Effetto del grado di coevoluzione e di specializzazione nella capacità di ooparassitoidi ad utilizzare le impronte chimiche dell'ospite

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[automatically translated] The chemical fingerprints left on the substrate by Pentatomidi stimulate oofagi parasitoids in the host search in the contaminated area and allow them to distinguish sex. The chemical fingerprint of the females are preferred since they are more reliable because the neighborhood is a greater probability of finding the host egg. In this work it has been hypothesized that the ability to discriminate the sex of the guests by ooparassitoidi was acquired only in respect of those co-evolved. We were therefore considered two associations of host-parasitoid co-evolved such Nezara viridula-Trissolcus basalis and Murgantia histrionica-Trissolcus brochymenae and as a guest not coevoluto you used the Scutelleride graphosoma semipunctatum. Bioassays were conducted in an open arena and recorded using a path and motion analysis system. It has been evaluated the response of the two parasitoids to the traces left by adults coupled guest co-evolved and not co-evolved and the areas treated with these extracts. The results confirmed the working hypotheses. In addition, the guest physiological state might have differently affect the search behavior of parasitoids oofagi depending on whether or monofagi polyphagous. To test this hypothesis was then assessed the response of T. brochymenae, parasitoid monophagous, to traces of adults of M. histrionica virgin and mated, the females with interrupted copulation and females who ovideposto. The host females were dissected to assess the presence of sperm in the bulb and secretions associated with the expansion of the spermatheca duct. T. brochymenae has discriminated against the host's sex only when this was then coupled preferring females mated host. It was also evaluated the search behavior of the parasitoid in areas contaminated with shanks and scutelli of guests paired adults. The residues released by the tarsiers of mated females induced a stronger response indicating the shanks as kairomonal source. Finally we evaluated the answers of the parasitoid to the areas treated with extracts of guests virgin and mated adults. The females mated extracts stimulated a greater response and showed quantitative differences in the composition of the cuticular hydrocarbons than those of males. These data, compared with those available for the polyphagous parasitoid T. basalis, confirm the working hypothesis and show that the degree of specialization leading to the definition of more sophisticated search strategies.
Original languageItalian
Number of pages1
Publication statusPublished - 2009

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