Abstract: Twig girdlers have a short adult life and a long larval stage (up to one year in some species). This fact, together with lack of morphological traits to identify the species from the larval stage, poses obstacles for the taxonomic identification and characterization of the many twig girdlers found in the wild. To solve this matter, Random Amplified Polymorphic DNA (RAPD) molecular markers have been applied to identify some insect species and to determine species boundaries. The aim of this study was to identify three species of Oncideres using the RAPD technique. Adults and larvae of O. saga, O. ocularis and O. ulcerosa were collected in Minas Gerais, Brazil. Two RAPD primers were used (OPA-05 and OPB-13), which produced different electrophoretic profiles that were used to construct a UPGMA phenogram. Three groups identified in the analyses accurately separated the three species, based on individuals in two different stages of development (adults and larvae): I: O. saga, II: O. ulcerosa, and III: O. ocularis. Molecular markers, such as RAPD, are valuable tools that help taxonomists in species identification.

Oncideres ocularis (Cerambycidae) es un escarabajo “corta palo” que tiene potencial para convertirse en plaga en plantaciones forestales de Fabaceae. La diversidad de los agroecosistemas puede afectar a las poblaciones de insectos plaga y sus enemigos naturales. El cultivo intercalado puede proporcionar recursos, como alimentos, presas alternativas, hospederos y refugio para los enemigos naturales. El objetivo de este trabajo fue verificar si el número de larvas y la acción de los enemigos naturales de este corta palo varían a lo largo de la rama anillada y con los diferentes métodos de plantación. Se colectaron ramas frescas de Acacia mangium anilladas por Oncideres ocularis en dos tipos de plantaciones, un monocultivo y otro intercalado con eucalipto y Brachiaria spp. Las larvas muertas y vivas fueron retiradas de las galerías a lo largo de la rama (secciones basal, media y apical). El número de larvas fue diferente entre las secciones de la rama anillada para todas las variables analizadas. La sección de la rama anillada afectó a todas las variables. Aunque el número total de larvas de O. ocularis no fue diferente entre los dos tipos de plantación, la supervivencia de las larvas fue mayor en el cultivo intercalado que en el monocultivo. El tipo de plantación afectó también a la acción de los depredadores de las larvas en los primeros estadios, además de variar a lo largo de la rama. En los sistemas con eucaliptos, acacias y pastos intercalados, los depredadores pueden ser incapaces de reducir la población de este “corta palo”.

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 and an 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 all 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 of plantation also affected the action of predators on larvae in the early instars, besides varying along the branch. In intercropping systems with eucalyptus, acacia, and grasses, the predators may not be able to reduce the population of this twig girdler.