Regulation of agricultural pests managing their natural enemies represents an alternative to chemical pesticides. We assessed the potential of insectivorous birds as pest regulators in woody crops located in central Spain. A total of 417 nest boxes installed in five field study sites (one vineyard, two fruit orchards, and two olive groves) were monitored for use and breeding of insectivorous birds and other species for four consecutive years (2013–2016). At all field sites except the two olive groves, where birds never occupied the nest boxes, predation experiments were conducted with Greater wax moth (Galleria mellonella) sentinel caterpillars, and food consumption by birds was estimated. Nesting of insectivorous birds, chiefly Great tit (Parus major), and sparrows (Passer domesticus and P. montanus) increased over time, averaging 60% per field site in the vineyard and fruit orchards by the fourth year. Use of nest boxes by sparrows and by Garden dormouse (Eliomys quercinus) was high at the fruit orchards (70%) and the vineyard (30%), respectively. Micro-habitat characteristics (nest box level) and meso-habitat characteristics (patch level) strongly affected use of nest boxes and bird breeding (i.e. number of laid eggs and produced chicks) in different years. Distance to natural or semi-natural vegetation did not consistently affect bird breeding, nor did we see consistent evidence of competition between adjacent breeding birds. Predation rates of sentinel caterpillars were approximately one-third higher near boxes with nesting birds (31.51 ± 43.13%) than at paired distant areas without nest boxes (22.45% ± 38.58%). Food consumption by insectivorous birds per ha and breeding season were conservatively estimated to range from 0.02 kg in one fruit orchard to 0.15 kg in the vineyard. We conclude that installation of nest boxes in Mediterranean woody crops enhances populations of insectivorous birds that regulate pests, but that the effects are moderate and highly context-dependent.

Background: The unexpected Xylella fastidiosa (Xf) outbreak in Europe has led to aggressive management of the disease in recent years. As there is no cure for infected plants, management of vector populations is mandatory to contain the spread of Xf in infected areas. We aimed to assess the suitability of plant species commonly used as cover crops for the population growth of Philaenus spumarius L. (Aphrophoridae). Thus, we conducted a series of no-choice and multiple-choice assays to assess the oviposition preference of P. spumarius adults as well as the development and mortality rate of nymphs on 10 candidate plant species under laboratory and semi-field conditions. Our results will help to design ecological infrastructures, including a pull-push strategy for effective management of Xf vectors in olive groves.Results: Results showed that Anthriscus cerefolium is a suitable plant to enhance oviposition but has a lethal effect on the first nymphal instars of P. spumarius. Moreover, Diplotaxis tenuifolia is not suitable for oviposition or nymphal development. Sinapis alba does not enhance oviposition but is suitable for nymphal development with a medium-high cumulative mortality of the nymphs. Conversely, adults and nymphs had a high preference and low mortality on Taraxacum officinale, and nymphs showed a medium-high preference on Lavandula angustifolia, suggesting that these two species should be avoided as ground cover plants on Xf-susceptible crops. Conclusion:The results obtained in our study open new ways to manage the vectors of Xf by using specific plant species as ground cover, which in turn will reduce the spread and prevalence of Xf.

Neophilaenus campestris is one of the recently identified spittlebugs (Hemiptera: Cercopoidea) able to transmit Xylella fastidiosa to olive trees.Considering its vector ability and the wide distribution of this species in Spain, N. campestris should be considered a serious threat to key crops that are vital for Spanish agriculture such as olive, almonds and grapevines. Migration and dispersal abilities of insect vectors have profound implications in the spread of vector-borne diseases. Thus, knowledge on the dispersal ability of N.campestris is essential to model, predict and limit the spread of the diseases caused by X. fastidiosa. A mark-release-recapture technique was developed to track between-field movements of N. campestris during its late spring migration from the ground cover grasses within olive groves to sheltered areas dominated by pine trees. An indoor assay showed that the fluorescent dust used for marking did not affect the survival nor the flying ability of N. campestris. Spittlebug adults captured in olive groves at Los Santos de la Humosa (Madrid, Spain) during late spring, 2019 were dusted with four fluorescent colours and released in four different locations. Six recapture samplings were performed 23 to 42 days after release in 12 different sites located within a maximum distance of 2.8 km from the release point. Results indicated that N. campestris was able to disperse a maximum distance of 2473 m in 35 days from the olive groves to areas dominated by pine trees. Furthermore, our flight mill studies also showed that N. campestris was able to fly long distances, reaching almost 1.4 km in an 82 minutes' single flight.Moreover, we carried out a survey of directional movement of potential vectors of X. fastidiosa in an olive grove located in Villa del Prado (Madrid).

SUMMARYNeophilaenus campestris is one of the recently identified spittlebugs (Hemiptera: Cercopoidea) able to transmit Xylella fastidiosa to olive trees. Considering its vector ability and the wide distribution of this species in Spain, N. campestris should be considered a serious threat to key crops that are vital for Spanish agriculture such as olive, almonds and grapevines. Migration and dispersal abilities of insect vectors have profound implications in the spread of vector-borne diseases. Thus, knowledge on the dispersal ability of N. campestris is essential to model, predict and limit the spread of the diseases caused by X. fastidiosa. A mark-release-recapture technique was developed to track between-field movements of N. campestris during its late spring migration from the ground cover grasses within olive groves to sheltered areas dominated by pine trees. An indoor assay showed that the fluorescent dust used for marking did not affect the survival nor the flying ability of N. campestris. Spittlebug adults captured in olive groves at Los Santos de la Humosa (Madrid, Spain) during late spring, 2019 were dusted with four fluorescent colours and released in four different locations. Six recapture samplings were performed 23 to 42 days after release in 12 different sites located within a maximum distance of 2.8 km from the release point. Results indicated that N. campestris was able to disperse a maximum distance of 2473 m in 35 days from the olive groves to areas dominated by pine trees. Furthermore, our flight mill studies also showed that N. campestris was able to fly long distances, reaching almost 1.4 km in an 82 minutes’ single flight.Moreover, we carried out a survey of directional movement of potential vectors of X. fastidiosa in an olive grove located in Villa del Prado (Madrid). We used yellow sticky bands, a Malaise trap and a vertical yellow sticky net to assess the directional movement from olive groves to surrounding managed and unmanaged areas. The captures obtained in the yellow sticky bands showed that spittlebugs dispersal from the olive grove to surrounding vegetation matched with the time when the ground cover dried out. The highest number of spittlebugs was captured in the border between the olive grove and a vineyard close by.Altogether, our findings suggest that eradication measures by rooting-up X. fastidiosa-infected and non-infected trees in a radius of 100 m are of limited value because vectors are able to disperse rapidly over distances much longer than expected.