Evaluation of insecticidal activity of diterpenes and lignans from Aristolochia malmeana against Anticarsia gemmatalis

The insecticidal activity of hexane extracts from the roots and leaves of Aristolochia malmeana was evaluated against Anticarsia gemmatalis larvae by topical application. Extract from the roots was the most active and caused 50% mortality in larvae at 308.4 mu g/mu L. From this extract, a clerodane diterpene, (-)-kolavenic acid, and three lignans, (-)-kusunokinin, (-)-hinokinin, and (8S,8'R,9S)cubebin, were isolated by chromatography and partition procedures and then evaluated for their insecticidal activities either individually or in pairs. (-)-Kusunokinin showed higher activity against A. gemmatalis (LD10 = 9.3, LD50 = 230.1 mu g/mu L) than the crude extract, and its activity was dosedependent, whereas the other constituents did not exhibit any significant activity. Together with (-)kusunokinin and (-)-hinokinin, (-)-copalic acid, (-)-2-oxokolavenic acid, (-)-ent-6-beta-hydroxy-copalic acid, (8R,8'R,9R)- and (8R,8'R,9S)-cubebins, (-)-fargesin, and (-)-phillygenin were isolated from the hexane extract of the leaves. The compounds were identified on the basis of spectroscopic analysis.

Insecticidal activity of chemical constituents from Aristolochia pubescens against Anticarsia gemmatalis larvae

Acetone and ethanol extracts of the tubercula and several compounds isolated from Aristolochia pubescens (Willd) were bioassayed on velvebean caterpillars, Anticarsia gemmatalis (Hubner), for evaluation of the insecticidal activities. of the extracts subjected to bioassay, the acetone extract showed the highest activity. (-)-Cubebin did not show activity against soybean caterpillars, whereas aristolochic acid and ent-kaur-15-en-17-ol increased the larval period. These compounds, and (+)-eudesmin and (+)-sesamin, reduced the viability of this period, giving rise to malformed adults. These extracts and compounds are therefore potential botanical insecticide agents for the control of velvetbean caterpillars in soybean crops. (C) 2003 Society of Chemical Industry.

Method for the evaluation of insecticidal activity over time in Atta sexdens rubropilosa workers (Hymenoptera: Formicidae)

The active ingredients used in the formulation of toxic baits for leaf-cutting ants (Hymenoptera: Formicidae) should possess a delayed action defined as an insecticidal activity whereby worker mortality is ≤15% at 24 hours and ≥90% at 21 days. Serious shortcomings have occurred in the search for new active ingredients, such as the initial selection of fenoxycarb, copper oxychloride and diflubenzuron, compounds considered very promising but whose inefficiency was verified only later, indicating methodological problems. In view of this situation, we developed a classification method for insecticidal activity over time using workers of the leaf-cutting ant Atta sexdens rubropilosa Forel. The insecticides used were fipronil, sulfluramid GX071HB and sulfluramid GX439, vehicled in an attractive pasty formulation prepared based on citrus pulp. The results obtained were consistent from a toxicological viewpoint and agreed with the literature in terms of the control of colonies. Sulfluramids were found to possess a delayed action at a broad range of concentrations, in agreement with the fact that these substances are highly effective in the control of all leaf-cutting ant species. The smaller range of concentrations of fipronil with delayed action is probably related to its lower efficacy for species more difficult to control such as Atta capiguara (Forti et al. 2003). We discuss the importance of relating behavioral particularities to the specific feeding habits of leaf-cutting ants, with methodological adequacy of the assessment of insecticides aimed at toxic baits.

Limonoids from Cipadessa fruticosa and Cedrela fissilis and their insecticidal activity

The chemical investigation of the fruits of Cipadessa fruticosa (Meliaceae) afforded the new limonoid cipadesin B and the known swietemahonolide. From the roots of Cedrela fissilis (Meliaceae) were isolated the limonoid 3β-acetoxycarapin, new as natural product, along with the triterpenes oleanolic and oleanonic acid. These compounds and other six mexicanolide limonoids previously isolated from C. fruticosa showed insecticidal activity against the leaf-cutting ants Atta sexdens rubropilosa. ©2005 Sociedade Brasileira de Química.

Limonoids from andiroba oil and Cedrela fissilis and their insecticidal activity

Nine limonoids were isolated from Carapa guianensis and Cedrela fissilis. Among them, 1,2-dihydro-3β-hydroxy-7-deacetoxy-7-oxogedunin is a new compound. Moreover, the assignments of some chemical shifts of xyloccensin k have been corrected and 1H NMR data of 7-deacetylgedunin have been assigned for the first time. These isolated limonoids were assayed on Atta sexdens rubropilosa workers showing moderate insecticidal activities. ©2006 Sociedade Brasileira de Química.

