One Host Shift Leads to Another? Evidence of Host-Race Formation in a Predaceous Gall-Boring Beetle

Abstract

We show that a predator, the tumbling flower beetle Mordellistena convicta (Coleoptera: Mordellidae), has formed host races in response to a host-plant shift and subsequent host-race formation by its prey, the gall-inducing fly Eurosta solidaginis (Diptera: Tephritidae). This fly has formed two host races, one that induces stem galls on the ancestral host plant, Solidago altissima (Compositae), and another that induces stem galls on the closely related S. gigantea. We found that subpopulations of M. convicta that attack E. solidaginis galls on the different host plants have significantly different emergence times and, although slight, these allochronic differences are consistent across a range of temperatures. More importantly, we found that beetles assortatively mate according to their natal host plants, and female M. convicta preferentially attack and/or their offspring have higher survival in galls on natal host plants. Our data suggest that subpopulations of M. convicta that attack E. solidaginis galls on S. altissima and S. gigantea have formed host races. This is one of the first studies to demonstrate that a host shift and subsequent host-race formation by an herbivorous insect may have resulted in subsequent diversification by one of its natural enemies.

Host‐associated differentiation in a highly polyphagous, sexually reproducing insect herbivore

“…2001; Eubanks et al. 2003; Stireman et al. 2005), pea aphids ( Acyrthosiphon pisum ) associated with plants in the Fabaceae family (Via 1999; Frantz et al.…”

“…For example, conservation biological control may not work in a particular crop if natural enemies co-evolve with their insect hosts on one host-plant species and become reproductively isolated on alternative host plants (Eubanks et al. 2003; Forbes et al. 2010; Heard et al.…”

Host‐associated differentiation in a pecan and water hickory Aphidomorpha community

“…In addition, galling parasites are further constrained as they require specific adaptations that allow them to manipulate host-plant metabolism to induce gall formation. These hypotheses are supported by the goldenrod system, wherein two-thirds of the endophagous feeders studied experienced HAD but no HAD was evident in either of the two exophagous feeders studied (Waring et al, 1990;Abrahamson & Weis, 1997;Eubanks et al, 2003;Stireman et al, 2005Stireman et al, , 2006. The existence of HAD in other systems involving single organisms tested in a host-plant pair supports these views (Waring et al, 1990;Blair et al, 2010;Egan et al, 2013).…”

A molecular phylogeny of the Cephinae (Hymenoptera, Cephidae) based on mtDNA COI gene: a test of traditional classification

“…Research on phytophagous insects has confirmed that adaptation and specialization to different plant species are central to generating diversification at all hierarchical levels (Mopper and Strauss 1998; Berlocher and Feder 2002; Funk et al 2002; Nosil et al 2002; Eubanks et al 2003; Lozier et al 2007). However, host specialization in the Cephinae, as observed in most phytophagous insect groups, might have led to evolutionary shift between higher taxonomic groups.…”