Dejane Santos Alves

Efeito de frações tânicas sobre parâmetros biológicos e nutricionais de Spodoptera frugiperda (Lepidoptera: Noctuidae)

Conduziu-se este trabalho, com o objetivo de quantificar taninos condensados presentes nas cascas do caule de Ochroma pyramidalis (Bombacaceae), Schinus terebinthifolius (Anacardiaceae), Enterolobium contortisiliquum (Fabaceae) e Peltophorum dubium (Fabaceae) e verificar o efeito de fracoes tânicas dessas especies sobre parâmetros biologicos e nutricionais de S. frugiperda. A partir das cascas das especies vegetais se prepararam extratos, dos quais aliquotas foram tomadas para a quantificacao dos taninos. Em seguida, os extratos foram submetidos a fracionamento para a obtencao das fracoes tânicas, que foram incorporadas a dieta artificial e oferecidas para lagartas de S. frugiperda. Todas as especies vegetais estudadas apresentaram taninos condensados, sendo que S. terebinthifolius apresentou menor quantidade desses compostos. A fracao tânica de P. dubium causou reducao no peso das lagartas e pupas, diminuicao na sobrevivencia de S. frugiperda durante as fases larval e pupal, e acarretou menor consumo alimentar, alem de prolongar a duracao das fases imaturas desse inseto. O tratamento com S. terebinthifolius causou reducao na percentagem de sobrevivencia, durante a fase de pupa. Pupas provenientes de lagartas que receberam tratamento com a fracao de E. contortisiliquum tiveram aumento no seu periodo de desenvolvimento. Lagartas alimentadas com a fracao proveniente de P. dubium apresentaram a menor taxa de crescimento relativo (RGR), menor eficiencia de conversao do alimento digerido (ECD) e maior custo metabolico (CM). A digestibilidade aproximada (AD) foi maior para os tratamentos com as fracoes tânicas de P. dubium e S. terebinthifolius.

Toxicity of copaiba extracts to armyworm (Spodoptera frugiperda)

The objective of this study was to evaluate the effects of methanolic extracts from leaves, peels, seeds and pulps from fruits of Copaifera langsdorffii on Spodoptera frugiperda. Extracts derived from leaves and fruit peels were more toxic to S. frugiperda than the others. Hence, they were added to the artificial diet and used in further experiments with the second instar larvae of the insect, which presented larval growth reduction, prolonged period of development, increased mortality, and lower fertility and fecundity of adults. Lower egg viability was also observed when the insect was treated with extracts of leaves and fruit peels in the larvae stage. Moreover, when subjected to ultrastructural analysis under a scanning electron microscope, such eggs showed abnormalities in the aeropylar and micropylar regions. Both extracts also increased the excretion of protein in the insect feces and inhibited trypsin activity in the in vitro test. Consequently, C. langsdorffii presents potential to be used in the development of new products to control the fall armyworm.

Toxicity of the phenolic extract from jabuticabeira (Myrciaria cauliflora (Mart.) O. Berg) fruit skins on Spodoptera frugiperda

Fall armyworm, Spodoptera frugiperda J.E. Smith, 1797 (Lepidoptera: Noctuidae) is the main pest of maize, besides attacking sorghum and cotton crops. The control of this pest has been accomplished mainly with the use of synthetic insecticides but, due to the growing concern about the environment and food quality, phenolic compounds have shown their potential for the biological control of this insect. Thus, the objective of the present study was to evaluate the efficiency of the extract of jabuticabeira, Myrciaria cauliflora [Mart.] O. Berg (Myrtaceae) fruit skin flour in the control of S. frugiperda. Skins of M. cauliflora Sabara genotype were dried at 45 °C in a forced air oven. In order to obtain the extract, 1.0 g flour was mixed with 10 mL acetone: water solution (7:3 v/v). Forty-eight-hour-old S. frugiperda caterpillars were placed in glass tubes with an artificial diet containing the extract at concentrations of 0, 250, 500, 1000, and 2000 mg L-1. The extract, in which the phenolic compounds gallic acid, gallocatechin, catechin, epicatechin, ellagic acid, and salicylic acid were identified at a concentration of 2000 mg L-1, in average, increased mortality rates by 150% in the larval stage, duration of larval stages by 60%, and pupal by 17%, and decreased amount of females by 55%. On the other hand, the extract at 1000 mg L-1 only increased duration of larval period by 24%. It was concluded that the extract is harmful to this insect, probably due to the presence of phenolic compounds.

