Dispersal and Migration Patterns of Freshwater Semiaquatic Bugs.

Tomáš Ditrich

doi:10.3390/insects12110976

Abstract

Simple SummarySemiaquatic bugs have colonized the water surface of most aquatic habitats, from small and temporary puddles and streams to the open ocean. Most semiaquatic bugs are wing-polymorphic, as some individuals have fully developed wings (macropterous) and others have shortened wings (brachypterous) or are wingless (apterous). This is characteristic for most temperate water striders, common on lakes, fishponds, and pools around the world. The report presented here is based on the collection of more than 23,000 individuals of nine species of semiaquatic bugs that were individually marked by a unique code and released. The recaptures revealed several distinct dispersal strategies, with differences among individual species. Collection of the marked bugs also helped to describe dispersal via the water surface by flightless individuals. Using the results of the presented survey, our knowledge of these interesting insects is considerably extended, and it can help us to understand the general dispersal patterns of aquatic insects.Semiaquatic bugs (Hemiptera: Heteroptera: Gerromorpha) are mostly wing-polymorphic species with flight dispersal as an important life history trait, but the specific flight ability and dispersal pattern remain unexplored in most species. This report presents the results of a long-term survey based on the individual marking of more than 23,000 specimens of eight water striders (Gerridae) and a water cricket Velia caprai (Veliidae). Three distinct lentic habitats were sampled (solitary fishponds, systems of nearby fishponds and systems of small, often temporary pools) and one lotic habitat—a small forest stream. Recaptures revealed that three gerrid species tend to stay at the breeding site, but can differ in dispersal via the water surface. Reproductive flightless females disperse most actively via the water surface, possibly bypassing the trade-off between dispersal and reproduction. One species has a sex-dependent dispersal pattern, with females being rather philopatric, whereas males often disperse. Three other gerrid species are highly dispersive and tend to change breeding site. V. caprai, the only lotic species included in this survey, tend to move upstream and possibly compensate for the downstream drift.

Highlights

Aquatic insects have surprisingly good dispersal abilities, as many natural freshwater habitats are more or less temporary
A similar situation was found at Kamenny fishpond—we marked 1124, 1052, and 1245 individuals, and species composition was: G. lacustris (37%), A. paludum (23%), G. argentatus (18%), G, odontogaster (12%), L. rufoscutellatus (7%), and G. thoracicus (3%)
Whereas G. odontogaster and G. argentatus tend to stay at their sites and likely do not move much, G. lacustris is more mobile and moves along the shore, as a high proportion of G. lacustris movements were by one sector

Summary

Introduction

Aquatic insects have surprisingly good dispersal abilities, as many natural freshwater habitats are more or less temporary. The dispersal flight by semiaquatic bugs is an important life-history trait [3], but the exact extent of migration and dispersal has rarely been studied, with the exception of a long-term survey of the seasonal aspects of flight in five Canadian water striders by Spence [7]. He identified four distinguished categories of seasonal flight activity, connected with overwintering sites and intersite movement. I present the results of a long-term study of nine gerromorphan species focused on individual migration and dispersal patterns of both inter- and intrasite movement

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Discussion

Conclusion