Semi-field assessment of the Gravid Aedes Trap (GAT) with the aim of controlling Aedes (Stegomyia) aegypti populations.

The mosquito Aedes aegypti is the main vector of arboviroses and current approaches to control this vector are not sufficiently effective. Adult traps, such as the BG-Sentinel (BGS), have been successfully used for mosquito surveillance and can also suppress vector populations. A new "passive" trap for gravid Ae. aegypti (Gravid Aedes Trap-GAT) has been shown efficient for Aedes collection and suppress Ae. albopictus populations using mass trapping techniques. Here the GAT was evaluated for the first time as a new tool to control Ae. aegypti in semi-field conditions using simulated outdoor environments (SOE). Two identical large screened chambers inside of a SOE containing different numbers and sizes of artificial breeding sites were used to assess the trapping efficiency of the GAT. One hundred mosquitoes were released into the chambers, and recapture rates evaluated after 48h. The parity status of the captured mosquitoes was also recorded. The number of eggs laid, and breeding productivity were also monitored when using different numbers and sizes of breeding sites. The BGS trap was used here as a control (gold standard) trap to compare capture rates to those of the GAT. The GAT recaptured between 50-65% of the mosquitoes independent of the number and sizes of the breeding sites in the SOEs, whereas the BGS recaptured 60-82% of the females. Both traps showed similar results regarding to the parity status of recaptured mosquitoes. Our results confirmed the effectiveness of GAT for the capture of adult female Ae. aegypti in simulated field environments. The BGS trap recaptured gravid Ae. aegypti before egg-laying in different sizes and number of breading sites, whereas the oviposition activity occurred prior to recapture mosquitoes in the GAT. Based on the results, we believe that GAT is a promising candidate for mass-trapping intervention in urban settings, but a source reduction intervention should be made prior trap deployment. Therefore, we suggest future field studies to confirm the use of GAT as a complementary tool in vector control activities.

Electrophysiological responses of the Naupactus bipes beetle to essential oils from Piperaceae species.

Electrophysiological responses based on electroantennographic detection (GC-EAD) and electroantennography (EAG) analysis of Naupactus bipes beetles (Germar, 1824) (Coleoptera: Curculionidae: Brachycerinae) were used to test volatile oils of Piper gaudichaudianum, P. regnellii and P. hispidum. In the EAG experiments, female and male beetles showed significant EAG response to the three volatile oils of Piper species, with the females' responses slightly higher than the males'. The experiments with GC-EAD revealed that some terpenoids (namely, alpha-pinene, beta-pinene, myrcene, alpha-copaene and germacrene) present in the leaf essential oils of the Piper species are perceptible to female and male beetles.

Pheromone gland development and pheromone production in lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae).

The sand fly Lutzomyia longipalpis (Lutz & Neiva) (Diptera: Psychodidae: Phlebotominae) is the main vector of American visceral leishmaniasis. Adult males produce a terpenoid sex pheromone that in some cases also acts as male aggregation pheromone. We have analyzed the correlation between male pheromone production levels and pheromone gland cell morphogenesis after adult emergence from pupae. The abdominal tergites of L. longipalpis males were dissected and fixed in glutaraldehyde for transmission electron microscopy, or the pheromone was extracted in analytical grade hexane. Pheromone chemical analysis was carried out at 3- to 6-h intervals during the first 24 h after emergence and continued daily until the seventh day. All extracts were analyzed by gas chromatography. For the morphological analysis, we used insects collected at 0-6, 9-12, 12-14, and 96 h after emergence. Ultrastructural data from 0- to 6-h-old adult males revealed smaller pheromone gland cells with small microvilli at the end apparatus. Lipid droplets and peroxisomes were absent or very rare, but a large number of mitochondria could be seen. Lipid droplets started to appear in the gland cells cytoplasm approximately 9 h after adult emergence, and their number and size increased with age, together with the presence of several peroxisomes, suggesting a role for these organelles in pheromone biosynthesis. At 12-15 h after emergence, the lipid droplets were mainly distributed near the microvilli but were smaller than those in mature older males (4 d old). Pheromone biosynthesis started around 12 h after emergence and increased continuously during the first 3 d, stabilizing thereafter, coinciding with the period when males are more able to attract females.

