The evolutionary ecology of the Lygaeidae

Abstract

The Lygaeidae (sensu lato) are a highly successful family of true bugs found worldwide, yet many aspects of their ecology and evolution remain obscure or unknown. While a few species have attracted considerable attention as model species for the study of insect physiology, it is only relatively recently that biologists have begun to explore aspects of their behavior, life history evolution, and patterns of intra- and interspecific ecological interactions across more species. As a result though, a range of new phenotypes and opportunities for addressing current questions in evolutionary ecology has been uncovered. For example, researchers have revealed hitherto unexpectedly rich patterns of bacterial symbiosis, begun to explore the evolutionary function of the family's complex genitalia, and also found evidence of parthenogenesis. Here we review our current understanding of the biology and ecology of the group as a whole, focusing on several of the best-studied characteristics of the group, including aposematism (i.e., the evolution of warning coloration), chemical communication, sexual selection (especially, postcopulatory sexual selection), sexual conflict, and patterns of host-endosymbiont coevolution. Importantly, many of these aspects of lygaeid biology are likely to interact, offering new avenues for research, for instance into how the evolution of aposematism influences sexual selection. With the growing availability of genomic tools for previously "non-model" organisms, combined with the relative ease of keeping many of the polyphagous species in the laboratory, we argue that these bugs offer many opportunities for behavioral and evolutionary ecologists.

Keywords: Ecology; Lygaeidae; entomology; evolution; life history; sexual selection.

Figure 1

A schematic of the relationships among the infra-order Pentatomomorpha (after Li et al. and Henry 2009). Between 5 and 15 families are thought to comprise the Lygaeoidea, including the family Lygaeidae sensu stricto. Photo credits: The Tree of Life Web Project and David Shuker.

Figure 2

Left - An adult Spilostethus pandurus feeding on a Lygaeus creticus nymph. Sicily. Right – A Lygaeus kalmii feeding on an ant. Photo credits: (left to right) David Shuker, Mary Holland.

Figure 3

Four extensively studies species of Lygaeidae. Top right Neacoryphus bicrucis (photo courtesy of Jillian Cowles), bottom right Oncopeltus fasciatus (photo courtesy of Alison Bockoven), bottom left Spilostethus pandurus (David Shuker) and top left Lygaeus equestris (Liam Dougherty).

Figure 4

Right – Laboratory raised second instar nymphs of the species Spilostethus pandurus showing characteristic black and red coloration. Left – an aggregation of late-instar Lygaeus creticus nymphs and adults. Sicily. Photo credits: Emily Burdfield-Steel.

Figure 5

An ant-mimicking Seed Bug - Daerlac nigricans – form the Family Rhyparochromidae. Photo courtesy of Peter Chew (http://www.brisbaneinsects.com).

Figure 6

Diagram of adegus of a male Lygaeus equestris. Courtesy of Liam Dougherty.