Effect of Intercropping on Predation of Oncideres Ocularis (Coleoptera: Cerambycidae) in Brazilian Acacia Mangium Plantations

Abstract

Oncideres ocularis (Cerambycidae) is a twig girdler beetle with potential to become a pest of Fabaceae forest plantations. The diversity of agroecosystems can affect populations of insect pests and their natural enemies, and intercropping may provide resources such as food, alternative prey and hosts, and shelter for the natural enemies. The objective of this work was to verify if the number of larvae and the action of natural enemies of this twig girdler vary along the girdled branch and with the different plantation methods. Fresh branches of Acacia mangium girdled by O. ocularis were collected at two types of plantations, a monoculture andan intercropping with eucalyptus and Brachiaria spp. The dead and living larvae were removed from the galleries along the branch (basal, middle, and apical sections). The number of larvae was different between sections of the girdled branch for ali variables analyzed. The total number of larvae of O. ocularis did not differ between the types of plantation, but larvae survival was significantly higher in the intercropping than in monoculture. The type ofplantation also affected the action ofpredators on larvae in the early instars, besides varying along the branch. In intercropping systems with eucalyptus, acacia, and grasses, the predators may not a ble to reduce the population of this twig girdler.