Activity of Ricinus communis (Euphorbiaceae) and ricinine against the leaf-cutting ant Atta sexdens rubropilosa (Hymenoptera : Formicidae) and the symbiotic fungus Leucoagaricus gongylophorus

The focus of this study was the identification of compounds from plant extracts for use in crop protection. This paper reports on the toxic activity of fractions of leaf extracts of Ricinus communis L (Euphorbiaceae) and isolated active compounds in the leaf-cutting ant Atta sexdens rubropilosa Forel and its symbiotic fungus Leucoagaricus gongylophorus (Singer) Moller. The main compounds responsible for activity against the fungus and ant in leaf extracts of R communis were found to be fatty acids for the former and ricinine for the ants. (C) 2004 Society of Chemical Industry.

Biological activity of astilbin from Dimorphandra mollis against Anticarsia gemmatalis and Spodoptera frugiperda

Astilbin was isolated in high yield from Dimorphandra mollis, and its insecticidal and growth inhibiting activity by stomach ingestion were evaluated against Anticarsia gemmatalis and Spodoptera frugiperda. The insecticidal activity of astilbin, the weight reduction of the larval phase and the prolongation of the larval and pupal phases were verified for both species. Astilbin was identified on the base of its NMR, MS and physical data. (C) 2002 Society of Chemical Industry.

Evaluation of the adequacy of diflubenzuron and dechlorane in toxic baits for leaf-cutting ants (Hymenoptera : Formicidae) based on formicidal activity

Studies assessing the characteristics of active ingredients (AIs) of toxic baits for leaf-cutting ants are still scarce, although the need for a delayed action of these compounds on adult workers has been well accepted (mortality <= 15% at 24 h and <= 90% at 21 days). Therefore, we determined the insecticidal action of two AIs used in commercial baits, diflubenzuron and dechlorane, over time in workers, and discussed the control of colonies in relation to the existing literature. Dechlorane presented excellent insecticidal activity with a delayed action at all concentrations tested, although its commercial use has been prohibited due to its organochlorine nature. In contrast, diflubenzuron did not cause significant mortality or symptoms of intoxication, indicating that the successful cases reported with the use of baits containing this AI were in fact due to an accidental contamination with dechlorane. We comment about the ineffectiveness of diflubenzuron on alternative targets, i.e., young forms and the mutualistic fungus, supporting the concept that the AI needs to a have a delayed action on adult workers.

Biological activity of Gomphrena elegans Mart. Var. Elegans (Amaranthaceae)

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Biological activity of limonoids from meliaceae against a subterranean termite (Heterotermes tenuis) (Isoptera: Rhinotermitidae)

Recent studies, proposed to obtain active compounds against termites (Heterotermes tenuis Hagen, as a model) have showed that attention could be driven to the limonoids, because they present high insecticidal activity against several insects. In this work, the limonoids nimbolin-A, 1,2- hydroxyamoorastatone, mexicanolide, cedrelone and 1,2-dihydrocedrelone were tested in order to verify their potential for the control of H. tenuis workers. The results indicated that cedrelone and 1,2-dihydrocedrelone are the limonoids with higher antifeeding activity, followed by 12-hydroxyamoorastatone, mexicanolide and nimbolin-A.

Expression of a new Bacillus thuringiensis Cry1Ia gene in Escherichia coli with strong activity against cotton pests

The control of cotton pests may be accomplished using Bacillus thuringiensis Cry proteins. For this purpose, the objective of this work was to evaluate the insecticidal activity of a new Cry1Ia protein against neonatal larvae of Spodoptera frugiperda and Anthonomus grandis. The complete cry1Ia gene, previously obtained by PCR with oligonucleotide primers based on the sequenced gene, was cloned into the vector pET28a(+), introduced into Escherichia coli BL21(DE3) and expressed by induction with IPTG. The expression of the Cry1Ia protein was confirmed with molecular weight of approximately 81 kDa. The results demonstrated the efficiency of the bacterial system for the expression of B. thuringiensis Cry1Ia protein, which was subsequently used in quantitative bioassays against S. frugiperda and A. grandis larvae, resulting in an extremely toxic protein for both species. This characteristic is exceptionally important for obtaining transgenic cotton plants resistant to these pests.

