Use of Basil Ocimum basilicum and Chrysoperla externa (Chrysopidae) in Agroecological Management of Rosebushes

Cultivation in the greenhouse has been extensively used by farmers and flowers and ornamental plants comprise about 650,000 ha in the world [1]. The estimate in Brazil is approximately 30,000 ha with greenhouses and the production of flowers represents about 10% of this area being the rose the most produced and commercialized cut flower [2]. One of the main issues associated with the loss of quality of flowers during cultivation refers to the pest arthropod infestation, affecting plant growth, flowering and causing aesthetic damage to floral buds. The most widely used pest control in flower production is still the chemical one, which has been causing problems of resistance and insecticide residues, besides affecting the populations of natural enemies and may contaminate workers and the environment [1,2,3]. The biological control of pests has been widely used in ornamental cultivation in greenhouses, which is mainly based on periodic releases of predators and parasitoids, that is, in the augmentative biological control [2,4]. Nevertheless, the effectiveness of this method may often be insufficient due to the difficulties of establishment and persistence of natural enemies in this environment [4,5], since intensive cultivation of flowers in a greenhouse usually presents low diversity of plant species, which limits the preservation of natural enemies for pest control.

Habitat management, through plant diversification, is a tool used to regulate pest populations in greenhouses. The conservative biological control can improve the establishment and maintenance of biological agents in the greenhouse. Studies have shown that more diversified agricultural systems can promote increased species richness and/or abundance of natural enemies of pests [5,6,7]. The use of flowering plants (floral resources) may promote the establishment and support of natural enemies’ populations, with the aim of improving the control of pests such as aphids, thrips, among others [6,7,8,9,10,11]. Selecting the plant with adequate floral resource is an important factor to promote the attraction and accessibility of natural enemies in the cultivation area.

The predator Chrysoperla externa (Neuroptera: Chrysopidae) is an efficient pest controller of various pests such as aphids, lepidopterans, among others, with 100,000 to millions of individuals being commercialized per week in Latin America [2]. This species' adults are highly mobile, have a high reproduction rate and their larvae are voracious and have a great capacity for foraging [12]. In rosebush cultivation, research has been conducted aimed at the effective using of this predator as a biological control agent [10,13].

Basil (Ocimum basilicum L.)is an aromatic plant widely used in cooking and in the cosmetics and perfumery industry. Studies have shown basil being used as an attractive plant to different predators and parasitoids [11,14,15]. Agroecological pest management is aimed at promoting the balance of the system by reducing the pest population and increasing the population of beneficial insects. Thus, the purpose of this work was to assess the effect of basil as an attractive plant and of releases of C. externa in agroecological pest management on rosebushes in greenhouse and compare it with conventional management.