Abstract In South America, Solenopsis saevissima and S. invicta are the most common fire ants. Nests are founded in areas under anthropic interference like urban or rural areas, but S. invicta is found preferentially in those with the greatest anthropic interference. However, we do not know the rates at which they exist in anthropized areas next to high density of native vegetation. Areas with 60 to 90% of native Atlantic Forest were selected to verify the occurrence of both species in rural and urban areas. We investigated the molecular diversity and applied the reconstruction of the ancestral state analysis for each species. A total of 186 nests were analyzed and we found that the two species had the same proportion in the urban area. However, S. saevissima had a higher rate of prevalence in the rural area, in addition to having a greater number of haplotypes and ancestry associated with this type of habitat for the region. S. invicta had the same number of haplotypes in both rural and urban regions, and less haplotypic diversity. We conclude that S. saevissima is a species typically associated with rural areas and S. invicta, although present, is not dominant in urban areas.

Pesticides offer a simple, cost-effective solution to ensure food supplies for a growing world population. However, their environmental performance needs improvement if pesticides are to continue contributing importantly. This study explores the insecticidal potential of a magnesium (II) metal complex containing 1,10-phenanthroline and isovanillic acid (MgPhenIso) against leaf-cutting ant (Atta sexdens rubropilosa) and its symbiotic fungus (Leucoagaricus gongylophorus). The MgPhenIso complex is easy-to-prepare, stable in solid state and in aqueous solution, and resistant to sunlight irradiation. The insecticidal activity of MgPhenIso-containing bait against A. sexdens rubropilosa and L. gongylophorus showed a delayed action mode at 2 mg g-1 (100% kill, 6th day, S50=2b) and suppressed fungus development and growth. These results, together with earlier investigations on MgPhenIso regarding its absence of toxicity to Zebrafish and Wistar male rats, emphasize the potential of this complex as an environmentally friendly insecticide candidate.

The present work describes the chemical constituents of Odontadenia lutea (Vell.) Markgr. leaves and the toxicities of its extract and fractions against Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae). Chromatographic procedures of the ethanolic extract resulted in the identification of the triterpene β-amyrin, the flavonoid rutin, two fatty acids palmitic and linolenic, and one glyceroglycolipid 3-O-(9,12,15-octadecatrienoyl)-glyceryl-β-D-galactopyranoside, which are known compounds, but they are described for the first time in the Odontadenia genus. The known triterpenes lupeol and α-amyrin were also identified. Structural identification of the compounds was performed by analysis of IR, ESI-MS, and 1D and 2D NMR spectra. The toxicity of its extract and fractions from O. lutea leaves was tested against leaf-cutting ants Atta sexdens rubropilosa Forel by employing ingestion bioassay procedures. The hexane fraction (2 mg mL-1) decreases the average survival of ants from sixteen to six days, causing 98% mortality on the 14th day and 100% at the end of the experiment.

Chitin synthase (CHS) is the enzyme specifically associated with chitin synthesis, an important component of diverse organisms including insects. Two alternative spliced transcripts of the CHS gene (AsCHS-A1 and AsCHS-A2) were identified by quantitative reverse-transcription polymerase chain reaction (RT-qPCR) during the development of the leaf-cutting ant Atta sexdens. Expression profiles of AsCHS-A transcripts increased from larva to pupae and decay in workers. Phylogenetic analysis showed both transcripts are classified within class A insect CHSs. AsCHS-A1 showed the highest expression level in larvae and pupae, while AsCHS-A2 is the main CHS transcript in workers. Our results suggest that these variants should be under regulation of different promoters. AsCHS-A1 has topology expected for insect CHSs, while the predicted AsCHS-A2 topology, with a missing A domain, is similar to some fungal CHSs. CHS-B (class B) was not identified in A. sexdens transcriptome. Ribonucleic acid interference (RNAi)-mediated gene silencing in pupae revealed that low reduction in CHS transcript levels (18%) was enough to cause morphological changes in the pupa exoskeleton impairing the process of cuticle sclerotization. To our knowledge, this work was the first to use and to show the feasibility of using RNA interference techniques on leaf-cutting ants.

