Prazaru Stefan Cristian, Zanettin Giulia, Pozzebon Alberto, Tirello Paola, Toffoletto Francesco, Scaccini Davide, Duso Carlo
Department of Agronomy, Food, Natural Resources, Animals and Environment, University of Padova, viale dell' Università 16, 35020 Legnaro, Italy.
Insects. 2021 Apr 6;12(4):321. doi: 10.3390/insects12040321.
Outbreaks of the Nearctic leafhopper represent a threat to vinegrowers in Southern Europe, in particular in North-eastern Italy. The pest outbreaks are frequent in organic vineyards because insecticides labeled for organic viticulture show limited effectiveness towards leafhoppers. On the other hand, the naturally occurring predators and parasitoids of in vineyards are often not able to keep leafhopper densities at acceptable levels for vine-growers. In this study, we evaluated the potential of two generalist, commercially available predators, and , in suppressing . Laboratory and semi-field experiments were carried out to evaluate both species' predation capacity on nymphs. The experiments were conducted on grapevine leaves inside Petri dishes (laboratory) and on potted and caged grapevines (semi-field); in both experiments, the leaves or potted plants were infested with nymphs prior to predator releases. Both predator species exhibited a remarkable voracity and significantly reduced leafhopper densities in laboratory and semi-field experiments. Therefore, field studies were carried out over two growing seasons in two vineyards. We released 4 adults and 30 larvae per m of canopy. Predator releases in vineyards reduced leafhopper densities by about 30% compared to the control plots. Results obtained in this study showed that the two predators have a potential to suppress the pest density, but more research is required to define appropriate predator-prey release ratios and release timing. Studies on intraguild interactions and competition with naturally occurring predators are also suggested.
新北区叶蝉的爆发对南欧的葡萄种植者构成威胁，尤其是在意大利东北部。害虫爆发在有机葡萄园很常见，因为有机葡萄栽培使用的杀虫剂对叶蝉的效果有限。另一方面，葡萄园里自然存在的捕食性天敌和寄生性天敌往往无法将叶蝉密度控制在葡萄种植者可接受的水平。在本研究中，我们评估了两种常见的、可商业化获得的捕食性天敌在抑制叶蝉方面的潜力。进行了实验室和半田间试验，以评估这两个物种对叶蝉若虫的捕食能力。试验在培养皿内的葡萄叶片上（实验室）以及盆栽和笼养的葡萄藤上（半田间）进行；在两个试验中，在释放捕食性天敌之前，叶片或盆栽植物上都已接种了叶蝉若虫。在实验室和半田间试验中，这两种捕食性天敌均表现出显著的捕食能力，并显著降低了叶蝉密度。因此，在两个葡萄园进行了两个生长季节的田间研究。我们每平方米树冠释放4只成年捕食性天敌和30只幼虫。与对照地块相比，在葡萄园释放捕食性天敌使叶蝉密度降低了约30%。本研究获得的结果表明，这两种捕食性天敌有抑制害虫密度的潜力，但需要更多研究来确定合适的捕食者与猎物释放比例和释放时间。还建议开展关于种内相互作用以及与自然存在的捕食性天敌竞争的研究。
