G. Mite occurrence in <em>Lantana camara L.</em> flowers

Abstract

Lantana camara L. is a perennial shrub with agronomical interest as it is a weed mainly of pastures in wild state and it is a beautiful ornamental plant in its cultivated varieties. Its flowers are pollinated by butterflies which are often seen visiting them, and by bees and hummingbirds. Cross pollination is needed in this plant for fruit and seed set, this latter being its main reproductive mechanism. On the body of these pollinators, mites of the orders Mesostigmata and Astigmata live in phoresy and thus, by a sort of “hitch-hiking”, arrive to lantana flowers, when those pollinators visit these plants. Mite distribution in these flowers is significantly affected by factors such as temperature and air relative humidity due to their body cover not being either sclerotized or waxed, this making them sensitive to dessication at high temperature and low relative humidity values. Relative frequency of mites in red flowers was nine times higher than in yellow flowers. In orange and pink flowers, this frequency was close to five times higher than in yellow flowers. This is related to the lantana flower corolla length, longer in red and pink flowers and shorter in yellow flowers. Mites consume 40 % of flower nectar volume, reducing the availability of this food to pollinators, who thus avoid visiting flowers whose nectar was partially consumed. This reduces seed production, but, on the other hand, forces the pollinators to visit different plants thus promoting cross fecundation. Thus the phoretic mites have a double role in lantana reproduction : they may be considered pests as well as beneficial organisms. On the other hand, the Mesostigmata, because they are predators, have another beneficial role as pest controllers. Additional keywords: Mesostigmata; Astigmata; phoresy; pollination.