Synthesis of a combinatorial library of amides and its evaluation against the fall armyworm, Spodoptera frugiperda.

The fall armyworm Spodoptera frugiperda is a polyphagous pest that causes important damage in different regions of America and mainly affects corn crops in both tropical and subtropical areas. Currently, control relies on both transgenic plants and/or chemical pesticides. In this work we describe the preparation of an indexed combinatorial library of amides and its toxic effect by contact against S. frugiperda . (E)-1-(1-Piperidinyl)-3-[4-(trifluoromethoxy)phenyl]-2-propen-1-one was the most active compound with an LD(50) = 0.793 µg mg(-1) of larva. This amide was also evaluated by ingestion and at the lowest concentration (1 mg kg(-1)) achieved 83.3% mortality.

Effects of limonoids from Cipadessa fruticosa on fall armyworm.

Six mexicanolide limonoids isolated from the dichloromethane extract of the fruits of Cipadessa fruticosa Blume (Meliaceae) were evaluated against Spodoptera frugiperda (J. E. Smith). Gedunin was used as a positive control. When incorporated into an artificial diet of neonates at 50.0 mg kg(-1), febrifugin A showed 73.3% mortality. All the compounds showed moderate insecticidal activity, except for ruageanin A, when compared with the control. Febrifugin also showed growth inhibition and antifeedant activities (at 100.0 mg kg(-1)). The correlation between the insecticidal activity of the isolated compounds and their chemical structure was discussed.

Electrophysiological responses of Atta sexdens rubropilosa workers to essential oils of eucalyptus and its chemical composition.

The leaf-cutting ant Atta sexdens rubropilosa Forel, 1908 is the most harmful of the Eucalyptus pests, causing severe losses in wood production through defoliation. Various strategies have been tried and effort spent on the development of methods to control this pest, however no practical and environmentally acceptable one currently exists. In this work the chemical composition of the essential oil of seven Eucalyptus species was identified and the selectivity and sensitivity of antennal receptors of A. sexdens rubropilosa workers to the volatile compounds were determined using the electroantennographic technique (EAG and GC-EAD). Analysis by GC-EAD showed in E. cloesiana and E. maculata, respectively, seventeen and sixteen terpenes that elicited responses in ant workers' antennae, indicating the potential role of the essential oils as allelochemicals that determine the choice of the foraging material.

Bioactivity of extracts and isolated compounds from Vitex polygama (Verbenaceae) and Siphoneugena densiflora (Myrtaceae) against Spodoptera frugiperda (Lepidoptera: Noctuidae).

The effects of crude extracts, fractions and isolated compounds from Vitex polygama Cham. and Siphoneugena densiflora Berg were evaluated on the development of Spodoptera frugiperda JE Smith, a destructive insect pest of corn and several other crops. The extracts and fractions were incorporated into an artificial diet at 1 mg g(-1) and offered to the insect during its larval stage. Length and viability of larval and pupal stages as well as pupal weight were assessed. Isolated compounds were tested through superficial contamination of the diet at 0.1 mg g(-1). Weight and viability of ten-day-old larvae were determined. Methanolic and hydroalcoholic S. densiflora extracts caused 100% larval mortality, while leaf and fruit hydroalcoholic extracts from V. polygama were the most active. Among the isolated compounds, flavonoids presented the best insecticidal results, and tannins the best larval growth inhibition.

Isolation, identification, synthesis, and field evaluation of the sex pheromone of the Brazilian population of Spodoptera frugiperda.

Several studies have shown intraspecific geographical variation in the composition of sex pheromones. Pheromone lures from North America and Europe were not effective against the fall armyworm Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) in Brazil, so we examined the composition of the sex pheromone produced by females from Brazilian populations. Virgin female gland extracts contained (Z)-7-dodecenyl acetate (Z7-12:Ac), (E)-7-dodecenyl acetate (E7-12:Ac), dodecyl acetate, (Z)-9-dodecenyl acetate, (Z)-9-tetradecenyl acetate (Z9-14:Ac), (Z)-10-tetradecenyl acetate, tetradecyl acetate/(Z)-11-tetradecenyl acetate (Z11-16:Ac), and (Z)-11-hexadecenyl acetate. The relative proportions of each acetate were 0.8:1.2:0.6:traces:82.8:0.3:1.5:12.9, respectively. This is the first time that E7-12:Ac has been reported from the pheromone gland of S. frugiperda. Only three compounds, Z9-14:Ac, Z7-12:Ac, and E7-12:Ac, elicited antennal responses, and there were no differences in catch between traps baited with either Z7-12:Ac + Z9-14:Ac or Z7-12:Ac + Z9-14:Ac + Z11-16:Ac blends. However, the Z7-12:Ac + Z9-14:Ac + E7-12:Ac blend was significantly better than Z7-12:Ac + Z9-14:Ac, indicating that E7-12:Ac is an active component in the sex pheromone of the Brazilian populations of S. frugiperda.

