1. Thaumetopoea pityocampa is the most important pine defoliator in the Mediterranean basin. Despite being attacked by a number of natural enemies, populations occur frequently at high density in several areas.
2. Egg parasitism was studied in 27 pine and cedar forests in Algeria, in relation to the host density (tents per tree) and the proportion of forest cover in the landscape.
3. Egg parasitism varied from 2% to 25%, accounted by two parasitoid species, the specialist Baryscapus servadeii and the generalist Ooencyrtus pityocampae.
4. Tent density was negatively correlated with parasitism by B. servadeii but not with that of O. pityocampae. Conversely, parasitism by O. pityocampae increased with the proportion of forest and agricultural cover, but not in the case of B. servadeii.
5. Maximum summer temperature showed no correlation with parasitism rates. Still, temperature frequently exceeded 40 °C during the period of adult parasitoid activity.
6. The low performance of the egg parasitoids at the southern edge of the host range could be explained by the reduced fecundity of the host, climate effects, and phenological mismatching between the parasitoids and the egg development. These and other factors potentially involved the need to be further explored with a long‐term study of population dynamics.

中文翻译：

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松树蛾的卵寄生虫对该范围南部边缘寄主密度和森林覆盖的响应

1. Thaumetopoea pityocampa是地中海盆地最重要的松树落叶者。尽管受到许多天敌的攻击，但人口频繁地在几个地区以高密度发生。
2. 在阿尔及利亚的27个松树林和雪松森林中，研究了卵的寄生性，涉及寄主密度（每棵树的帐篷）和景观中森林覆盖的比例。
3. 卵寄生虫的发生率从2％到25％不等，其中有两种寄生虫，即专业的Baryscapus servadeii和普通的Ooencyrtus pityocampae。
4. 帐篷密度呈负与寄生相关B. servadeii但不与中澳pityocampae。相反，由O引起的寄生。随着森林和农业覆盖率的增加，海豚科的数量增加，但B. servadeii的情况却没有。
5. 夏季最高温度与寄生率无关。但是，在成年寄生虫活动期间，温度经常超过40°C。
6. 寄主范围南缘的卵寄生虫性能低下，可以通过宿主的繁殖力降低，气候影响以及寄生虫与卵发育之间的物候失配来解释。这些因素和其他潜在因素涉及需要通过长期的人口动态研究来进一步探索。