Ernesto Ragusa

Distribution of Phytoseiid Mites (Parasitiformes, Phytoseiidae) on Hazelnut at Two Different Altitudes in Sicily (Italy)

Abstract Phytoseiid mites associated with hazelnut in Sicily were sampled during 1991–1993. Two orchards at two different altitudes (500 and 1,000 m above sea level) were taken into account. No chemicals had been applied in the two fields for at least 7 yr and the agricultural practices were limited (spring tillage and removal of dead branches). Thirteen species, out of a total of 19, were collected at the lower altitude and 14 at the higher; eight of these species [ Kampimodromus aberrans (Oudemans), Typhlodromus intercalaris Livshitz & Kuznetsov, Amblydromella crypta (Athias-Henriot), Typhlodromus rhenanoides Athias-Henriot, Amblyseius andersoni (Chant), Euseius stipulatus (Athias-Henriot), Paraseiulus erevanicus Wainstein & Arutunjan, Phytoseius finitimus Ribaga sensu Denmark] were common to both fields. As far as the distribution of phytoseiids was concerned, we took into consideration their presence on three different sites of the plants: trunk, low branches, and high branches. On the whole the population of phytoseiid mites was uniformly distributed on the plant from October through April, although as far as the single species were concerned, some were uniformly distributed on the plant and some showed a preference toward a particular part of the plant. K. aberrans showed a preference toward high and low branches at 1,000 m above sea level (asl), whereas T. intercalaris showed such a preference in both sites. However, at 500 m asl, A. crypta preferred the trunk, whereas T. rhenanoides was uniformely distributed on the plant in both sites.

Effects of Neem oil (Azadirachta indica A. Juss) on Tetranychus urticae Koch (Acariformes, Tetranychidae) in laboratory tests

The effects of a commercial neem oil titolated in azadirachtin at 10,000 ppm on the phytophagous mite Tetranychus urticae Koch were investigated in laboratory trials. The material provoked a high mortality on the post embryonic developmental stages of the mite when citrus leaves were used as substrate, while mortality was lower (40%) on bean leaves. Neem oil caused a high mortality of young females (100%) and also a remarkable reduction of the oviposition rate in contaminated females (from 10.9 to 93.5%). The two choice-tests, carried out in order to evaluate the repellent effect of the material, showed that neem oil has long term repellent properties.