Olive Production Threatened by a Resurgent Pest Liothrips oleae (Costa, 1857) (Thysanoptera: Phlaeothripidae) in Southern Italy

SIMPLE SUMMARY: Liothrips oleae (Costa, 1857) (Thysanoptera: Phlaeothripidae) is widespread in the Mediterranean area, and in all regions, it is reputed to be a secondary pest in olive crops, mainly associated with damage to leaves and secondarily with damage to drupes, for which this thrips pest has a marginal impact on olive production. Taking into account the increase in the frequency of extreme damage by this species in Southern Italy in the last decade, this research aimed to elucidate the real impact (i.e., damage to leaves and drupes) by feeding thrips’ activity in olive orchards. Our results revealed that the impact of thrips was significant in all monitored olive orchards and the estimated damage level on drupes and leaves was higher in organic olive than in integrated olive management. A detailed morphological description of the Italian specimens and their molecular characterization are also provided. ABSTRACT: This study investigated a resurgence of Liothrips oleae Costa (Thysanoptera: Phlaeothripidae), an insect pest of olive crops, in a focal Southern Italian olive-producing area (Calabria Region). The young and adult olive thrips feed on the leaves and fruits of wild and cultivated olive trees, producing distortions, necrosis, and premature dropping of fruit. In our study, organic and integrated olive groves were compared for two years in order to establish the relationship between leaf and fruit damage among olive groves managed under different phytosanitary conditions. Sampling techniques were used in order to collect and count leaves and fruits (on plants and dropped premature drupes) presenting symptoms of thrips’ feeding activity. The impact of the thrips was significant in all orchards, and the estimated damage level on drupes and leaves was higher in organic olive management in each year. A morphological description of the adult females of the species is provided, and the first molecular characterization of the Calabrian olive thrips population was performed by using three different genetic regions (cytochrome c oxidase subunit I (COI), 28S ribosomal subunit (28S), and internal transcribed spacer 2 (ITS2)).