CLASSICAL BIOLOGICAL CONTROL OF TOUMEYELLA PARVICORNIS: CHALLENGES AND OPPORTUNITIES FOR A POTENTIAL CANDIDATE

Abstract

Toumeyella parvicornis, native to the Nearctic regions, represents an increasing threat to pine forests worldwide. Severe infestations of this invasive scale have long been present in the Caribbean Islands of Turks and Caicos (TCI), and recently in Europe (Italy and France). Classical biological control could represent the most promising method for the long-term management of To. parvicornis in newly invaded areas. This study, based on an entomological expedition to Turks and Caicos Islands, allowed the discovery and selection of the coccinellid predator Thalassa montezumae as a potential biological control agent. This predator was never recorded before on TCI and was probably introduced from the area of origin of To. parvicornis. Here, the rate of infestation was evaluated and the pest suppression impact of Th. montezumae was investigated, both in the field and under laboratory conditions. Given the promising results of field studies and predation tests, the predator was imported into Italy, under quarantine conditions, to carry out a preliminary risk assessment to evaluate its potential impact on non-target species. Predation tests were conducted on different developmental stages of various scales and other Hemiptera (e.g., Aphididae, Aleyrodidae) common in Europe. The results reveal that Th. montezumae predates only scales, mainly at juvenile stages, but with a rate of predation significantly higher for To. parvicornis. Further studies are needed to mitigate the risk of underestimating environmental impacts in the use of Th. montezumae as a biological control agent for To. parvicornis. Key Words: Coccinellidae; pine tortoise scale; predator; risk assessment; Thalassa montezumae