Ecological Entomology (2013) 38, 355-363

Mohannad Ismail, Joan van Baaren, Thierry Hance, Jean-Sebastien Pierre and Philippe Vernon (2013)
Stress intensity and fitness in the parasitoid Aphidius ervi (Hymenoptera: Braconidae): temperature below the development threshold combined with a fluctuating thermal regime is a must
Ecological Entomology 38 (4), 355-363
Abstract: An increasing intensity of stress is expected to affect the fitness traits of an organism more and more negatively, but in particular cases, extremely resistant individuals have been observed. The present study was undertaken to determine the effects of different stress intensities on fitness traits of the parasitoid wasp Aphidius ervi Haliday.
We exposed 1-day-old mummies (dead aphids containing the parasitoid pupa) for 4 weeks to combinations of two low temperatures (4 and 0 °C, 0 °C being the most stressful) and two thermal regimes (constant and fluctuating, constant being the most stressful), representing four stress levels.
The present results showed that resistant individuals occurred only in the most stressful treatment (0 °C, constant temperature), which induced a higher mortality rate. These resistant individuals performed almost as well as those of the control, but showed a reduction in their size. The fluctuating regimes, at both temperatures, presented a high emergence rate, but at the expense of higher lipid consumption. Unexpectedly, the fluctuating regime associated with the presumably more stressful temperature (0 °C) produced individuals without any decrease in the measured fitness traits, in contrast to the treatment expected to be less stressful (4 °C, fluctuating temperature).
This result opens a new area of research in stress ecology and could modify the practice of cold storage in biological control.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Joan van Baaren, Thierry Hance

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation
formulation/storage of bioagents

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
Aphidius ervi (parasitoid)