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Simple Summary: Hazelnut cultivation is quickly expanding worldwide due to increasing hazelnut demand. Despite its resilience and tolerance to many abiotic and biotic stresses, Corylus avellana expansion is continuously exposing the crop to new adversities, while climate change is causing the resurgence of many native pests and diseases. The mite pest Phytoptus avellanae is responsible for substantial yield reductions in many productive areas. Cultivar and pest management strategies can affect the incidence and the population dynamics of this pest, but to date understanding remains limited. This lack of knowledge inspired the present study. The big bud mite Phytoptus avellanae is a resurgent pest of hazelnut, Corylus avellana, causing substantial yields reductions in many productive areas. Mites colonise and develop within healthy buds which become swollen, with subsequent alteration to the plant's development. To date, there has been limited knowledge on how the cultivar and pest management strategies affect infestations. This study explored these aspects through two ad hoc experiments carried out in central Italy. In the first experiment, the susceptibility of 11 cultivars with different geographic origins was tested in a germplasm hazelnut collection. The second experiment assessed the infestation level in orchards with integrated pest management (IPM) and organic pest management strategies and in a renaturalised environment (a former agricultural area now converted in a natural park). The results showed that the most and the least susceptible cultivars were Tonda Gentile and Nocchione, respectively. No significant differences were found between IPM and organic management, but they were both different to the renaturalised environment. The outcomes of this research can serve as a valuable reference and can be applied to all current or potential hazelnut cultivation areas characterised by the same environmental conditions. [ABSTRACT FROM AUTHOR]

The aim of this study was to identify the allelopatic effect of the components of a mixture of essential oils (EO) contained in the buds and leaves of hazel ( Corylus L.) on herbivores. We examined the effect of these compounds on the choice of plants of two different hazel cultivars by Phytoptusavellanae Nal. (filbert big bud mite) and Myzocalliscoryli Goetze (filbert aphid), which are the most important pests of hazel in Poland and throughout the world. Our results show that plants of cv. ‘Mogulnus’ were more resistant than those of cv. ‘Barra’ to the feeding of mites and aphids in all study years. Using gas chromatography (GC) and GC/mass spectrometry methodology, we determined the qualitative and quantitative composition of EO in the buds and leaves of plants of these two hazel cultivars. The EO obtained from the analysed materials was a mixture of mono- and sesquiterpenes. The emission of volatile organic compounds from plants is known to repel or attract pests. The mixture of EO present in the hazel buds of cv. ‘Mogulus’, which is resistant to filbert big bud mite, was characterized by a high content of nerol, α-campholenol, methyl salicylate, spatulenol, β-caryophylene and δ-cadinene. In contrast, the leaves of this cultivar, colonized by filbert aphid but to a relatively small extent, contained greater quantities of nerol, α-campholenol, p-cymene, α-terpineol and germacrene D, than the leaves of cv. ‘Barra’, which is more accepted by aphids. However, the leaves of cv. ‘Barra’ were characterized by a considerably high content of menthol, limonene, isomenthone, methyl salicylate and L-menthone. [ABSTRACT FROM AUTHOR]

The biology of Kampimodromus aberrans (Oudemans), a predator of the big bud mite, Phytoptus avellanae Nalepa, was studied under laboratory conditions. All experiments were conducted on hazelnut leaf discs in an incubator at 25 ± 1 °C, with 16:8 h L:D, at an average daily relative air humidity of 76%. Observations were made twice daily for the immature stages and daily for the adults to determine developmental time, survival and fecundity. The mean developmental time for females was 6.90 days and for males was 7.10 days, and mean adult longevity for females was 11.67 days. The mean total and daily egg production were 12.67 and 1.85 eggs, respectively. The net reproduction rate (R0) was 7.09 females/female, intrinsic rate of increase (rm) was 0.153 female/female/day and mean generation time (T0) was 12.80 days. The mortality rate of immature stages was 0.66% and the sex ratio was 0.51 female. [ABSTRACT FROM AUTHOR]