Birds Bug on Indirect Plant Defenses to Locate Insect Prey

Abstract

It has long been thought that most birds do not use volatile cues to perceive their environment. Aside from some scavenging birds, this large group of vertebrates was believed to mostly rely on highly developed vision while foraging and there are relatively few studies exploring bird response to volatile organic compounds. In response to insect herbivory, plants release volatile organic compounds to attract parasitoids and predators of the pests. To test if insectivorous birds use herbivore-induced plant volatiles (HIPV), dispensers emitting a synthetic blend of HIPV typically emitted after insect herbivory were deployed in a maize field along with imitation clay caterpillars. Significantly more imitation insects were attacked by birds when located close to dispensers releasing HIPV than close to dispenser with organic solvent only. Seven times more peck marks, an index of avian predation, were counted on caterpillars in the vicinity of the HIPV dispensers than on insects close to control dispensers. This is the first field demonstration that insectivorous birds cue on HIPV to locate prey in agricultural settings. These results support the growing evidence that foraging birds exploit volatile cues. This more accurate understanding of their behavior will be important when implementing pest management program involving insectivorous birds.

A larval aggregation pheromone as foraging cue for insectivorous birds

“…Furthermore, artificial larvae near dispensers with the aggregation pheromone had proportionally more bird pecks than larvae near the control dispenser. These results support previous findings showing that insectivorous birds can use chemical cues to locate and consume their prey 8,9,11,25,27,49,50]. Considering that many birds prey on immature stages of insects, the capacity to perceive chemical cues emitted by insect larvae would be of great ecological relevance in birds' foraging strategies.…”

“…For instance, woodpeckers (Picidae) were shown to regulate the population of bark beetles (Curculionidae) in coniferous forest landscapes [67]. Moreover, different studies have demonstrated that insectivorous birds use herbivore-induced plant volatiles as olfactory cues to locate their prey in agricultural ecosystems [25,49]. Within this context, the capacity of birds to detect insect-derived chemical cues, such as sexual or aggregation pheromones, may present an opportunity for the regulation of insect populations in human-modified landscapes.…”

“…Insectivorous birds have also been documented to rely on olfaction to locate their prey. It has been shown that herbivore-induced plant volatiles can guide birds to prey on the insects inducing the emissions of those volatiles [24][25][26]. Furthermore, a recent study revealed that birds could exploit the pheromones of adult insects to locate their prey.…”

Great Tits Learn Odors and Colors Equally Well, and Show No Predisposition for Herbivore-Induced Plant Volatiles

“…Even though olfaction previously has been dismissed as being unimportant for most bird species, it has turned out to play an important role in bird foraging behavior (Mäntylä et al, 2004;Hiltpold and Shriver, 2018;Potier, 2020;Danel et al, 2021). Some bird species can use their sense of smell to identify caterpillarinfested trees by detection of herbivore induced plant volatiles (HIPVs) (Mäntylä et al, 2004(Mäntylä et al, , 2020Amo et al, 2013).…”

“…Herbivorous larvae may also be the most important part of the diet for many bird species, especially while provisioning their young, which suggests that HIPVs could be important for foraging efficiency. Indeed, several studies have demonstrated bird attraction to or preference for HIPVs both in the laboratory (Amo et al, 2013;Mäntylä et al, 2017) and in the field (Mrazova and Sam, 2017;Hiltpold and Shriver, 2018;Rubene et al, 2019).…”