Title "Testing Bugshield strips against ambrosia betlees in apple orchards: a new repellent low-impact method"

Ambrosia beetles (Coleoptera: Curculionidae: Scolytidae) are a group of very small, wood-boring insects defined by living in nutritional symbiosis with ambrosia Ascomycetes fungi of the genera Ambrosiella, Rafaellea and Dryadomyces. These beetles are found in forests, but are increasingly important pests of apple orchards. They typically attack trees that are already stressed, dying, or dead by boring into their trunks or principal braches. The gallery are created in the sapwood and the gallery walls are inoculated with the associated fungi. These fungi interfere with the plant vascular transport resulting in fast branch or tree death, particularly in young trees. Val di Non is an important area of apples production of Italy. During last years this area suffered severe infestations of ambrosia beetles leading to more than 50% of dead trees in some orchards. Among the tribe Xyleborini, the species present in Val di Non are Xyleborus dispar, Xyleborinus saxesenii, Xylosandrus germanus, but only the first specie is responsible of heavy attacks. X. dispar has a large host range including several angiosperm fruit and forest trees, but typically attacks only weak stressed trees. However, in epidemic or outbreak situation, this species attacks also healthy trees in close proximity to the preferred hosts. Insecticide applications using atomizers showed a low efficacy, due to the relatively long flight period of the insect and to the fact that insects are susceptible only when they are out of the tree trunks.
In this research we aim to evaluate the efficacy of a novel approach to control ambrosia beetle infestations by using a new permethrin-treated polymeric membrane, called Bug Shield (Silcart S.p.A, Italy). Laboratory, semi-field and open field bioassays re planned for summer 2012. Laboratory experiments will be conducted by using a Y-tube olfactometer, to assess the repellent effects of the tested membrane against X. dispar. Semi-field experiments will be done by using confined apple plants, while field tests will be carry out on-site by applying ca. 300 Bug Shield stripes near tree trunks of apple orchards. Beetle populations will be monitored weekly during spring and summer seasons by using traps baited with ethanol solution. Collected specimens of ambrosia beetles will be later classified in laboratory by a careful examination of their morphology under a binocular microscopy. Each experiment will be analysed statistically.