Linepithema humile Mayr is an ant species originally native to South America that has been spread accidently throughout the globe through international trade. It is a serious urban and crop pest. Despite its economic importance, little is known about the larvae of this species apart from a brief description based on a few specimens. The present investigation is aimed at describing every immature stage of L. humile. Three larval instars were determined through the frequency distribution of the maximum width of head capsules from a sample of 525 larvae. The morphological descriptions were based on 150 eggs, 70 larvae, and 90 pupae examined by light and scanning electron microscopy. Some morphological characteristics reported to be typical of Linepithema Mayr larvae were confirmed - dolichoderoid body shape, presence of dorsal protuberance, sparse simple body hairs, presence of nine pairs of spiracles and dolichoderoid mandibles. We concluded that an earlier published description was based on queen larvae, and that the protuberance is only present in worker larvae. The information provided in this study may aid ant systematics and phylogenetics, as well provide a better understanding of the biology of this species.

O estudo dos extratos dos galhos da planta Spiranthera odoratissima St. Hil. (Rutaceae) levou ao isolamento de alcalóides furoquinolínicos (dictamina, γ-fagarina e esquimianina) e 2-arilquinolin-4-ona (2-fenil-1-metilquinolin-4-ona) e limonóides (ácido limonéxico e limonina). Os compostos 2-fenil-1-metilquinolin-4-ona e ácido limonéxico foram isolados pela primeira vez no gênero Spiranthera. Os alcalóides furoquinolínicos, 2-arilquinolin-4-ona e os limonóides mostraram atividade inseticida e/ou fungicida no ninho da formiga Atta sexdens rubropilosa.

The study of the Spiranthera odoratissima St. Hil (Rutaceae) branches extracts led to the isolation of the furoquinoline (dictamine, γ-fagarine and skimmianine) and 2-arylquinoli-4-one (1-methyl-2-phenylquinolin-4-one) alkaloids and limonoids (limonexic acid and limonin). The compounds 1-methyl-2-phenylquinolin-4-one and limonexic acid were isolated for the first time from the Spiranthera. These furoquinoline and 2-arylquinoli-4-one alkaloids and limonoids showed insecticidal and/or fungicidal activity in the nest of the Atta sexdens rubropilosa.

Muitas substâncias de origem vegetal podem ser tóxicas ou apresentar potencial inseticida. Com o objetivo de diminuir a problemática da poluição ambiental alguns estudos vêm tentando substituir os inseticidas artificiais pelos inseticidas botânicos. Ricinus communis (Euphorbiaceae) apresenta uma grande variedade de substâncias sendo a ricinina o principal componente tóxico. Considerando que as abelhas são insetos benéficos por atuarem como agentes polinizadores das plantas, este estudo teve por objetivo avaliar o efeito tóxico da ricinina para as operárias e larvas de Apis mellifera (Linnaeus, 1758) (Hymenoptera, Apidae) e Scaptotrigona postica (Latreille, 1907) (Hymenoptera, Meliponini). Para isso, foram realizados testes de ingestão em operárias confinadas recebendo ricinina incorporada à dieta e testes de aplicação tópica com a substância solubilizada em metanol e aplicada no pronoto das abelhas com auxílio de uma microseringa. Para as larvas foram realizados testes de ingestão e calculada sua taxa de mortalidade. Os resultados mostram atividade tóxica significativa (p < 0.0001) da ricinina nas abelhas adultas das duas espécies para a concentração 0,1% nos testes de ingestão e 0,2% nos testes de aplicação tópica. Outrossim, uma elevada porcentagem de larvas foi afetada negativamente pela ricinina logo nos primeiros dias de vida para todas as concentrações testadas (0,25%, 0,5% e 1%).

