It is widely accepted that climate has an essential influence on the distribution of species
and that temperature is the major abiotic factor that affects their life-history traits.
Species with very restricted active dispersal abilities and a wide geographical distribution
are thus expected to encompass distinct populations adapted to contrasted local
conditions. The beet cyst nematode Heterodera schachtii is a good biological model
to study temperature adaptation in populations collected from different environments.
Here, we tested the effect of temperature on H. schachtii life-history traits using seven
field populations from Morocco, Spain, France, Germany, Austria, Poland and Ukraine.
We tested hatching and multiplication rates of each population at different temperatures,
as well as hatching rates of each population after storage at different temperatures –
simulating survival conditions during the inter-cropping period. Results showed a strong
temperature effect on the life-history traits explored. Temperature impact on hatching
(at different temperatures and after storage at different temperatures) depended on
the origin of populations, separating southern from northern ones. Surprisingly, low
temperatures influenced hatching less in southern populations. However, for these
populations, a storage period at low temperatures strongly reduce subsequent hatching.
Conversely, nematode multiplication was not differentially affected by temperatures, as
favorable conditions for the host are also favorable for the parasite. Finally, a significant
correlation between the genetic diversity and the level of specialization showed that the
less diverse populations were more specialized than the more diverse ones.