Diversity and pollination value of insects visiting the flowers of a rare buckwheat (&lt;i&gt;Eriogonum pelinophilum&lt;/i&gt;: Polygonaceae) in disturbed and "natural" areas

V J Tepedino,T L Griswold,W R Bowlin

doi:10.26786/1920-7603(2011)9

Abstract

We compared flower-visitors of the endangered plant Eriogonum pelinophilum, at relatively undisturbed and highly disturbed sites. We found no difference between sites in flower visitation rate or species richness of flower-visitors; species diversity of flower-visitors was higher at disturbed than at undisturbed sites but there was no difference in equitability. We found significant differences in total E. pelinophilum pollen carried on the body among 14 abundant bee species; eight abundant wasp species; and 12 abundant fly species. Both bee and wasp species carried significantly more pollen on the ventral compared to dorsal segments of the body; pollen on the body of fly species was more equally distributed across body surfaces. Total pollen carried on flower-visitor bodies was significantly related to visitor length, suggesting that larger visitors were more effective pollinators. Total Pollination Value, a measure combining both visitor abundance and body pollen was greater at the disturbed site than the undisturbed site, further suggesting that pollination in fragments of this rare species is not a major concern. We conclude that the high diversity of insect flower-visitors and the generalized nature of E. pelinophilum flowers make a special management programme to conserve pollinators unnecessary. Conservation of this buckwheat is best achieved by simple habitat preservation, together with a program to enlist private citizens to include buckwheat plants in their backyard gardens. download Appendix

Highlights

Foremost among the important causes of plant rarity are habitat loss, modification and fragmentation (Ehrlich 1988; Wilson 1988; McNeeley et al 1990; Gentry 1996)
Tepedino (1979), Bond (1994), Kearns et al (1998) and others have noted that self-incompatible plant species and those that have evolved specialized associations with a few selected pollinator species are more vulnerable to pollinator loss than are self-compatible species and those whose unspecialised flowers are used by many generalised
With its canopy of open, accessible flowers produced over two months, E. pelinophilum attracted a wide variety of insects (Appendix I)

Summary

Introduction

Foremost among the important causes of plant rarity are habitat loss, modification and fragmentation (Ehrlich 1988; Wilson 1988; McNeeley et al 1990; Gentry 1996). Such deterioration of habitat can adversely affect the pollinators (Vinson et al 1993; Gess & Gess 1993; Westrich 1996) that many rare plants in the western United States depend upon (Tepedino 2000), and thereby further impair their seed production and recruitment. A recent estimate of the percent of species whose reproduction is aided by pollinators is 85 – 90% (Ollerton et al 2011), but vulnerability to pollinator loss varies even among pollinatorrequiring species. Tepedino (1979), Bond (1994), Kearns et al (1998) and others have noted that self-incompatible plant species and those that have evolved specialized associations with a few selected pollinator species are more vulnerable to pollinator loss than are self-compatible species and those whose unspecialised flowers are used by many generalised

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