Avian pest control in vineyards is driven by interactions between bird functional diversity and landscape heterogeneity

Abstract

1. Insectivorous birds are increasingly recognized for the crucial pest control services they provide to agroecosystems. While both the foraging activity and functional diversity of birds are enhanced by multiscale habitat heterogeneity, little is known about how these relationships may influence avian top-down control of insects. Specifically, interactive effects of bird community structure and habitat heterogeneity on pest control across spatial scales have rarely been explored. 2. We sampled bird communities and measured avian predation on plasticine model prey, as a proxy for lepidopteran pest control, in 20 vineyards of south-western France. Vineyards differed both in sward heterogeneity at the local scale and amount of surrounding semi-natural habitats at the landscape scale. Functional diversity metrics and community-weighted mean traits were computed for bird communities based on a species-trait table including diet, foraging method, nesting site, migration strategy, laying date, home range size, clutch size and body mass. We used mixed models to test for the interacting effects of habitat heterogeneity and bird functional diversity on avian predation rates of plasticine prey. 3. Contrary to expectations, bird functional diversity decreased with landscape-scale heterogeneity, but was higher in vineyards managed with heterogeneous sward structures. In contrast, foliage-gleaning insectivores were more abundant in landscapes supporting more semi-natural habitats, suggesting an increase in their contribution to pest control along the landscape heterogeneity gradient. Accordingly, we found that avian predation on plasticine prey increased with bird functional evenness both in more heterogeneous vineyards at the local scale and in landscape mosaics supporting more semi-natural habitats. 4. Synthesis and applications. Our study demonstrates that habitat heterogeneity at both local and landscape scales influenced avian insectivory in vineyard agroecosystems by interacting with bird community structure. It provides important insights for ecological intensification in vineyards, pointing out that management options need to be adapted to both the functional composition of local bird communities and landscape context. We suggest that both on-field and off-field management can be used to enhance natural pest control services provided by birds in vineyards, especially by favouring sward heterogeneity and patches of semi-natural habitats within large vineyard stands at the landscape scale.

Maize‐field complexity and farming system influence insectivorous birds’ contribution to arthropod herbivore regulation

“…This latter point relates to suggestions by Barbaro et al. () who showed that narrow‐ranging bird species may be more effective than their wide‐ranging counterparts in contributing to arthropod suppression. This is likely the case in the present study given that herbivorous arthropod abundance related positively to diversity and richness of insectivorous birds.…”

Multiscale habitat mediates pest reduction by birds in an intensive agricultural region

“…A few studies have explicitly tested the intermediate landscape‐complexity hypothesis for pest reduction services by avian predators, and the results have been mixed (Barbaro et al. , Birkhofer et al. ).…”

“…Barbaro et al. () found a negative effect of avian functional evenness on plasticine sentinel prey predation in landscapes with the lowest percentage of seminatural cover, and a strong positive effect of evenness on predation in the landscapes with the greatest amount of seminatural cover. After statistically controlling for the effect of seminatural habitat amount in the landscape, Birkhofer et al.…”

A critical review of plant protection tools for reducing pesticide use on grapevine and new perspectives for the implementation of IPM in viticulture

“…insects, mites, birds, bats) efficiently acting as predators or parasitoids, which have long been known as natural enemies of viticulture pests. As already noted previously, despite the large amounts of fungicides and insecticides used over decades, the vineyard is far from being a "no parasitoid's land" (Marchesini and Dalla Mont a, 1994;Barbaro et al, 2016; see Thi ery, 2011; for a review). Biological control in vineyards is now promising, but is still a challenging issue, with viticulture still suffering from a lack of basic and applied studies.…”