Plant–Derived Products for Leaf–Cutting Ants Control

Leaf-cutting ants of the genera Atta sp. Fabricius (Hymenoptera: Formicidae) and Acromyr‐ mex sp. Mayr (Hymenoptera: Formicidae) are among the best known species of the family Formicidae in the New World, mainly due to their behaviour of cutting live plants to grow the symbiotic fungus Leucoagaricus gongylophorus (Moller) Singer (Agaricales: Agaricaceae) [1] (Figure 1). This interaction, which emerged more than 50 million years ago [2] has evolved to such a complex level that the ants and fungi cannot survive separately; they live in symbiosis. The fungus supplies the ants with nutrients obtained from metabolising plant materials that can be easily assimilated. In exchange, its environment is highly protected by the ants, which remove contaminants and secrete antibiotics from their metapleural glands [3, 4].

Malpighia emarginata DC. bagasse acetone extract: Phenolic compounds and their effect on Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

Annually, several tons of residues that are rich in phenolic compounds are produced during the processing of acerola (Malpighia emarginata DC.) juice. Adding value to these residues is of great interest, since they can be a viable solution in the search for natural substances with insecticidal action and low impact on the environment and humans. Taking into account the economic losses from the attacks by the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in different crops, the objective of this study was to evaluate the effect of the extract of acerola bagasse flour (ABF) against this insect and determine the phenolic compounds in this extract. Bagasse of acerola (BRS238 or Frutacor clon) generated after juice production, was frozen and lyophilized. To obtain the extract, 6 g ABF was mixed with 60 mL acetone:water solution (7:3 v/v), and the extract was lyophilized. Spodoptera frugiperda caterpillars, 48 h-old, obtained by the maintenance breeding, were transferred to glass tubes supplied with an artificial diet containing the ABF extract at 0, 250, 500, 1000, and 2000 mg L-1 diet. The following variables were evaluated: duration and survival of larval and pupal stages, pupal weight, sex ratio, adult longevity, oviposition period, number of egg masses, and total number of eggs. The ABF extract contained several phenolic compounds including gallic acid, epigallocatechin gallate, catechin, p-coumaric acid, salicylic acid, and quercetin. The extract was toxic to S. frugiperda, prolonging the pre-pupal stage and increasing the mortality of caterpillars.

URSOLIC ACID AND CIS-TILIROSIDE PRODUCED BY Merremia tomentosa AFFECT OVIPOSITION OF Leucoptera coffeella ON COFFEE PLANTS

To contribute to the development of new products to control the coffee leaf miner (Leucoptera coffeella), which is a major pest for coffee plants, this work aimed to select plant species able to produce substances active against this insect and to identify the active substances in the selected plant and their protein targets in the insect. Among the extracts of nineteen plant species, only that from leaves of Merremia tomentosa (Choisy) Hall. f. (Convolvulaceae) reduced the oviposition of L. coffeella on leaves of coffee plants. This extract was submitted to successive fractionation steps to achieve the isolation and identification of two active substances, ursolic acid (UA) and cis-tiliroside (CT). An in silico study showed that UA inhibits glycogen phosphorylases (GP) by binding to their allosteric site, while CT probably inhibits xanthine dehydrogenases (XT). As both GP and XT appear to be essential enzymes for insects, these results suggest that, during evolution, L. coffeella learned to identify plants producing inhibitors of these enzymes to avoid oviposition on such plants. Thus, both UA and CT have potential to be used as lead compounds in the development of new products for the control of the coffee leaf miner.

Toxicity of Cymbopogon flexuosus essential oil and citral for Spodoptera frugiperda

Fall armyworm (FAW) (Spodoptera frugiperda) is a polyphagous insect responsible for damage to several crops. Synthetic chemical insecticides and genetically modified plants are the most commonly used methods for FAW control. However, the selection of resistant populations has been reported in several studies, justifying the search for new molecules to be used in the control of S. frugiperda. The aim of the present study was to evaluate the toxicity of lemongrass (Cymbopogon flexuosus) essential oil (LEO) and its major component (citral) in relation to FAW. Additionally, the anticholinesterase activity of LEO and citral was evaluated using acetylcholinesterase (AChE) from Electrophorus electricus. The LEO was toxic to FAW when added to an artificial diet (LC50 = 1.35 mg mL -1) at the highest concentrations tested, and the median lethal time (LT50) was 18.85 h. Major components of LEO were identified by gas chromatography-mass spectrometry, and citral, the most abundant component, was used in FAW bioassays. The insecticidal activity of citral was statistically similar to that of LEO, demonstrating that citral was responsible for the insecticidal activity of LEO. Inhibition of AChE was measured, and the mean inhibitory concentration (IC50) values for LEO and citral were 650and 405-fold higher, respectively, than that verified for the positive control (methomyl insecticide), suggesting selectivity for non-target organisms. Based on these results, citral and C. flexuosus have the potential to be applied in the development of new products for the control of S. frugiperda.

