ALIEN PEST TOUMEYELLA PARVICORNIS (COCKERELL) (HEMIPTERA: COCCIDAE) ON PINUS PINEA L.: SHORT TIME EVALUATION OF ENDOTHERAPIC TREATMENT

Abstract

The Pine Tortoise Scale Toumeyella parvicornis (Cockerell) is native to North America and was found for the first time in Italy in 2014, in Campania Region. This alien species gradually colonized woods and urban areas in Latium and subsequently moved northward in Tuscany and Abruzzo, and southward in Apulia. The scale was responsible for severe damages on the Stone Pine Pinus pinea L., a conifer representing an element of great importance in the Italian landscape and included in the Area Natura 2000 Network for its significant naturalistic interest. Heavy attacks of T. parvicornis on P. pinea cause a progressive defoliation on the canopies, and the plants quickly decline and are often irreversibly compromised. Such severe symptoms prompted studies for seeking control strategies with a low environmental impact that are suitable in urban areas. In this context, the National Reference Institute for Plant Protection was commissioned by the Italian Ministry of Agricultural, Food and Forestry Policies to verify the potential of endotherapic methods against T. parvicornis. The effect of abamectin distributed by trunk injection technology (Nuovo Metodo Corradi®) was experimentally evaluated from April to October 2021 in a park in Rome (Central Italy) on 72 pine trees that showed strong and homogeneous scale infestations. 0.9 ml of a commercial product containing abamectin at 18.37 g/l concentration was injected per cm of plant diameter at breast height (dbh) through holes that were 6 mm in diameter and 6-7 cm in depth. This treatment provided an efficient control of T. parvicornis infestations on the pine trees throughout the growing season. The presence of mature females on the one-years-old twigs significantly decreased in treated pines from April to July (about 2 females/twig on average) and to October (about 1.8 females/twig) compared to the control untreated pines (about 40 and 14 females/twig in July and October, respectively). These results showed that a single endotherapic treatment with abamectin can efficiently reduce the populations of T. parvicornis at low density levels at least 25 weeks after the trunk injection. The treated pines also visibly appeared to recover from the severe infestation symptoms and no injury and bark lesions ascribable to the trunk drilling were observed. Key Words: Pine Tortoise Scale, trunk injection, abamectin, urban area.