Potential of pest regulation by insectivorous birds in Mediterranean woody crops

Abstract

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.

Enhancing ecosystem services in apple orchards: Nest boxes increase pest control by insectivorous birds

“…On the one hand, models mimicking lepidopteran caterpillars indicate increased insectivory rates attributable to birds, in accordance with previous studies (e.g. Jedlicka et al., 2011; Rey Benayas et al., 2017). On the other hand, the beating sampling evidenced that the use of nest boxes decreased arthropod biomass on apple trees.…”

“…no granivore species occurred, e.g. Rey Benayas et al., 2017). Nest boxes thus lead to increased occurrence of food‐demanding insectivores in the season when apple pest infestations typically increase (Miñarro et al., 2011).…”

“…Indeed, several small‐scale studies have found increased insectivory or reduced plant damage in cropland harbouring nest boxes with insectivorous birds (e.g. Mols & Visser, 2007; Rey Benayas et al., 2017). Despite these findings, and the fact that the installation of nest boxes may be seen by farmers as a non‐disruptive and low‐cost practice (Bardenhagen et al., 2020), we still need to extend our knowledge, at large spatial scales and taking into account differences between bird species and prey types, in order to fully understand nest boxes' potential for ecological intensification.…”

Landscape drivers and effectiveness of pest control by insectivorous birds in a landscape-dominant woody crop

“…To our knowledge, this is the first study to assess pest control by birds in olive orchards, which hinders further comparison of our results. However, Rey Benayas et al, (2017) set an experiment in several Mediterranean woody crops, including olive orchards, using bird nest boxes and alive sentinel preys. The nest boxes set in olive orchards were not occupied throughout the four-year study, and therefore, no attack rates were available for this system.…”

Unravelling pest infestation and biological control in low-input orchards: the case of apple blossom weevil

“…Ecological intensification at the farm level to promote biological control has been recommended (Bommarco et al 2013). For example, nest boxes for insectivorous birds are readily occupied and can promote the biological control of agricultural pests (Mols and Visser 2002;Benayas et al 2017) and other measures favouring the biodiversity of natural enemies (flower strips, hedgerows) have also been recommended (e.g. Wratten et al 2012;Sidhu and Joshi 2016).…”