Many substances of vegetal origin can be toxic or present an insecticidal potential. With the aim of decreasing the environment pollution problem, a few studies are trying to substitute synthetic insecticides with botanical ones. Ricinus communis (Euphorbiaceae) presents a great variety of substances, being the ricinine the main toxic component. Considering that bees are useful as pollinator agents of plants, this study evaluates toxicity potential of ricinine on workers and larvae of Apis mellifera (Linnaeus, 1758) (Hymenoptera, Apidae) and Scaptotrigona postica (Latreille, 1907) (Hymenoptera, Meliponini). In order to determine ricinine toxicity, ingestion tests were carried out with isolated workers bees that received ricinine on its diet. Furthermore, for topic tests, solutions of ricinine in methanol were applied on pronotum of worker bees with an "Agla" brand micrometer syringe outfit. For larvae of bees, ingestion tests were used and mortality rates were calculated. According to the results, it was detected a significant toxic activity (p < 0.0001) of ricinine on the workers of the two bee species at concentrations of 0.1% in the ingestion tests and 0.2% in the topic tests. For all concentrations (0.25%, 0.5% and 1%), a high percentage of larvae bees was negatively affected by ricinine on the first days of life.

Descreve-se um novo Zygentoma (Nicoletiidae: Subnicoletiinae), mirmecófilo da formiga lava-pés Solenopsis saevissima (Formicidae: Myrmicinae) no Estado do Rio de Janeiro, Brasil: Allotrichotriura saevissima gen. nov. sp. nov. que é comparado com os géneros e subgéneros conhecidos na subfamília. As principais características diagnósticas respeitam a combinação da forma do corpo, quetotaxia cefálica e do corpo, morfologia do prétarso e número de estilos e vesículas abdominais. Embora prospecções recentes tenham sido levadas a cabo na localidade típica, apenas se conhece a amostra original, que integra exclusivamente fêmeas.

A new myrmecophilous silverfish (Zygentoma: Nicoletiidae: Subnicoletiinae) from Rio de Janeiro, Brazil, found living in fire ant (Solenopsis saevissima, Formicidae: Myrmicinae) nests is described: Allotrichotriura saevissima gen. nov. sp. nov. is compared with the other genera and subgenera known in the subfamily. The main diagnostic features would include the combination of body shape, body and head setation, morphology of praetarsus, and number of abdominal stylets and vesicles. Although further quests were attempted at the type-locality, only the original described material, exclusively composed of females, remains known.

O fluído fecal (FF) e a secreção da glândula mandibular (MGS) de operárias da formiga cortadeira Atta sexdens rubropilosa Forel afetaram a germinação dos esporos de microfungos isolados dos formigueiros. MGS foi mais eficiente que FF, inibindo quatro espécies de microfungos dentre as seis estudadas.

The mandibular gland secretion (MGS) and the faecal fluid (FF) of the leaf-cutting ant Atta sexdens rubropilosa Forel affected the spore germination of selected microfungi isolated from nests of this insect. MGS was more effective than the FF, completely inhibiting the spore germination of four out of six microfungi species.

Nove limonóides foram isolados de Carapa guianensis e Cedrela fissilis. Entre eles, a 1,2-diidro-3beta-hidroxi-7-desacetoxi-7-oxogedunina é uma substância inédita. Além disso, alguns deslocamentos químicos da xilocensina k foram corrigidos e os dados de RMN ¹H da 7-desacetilgedunina são descritos pela primeira vez na literatura. Seis dos limonóides isolados foram submetidos a ensaios com formigas Atta sexdens rubropilosa e apresentaram atividade inseticida moderada.

Nine limonoids were isolated from Carapa guianensis and Cedrela fissilis. Among them, 1,2-dihydro-3beta-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.

