REPRODUCTIVE BIOLOGY OF Acacia mearnsii DE WILD. (FABACEAE) IV: FLOWER VISITORS

To ensure the success of the strategies of genetic improvement in tree species, knowledge of the reproductive biology of the species involved is essential. One of these critical factors in reproductive success of the genus Acacia is the presence of vectors to pollination. The purpose of this study was to identify flower visitors to a commercial plantation of Acacia mearnsii De Wild. and quantify the polyads attached to the body surface of the insects. The observations were made from a tower in a commercial stand during flowering, in 2002 and 2003. During the day, flower visitors were captured with an entomological net and an air basket installed on a tractor. At night, insects were caught with light traps installed between the flowering crowns. Insects belonging to orders Coleoptera, Hymenoptera, Diptera, Hemiptera and Lepidoptera were observed. Beetles of the species Macrodactylus suturalis were considered dispersers of black wattle pollen, based on the high frequency of individuals in the population studied and the high quantity of polyads adhered to the body of the caught insects (X=229,36 polyads/insect). The amount of polyads verified on bees of the species Apis mellifera was significantly greater (X=448,50 polyads/insect), but the frequency in the study area was insignificant. One of the recommended ways to increase the frequency of bees and wasps in black-watle commercial plantations is the maintenance of sources of nectar and the introduction of bee hives.