Population differentiation of Trichogramma cacoeciae for the adaptation to low temperatures along altitudinal and / or latitudinal transects
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عنوان دوره: سومین کنگره بین المللی حشره شناسی ایران
نویسندگان
INRA, Institut Sophia Agrobiotech, Sophia Antipolis,
چکیده
According to their biology (dispersal ability, phenotypic plasticity, local genetic variability, etc.), species and populations respond differently to the spatial and / or temporal heterogeneity that they are encountering. For ectotherms located in most temperate areas, the survival to low temperatures is undoubtedly an recurrent challenge because of both the various direct impacts of temperature on their physiology as well as the indirect impacts (in particular, quantity/quality of resources). In this context, we investigated whether Trichogramma cacoeciae populations are phenotypically differentiated one with another according to a very local altitudinal gradient and/or a more extended latitudinal one. During Michela Ion Scotta’s PhD Thesis, three facets of the adaptation to low temperatures were more precisely investigated: (i) Thermal tolerance indices (CTmin, Chill Coma and Chill Coma Activity Recovery), (ii) Overwintering strategy in semi-field experiments and (iii) propensity to diapause in laboratory conditions. Only results on Thermal tolerance will be presented in details here. These results not only evidenced that seemingly adaptive latitudinal differentiation exist for Chill Coma but also that this index is also positively correlated with CTmin. Taken as a whole, this study unambiguously concludes that there is a significant intra-specific variability in T. cacoeciae for traits related to adaptation to low temperatures. These results, obtained for a single species and on a small geographical scale, thus, open the way towards a more systematic study of these traits and their exploitation for a better selection of strains used as biological control agents.
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