Camera traps reveal interspecific differences in the diel and seasonal patterns of cicada nymph predation

Abstract

Cicadas, a group of large-bodied insects, are preyed upon at both nymphal and adult stages by diverse range of vertebrates such as birds and mammals. Although the behavior of predators toward adult cicadas is well documented, there is a lack of research on the predation on cicada nymphs. In this study, camera-traps deployed in conifer plantations, in which high population densities of cicadas Lyristes bihamatus emerge, were used to evaluate the seasonal and diel patterns of predation upon cicada nymphs by three predator species, namely brown bears, red foxes, and jungle crows from May to September in 2018 and 2019 in northern Japan. Among all three species, cicada nymph predation occurred until early August when the final instar nymphs fully emerged. Bears were observed to constantly dig for cicada nymphs until early August, whereas foxes and crows were frequently observed foraging from late July to early August, during the season of L. bihamatus emergence. In contract to the powerful digging ability of bears, which facilitates efficient predation upon subterranean cicada nymphs, it is generally difficult for foxes and crows with limited or no digging ability to gain access these nymphs until the period of emergence. Cicada nymph predation by bears and crows was observed primarily during the daytime, despite the typical crepuscular/nocturnal emergence schedules of these insects. Contrastingly, the predatory activities of foxes tended to be nocturnal during the period prior to the beginning of cicada emergence, although subsequently became diurnal during the cicada emergence period. These observations indicate that the temporal activity patterns of cicada nymph predators are determined by interspecific differences in predation abilities and cicada emergence schedules. Accordingly, the findings of this study provide evidence to indicate that the timing and duration of trophic interactions between above-and belowground communities might vary among predator species, depending on their predation abilities.

Brown bear digging decreases tree growth: Implication for ecological role of top predators in anthropogenic landscapes

“…We detected the negative effects of digging on soil nutrients in 2017 and 2018 (Tomita & Hiura, 2022; Tomita, unpublished data), suggesting that their effects on soil are consistent across years as long as bears dig in the larch plantations every year. Although bears may cease digging for cicada nymphs in poor emergence years, the occurrence frequency of digging in larch plantations remains high even in poor emergence years (Tomita, 2021; Tomita & Hiura, 2021a). Thus, brown bear digging has constantly have affected tree growth since 2000.…”

Periodical cicadas disrupt trophic dynamics through community-level shifts in avian foraging

“…Because adult periodical cicadas are relatively large insects (3 to 4 cm in length), we had hypothesized that their consumption might be limited by avian gape width ( 20 ) or bird size more generally, as has been reported previously ( 21 , 22 ). However, we observed varied prey-processing behaviors that allowed birds of all sizes to feed successfully on cicadas ( 17 ).…”