ISHS Acta Horticulturae 556: V International Congress on Hazelnut
INFLUENCE OF BUG (HETEROPTERA, COREIDAE AND PENTATOMIDAE) FEEDING ACTIVITY ON HAZELNUT IN NORTHWESTERN ITALY |
| Authors: | L. Tavella, A. Arzone, M.L. Miaja, C. Sonnati |
| Keywords: | Gonocerus acuteangulatus, Palomena prasina, nutritional stings, kernel damage, brown stain |
| DOI: | 10.17660/ActaHortic.2001.556.68 |
| Abstract:
In northwestern Italy, hazelnut yield losses and kernel defects are increasing. Early fruit drop and defects like blanks, shriveled or spotted kernels are usually attributed to insect feeding. Previous research has shown that the pests most commonly found were bugs, in particular Gonocerus acuteangulatus and Palomena prasina. The aim of this research was to determine if both species cause early nut drop, and which defects are due to bug feeding on developing nuts. The trials were performed in a nut orchard at Cravanzana (Cuneo province) during 1997-1998. In early spring, six hazelnut trees sprayed with insecticides were singly isolated in net cages. After one month, bugs were introduced into the cages as follows: G. acuteangulatus in two cages, P. prasina in another two, and no insects in the last two. To assess the influence of the cages on yield, two non-isolated trees were checked. Dropped nuts were collected every week in June and July and then examined. At harvest, the nuts of the eight trees were harvested and nut samples were observed for damage. In both years, independent of insect introduction, the quantity of early nut drop was similar in the caged plants but higher in the uncaged plants. However, this drop did not influence the yield. At harvest, spotted kernels were observed in the cages with bugs but not in those without insects, and we therefore conclude that this damage was due to bug stings. The frequency of injured kernels varied from 0.7 to 1.0% with G. acuteangulatus, and from 1.3 to 4.0 % with P. prasina. | |
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