Aliens hiding in greenhouses: update of scale insects (Hemiptera: Coccomorpha) diversity on botanical gardens of Germany, with six new records for the country

Botanical gardens provide important services for research, education and the conservation of plant diversity. Many of these activities depend on the movement of plant material, which inevitably includes alien organisms. One such group is scale insects (Hemiptera, Coccomorpha), obligate phytophagous insects with agricultural implications. To understand scale insect diversity and host-plant associations in greenhouse environments, we conducted a three-year survey across five German botanical gardens in Berlin, Bonn, Frankfurt am Main, Hamburg and Munich, respectively. We collected and analysed more than 3,000 specimens from 362 plant species. Morphological identification revealed 37 species belonging to five families: Coccidae, Diaspididae, Eriococcidae, Monophlebidae, Ortheziidae and Pseudococcidae. Amongst these, Saissetia neglecta , Ovaticoccus agavium , Dysmicoccus brevipes , Dysmicoccus mackenziei and Pseudococcus importatus are recorded for the first time in Germany, while Acutaspis umbonifera is recorded for the first time in Europe. Additionally, we record 373 new host-plant associations. The spectrum of taxa we report from the greenhouse fauna clearly differs from the outdoor fauna as reported in literature. The species found here correspond with previous indoor records from Germany, but some previously recorded taxa could not be confirmed in our study. These findings suggest that botanical gardens are not static repositories, but dynamic systems where constant monitoring is essential to detect alien scale insects before they establish themselves beyond greenhouses.