Time‐Traveling Larvae Ensure Survival in Small, Synchronously Fluctuating Populations

Christer Solbreck,Olof Widenfalk

doi:10.1002/bes2.1692

Abstract

The tiny gall midge Contarinia vincetoxici is a long-lived insect, although its active life, as adult–egg–growing larva, is brief. Eggs are laid in young flower buds of a swallow-wort, which then develop into conspicuous galls harboring the developing larvae. Mature larvae fall to the ground where they enter a long dormancy, which may last over a decade. Gall populations were monitored in a large host plant patch system over 12 years. Despite poor colonization rates, low local gall densities, and large synchronous density fluctuations, almost all patches seemed to be continually inhabited due to the large hidden underground pool of time-traveling larvae. This photograph illustrates the article “Time-traveling larvae ensure survival in small, synchronously fluctuating populations” by Christer Solbreck and Olof Widenfalk published in Ecosphere. https://doi.org/10.1002/ecs2.3086.

Highlights

Population structure is an important aspect of patchy populations
Small local populations, large synchronous population fluctuations, and low inter-patch migration rates are all likely to lead to low rates of occupancy and population persistence
Dormant individuals can form an insurance against local extinctions, allowing local populations to persist despite low rates of colonization

Summary

Introduction

Population structure is an important aspect of patchy populations. For example, small local populations, large synchronous population fluctuations, and low inter-patch migration rates are all likely to lead to low rates of occupancy and population persistence. Active cohorts may disappear for several years, by entering the hidden dormant stage. When they reemerge much later from the refuge, this is like being colonized in time (Chesson and Warner 1981, Hairston et al 1996). Examples of such bridging mechanisms are provided by the soil seed banks of plants (Bulmer 1984, Klinkhamer et al 1987, Thompson 2000), zooplankton resting stages in bottom sediments (Hairston 1996), and by prolonged diapause among insects (Hanski 1988)

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Conclusion