The effect of hummingbird flower mites on nectar availability of two sympatric Heliconia species in a Brazilian Atlantic forest.
OBJECTIVE
Hummingbird flower mites feed and reproduce in flowers of host plants pollinated by hummingbirds, and use the nostrils and bill of the hummingbird to move from plant to plant. These mites compete with the pollinator for the nectar produced by flowers. An investigation was made of the relationship between the pattern of nectar production and the effects of hummingbird flower mites in the flowers of two sympatric species of Heliconia (Heliconiaceae).


METHODS
Nectar production was sampled by carrying out two experiments: 2-hour intervals and accumulated nectar. Flowers with and without mites were used in both experiments.


RESULTS
Exclusion of mites increased nectar production, especially in accumulated daily production (a maximum of 49 % more nectar). Both Heliconia species had the same pattern of nectar production: a high concentration in the morning, which was progressively reduced as the day passed. This pattern of nectar production coincides with the behaviour of the pollinator, which makes more frequent visits in the morning, as observed in a previous study.


CONCLUSIONS
The results suggest that the impact of mites on nectar availability of Heliconia is more important with regard to total volume of nectar produced irrespective of flower longevity. A high variation among individuals in nectar produced in the populations was also observed. Hummingbird flower mites strongly affect availability of nectar for hummingbirds.
Da Cruz
Denise Dias
DD
Universidade do Estado do Rio de Janeiro, IBRAG, Departamento de Ecologia, Rua São Francisco Xavier 524, 20550-013 Rio de Janeiro, RJ, Brazil. denidcruz@hotmail.com
Righetti De Abreu
Vanessa Holanda
VH
Van Sluys
Monique
M
D000818:Animals; D001267:Atlantic Ocean; D001938:Brazil; D035264:Flowers / Q000502:physiology*; D032427:Heliconiaceae / Q000469:parasitology*; D008925:Mites / Q000502:physiology*; D014197:Trees