A food web approach reveals the vulnerability of biocontrol services by birds and bats to landscape modification at regional scale

Abstract

Pest control services provided by naturally occurring species (the so-called biocontrol services) are widely recognized to provide key incentives for biodiversity conservation. This is particularly relevant for vertebrate-mediated biocontrol services as many vertebrate species are of conservation concern, with most of their decline associated to landscape modification for agricultural purposes. Yet, we still lack rigorous approaches evaluating landscape-level correlates of biocontrol potential by vertebrates over broad spatial extents to better inform land-use and management decisions. We performed a spatially-explicit interaction-based assessment of potential biocontrol services in Portugal, using 1853 pairwise trophic interactions between 78 flying vertebrate species (birds and bats) and 53 insect pests associated to two widespread and economically valuable crops in the Euro-Mediterranean region, olive groves (Olea europaea subsp. europaea) and vineyards (Vitis vinifera subsp. vinifera). The study area was framed using 1004 square cells, each 10 × 10 km in size. Potential biocontrol services were determined at all those 10 × 10 km grid-cells in which each crop was present as the proportion of the realized out of all potential pairwise interactions between vertebrates and pests. Landscape correlates of biocontrol potential were also explored. Our work suggests that both birds and bats can effectively provide biocontrol services in olive groves and vineyards as they prey many insect pest species associated to both crops. Moreover, it demonstrates that these potential services are impacted by landscape-scale features and that this impact is consistent when evaluated over broad spatial extents. Thus, biocontrol potential by vertebrates significantly increases with increasing amount of natural area, while decreases with increasing area devoted to target crops, particularly olive groves. Overall, our study highlights the suitability of our interaction-based approach to perform spatially-explicit assessments of potential biocontrol services by vertebrates at local spatial scales and suggest its utility for integrating biodiversity and ecosystem services in conservation planning over broad spatial extents.

Avian predation of insects on corn (Zea mays): Effects of methyl jasmonate, methyl salicylate, and weather conditions

“…The local landscape surrounding agricultural fields may also influence the level of avian predation. Several studies supported that avian predation was highest in agricultural fields surrounded by or adjacent to woody areas (Puckett et al 2009, Milligan et al 2014, García et al 2018, Herrera et al 2021, Lourenço et al 2021. In contrast, predation decreased in agricultural fields surrounded by few to no forest fragments (Milligan et al 2014).…”

“…While we did not observe any difference in HIPV treatments, we did measure appreciable levels of bird attacks on our caterpillars. In an effort to reduce the use of pesticides in agricultural settings, the efficacy of bird predation as a natural form of biocontrol has been demonstrated in many agricultural contexts (Puckett et al 2009, Milligan 2014, García et al 2018, reviewed in Díaz-Siefer et al 2021, Herrera et al 2021, Lourenço et al 2021), but not all (Martínez-Núñez et al 2020). These recent studies have shown promising data that bird predation could be an alternative form of pest control that can be artificially exploited, for example using nest boxes (Mols and Visser 2007, Koh 2008, Olmos-Moya et al 2022).…”

“…Birds may be an important potential form of biocontrol in agricultural settings (Koh 2008, Herrera et al 2021). Corn ( Zea mays ) is one of the most important agricultural crops worldwide (USDA 2022).…”

Canopy arthropod declines along a gradient of olive farming intensification

“…Still, ours and previous studies suggest that impacts of intensification could be less pronounced in orchards with reduced use of agrochemicals and with a more developed herbaceous layer 13 , 94 , though the feasibility and consequences of implementing such practices in intensive and superintensive orchards is still uncertain. Likewise, there is some support for the importance of maintaining semi-natural habitats at the landscape scale to reduce biodiversity impacts and pest abundance within orchards 25 , 101 , but quantification of the amount and types of habitats required to achieve such goals is still lacking. Overall, our results suggest that the rapid expansion of intensive and superintensive orchards is negatively impacting arthropod communities that inhabit Mediterranean farmland.…”

The Location and Vegetation Physiognomy of Ecological Infrastructures Determine Bat Activity in Mediterranean Floodplain Landscapes

“…Due to their insectivorous diet, European bats represent efficient natural enemies of many pest insects (Aizpurua et al, 2018;Herrera et al, 2021) that could potentially exert top-down pest control (Russo et al, 2018). However, bats have shown marked population declines that are believed to have occurred during the second half of the twentieth century in Europe (Browning et al, 2021) and many species are still threatened with extinction (IUCN, 2021).…”