Biologia e dinamica di Anisandrus dispar F. (Coleoptera, Scolytidae) e suo possibile ruolo nella diffusione dei batteri agenti causali della moria del nocciolo
Author(s)
Bucini, Danilo
Date Issued
January 25, 2006
Type
Doctoral Thesis
Abstract
Hazelnut is one of the most important orchards in central Italy (province of Viterbo) for its quality and production. More than eighty phytophagous insect pests are dangerous in hazelnut orchards, but only few of them, as Anisandrus dispar F. (Coleoptera, Scolytidae), can induce severe damages. Moreover, a bacterial disease (called "moria") is one of the main phytopathological problems of hazelnut plants in central Italy. Three years ago, "Assofrutti" Cooperative and Regional (Latium) financial support allowed to develop a research on the bio-ethology of A. dispar and its possible involvement on spreading of the "moria" disease on hazelnut plants in the province of Viterbo. The aims of the research are been: i) clarify the bio-ethology of A. dispar; ii) point out the role (direct and/or indirect) of the insect respect to the epidemiology of moria disease; iii) carry on pathogenicity tests on bacterial isolates to prove their involvement in the bacteriosis; iv) verify the influence of environmental parameters on the biology of the insect and on the disease. In the seasons of 2003, 2004, 2005 two experimental hazelnut areas were selected in Capranica and Caprarola districts (Viterbo), where eighteen chemio-chromotrophic traps were installed to study weekly the dynamic population of A. dispar females and to catch live Scolytidae females. Representative samples of live A. dispar females from each sampling were used to isolate and to identify the bacterial populations present outside and inside the insects. After three years 12.316 A. dispar females were caught. The flight of the insect started in the month of March and stopped in June. April and May resulted to be the months with the capture peaks of the adult Scolytidae. The flight of the Scolytidae resulted to be influenced from rains and temperatures (low and high). In fact, in the periods with low temperature and/or strong rains the flight of A. dispar stopped, to start again when weather conditions got better. From more than 5.600 live A. dispar females, 16% (915) were submitted to microbiological analyses. Bacterial populations isolated from A. dispar were purified and identified by morphological, physiological, biochemical and molecular techniques. The populations of the micro-organisms mainly associated (outside and inside) with the phytophagous were identified as Erwina billingae, Brenneria quercina, Pantoea cedenensis and Pseudomonas spp. Pathogenicity tests on bacterial isolates obtained from the insect (outside and inside) during the three years of research, hadn't reproduced the symptoms of the "moria" when inoculated in hazelnut plants. At the moment it's impossible affirm the direct involvement of the insect in the diffusion of the "moria".
Additional information
Dottorato di Ricerca in Protezione delle Piante. XVIII Ciclo
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