In vitro activity of pineapple extracts (Ananas comosus, Bromeliaceae) on Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

Measures to control the cattle tick, Rhipicephalus (Boophilus) microplus, based only on chemical products are becoming unsustainable, mainly because of the development of resistance. The objective of this study was to test the effect of the aqueous extract of pineapple skin (AEPS) and bromelain extracted from the stem (Sigma-Aldrich®, B4882) on engorged females and larvae of R. (B.) microplus in vitro. These substances were diluted in water and evaluated at eight concentrations. Engorged females were collected and distributed in groups of 10, with three repetitions for each treatment. After immersion in the solutions, the females were placed in an incubator for observation of survival, oviposition and larval hatching. The larval packet method was used, also with three repetitions with about 100 larvae each. The packets were incubated and the readings were performed after 24h. The estimated reproduction and efficacy of the solutions were calculated. The LC50 and LC90 were estimated using the Probit procedure of the SAS program. The eight concentrations were compared within each treatment by the Tukey test. For the experiment with engorged females, the most effective concentrations were 125, 250 and 500mg/mL: 33%, 48% and 59% for the AEPS and 27%, 51% and 55% for the bromelain. The LC50 and LC90 values were, respectively, 276 and 8691mg/mL for AEPS and 373 and 5172mg/mL for bromelain. None of the dilutions tested was effective against the larvae of R. (B.) microplus. This is the first report of the action of pineapple extracts or their constituents on cattle ticks. The results demonstrate that further studies regarding composition of tick cuticle, with evaluation of other solvents and formulations, should be conducted seeking to enhance the effect of pineapple extracts and compounds against this ectoparasite. © 2013 Elsevier Inc.

Insecticidal potential of the annonaceae family plants

The use of plants compounds for the control of insects has increased worldwide. This occurs because the vegetal insecticides contains biodegradable compounds, nontoxic products and potentially suitable for use in pest control. Plants of the family Annonaceae are standing out as biopesticides because they are bioactive naturally in addition to presenting cytotoxic activity, antitumor, vermifuge, antimicrobial, immunosuppressive, anti-emetic, inhibiting appetite, antimalarial and also insecticide. The insecticidal activity of Annonaceae is due to the presence of acetogenins, substances that act on mitochondria inhibiting the NADH -ubiquinone oxidoreductase, causing the death of insects. In this review we report the use of Annonaceae in insect control, showing that so far, only 42 species of Annonaceae have information insecticidal activity against just over 60 species of insect pests. This information shows that much research is still needed, especially to get to know the insecticidal activity of other Annonaceae species, in addition to its effects on insect pests not yet studied. So we will have as an alternative to sustainable development, new vegetal insecticides such as those obtained from different Annonaceae species, which can act as an additional tool to balance the excesses of agriculture chemical or conventional.

Synthetic amides toxic to the leaf-cutting ant Atta sexdens rubropilosa L. and its symbiotic fungus

1 Nine synthetic amides similar to natural N-piperidine-3-(4,5-methylenedioxyphenyl)-2-(E)-propenainide and N-pyrrolidine-3-(4,5-methylenedyoxiphenyl)2-(E)-propenamide were synthesized and identified by their spectroscopic data.2 the toxicity of these synthetic amides to the Atta sexdens rubropilosa workers and the antifungal activity against Leticoagaricus gongylophorus, the symbiotic fungus of the leaf-cutting ants, were determined.3 Workers ants that were fed daily on an artificial diet to which these compounds were added had a higher mortality rate than the controls for N-pyrrolidine-3(3',4'-methylenedioxyphenyl)-2-(E)-propenamide and N-benzyl-3-(3',4'-methylenedioxyphenyl)-2-(E)-propenamide at a concentration of 100 mu g/mL.4 the completely inhibition (100%) of the fungal growth was observed with N-piperldine-3-(3',4'-methylenedioxyphenyl)-2-(E)-propenamide and N,N-diethyl-3-(3',4'-methylenedioxyphenyl)-2-(E)-propenamide at concentrations of 50 and 100 mu g/mL and N-pirrolidine-3-(3',4'-methylenedioxyphenyl)-2-(E)-propenamide at a concentration of 100 mu g/mL.5 the possibility of controlling these insects in the future using synthetic piperamides that can simultaneously target both organisms is discussed.

Chemical composition and fumigant effect of essentialoil of Lippia sidoides Cham. and monoterpenes against Tenebrio molitor (L.) (coleoptera: tenebrionidae)

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