THE EGG PARASITOIDS OF THAUMETOPOEA-PITYOCAMPA IN THE ATLAS MOUNTAINSNEAR MARRAKECH (MOROCCO)

Studies were performed on 25 egg batches of Thaumetopoea pityocampa (D en. & Schiff.) collected on Pinus pinaster Ait. on 29.XI.1995, in the Atlas Mountains of Morocco near Marrakech at 1400-1800 m above sea lev el. All the egg masses had been deposited in the autumn of 1995 and we re exposed to the parasitoids throughout the developmental period of t he host. In 1996, the egg batches, kept singly in test tubes, were obs erved almost daily. Emerged parasitoids were recorded and separated. T he final analyses were made in November 1996 based on the meconia and remains of the emerged or the dead parasitoids in the eggs. In all cas es, oviposition occurred from the base to the tip of the needles, dist ances varying up to 62 mm from the base. The mean number of eggs per b atch was 175 (range 34-245), the number of egg-rows varied between 6 a nd 11, and a 1-cm egg-row contained a mean of 9 eggs. Caterpillars hat ched from 72.7% of the eggs; total mortality of the eggs was thus 27.3 %. The impact of egg parasitoids was 21.4%. Most of the parasitized eg gs were attacked by Balyscapus servadeii (Dom.) followed by Ooencyrtus pityocampae (Mercet). Males (1.5%) were found only in B. servadeii. T he emergence rate of O. pityocampae was much higher in the year of hos t oviposition than in the following year. B. servadeii emerged in equa l numbers before and after hibernation, and in the subsequent year in equal numbers in spring and autumn. The high rate of emergence of B. s ervadeii in April-May is discussed in relation to the embryonic develo pment of Thaumetopoea bonjeani (Powel) until the end of winter, as an alternative host of B. servadeii in the Atlas region.