Evaluation and Selection of New Trichogramma spp. as Biological Control Agents of the Guatemalan Potato Moth (Tecia solanivora) in Europe

SIMPLE SUMMARY: The Guatemalan potato moth, Tecia solanivora, is an invasive pest that has spread to several countries of South America and reached Spain, arriving in Tenerife in 1999, now representing the most important pest in potato crops in the Canary Islands, where it causes significant crop losses, both in the field and in storage. In the field, the use of phytosanitary treatments to manage Guatemalan potato moth populations has been ineffective, and chemical control in warehouses has limited potential, as most insecticides cannot be applied to crops shortly before they are marketed, in addition to the current lack of authorized chemical product treatments. In this context, the search for biological control agents for Guatemalan potato moth pest has become especially important. In this sense, the evaluation of the potential use of Trichogramma species is of interest because egg parasitoids kill the host before hatching, resulting in a direct reduction in damage to the crop and harvest. In the present work, two species (T. achaeae and T. euproctidis) were evaluated under laboratory and semi-field conditions. T. achaeae was found to have potential as a biocontrol agent under field conditions, and T. euproctidis was found to be suitable for use under storage conditions. ABSTRACT: The Guatemalan potato moth (Tecia solanivora) is designated a quarantine pest by the European Union, causing severe production losses in potato crops. No effective chemical control alternatives are currently available, and cultural techniques are unable to reduce harvest losses to acceptable levels. With a focus on biological control, two egg parasitoids (Trichogramma euproctidis and Trichogramma achaeae) were selected and evaluated for use under field and storage conditions. Laboratory assays (choice and no-choice) indicated the preference of both parasitoids for T. solanivora vs. Phthorimaea operculella. Trichogramma euproctidis showed the highest parasitic activity for both moths. Analysis of functional response (at 15, 20, 25 and 27 °C) confirmed the high parasitic potential of T. euproctidis. Furthermore, in assays conducted under darkness conditions, T. achaeae was unable to parasitize eggs. However, in semi-field assays, T. achaeae was more efficient in searching for eggs in the soil than T. euproctidis. Based on these results, T. achaeae was selected to be tested under field conditions, and T. euproctidis was selected for testing under storage conditions.