A investigação fitoquímica das raízes de Raulinoa echinata, planta endêmica do Vale do Itajaí/SC, levou ao isolamento e identificação dos limonóides degradados: fraxinelona, fraxinelonona e epoxi-fraxinelona. O último foi anteriormente isolado dos caules, porém sua configuração relativa não foi resolvida por experimentos de RMN. Este trabalho apresenta a análise de difração de raios-X da epoxi-fraxinelona, descreve o isolamento da fraxinelonona e fraxinelona pela primeira vez em Raulinoa, e a atividade tóxica da primeira sobre formigas cortadeiras (Atta sexdens rubropilosa). Pouca atividade foi observada para o limonóide degradado testado; entretanto, o limonóide ácido limonéxico isolado dos caules, apresentou alta toxicidade contra as formigas cortadeiras, reduzindo consideravelmente a longevidade das mesmas, em comparação com o controle.

Phytochemical survey of roots extracts of the South Brazilian endemic plant Raulinoa echinata Cowan, Rutaceae led to the isolation of known degraded limonoids: fraxinellone, fraxinellonone and epoxy-fraxinellone. The latter was previously isolated also from the stems, but the relative configuration could not be solved by NMR experiments. This paper deals with the X-ray diffraction analysis of epoxy-fraxinellone and its toxicity to leaf-cutting ants, describes the isolation of fraxinellonone and fraxinellone for the first time in Raulinoa. Epoxy-fraxinellone showed no toxicity to the leaf-cutting ants (Atta sexdens rubropilosa). The limonoid limonexic acid, isolated from stems, presented high toxicity to the leaf-cutting ants, diminishing considerably their longevity.

O estudo químico dos frutos de Cipadessa fruticosa (Meliaceae) permitiu o isolamento dos limonóides cipadesina B (inédito) e swietemahonolídeo. Das raízes de Cedrela fissilis (Meliaceae) foi isolado o limonóide 3beta-acetoxicarapina, inédito como produto natural, juntamente com os triterpenos ácido oleanólico e ácido oleanônico. Estes compostos, e outros seis mexicanolídeos anteriormente isolados de C. fruticosa, apresentaram atividade inseticida para as formigas cortadeiras Atta sexdens rubropilosa.

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 3beta-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.

Formigas cortadoras de folhas são consideradas pragas para a agricultura devido à grande quantidade de material vegetal utilizado por elas para cultivar um fungo simbionte que lhes serve de alimento e enzimas. O mutualismo entre o fungo e as formigas é um ponto a ser explorado quando se considera sua possível aplicação em métodos alternativos para o controle desses insetos. Sabendo-se que algumas plantas são naturalmente resistentes aos insetos fitófagos, alguns produtos naturais (metabólitos secundários) devem ser avaliados em relação às suas propriedades inseticidas e/ou fungicidas. Neste trabalho foram isoladas oito cumarinas de quatro espécies de plantas e o efeito no desenvolvimento do fungo simbionte das formigas cortadeiras Atta sexdens foi determinado. Com exceção da clausarina, todas as outras cumarinas foram inibitórias de 64 µg mL-1 à 80 µg mL-1 sendo que a xantiletina inibiu o fungo na concentração de 25 µg mL-1.

Leaf-cutting ants are known to be a serious pest for agriculture due to the high amounts of vegetal matter from crops used by them in order to cultivate a symbiotic fungus on which they rely for food and enzymes. The mutualism between the fungus and the ants is a point to be explored when alternative methods of control are being thought of. Considering that some plants are naturally resistant to phytophagous insects, some natural products (secondary metabolites) should be evaluated with respect to their insecticide and/or fungicide properties. In this paper we isolated eight coumarins from four different plant species and we determined their effect on the development of the symbiotic fungus of the leaf-cutting ant Atta sexdens. With the exception of clausarin, all the other coumarins were inhibitory from 64 µg mL-1 through 80 µg mL-1 and xanthyletin inhibited the fungus at 25 µg mL-1

