Endosymbiosis is very common between bacteria and insects, and it has been deeply studied for over a century on model insects such as Bactrocera oleae, the key pest of the olives. It was demonstrated that “Candidatus Erwinia dacicola” is the main component of its midgut bacterial communities, acting a fundamental role in the fly’s nutrition process and thus on its fitness. In this study, Trichoderma secondary metabolites have been used to treat olive fruit fly in order to alter the “Ca. Erwinia dacicola” titer and to assess the subsequent effects on its host. The selected metabolites, 6-pentyl-α-pyrone and harzianic acid, directly affect the insect’s fitness also on the subsequent generation, but not always in a concentration-dependent manner. Aside from the direct effects, the treatments also showed a modification of the bacterial titer. Therefore, real-time qPCRs were carried out on wild individual flies highlighting natural variations of the symbiont presence and activity during the seasons. The data obtained suggest that bioactive fungal metabolites can be formulated for direct or indirect control strategies of B. oleae in integrated pest management programs.

内共生在细菌和昆虫之间非常常见，一个多世纪以来，人们对模型昆虫（例如橄榄的主要害虫油杆菌）进行了深入研究。结果表明，“Candidatus Erwinia dacicola”是其中肠细菌群落的主要组成部分，在果蝇的营养过程及其健康状况中发挥着重要作用。在这项研究中，木霉次生代谢物已被用来治疗橄榄果蝇，以改变“Ca.达西科拉欧文氏菌”滴度并评估对其宿主的后续影响。所选择的代谢物 6-戊基-α-吡喃酮和哈茨酸直接影响昆虫对后代的适应性，但并不总是以浓度依赖性方式。除了直接影响之外，治疗还显示出细菌滴度的改变。因此，对野生果蝇个体进行了实时 qPCR，突出了季节期间共生体存在和活动的自然变化。获得的数据表明，可以在综合害虫管理计划中制定生物活性真菌代谢物，用于直接或间接控制油菜籽的策略。