European Journal of Entomology (2008) 105, 81-85

S.Y. Reznik, N.D. Voinovich, N.P. Vaghina and S.G. Karpova (2008)
Arrhythmic adult ecdysis but rhythmic emergence from the host chorion in Trichogramma embryophagum (Hymenoptera: Trichogrammatidae)
European Journal of Entomology 105 (1), 81-85
Abstract: In many insect species with a pupa covered by various 'shells' (puparium, host remains, etc.) pupal-adult ecdysis and emergence to the open air represent two discrete steps. However, in Trichogramma, as well as in other insect parasitoids, these two processes have never been studied separately. We investigated the temporal pattern of pupal-adult ecdysis and of adult emergence from the host chorion in Trichogramma embryophagum Hartig (Hymenoptera: Trichogrammatidae) in laboratory conditions (12L : 12D, 20°C). Adult ecdysis was arrhythmic, while adult emergence showed a strong rhythmicity. The time lag between ecdysis and emergence varied from one to almost two days, depending on the circadian time of the ecdysis. The proportion of ecdysed adults that stayed in the host chorion ranged up to 60% (just before the highest peak of emergence). The cumulative percentage of ecdysed adults gradually increased with time, independently of whether the light was turned on in accordance with the entrained circadian rhythm or 4 h earlier. This arrhythmic ecdysis could be explained by the fact that the ecdysed adults get into a well protected space inside the host chorion and the timing of this event is adaptively neutral.
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Database assignments for author(s): Sergey Ya. Reznik, Svetlana G. Karpova

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
Trichogramma embryophagum (parasitoid)