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1.
Ecotoxicology ; 28(8): 973-982, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31420785

RESUMO

The diamondback moth Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae) is a destructive pest of brassica crops of economic importance that have resistance to a range of insecticides. Indole derivates can exert diverse biological activities, and different effects may be obtained from small differences in their molecular structures. Indole is the parent substance of a large number of synthetic and natural compounds, such as plant and animal hormones. In the present study, we evaluate the insecticidal activity of 20 new synthesized indole derivatives against P. xylostella, and the selectivity of these derivatives against non-target hymenopteran beneficial arthropods: the pollinator Apis mellifera (Linnaeus, 1758) (Hymenoptera: Apidae), and the predators Polybia scutellaris (White, 1841), Polybia sericea (Olivier, 1791) and Polybia rejecta (Fabricius, 1798) (Hymenoptera: Vespidae). Bioassays were performed in the laboratory to determine the lethal and sublethal effects of the compounds on P. xylostella and to examine their selectivity to non-target organisms by topical application and foliar contact. The treatments consisted of two synthesized derivatives (most and least toxic), the positive control (deltamethrin) and the negative control (solvent). The synthesized compound 4e [1-(1H-indol-3-yl)hexan-1-one] showed high toxicity (via topical application and ingestion) and decreased the leaf consumption by P. xylostella, displaying a higher efficiency than the pyrethroid deltamethrin, widely used to control this pest. In addition, the synthesized indole derivatives were selective to the pollinator A. mellifera and the predators P. scutellaris, P. sericea and P. rejecta, none of which were affected by deltamethrin. Our results highlight the promising potential of the synthesized indole derivatives for the generation of new chemical compounds for P. xylostella management.


Assuntos
Abelhas/efeitos dos fármacos , Indóis/toxicidade , Inseticidas/toxicidade , Mariposas/efeitos dos fármacos , Vespas/efeitos dos fármacos , Animais , Indóis/farmacologia , Inseticidas/farmacologia , Larva/efeitos dos fármacos
2.
Molecules ; 22(3)2017 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-28245600

RESUMO

Plants of the genus Aristolochia have been frequently reported as important medicinal plants. Despite their high bioactive potential, to date, there are no reports of their effects on leaf-cutting ants. Therefore, the present study aimed to evaluate the insecticidal activity of the essential oil of Aristolochia trilobata and its major components on Atta sexdens and Acromyrmex balzani, two species of leaf-cutting ants. The bioassays were performed regarding routes of exposure, acute toxicity, binary mixtures of the major components and behavioral effects. Twenty-five components were identified in the essential oil of A. trilobata using a gas chromatographic system equipped with a mass spectrometer and a flame ionization detector. The components found in higher proportions were sulcatyl acetate, limonene, p-cymene and linalool. The essential oil of A. trilobata and its individual major components were efficient against A. balzani and A. sexdens workers when applied by fumigation. These components showed fast and efficient insecticidal activity on ants. The components acted synergistically and additively on A. balzani and A. sexdens, respectively, and caused a strong repellency/irritability in the ants. Thus, our results demonstrate the great potential of the essential oil of A. trilobata and its major components for the development of new insecticides.


Assuntos
Formigas/efeitos dos fármacos , Aristolochia/química , Inseticidas/química , Óleos Voláteis/química , Animais , Formigas/fisiologia , Comportamento Animal/efeitos dos fármacos , Cromatografia Gasosa , Fumigação , Inseticidas/farmacologia , Óleos Voláteis/farmacologia , Folhas de Planta/química , Óleos de Plantas/química , Óleos de Plantas/farmacologia
3.
Environ Sci Pollut Res Int ; 27(14): 17303-17313, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32157534

RESUMO

Leaf-cutting ants have great potential for damage to agricultural and forest crops. Although chemical control is the most used method for the management of this pest, more friendly alternative methods have been investigated. Thus, this study aimed to evaluate the insecticidal and antifungal potential of essential oils obtained from Aristolochia trilobata, as well as the potential of two chemotypes of Myrcia lundiana and their major compounds (isopulegol and citral) on Acromyrmex balzani and its symbiotic fungus Leucoagaricus gongylophorus. Toxicity and synergism and/or antagonism tests were performed using essential oils and their major compounds on A. balzani ants. The antifungal activity of these compounds was tested on the fungus L. gongylophorus. The essential oils and their major compounds were toxic to A. balzani. The mixture of essential oils of A. trilobata with those of M. lundiana had higher toxicity to the ants. This synergistic effect is mainly due to the interactions between the citral compound and the major compounds present in A. trilobata essential oil. The essential oils of M. lundiana chemotypes showed antifungal properties against L. gongylophorus, and the citral compound proved to have fungicidal activity. These results show that the use of M. lundiana and A. trilobata essential oils and their major compounds is a potential alternative for the management of leaf-cutting ants A. balzani, as they have a toxic effect on worker ants and antifungal activity on their symbiotic fungus.


Assuntos
Agaricales , Formigas , Óleos Voláteis , Animais , Antifúngicos , Óleos de Plantas , Simbiose
4.
Pest Manag Sci ; 74(4): 1001-1012, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29160036

RESUMO

BACKGROUND: The mosquito Aedes aegypti is intensively controlled because it is a vector of viruses that cause numerous diseases, especially in tropical regions. As a consequence of the indiscriminate use of insecticides, populations from different regions have become resistant to pyrethroids. Here, we analyzed the lethal and sublethal effects of essential oil of Aristolochia trilobata and its major compounds on A. aegypti from susceptible and pyrethroid-resistant populations. RESULTS: Our results showed that the toxicity of the different compounds and behavioral changes in response to them are dependent on the stage of the insect life cycle. The monoterpene ρ-cymene caused high mortality in both larvae and adult females of A. aegypti, including those from the pyrethroid-resistant population. The monoterpenes limonene and linalool caused a sublethal effect in the larvae, triggering changes in the swimming pattern. CONCLUSION: This study highlights the potential of the essential oil of A. trilobata and its major compounds ρ-cymene and limonene for the control of A. aegypti and reveals the importance of analyzing sublethal effects on the population dynamics of the A. aegypti mosquito. © 2017 Society of Chemical Industry.


