engleski

How to control an invasive forest pest? Biological control of invasive Dryocosmus kuriphilus with introduced parasitoid Torymus sinensis in Croatia, Slovenia and Hungary

Dryocosmus kuriphilus is considered as one of the major pests of sweet chestnut (Castanea) and the effective method of controlling its populations and damage is classical biological control with its introduced parasitoid Torymus sinensis. T. sinensis is a univoltine, host specific parasitoid, phenologically synchronized and morphologically adapted to D. kuriphilus, it has good dispersal ability, builds up populations quickly and effectively controls the pest already few years after release. We describe the first results of introduction and release of T. sinensis for controlling the populations of invasive D. kuriphilus in sweet chestnut forests and orchards in Croatia, Hungary and Slovenia. Withered D. kuriphilus galls with T. sinensis larvae were collected in Torino vicinities, Italy in March 2014 and 2015. After emergence, males and females were put together, kept at 14°C and fed with liquid honey until release. To confirm the establishment of population of T. sinensis on release sites in Croatia, Slovenia and Hungary morphological and DNA identification were used.. In total 10, 590 females and 5, 295 males of T. sinensis were released in sweet chestnut forests across in Croatia, Hungary and Slovenia in 2014 and 2015. Minimum release number of T. sinensis was 100 females/50 males and maximum 1, 200 females per site. Subsequent releases with larger number of females (1, 200 and 800 in two years) resulted in rapid establishment of population of T. sinensis and parasitism rates of 76 % only one year after the first release was achieved. Establishment of population of T. sinensis was confirmed with molecular analyses and morphological identification High levels of genetic diversity indices showed that populations of T. sinensis did not suffer from bottleneck-induced founder effect phenomenon. Prior to release of T. sinensis all advantages and disadvantages of introduction of this alien biocontrol species into natural stands in Croatia, Hungary and Slovenia have been considered.

Torymus sinensis; classical biological control; parasitism rates; rearing and release; parasitoid; sweet chestnut gall wasp;

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