Context : The presence of g - and p -modes allows testing stellar models from the core to the envelope .
Moreover , binarity in an eclipsing system constrains the physical parameters of the pulsating star .

Aims : CoRot ID 100866999 is a relatively large-amplitude hybrid \gamma Doradus- \delta Scuti star with two clearly distinct frequency domains .
The large number of detected frequencies allows a detailed study of the interaction between them .
In addition , we can derive the fundamental parameters of both components from the study of the eclipsing light curve .

Methods : After removing the eclipsing phases , we analyzed the data with the Period04 package up to a signal-to-noise ratio S/N=4 .
The light curve was then prewhitened with these oscillation frequencies to derive the fundamental parameters of the two components .

Results : The eclipsing light curve analysis results in a ( 1.8+1.1 ) M _ { \odot } system , both components being main sequence stars .
We detect 124 frequencies related to luminosity variations of the primary .
They are present in two well-separated domains : 89 frequencies in the interval [ 0.30 ; 3.64 ] d ^ { -1 } and 35 in the interval [ 14.57 ; 33.96 ] d ^ { -1 } .
There are 22 \gamma Doradus frequencies separated by a constant period interval \Delta P = 0.03493 d. These frequencies correspond to a series of g-modes of degree \ell = 1 with successive radial orders k .
We identify 21 linear combinations between the first nine \gamma Doradus frequencies .
The \delta Scuti domain is dominated by a large-amplitude frequency F = 16.9803 d ^ { -1 } .
The eight first \gamma Doradus frequencies f _ { i } are present with much lower amplitude in the \delta Scuti domain as F \pm f _ { i } .
These interactions between g - and p -modes confirm the phenomenon we detected in another CoRoT star . The amplitude and the phase of the main frequency F shows a double-wave modulation along the orbital phase , giving rise to series of combination frequencies .
Such combination frequencies are also detected , with lower amplitude , for the first \gamma Doradus modes .

Conclusions :