Diversity and parasitism of scale insects (Hemiptera: Coccoidea) in ten varieties of olive trees (Olea europaea L.) in Southern Brazil

Abstract: Commercial plantations of olive trees (Olea europaea L., Oleaceae) are being developed in the State of Rio Grande do Sul, southern Brazil. One recent problem with olive production in this region is the presence of scale insects (Hemiptera, Coccoidea). Scale insects suck the sap of host plants and can negatively affect olive trees and reduce the yields of olive fruit and oil. This study surveyed the scale insect species and their associated parasitoids in ten olive varieties, including Alfafara, Arbequina, Arbosana, Cipressino, Coratina, Frantoio, Koroneiki, Leccino, Manzanilla and Picual in an olive grove located in the Fundação Estadual de Pesquisa Agropecuária – Fepagro (Research Center of State Foundation for Agricultural Research) (30°33’15” S, 52º23’45” W; 420 m a.s.l.), Encruzilhada do Sul, southern Brazil. The surveys were carried out twice in each season (spring, summer, fall and winter), from April 2013 to February 2014. For each sample, two branches (upper and lower canopy), each 20-30 cm long with at least 20 leaves infested with scale insects, from each of three randomly selected trees, were examined for the presence and population densities of scale insects. The material was examined under a stereomicroscope or in an optical microscope to identify the scale insects. Scale insects were separated from the substrate and the number of alive individuals, those with parasitoid and those with perforations in the body after the emergence of the parasitoid. The percentage of parasitism was evaluated without identifying species of parasitoids and without distinguishing between immature and adult stages. The following species of scale insects were determined: Acutaspis paulista, Aonidiella aurantii, Aspidiotus nerii, Hemiberlesia cyanophylli, Hemiberlesia lataniae and Pinnaspis strachani (Diaspididae); Saissetia coffeae, Saissetia oleae (Coccidae). The most common scale insect was S. oleae (88.15%) found in all varieties of olive trees, followed by A. nerii (5.85%), which also occurred in all the varieties. S. coffee (4.51%) occurred only in five varieties, while the other scale insects occurred in a few cases in the olive grove. More scale species were found in Arbequina, Frantoio and Cipressino and only one species was found in Frantoio. Parasitoids were found in five scale insect species, but the percentage of parasitism was higher than 1% only on A. nerii (31.86%), A. paulista (26.95%) and P. strachani (5%). The identification of the parasitoids will be carried out in a subsequent study.