from the mummies show no preference for Brussels sprout odour. Thus, although the Brussels sprout cue had been experienced early in the development of the parasitoids, they only become conditioned to it when emerging from the mummy. Both male and female parasitoids respond very similarly in all experiments. It is proposed that the chemical cue (probably glucosinolates in these experiments) is most likely in the silk surrounding the parasitoid pupa, and that the mother may leave the chemical in or around the egg at oviposition, inducing chemical defences in her offspring to the secondary plant compounds that the offspring are likely to encounter.

Fungal endosymbionts of plants reduce lifespan of an aphid secondary parasitoid and influence host selection

“…For primary parasitoids, it has been proposed that mothers deposit a chemical cue inside the silk surrounding the pupa, which may condition the offspring to the environment in which they developed (van Emden et al 1996;Douloumpaka & van Emden 2003). The fact that, in our experiment, the degree of preference exhibited by female wasps for EK mummies was time dependent suggests that the mechanism is likely to be different.…”

Drought and Root Herbivory Interact to Alter the Response of Above-Ground Parasitoids to Aphid Infested Plants and Associated Plant Volatile Signals

“…Both aphid species were sub-cultured fortnightly and transferred to fresh plants. The parasitoids were established on aphid species for at least two generations before use in the experiments [123] to minimize maternal host plant effects. Insect cultures were maintained at 20±2°C at 75% relative humidity under an LD 16∶8 h.…”

The Role of Fresh versus Old Leaf Damage in the Attraction of Parasitic Wasps to Herbivore-Induced Maize Volatiles

“…One possibility is that they learn during emergence from the cocoon and initially focus on the same cues that guided their mother to hosts. Such early adult learning was found, for example, in Microplitis demolitor (Hérard et al, 1988), Cotesia plutella (Bogahawatte and Van Emden, 1996), and Aphidius colemani (Douloumpaka and Van Emden, 2003). A second possibility is that, as they emerge from the cocoon, the wasps will first cue on general plant odors, and that they will learn plant odors that are associated with the specific host only as soon as the first host is encountered and parasitized.…”