Preparações de cladódios de Opuntia ficus-indica Mill. (Cactaceae): efeito sobre parâmetros biológicos, fisiológicos e reprodutivos de Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

Abstract

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) is a cosmopolitan pest, which despite having a preference for plants of the family Poaceae, also causes harms in several other cultures. Population control using synthetic insecticides is still the most used method, however, more and more studies with natural products have been made. Considering that fact, this research had the following aims: 1. To evaluate the chemical composition of the cladodes extract of Opuntia ficus-indica; 2. To evaluate the effect of cladodes extract and sodium chloride (NaCl) on biological and reproductive parameters of S. frugiperda; 3. To determine whether cladodes lectin (OfiL) is the active ingredient of the extract; 4. To investigate the effect of cladodes extract and OfiL on the activity of enzymes present in the intestine of S. frugiperda larvae. In addition, the effect of cladode extract on the histology and histochemistry of the midgut of larvae was also evaluated. Based on the results, it was possible to observe that NaCl when acting alone or added to the cladodes extract altered significantly the development of S. frugiperda, sometimes affecting its reproductive parameters. The cladodes extract showed to be a promising food phagostimulatory agent over the exposure time of 48 h. The cladodes extract also interfered in the histology of the epithelial tissue, in the neutral polysaccharide and proteins of midgut of S. frugiperda. When the experiments were conducted with OfiL, it was not possible to indicate its participation as an active principle in the insecticidal activity of the extract. This work contributes, therefore, to the panel of natural insecticides compounds for presenting a new bio-product with toxic effect on an important agricultural pest. Future experiments are needed to show the effect of the extract under field conditions and indicate its active(s) principle(s).