Problems and perspectives for the use of exotic predators and parasitoids in biological control

Abstract

The accidental introduction of alien organisms potentially harmful to agriculture can cause extensive damage to vegetable crops and fruit plants and is favoured by the global mobility of people, trade of goods and the ongoing climate change. The use of alien predators and parasitoids is well known in the agricultural field, where they are often used for biological control to protect fruit and horticultural plants. The management of invasive species is and will be one of the key issues for preserving biodiversity and the profitability of crops, the latter can now count on an effective, consolidated and lasting strategy: Integrated Pest Management (IPM). The legislation on this subject is complex and articulated and is continuously being updated. It allows for the development of specific skills in biological control and the availability to use quarantine chambers where it is possible to breed and study the behaviour of antagonists (predators and parasitoids), even exotic ones. If successful, their subsequent release to targeted biological control interventions of infestations of the IAS ‘Invasive Alien Species’ can be carried out. This contribution highlights the risk that such practices may involve and takes into account the following points: 1. The behaviour of an alien species can be very different in different contexts, being able to be a real IAS or not showing any character of invasiveness; 2. The behavior of an alien species can vary over time in the same context, diversifying and also expanding its trophic niche; 3. A good number of indigenous predators and parasitoids can over time adapt to new alien prey/hosts and could potentially be used for biological control. In future, biological control will be increasingly used given that EU funds reward and support this type of approach and the intentional introduction of alien natural predators and parasitoids into agroecosystems, although subject to strict protocols, cannot exclude spontaneous colonization by these last of natural environments with currently not assessable consequences on their biocoenosis. In conclusion, the rigorous risk analysis alone does not currently seem sufficient to exclude potential damage to local biodiversity, and programs for the release of exotic predators and parasitoids should be associated with mandatory monitoring of at least five years to verify the behaviour of these aliens in nature and their possible impact on ecosystems.