Assuntos
Aedes , Controle de Insetos , Inseticidas , Monoterpenos , Aedes/crescimento & desenvolvimento , Animais , Feminino , Resistência a Inseticidas , Larva/crescimento & desenvolvimento , Pupa/crescimento & desenvolvimento , Piretrinas/farmacologia
5.
Rev. bras. entomol ; 63(1): 9-11, Jan.-Mar. 2019. graf
Artigo em Inglês | LILACS | ID: biblio-1045544

RESUMO

ABSTRACT Laboratory bioassays should be performed under appropriate conditions that minimize stress and promote greater longevity to tested animals. For social insects, for instance, the stress triggered by removal individuals from nests may result in changes in their survival and behavior. Here we analyzed the effects of variations of different combinations of temperature and substrate moisture (mL of water/g of nest substrate) on group survival of Constrictotermes sp. (Termitidae: Nasutitermitinae). In general, lower substrate moisture resulted in faster mortality. On the other hand, groups survival longer at a temperature of 26 ºC and under higher substrate moisture (2-3 mL/7 g of nest substrate). The result of this study may contribute to the establishment of bioassay protocols performed with Constrictotermes sp. in the laboratory.

6.
Acta Trop ; 127(3): 181-6, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23643519

RESUMO

Ants are highly abundant in neotropical regions, with certain species adapted to the urban environment, where they can cause damage to human health. The main method for controlling ants consists of using organosynthetic insecticides, which are potentially toxic to the environment. Essential plant oils are considered a viable alternative to the use of conventional insecticides. In this study, we analyze the bioinsecticidal activity and repellence of patchouli essential oil (Pogostemon cablin) against three species of urban ants: Camponotus melanoticus, Camponotus novograndensis, and Dorymyrmex thoracicus. The chemical composition of the essential oil was analyzed by GC-MS and GC-FID. The major compounds were patchoulol (36.6%) followed by α-bulnesene (13.95%), and α-guaiene (11.96%). Toxicity and repellency bioassays were performed using the essential oil over the ants, and mortality evaluations were performed at 4, 24, and 48 h after performing the bioassays. Mortality percentage of the ants on 7 µg/mg was on average 84%. The essential oil of P. cablin displayed toxicity against all three species of urban ants, with the lowest LD50 being observed for D. thoracicus (2.02 µg oil/mg insect) after 48 h of exposure compared to C. melanoticus (2.34 µg oil/mg insect) and C. novogranadensis (2.95 µg oil/mg insect). The essential oil of P. cablin was strongly repellent to the three species of ants in all concentrations tested (0.01% and 1% v/v). Considering the potential toxicity and repellency of the P. cablin essential oil to the urban ants, future studies could investigate the practical application of this oil to control of this insects.


Assuntos
Formigas/efeitos dos fármacos , Repelentes de Insetos/farmacologia , Inseticidas/farmacologia , Lamiaceae/química , Óleos Voláteis/farmacologia , Óleos de Plantas/farmacologia , Animais , Bioensaio , Repelentes de Insetos/química , Inseticidas/química , Óleos Voláteis/química , Óleos de Plantas/química , Fatores de Tempo
7.
Rev. bras. entomol ; 47(4): 483-490, dez. 2003. ilus, tab, graf
Artigo em Português | LILACS | ID: lil-388770

RESUMO

Several hypotheses have been proposed to explain the patterns of host plant utilization by herbivorous insects in natural communities. We tested four hypotheses aiming to understand the pattern of attack by gall-inducing insects on the dioecious shrub, Baccharis pseudomyriocephala (Asteraceae). The shrub occurs in the Parque Estadual do Itacolomi, Southeastern Brazil, and supports ten species of galling insects. The following hypotheses were tested: i) male plants are more attacked by galling insects than female plants; ii) larger plant modules are preferentially attacked by galling insects; iii) galling insects perform better on larger modules than on smaller modules; iv) galling insects increase in abundance with meristematic availability. To address these questions, 240 plants (120 of each sex) were sampled in both reproductive and vegetative periods. We recorded the growth rate (4 cm), inflorescence and fruit production, attack rates of the galling insects, and their survivorship and mortality per shoot (module). Modules were separated into size classes (cm) and analyzed by regressions and ANCOVAs. Module size and reproductive effort were positively correlated with host plant size. We did not observe any effect of host plant gender on either variables. In the same way, host plant sex did not show any influence on the abundance and richness of galling insects. Although the abundance of galling insects showed a positive correlation with shoot size, the trend disappeared when the analyses were performed taking into consideration the number of galls per unit of growth (number of galls/cm of shoot) or biomass (number of galls/dry weight). Larval survivorship was not influenced by shoot size. Also, we observed that the abundance of one species of hemipteran galling insect showed a positive relation with leaf biomass. Therefore, we conclude that gender and vigor of this plant species do not influence the community structure of its galling herbivores.


Assuntos
Animais , Asteraceae/parasitologia , Insetos/fisiologia , Tumores de Planta , Interações Hospedeiro-Parasita
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