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Reproductive strategies of males in the egg parasitoid Trichogramma turkestanica Meyer (Hymenoptera:Trichogrammatidae)

In most animals, males are assumed to have access to an unlimited supply of sperm, while females produce few eggs that are large and costly to produce. In parasitoids, there is a paradigm to the effect that males are polyandrous, inseminate as many females as possible and express no optimization in their behaviours. In reality, sperm production incurs non-trivial costs. Because sperm are transferred in ejaculates and that their cost is greater than that of individual sperm, males can gain by carefully allocating their ejaculates. In this thesis I have investigated different aspects of males' reproductive strategies, mainly sperm and time allocation, in the egg parasitoid Trichogramma turkestanica Meyer (Hymenoptera: Trichogrammatidae). / In T. turkestanica, mating mainly occur on the emergence patch. However, results show that mating opportunities are not distributed equally among males and 2.9% of successful males are sperm-depleted when they disperse from the emergence patch. Nevertheless, 97.1% of males disperse non sperm-depleted, suggesting off-patch mating potential. Male T. turkestanica have thus an insemination capacity higher than necessary to inseminate the females present on the emergence patch, a pattern that seems to be common among parasitic wasps. / On the emergence patch, both virgin and mated females can be encountered. Males are able to discriminate between those mates and prefer virgin ones. This preference is stronger for energy- and time-limited males. / Sperm competition risks and/or intensity are important for males that decrease their sperm investment when the number of rivals increases. Such response is optimal when the benefits from investing more sperm become lower than the costs of a low paternity assurance under intense sperm competition. / Finally, male T. turkestanica express behaviours enabling them to optimize their patch time exploitation. Depending on their evaluation of the patch quality, males modify their patch residence time. / This thesis shows that time- and sperm-limited male T. turkestanica are not simply maximizing the number of females inseminated, but rather maximize their lifetime fitness by optimizing sperm and patch time allocation.
Date January 2007
CreatorsMartel, Véronique.
PublisherMcGill University
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
CoverageDoctor of Philosophy (Department of Natural Resource Sciences.)
RightsAll items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated.
Relationalephsysno: 002614113, proquestno: AAINR32311, Theses scanned by UMI/ProQuest.

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