Thrips population dynamics, composition and first survey of ground-dwelling predatory mites in lemon orchards in Italy

Several thrips species are known to infest citrus orchards worldwide. Flowers are usually preferential feeding sites, but developing fruits are also attacked. Pezothrips kellyanus has emerged as a key thrips pest on citrus in Italy, and knowledge on its biology and natural enemies are still largely insufficient. We conducted a survey in two Sicilian lemon orchards, aimed at assessing the thrips species composition and population dynamics on lemon flowers, young fruits and weed flowers. Thrips ecology was also studied placing double-sided sticky traps under the tree canopy. Ground-dwelling predatory mites were collected in the soil samples from below the canopy using a Berlese apparatus. Kelly’s thrips was the most abundant species (88.6-91.2%) infesting lemon and its presence was well correlated to blooming. On the 23 weed species sampled, the commonest thrips were Frankliniella occidentalis and Megalurothrip ssp., while P. kellyanus was observed only on 6 species, mainly Asteracee. The data obtained confirmed a significant soil phase of the pest, since in the up and bottom trap sides there were two peaks of nymphs and adults, respectively. Of sampled mites, 20% were predaceous Laelapidae, Macrochelidae and Phytoseiidae. This study is the first step towards establishing a scientific basis for an effective soil and weed management system aimed at reducing thrips infestation in Italian lemon orchards.