Toxic effects of Ricinus communis non-protein trypsin inhibitor on Spodoptera frugiperda (J. E. Smith) (Lepidoptera:Noctuidae)

In the study reported herein, we aimed to isolate a trypsin inhibitor from Ricinus communis leaves through chromatographic and spectrometric techniques and evaluate its toxic effects on the development of Spodoptera frugiperda larvae. Plant extracts were submitted to fractionation in adsorption column. The fraction 10, which showed the highest inhibitory activity, were incorporated into an artificial diet at the concentrations of 0, 0.06, 0.12, 0.25 and 0.5%, and offered to S. frugiperda larvae. Fresh weight of larvae, food consumed and weight of eliminated faeces were registered. Based on these parameters the following nutritional index were calculated: Relative Consumption Rate (RCR), Relative Metabolic Rate (RMR), Relative Growth Rate (RGR), Approximated Digestibility (AD), Efficiency of Ingested Food Conversion (EIC), Efficiency of Digested Food Conversion (EDC) and the Metabolic Cost (100 - EDC). The inhibitor at 0.5% concentration was deleterious to S. frugiperda , extending the larval stage in 11 days, with higher RCR and ECD, and lower RGR, ECI and ECD. Therefore, the trypsin inhibitor from leaves of R. communis affected the S. frugiperda larval development, being promising in studies of alternative and sustainable control methods for lepidopteran pest species. Keywords: Castor beans, enzymatic inhibition, integrated pest management, plant defense against herbivory

Extraction and isolation of anti-tryptic castor-bean (Ricinus communis L.) substances and their effects on Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae)

The search for alternative methods aiming to the control of agricultural pests that cause less environmental impact has been a recurring theme in several studies. For this purpose, the factors influencing the extraction and isolation of the trypsin inhibitor found in castor-bean (Ricinus communis L.) cake and seeds were studied, and its effect on the development of fall armyworm Spodoptera frugiperda (Smith, 1797) was evaluated. Therefore, the type and proportion of the solvent (w/v), extraction period and oil content were evaluated. The castor-bean cake extract with oil content of 20% in water at a ratio 1:40 (w/v) for 30 min showed the greatest trypsin inhibition, with 21.23 mUTI g-1 seed. The isolation of the trypsin inhibitor contained in the extract was performed by flash chromatography, with inhibition peaks of up to 8906.12 mUTI g-1 fraction, as well as inferring that the best eluent was ethyl acetate with a small percentage of ethanol (< 30%). In order to evaluate the effect of the inhibitor on the development of this insect, the aqueous extract of castor bean cake with oil content of 20% was incorporated into the diet that was provided to the caterpillars at a concentration of 4000 ppm. There was reduction in the oviposition period and an increase in the concentration of proteins in the feces, with 20.55 ± 3.73 d and 177.70 ± 16.90 μmol g-1, respectively. The increase in protein excretion indicates that the trypsin inhibitor was able to reduce the absorption of essential amino acid residues by the insect without, however, impairing the development of S. frugiperda.

Extrato de Coffea racemosa como alternativa no controle do bicho-mineiro do cafeeiro

Objetivou-se, com o presente trabalho, verificar o efeito do extrato metanolico de Coffea racemosa Lour., especie silvestre de cafeeiro portadora de resistencia a uma das principais pragas da cultura cafeeira, o bicho-mineiro. Inicialmente, o extrato metanolico das folhas de C. racemosa foi pulverizado em mudas de cafeeiro Coffea arabica cv. Catuai, em casa-de-vegetacao, as quais foram expostas a adultos de L. coffeella para o teste de oviposicao com chance de escolha. Observou-se que as plantas tratadas foram menos preferidas para oviposicao. A seguir, realizou-se o teste de efeito ovicida, no qual mudas de C. arabica contendo ovos do bicho-mineiro foram pulverizadas com o mesmo extrato. Os experimentos foram conduzidos em delineamento inteiramente casualizado com cinco repeticoes. Verificou-se reducao significativa na eclosao de larvas, e segundo analise por microscopia eletronica de varredura, os ovos nao viaveis apresentaram anomalias nas superficies externas. Entretanto, os adultos provenientes de ovos tratados nao foram afetados na percentagem de emergencia, razao sexual e oviposicao. Os resultados obtidos demonstram que C. racemosa apresenta-se como uma alternativa promissora ao controle do bicho-mineiro, necessitando, no entanto, de novos estudos para isolamento e identificacao das substâncias bioativas.