Host Plant Association and Distribution of the Onion Thrips, Thrips tabaci Cryptic Species Complex

Simple Summary Onion thrips, Thrips tabaci Lindeman, 1889, is a key insect pest of several cultivated plant species around the world. Current genetic evidence suggests the existence of three lineages within the species; these lineages are different from each other in several aspects, including reproductive mode, ecological parameters, orthotospovirus transmission efficiency, host plants and distribution range. Despite its importance as a crop pest and the fact that it is one of the most studied thrips species, there is not a comprehensive review of plants in which evidence of breeding occurs among the lineages and the whole species complex. Since identifying the breeding sites of onion thrips has a direct impact on successful pest management strategies, in this paper, we aim to provide a literature review about the host plant association and distribution of the three onion thrips lineages. The results indicate that leek-associated 2 is the most widespread lineage by number of host plants and distribution; leek-associated 1 lineage is primarily found on onion crops and with localised distribution and the tobacco-associated lineage is only reported from tobacco in few locations. In addition, we present a list of host plants for the species, regardless of lineage: 391 plant species from 64 families. Onion thrips, Thrips tabaci Lindeman, 1889 (Thysanoptera: Thripidae) is a pest of economic importance traditionally treated as a polyphagous, cosmopolitan single species. Recent genetic evidence, however, suggests that it is rather a cryptic species complex of three lineages referred to by their host association and displaying different biological and ecological characteristics: leek-associated 1, leek-associated 2 and tobacco-associated. This study reviews host plant associations and distribution of the lineages of this cryptic species complex and discusses its consequences from an agronomical perspective. Overall, leek-associated 2 lineage has the broadest host range, including major crops from different plant families, and it is the only lineage with a confirmed worldwide distribution. Leek-associated 1 lineage shares some host plants with leek-associated 2. It is often found in Allium crops and its geographic distribution is limited to a few dozen countries. Finally, tobacco-associated lineage has only been collected from tobacco and their associated weeds in central and east Europe, and the Middle East. Additionally, this work presents a list of 391 plant species on which breeding and development of T. tabaci occurs, regardless of lineage. These host plant species belong to 64 different families, most importantly Asteraceae, Fabaceae, Brassicaceae, Poaceae, and Solanaceae.