Attraction to Smelly Food in Birds: Insectivorous Birds Discriminate between the Pheromones of Their Prey and Those of Non-Prey Insects

Abstract

Natural selection has favored the evolution of different capabilities that allow animals to obtain food—e.g., the development of senses for improving prey/food detection. Among these senses, chemical sense is possibly the most ancient mechanism used by organisms for environmental assessment. Comparative studies suggest the prime role of foraging ecology in the evolution of the olfactory apparatus of vertebrates, including birds. Here, we review empirical studies that have shown birds’ abilities to detect prey/food via olfaction and report the results of a study aiming to analyze the specificity of eavesdropping on prey pheromones in insectivorous birds. In a field study, we placed artificial larvae and a dispenser with one of three treatments—prey (Operopthera brumata) pheromones, non-prey (Rhynchophorus ferrugineus) pheromones, or a control unscented dispenser—on the branches of Pyrenean oak trees (Quercus pyrenaica). We then measured the predation rate of birds on artificial larvae. Our results show that more trees had larvae with signs of avian predation when they contained a prey pheromone dispenser than when they contained a non-prey pheromone dispenser or an unscented dispenser. Our results indicate that insectivorous birds can discriminate between the pheromones emitted by their prey and those emitted by non-prey insects and that they only exhibit attraction to prey pheromones. These results highlight the potential use of insectivorous birds in the biological control of insect pests.

Exogenous Application of Methyl Jasmonate Increases Emissions of Volatile Organic Compounds in Pyrenean Oak Trees, Quercus pyrenaica

“…However, in the current study we had an unexpected result, as we did not find any caterpillars being attacked by avian predators. The use of similar artificial larvae for estimating bird attraction to trees has been used successfully in several studies [ 24 , 31 , 36 , 40 , 41 , 42 , 43 , 44 , 45 ], even within the same bird population [ 46 ]. Therefore, the lack of attraction even to Herbivore-infected trees is unlikely due to the use of artificial caterpillars.…”

“…We measured the attraction of birds to each tree by checking the number of plasticine larvae with marks indicating predation by birds. This method has been used in previous studies of avian predation [ 24 , 31 , 35 , 36 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ]. The artificial larvae are considered damaged when they had triangle-shaped marks and deep cuts made by bird beaks and when a part of their body was taken by the birds (see [ 24 , 35 ]).…”

Exogenous Application of Methyl Jasmonate Increases Emissions of Volatile Organic Compounds in Pyrenean Oak Trees, Quercus pyrenaica

“…The use of similar artificial larvae for estimating bird attraction to trees has been used successfully in several studies [24,31,36,[40][41][42][43][44][45]. Even the results of a previous study in the same population of birds using artificial caterpillars of similar shape and coloration [46] showed that birds were attacking them. Therefore, the lack of attraction to even to Herbivore-infected trees is unlikely to be due to the use of artificial caterpillars.…”

“…We measured the attraction of birds to each tree by checking the number of plasticine larvae with marks indicating predation by birds. This method has been used in previous studies of avian predation [24,31,35,36,[40][41][42][43][44][45][46]. The artificial larvae are considered damaged when they had triangle-shaped marks and deep cuts made by the beak of the birds and when a part of their body was taken by the birds (see [24,35]).…”

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

“…Other vertebrate predators have long been known to use odor cues to find prey (Conover 2007, Gardiner and Atema 2007, Johannesen et al 2012. Recent work has shown that birds can also locate prey directly via odor cues (Nevitt 2000, Cunningham et al 2008, Saavedra and Amo 2018a, Amo and Saavedra 2021, Díaz-Siefer et al 2021. Predation on herbivorous insects is well known to be governed by tritrophic interactions mediated by the release of herbivore induced plant volatiles (HIPVs) upon plant wounding (D' Alessandro and Turlings 2006, Heil 2008, Arimura et al 2009, Kaplan 2012.…”