Controle biológico em roseiras: avaliação do predador Chrysoperla externa na redução populacional do afídeo Rhodobium porosum

Abstract

The Rhodobium porosum aphid has a frequent occurrence in rose bushes and the use of insecticides for its control has caused several problems, including the resistance of the pest, acquired by the indiscriminate use of these chemicals. In order to search for an efficient form of population management of R. porosum in rose cultivations, the use of the aphidophagous predator Chrysoperla externa as a control agent was evaluated in the laboratory. Considering the growing importance of floriculture in several regions of the country and the possibility of biological control of this herbivore, the search for efficient natural enemies that can be applied as control agents should be investigated. Thus, the present work aimed to evaluate aspects of biology and to elaborate the life table of C. externa fed with R. porosum, as well as to know its predatory capacity and behavioral responses of predator larvae in different abiotic and biotic conditions. It was verified that this aphid is an adequate prey for the development of C. externa, without causing negative effects on its biology. Behavioral aspects of chrysopid larvae are associated with their satiety, density of available prey and predator: prey ratio. The control of R. porosum by larvae of C. externa proved to be efficient in both confined environments tested, and, in the 1:10 ratio, the aphid population was completely eliminated. The behavior of fasting larvae reiterates the knowledge about the voracity of these insects. The consumption of aphids by the larvae is affected by different temperature and photoperiod conditions. The results obtained may support proposals for changes in the way of handling this pest in rose bushes through the application of augmentative biological control with the use of C. externa.