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• Cover crops might enhance entomopathogenic nematodes (EPN) presence in vineyards. • More EPNs and higher activity observed in spontaneous cover (SPO) than tilled (TIL). • Lower presence of EPN natural enemies in SPO than TIL treatments. • The cover crops seeded (SEE) and flower-driven (FLO) produced alteration on EPN assemblage. • SPO covers could be a promising strategy to support EPN in Mediterranean vineyard. Viticulture is a valuable sector worldwide with an extraordinary socio-economic impact in Spain. Numerous pests and diseases threaten vineyards, and their management primarily relies on the use of conventional agrochemicals. The current paradigm of sustainability pursues the implementation of ecologically sound strategies in vineyard ecosystems. The use of cover crops is arising as an alternative with numerous benefits, including favoring above-belowground biodiversity and the presence of beneficial soil organisms such as the entomopathogenic nematodes (EPNs). We hypothesized that the use of specific cover crops in vineyards might enhance the natural occurrence and activity of EPNs by modulating the assemblage with associated organisms. We performed the experiments in an ongoing experimental vineyard (Vitis vinifera var Tempranillo, clon RJ-26, rootstock '110-Richter') located in Logroño (Spain), drove with different soil management systems (three replicates each): conventional tillage practice and the cover crops (i) seeded with Bromus catharticus (Poaceae), (ii) flower-driven, and (iii) spontaneous. We took four soil composite samples per plot (n = 48 per sampling time) late spring and early autumn in two consecutive years (2017 and 2018). By using species-specific primers/probes qPCR sets, we screened for the presence and abundance of eight EPNs species and 12 related soil organisms: six nematophagous fungi, four free-living nematodes, and two ectoparasitic bacteria. Additionally, we assessed the EPN activity by the traditional insect-bait method. Overall, we recorded higher EPN numbers or activity rates on cover crops than on bare soils. However, some of the results were divergent among no-till treatments. We observed not only higher EPN abundance and activity on spontaneous covers but lower numbers of antagonistic organisms, particularly endoparasitic nematophagous fungi. Thus, according to our results, the use of spontaneous covers could be the most promising strategy to support the conservation biological control service provided by the naturally occurring EPN species in vineyards, plus with a low cost for the sector. [ABSTRACT FROM AUTHOR]

• Ground cover management clearly increased insect abundance at the ground level. • Few families dominated both epigeal and canopy insect assemblages. • Total biodiversity was higher in cover crop treatments than tillage. • Native plants positively influence generalist epigeal predator abundance and richness. Sustainable agriculture requires the support of new tools for successful and low-impact management of pests and diseases at global and local scales. The implementation of cover crops is considered a promising alternative ecological structure for sustainable agriculture, because they provide refuge to natural enemies of pests. Specifically, we hypothesised that implementing cover crop vegetation in a vineyard can enhance populations of natural enemies as a measure to support conservation biological control. We analysed insect abundance and diversity on Vitis vinifera var. Tempranillo (clon RJ-26, rootstock "110-Richter") in a Mediterranean vineyard located in La Rioja, Spain from spring to autumn 2016–2017. Two types of sampling systems (pitfall traps and vacuum sampling) were used in each of the three evaluated ground cover management approaches (n = 3): (i) tillage, (ii) spontaneous cover, and (iii) flower-driven cover. A total of 58 families that belonged to four functional subgroups of insects (predators, parasitoids, phytophagous insects, and pollinators) were found. Overall, differences among the three treatments were only detected for total abundance of insects collected in the ground traps, and the "spontaneous cover" treatment showed significantly higher predator richness and abundance. However, the higher Shannon–Wiener value was recorded for "flower-driven cover" at both the ground and canopy levels. In addition, the abundance of predators, parasitoids and phytophagous insects in the ground traps for both cover crop treatments was more than two times higher than that observed in "tillage" treatment. Several predator taxa, such as ants, ground beetles, earwigs, and vespoid wasps had significantly higher representation under spontaneous cover treatment. Moreover, for parasitoids, the "flower-driven cover" treatment revealed higher Hill numbers values (0D, 1D, and 2D) at the canopy level, although no significant differences were observed. These results indicate that vegetation cover could be used to promote beneficial entomofauna in vineyards and thus be an effective conservation biological control tool. [ABSTRACT FROM AUTHOR]