From: Adam Andrus, MONGABAY.COM, More from this Affiliate
Published June 19, 2013 12:16 PM

Warming world hits fig wasps and figs

Recent experiments concerning hugely-important fig plants (Ficus) and their relationship with small, short-lived fig wasps suggest dire potential consequences due to human induced climate change, finds a study published in the journal Biology Letters.

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The researchers, lead by Richard T. Corlett of Xishuangbanna Tropical Botanical Garden, Center for Integrative Conservation in the Peoples Republic of China, collected four species of adult female fig wasps from the lowland tropical forests of Singapore to test their tolerance to gradually increased temperatures. The results of the experiment showed a steady decrease in fig wasp life-expectancy as temperatures rose, suggesting the vulnerability of these pollinator wasps to a warmer world.

"A decline in fig populations is thus likely to lead to a decline in the ability of the area to support vertebrate frugivores [fruit-eaters], with possible implications for other plant species that need these frugivores to be available when they fruit," Corlett explained.

These particular figs are pollinated by female wasps, which only lay their eggs exclusively in fig flowers. In turn wasp larvae feed on some of the developing seeds, exemplifying the specialized relationship.

The data collected from the experiment suggests that an increased temperature of three degrees Celsius or higher above current temperatures experienced across the equatorial tropics could significantly impact the delicate relationship between the wasps and its host plant.

The possible consequences of increased mean temperatures include: "declines in the potential populations of fig wasps; reduced pollination services leading to fig population declines; and reduced fig populations reducing food abundance for frugivores, resulting in secondary population declines," according to the study.

Although these threats are substantial, Corlett believes conservation efforts to preserve and mitigate the effects of global warming on fig wasps "appear not to be needed under normal circumstances."

He notes that "the wasps are amazingly good at finding the correct fig species at the correct stage for them to enter the developing figs, pollinate them and lay their eggs."

The ability for wasps to acclimatize to gradual increased temperature is essential to their survival. "If warmed slowly during their larval stage, the wasps might acclimatize to higher temperatures to at least some extent," explains Corlett. "Moreover, the fig wasps go through a generation a month, or around a thousand generations by the end of this century. This is plenty of time to evolve more thermal tolerance if the population has the genetic variation needed to do this."

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Fig image via Shutterstock.

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