O isolamento e a manutenção de fungos basidiomicetos simbiontes de formigas da tribo Attini tem sido dificultado pela baixa velocidade de crescimento desses fungos, bem como pela presença de muitos microrganismos que vivem na superfície do material que as formigas mantêm no interior nos ninhos como substrato para o crescimento dos seus fungos simbiontes. No presente trabalho nós descrevemos um método que aumenta em mais de sete vezes a eficiência de isolamento desses fungos, quando comparada àquela obtida por procedimentos tradicionais. Ninhos subterrâneos de formigas atíneas dos gêneros Atta, Acromyrmex, Trachymyrmex e Mycetarotes foram localizados e deles foram coletadas amostras contendo fungos simbiontes e formigas, que foram transportadas para o laboratório, onde as formigas foram capazes de limpar a cultura do fungo e estimular o seu crescimento. Em seguida, porções dos micélios foram assepticamente coletadas e transferidas para meio Yeast Nitrogen Base contendo glicose e cloranfenicol. Para facilitar a manutenção dos isolados em culturas de laboratório, diferentes nutrientes foram analisados para a elaboração de um meio de cultivo complexo, que possibilitou aumentar a velocidade de crescimento dos fungos e estocá-los por longos períodos. O método foi aplicado com sucesso para os fungos simbiontes de todos os gêneros de formigas estudados, gerando, assim, um procedimento extremamente útil para a formação e manutenção de uma coleção representativa de diferentes fungos simbiontes de formigas da tribo Attini.

The isolation and maintenance of symbiotic basidiomycete fungi living in association with ants of the tribe Attini has been hindered by the slow growth rate of these fungi and the presence of other microorganisms on the surface of the material which the ants maintain inside their nests to provide a growth substrate for their symbiont. In this paper we describe a method which increases the efficiency of isolation of these fungal symbionts by over seven fold as compared to traditional isolation procedures. Underground nests of attine ants of the genera Atta, Acromyrmex, Trachymyrmex and Mycetarotes were located, from which samples containing the fungal symbiont and ants were collected and transported to the laboratory where the ants were able to clean the fungal culture and stimulate its growth. As the symbiotic fungus grew, portions of its mycelium were collected and transferred to solid Yeast Nitrogen Base culture medium containing glucose and chloramphenicol. To facilitate the maintenance of the isolates in laboratory cultures, several nutrients were tested to formulate a complex culture medium for fast fungal growth and long-term storage. We successfully applied this methodology to the fungal symbionts of all the ant genera studied, thus producing a useful tool for the creation and maintenance of a comprehensive collection of fungi symbiotic of ants in the tribe Attini.

O cupim subterrâneo Heterotermes tenuis (Isoptera: Rhinotermitidae) é uma importante praga na economia brasileira, causando danos em reflorestamentos de eucalipto e plantações de cana-de-açúcar. O (3Z,6Z,8E)-dodecatrien-1-ol tem sido descrito como feromônio de trilha em várias espécies da família Rhinotermitidae. Este trabalho teve como objetivo sintetizar este trieno e determinar, através da eletroantenografia, a seletividade e sensibilidade dos receptores antenais de H. tenuis ao (3Z,6Z,8E)-dodecatrien-1-ol e ao seu respectivo extrato de glândula esternal.

The subterranean termite Heterotermes tenuis (Isoptera: Rhinotermitidae) is a pest of great importance for the Brazilian economy as it causes serious damages in commercial reforestations of Eucalyptus spp. and sugarcane cultures. (3Z,6Z,8E)-Dodecatrien-1-ol has been identified as a pheromone of some species of subterranean termites. The objective of this research was to synthesize (3Z,6Z,8E)-dodecatrien-1-ol and determine by electroantennographic (EAG) bioassays the selectivity and sensitivity of H. tenius antennae to its whole worker extract and to the synthetic triene alcohol.