Produção de néctar e visitas por abelhas em duas espécies cultivadas de passiflora L. (passifloraceae)

Abstract

Pollinator activity is affected by resource availability. Flowers that produce more nectar are visited more, which results in a greater fruit set. The effect of nectar production on pollinator activity was tested in two cultivated species of passion fruit, Passiflora alata Curtis and Passiflora edulis Sims, in Morretes, Paraná. Flower buds were bagged and the accumulated nectar of flowers was collected hourly. The volume and concentration of nectar of P. alata increased during anthesis, which was associated with rising temperatures. The volume of nectar of P. edulis increased during the diurnal period of anthesis, falling after 6 pm. The nectar concentration was constant during anthesis. The visitation rate of Xylocopa frontalis (Olivier) was constant for P. alata (1.7 visits/100flowers/hour) and for P. edulis (6.6 visits/100flowers/hour). The visitation rate of Bombus morio (Swederus) for P. alata was 5.8 visits/100flowers/hour, and was higher at the beginning of anthesis. The constant rate of visits by X. frontalis may be associated to the continuous nectar production by both species of passionflower. Since both species are xenogamous, the maintenance of visits during anthesis may favor pollen flow among the individuals assuring good crop production.