Abstract:Periodical cicadas have mass emergences once every 13 or 17 years. Plants may need to upregulate defense production in response to an emergence. Defense production is energetically expensive, so plants may downregulate their production after periodical cicada populations dissipate. We examined the defensive responses in leaves, branches, and roots of a common host, white oak (
Quercus alba
), prior to, during, and after a 17‐year periodical cicada (
Magicicada
spp.… Show more
Periodical cicadas have mass emergences once every 13 or 17 years. Plants may need to upregulate defense production in response to an emergence. Defense production is energetically expensive, so plants may downregulate their production after periodical cicada populations dissipate. We examined the defensive responses in leaves, branches, and roots of a common host, white oak (
Quercus alba
), prior to, during, and after a 17‐year periodical cicada (
Magicicada
spp.) emergence in western Pennsylvania, United States. During the emergence, total tannins and condensed tannins increased in foliar tissue, while simultaneously decreasing in root tissue compared to the prior and subsequent years. Non‐structural carbohydrates were low prior to the mass emergence but were re‐allocated to belowground storage during the emergence year and dropped thereafter. In the year after the emergence, there was a relaxation of foliar defenses, and root defenses returned to pre‐emergence concentrations. We also tested for differences in damaged and undamaged branches on the same tree during (2019) and the year after the emergence (2020). Both damaged and undamaged branches had significantly greater chemical defenses (polyphenols, total tannins, and condensed tannins) during the emergence than in the following year when there was no emergence. We propose that re‐allocation of resources may help maximize oak tree fitness by moving resources away from areas that are not in immediate threat to areas that are under immediate threat. Changes in aboveground and belowground phytochemistry in response to periodical cicada mass emergences may help us better understand which resource re‐allocation strategies are used by plants to minimize the effects of insect emergencies.
Periodical cicadas have mass emergences once every 13 or 17 years. Plants may need to upregulate defense production in response to an emergence. Defense production is energetically expensive, so plants may downregulate their production after periodical cicada populations dissipate. We examined the defensive responses in leaves, branches, and roots of a common host, white oak (
Quercus alba
), prior to, during, and after a 17‐year periodical cicada (
Magicicada
spp.) emergence in western Pennsylvania, United States. During the emergence, total tannins and condensed tannins increased in foliar tissue, while simultaneously decreasing in root tissue compared to the prior and subsequent years. Non‐structural carbohydrates were low prior to the mass emergence but were re‐allocated to belowground storage during the emergence year and dropped thereafter. In the year after the emergence, there was a relaxation of foliar defenses, and root defenses returned to pre‐emergence concentrations. We also tested for differences in damaged and undamaged branches on the same tree during (2019) and the year after the emergence (2020). Both damaged and undamaged branches had significantly greater chemical defenses (polyphenols, total tannins, and condensed tannins) during the emergence than in the following year when there was no emergence. We propose that re‐allocation of resources may help maximize oak tree fitness by moving resources away from areas that are not in immediate threat to areas that are under immediate threat. Changes in aboveground and belowground phytochemistry in response to periodical cicada mass emergences may help us better understand which resource re‐allocation strategies are used by plants to minimize the effects of insect emergencies.
Periodical cicadas (Magicicada spp.) are endemic to deciduous forests in the eastern United States. In successional forests, they must partition resources such as host trees to coexist. We measured tree size, emergence holes, oviposition scar bundles, and chorusing center abundances of Magicicada species on 12 common tree species in a deciduous forest to understand host-tree use. We predicted that the abundance of periodical cicadas and use of specific host-tree species would change depending on the Magicicada species and tree life stage. We considered the size of the tree (diameter at breast height) as a covariate to control for tree size and collected eggs for a greenhouse experiment to assess whether nymphs prefer to feed on Quercus rubra or Acer saccharum. More emergence holes were found below Quercus species than any other tree species. The abundance of periodical cicadas on host trees used for chorusing centers varied depending on the Magicicada species, but were most abundant on Quercus species. Oviposition scar bundles were also more frequent on Quercus. More nymphs were found on Quercus than Acer in the nymph preference study. Though periodical cicadas used Quercus hosts more than other tree species, their abundances on different host tree sizes and species differed significantly. Periodical cicada species may use specific host species and life stages as a way to partition resources and minimize competition among the Magicicada species during emergence years.
Climate change affects various scales of biotic interaction through phenological shifts. The emergence phenology of cicadas is ecologically important because these insects have large effects on the ecosystem as herbivores, as food resources, and in nutrient flux from subterranean resources. However, little is known about the weather factors affecting their emergence patterns in the field because their nymphal stages grow underground for several years.
Here, we used long‐term observation data on the first singing date (i.e. the first emergence of male individuals) of Graptopsaltria nigrofuscata, recorded by the Japan Meteorological Agency and citizen scientists throughout Japan, to (1) explore the most influential weather factors across a variety of time spans on the first singing date of G. nigrofuscata and (2) determine whether the temporal trend of the first singing date could be explained by temporal weather trends caused by climate change by using a state space model.
Our results indicated that higher temperatures from midsummer to early winter in the previous year are bringing the cicadas' emergence forward, and the annual increase in temperature is causing the advancement of emergence patterns. Other weather factors, such as precipitation and humidity, did not have a strong effect.
Our findings suggest that increased growth rates at the nymphal stage due to warming in the previous year influence cicada emergence timing. To understand the mechanisms of how rising temperatures are advancing cicada emergence, we need an approach based on the physiology and ecology of their nymphs.
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