Evaluation of Pteridium aquilinum (Dennstaedtiaceae) and Urtica dioica (Urticaceae) as alternatives to populational aphid balance in organic crops in southern Brazil

Abstract

The fern Pteridium aquilinum L. Kunh (Dennstaedtiaceae) is a cosmopolitan species, allelopathic, considered as indicator of acid soils and also used for management of insect populations, mites and nematodes, as incorporated in extracts and biofertilizers. Urtica dioica L. (Urticaceae) is a perennial herb from Europe, introduced in Brazil for medical purposes, growing in nitrogen-rich soils, hostess of natural enemies, when applied on crops as extracts or biodynamic preparations. It's important to note that vast majority of the intended use for these two botanical species, refers to the accumulated empirical knowledge, highlighting that there are few scientific researches involving its bioactivity on agroecosystems. In this sense, this study aimed to evaluate the effect of aqueous extracts of P. aquilinum (10% w / v) and U. dioica (5% w / v) on the repellency, mortality, survival, production of nymphs and instantaneous rate of growth population of the aphid Brevicoryne brassicae (Hemiptera: Aphididae) in kale. Simultaneously to the crude extract of plants, the dilutions of 30 and 10% were evaluated, beyond the distilled water as control and the product AGV Xispa-praga. The P. aquilinum extract resulted in repellent and insecticide action, reduction of the offspring and survival, as well as rinegative, suggesting decline of the aphids populations exposed to treatment. Yet, the extract made from U. dioica showed repellent action, decreasing the offspring and survival of nymphs. In general, the two species studied are considered as promising botanical strategies for managing aphids in organic crops of brassica, legitimizing information coming from the popular knowledge.