Red anemone guild flowers as focal places for mating and feeding by Levant glaphyrid beetles

Abstract

Several species of glaphyrid (Scarabaeoidea: Glaphyridae) beetles forage and mate on Mediterranean red bowlshaped flowers. In red anemones and poppies in Israel, female beetles occupy only a subset of the flowers, do not aggregate, and are hidden below the petals. This raises the question of how males find their mates. In the present study, we investigated the hypothesis that males and females orient to similar plant-generated cues, thereby increasing their mate encounter prospects. Previous studies have demonstrated that beetle attraction to red models increases with display area. Choice tests with flowers and with models indicate that both male and female beetles prefer large displays. In anemones, beetles rest, feed, and mate mainly on male-phase flowers, which are larger than female-phase flowers. Poppies that contain beetles are larger than the population average. These findings support the hypothesis that males and females meet by orienting to large red displays. Corolla size correlates with pollen reward in both plant species, suggesting that visits to large flowers also yield foraging benefits. Male beetles often jump rapidly among adjacent flowers. By contrast to the preference for large flowers by stationary individuals, these jump sequences are random with respect to flower sex-phase (in anemone) and size (in poppy). They may enable males to detect females at close range. We hypothesize that males employ a mixed mate-searching strategy, combining orientation to floral signals and to female-produced cues. The glaphyrids' preference for large flowers may have selected for extraordinarily large displays within the 'red anemone' pollination guild of the Levant.

Pollinator‐mediated selection on floral size and tube color inLinum pubescens: Can differential behavior and preference in different times of the day maintain dimorphism?

“…The role of dark flower center in the pollination system of L. pubescens was not revealed here. Several studies have examined the role of central dark-color spot in flowers (Dafni et al, 1990;Eisikowitch, 1980;Johnson & Midgley, 1997;Keasar et al, 2010;Lamborn & Ollerton, 2000) but to date, there is no clear explanation for their adaptive role. In L. pubescens, both dark and light flowers had similar fitness, and overall visit frequencies were not different between tube-color morphs.…”

“…A dark flower center was proposed to play a role in attracting pollinators as an orientation mark toward the location of both reproductive organs and reward (e.g., Dafni et al, 1990;Ellis & Johnson, 2010;Ellis et al, 2014;de Jager & Ellis, 2012Johnson & Dafni, 1998;Johnson & Midgley, 1997Keasar et al, 2010;Papiorek et al, 2016). Darwin (1888) proposed that a dark flower center is of no functional importance to the plant and it may reflect past adaptation that is not functioning in present environment.…”

Evidence of red sensitive photoreceptors in Pygopleurus israelitus (Glaphyridae: Coleoptera) and its implications for beetle pollination in the southeast Mediterranean

“…In the east Mediterranean region, the phenology of glaphyrid beetles and red flowers overlaps in a temporal succession of species that conserve this mode of plant-pollinator interaction (Dafni et al 1990). While beetles mediate the reproduction of the plants, flowers provide food resource, mating site and shelter for the beetles (Keasar et al 2010) (Fig. 1).…”

“…It has been observed that glaphyrid beetles tend to visit red flowers almost exclusively when they are present (Tamar Keasar and Avi Shmida personal observations). Colored trap experiments indicate that red coloration alone would explain this preference (Dafni et al 1990;Keasar et al 2010).…”

A molecular phylogeny of Glaphyridae (Coleoptera: Scarabaeoidea): evolution of pollination and association with ‘Poppy guild’ flowers

“…But flowers are also mating sites for insects (Thornhill & Alcock, ; Barth, ). This is the case for many species of Glaphyridae, whose adults feed on floral pollen and mate on flowers (Keasar et al ., ). Several species of these beetles rely strongly on visual cues to find particular flowers, as receptive females on flowers are highly dispersed in space and to find them may be difficult for males, especially if the density of females is lower than that of flowers.…”