Pollen consumption by flower mites in three hummingbird-pollinated plant species

Abstract

Laboratory studies suggest that pollen consumption by flower mites may decrease the male fitness of the plant by reducing the available pollen for dispersal. Here we assessed pollen consumption by flower mites under natural conditions in three plant species with long-lived, protandrous flowers, Moussonia deppeana (Gesneriaceae), Lobelia laxiflora and L. cardinalis (Lobeliaceae). Total pollen mass was measured after 24 and 48 h in flowers exposed to flower mites and excluded from hummingbirds, flowers exposed to mites and hummingbird visitation, and in flowers recently opened with dehisced anthers. Compared with recently opened flowers, pollen availability was reduced about half in the presence of flower mites and the same effect was observed in the three plant species. Our results suggest that flower mites are removing a great deal of pollen and the reduction of pollen implies the possibility of direct impact on pollen transfer.

How many species of arthropods visit flowers?

“…bees, hummingbirds) to move from one flower to another (Colwell 1995;Guerra et al 2012). These species deplete flowers of available nectar (Colwell 1995) and pollen (Velázquez and Ornelas 2010), but the effect this has on pollinator visitation and plant pollination is unknown. The overall diversity of flower-visiting mites is difficult to estimate because as few as 5 % of mite species (*30,000) have been described.…”

Effects of Pollen in Lobelia laxiflora (Lobeliaceae) Long-Lived Flowers on Fecundity of Tropicoseius chiriquensis (Acari: Mesostigmata: Ascidae)

“…Our data suggest that pollen may provide nutrients that mites do not obtain in nectar. Pollen consumption by hummingbird ßower mites can reduce the availability of pollen in host plant ßowers by up to 50% (Paciorek et al 1995, Velázquez andOrnelas 2010), thus behaving as ßoral parasites because the male Þtness of the host plant is potentially reduced. Although pollen limitation was out of the scope of this study, pollen consumption by ßower mites can cause pollen limitation at the population level by depleting the overall pool of male gametes available to fertilize ovules (reviewed in Hargreaves et al 2009).…”

“…Tropicoseius chiriquensis Baker & Yunker ßower mites inhabit L. laxiflora ßowers (Ϸ51 ßower mites per ßower). They consume up to 25% of the nectar otherwise available to hummingbirds (Lara and Ornelas 2002a) and 31% of available pollen in 48 h by the end of the staminate phase of L. laxiflora ßowers (Velázquez and Ornelas 2010). Under laboratory conditions, eggs of T. chiriquensis hatch in approximately a day, larvae and nymphs take Ϸ2 d to develop and most eggs reach the adult stage in 5 d when nectar and pollen from L. laxiflora ßowers is provided daily ad libitum (our unpublished data).…”

“…(Rubiaceae). In the laboratory, they placed various densities of mites in plastic dishes to consume pollen grains ad libitum from dehisced anthers and estimated that an average ßower mite population of 45 mites in H. patens could consume Ϸ16% of the pollen in a ßower in Ϸ12 h. Under natural conditions, Velázquez and Ornelas (2010) showed that Tropicoseius ßower mites consume approximately half the pollen in ßowers of Moussonia deppeana (Schlecht. & Cham.)…”

Mites on Plants

“…If a pollinator transmits an organism that infects plant reproductive structures, then this is analogous to venereal transmission of diseases in animals. At least seven, and possibly as many as ten, unrelated groups of Mesostigmata have evolved a specialised life style that has been appropriately described as a venereal disease of plants; they ride pollinators from fl ower to fl ower, infest fl owers and consume signifi cant amounts of nectar and pollen (Colwell 1995 ;Paciorek et al 1995 ;Velazquez and Ornelas 2010 ).…”