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Theses

LA DISCRIMINATION INTERSPECIFIQUE PAR EUPELMUS VUILLETI (HYMENOPTERA : EUPELMIDAE) DES HOTES PARASITES PAR DINARMUS BASALIS (HYMENOPTERA : PTEROMALIDAE).

Abstract : n the parasitoid way of life, hosts represent a limited resource. Females of parasitoid
species will compete ether with conspecific or allospecific female for reaching this resource.
The competition between individuals foraging for the same hosts limits the fitness of each
competitor. Foraging strategies have been selected to reduce consequences of the competition.
A few species adopt, in interspecific competition, an original strategy named
kleptoparasitism. A kleptoparasitoid female searches actively for the hosts parasitised by a
concurrent species, destroys the egg and lays its own egg instead of the competitor's one. This
strategy requires the ability to recognize the host parasitised by the competitor. Eupelmus
vuilleti, competing with Dinarmus basalis, seems to act as a kleptoparasitoid.
We have studied the mecanisms allowing E. vuilleti to discriminate between
unparasitised hosts and hosts parasitised by D. basalis. E. vuilleti recognizes chemical cues
left by D. basalis on the tegument of the seed containing the host. These cues are composed
of hydrocarbons produced by the Dufour gland and found on the cuticle of the D. basalis
female. These secretions are attractive for the E. vuilleti females. Another protean secretion,
produced by the venom gland seems to be active and stimulate the egg laying behavior of the
E. vuilleti females.
We have then studied some evolutive aspects to understand which processes would
have been involved in the selection of this interspecific discrimination. The recognition is
specific of the sympatric populations of D. basalis. Reusing hosts parasitised by the D.
basalis female involves some benefits for the E. vuilleti female. In particular, reusing the hole
drilled by D. basalis, which have a more efficient ovipositor, reduces the time and the energy
spent to drill the seed, and could allow E. vuilleti females to access hosts inaccessible with
their own ovipositor. These benefits constitute an adaptative advantage that could have lead to
the selection of the kleptoparasitism in this species. However, kleptoparasitism doesn't seem
to be the best strategy, except when competition between the two species is strong. The
selection of interspecific discrimination seems to be linked to particular competitive ability of
the two species. A high genetic variability and behavioral plasticity could allow the female to
adapt their strategy to the local competition intensity.
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https://tel.archives-ouvertes.fr/tel-00108221
Contributor : Christine Besse <>
Submitted on : Friday, October 20, 2006 - 9:08:16 AM
Last modification on : Wednesday, June 19, 2019 - 5:17:16 PM
Long-term archiving on: : Tuesday, April 6, 2010 - 8:16:02 PM

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  • HAL Id : tel-00108221, version 1

Citation

Bruno Jaloux. LA DISCRIMINATION INTERSPECIFIQUE PAR EUPELMUS VUILLETI (HYMENOPTERA : EUPELMIDAE) DES HOTES PARASITES PAR DINARMUS BASALIS (HYMENOPTERA : PTEROMALIDAE).. Ecologie, Environnement. Université François Rabelais - Tours, 2004. Français. ⟨tel-00108221⟩

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