Insecticidal activity of synthetic amides on Spodoptera frugiperda.

The phytochemistry of the genus Piper (Piperaceae) has been widely studied due to the biological properties of amides from these plants. In this work, we have synthesized and evaluated the toxic effect of 11 amides against the fall armyworm Spodoptera frugiperda larvae. The naturally occurring piperine was also evaluated. The most active amide was N-[3-(3',4'-methylenedioxyphenyl)-2-(E)-propenoyl]piperidine with a LD50 of 1.07 microg mg(-1) larvae. This amide was also evaluated by ingestion.

Pollination by sexual mimicry in Mormolyca ringens: a floral chemistry that remarkably matches the pheromones of virgin queens of Scaptotrigona sp.

The chemical composition of some volatile (2-heptanol) and nonvolatile constituents (a homologous 9-alkene/alkane series) of Mormolyca ringens flowers and Scaptotrigona sp. queen waxes (homologous 9-alkene/alkane series) and cephalic extracts (homologous series of 2-alkanols, including 2-heptanol) involved with the pseudocopulation or sexual mimicry in Orchidaceae pollination is compared. The similarity in chemical composition of flowers and insects is assigned to the chemically induced copulatory activity in Scaptotrigona males.

Volatile oil from Guarea macrophylla ssp. tuberculata: seasonal variation and electroantennographic detection by Hypsipyla grandella.

GC and GC-MS analyses of the volatile oils from Guarea macrophylla (Meliaceae) collected during three different periods in one year (February, June and October) indicated a seasonal variation in chemical composition. Whilst sesquiterpenes were the predominant class of components present in the leaf oil, a seasonal dependent variation in the degree of oxygenation of these compounds was detected, which seemed to be associated with phenological factors. The leaf oil, and fractions thereof, were subjected to GC coupled with electroantennographic detection employing antennae of females of Hypsipyla grandella, an insect pest that attacks several meliaceous species. Five compounds elicited significant responses and these were identified as ledol, 1-cubenol, guai-6-en-10beta-ol, 1-epi-cubenol, and tau-muurolol. The results suggest that these components could be responsible for the attraction of H. grandella to G. macrophylla.

Cuticular hydrocarbons of Heterotermes tenuis (Isoptera: Rhinotermitidae): analyses and electrophysiological studies.

Termites have become an important pest of Eucalyptus and Pinus reforestations, sugarcane and other cultures. An alternative for the control of this pest would be the use of attractive traps that take in account the social behavior of these insects. Diverse factors are important for the insects in the localization of the habitat and the choice of the food and specific odors can facilitate this. Studies referring to Heterotermes tenuis (Isoptera: Rhinotermitidae) are scarce. The objective of this work was to analyze the tergal cuticular extract of H. tenuis and determine the selectivity and sensitivity of its antennae to the components of this extract by electroantennography (EAG). The composition of the cuticular extract was determined by GC-MS analysis. The hydrocarbons found were restricted to linear alkanes, being most abundant C24 to C27 that comprises ca. 65% of the total. Olefins were not detected. EAG and behavioral test responses to the cuticular hydrocarbons were greater and significantly different from the control and the high selectivity of the antennae to the extract indicates its potential as chemical messenger. Cuticular hydrocarbons mixture is species-specific and can be used to identify a given taxon without the diagnostic castes, soldiers or imagoes Difference in the composition appears to relate with the type of habitat of specie.

Comportamento de chamamento de Thyrinteina arnobia (Stoll) (Lepidoptera: Geometridae) em Psidium guajava, Eucalyptus grandis e em dieta artificial / Calling behavior of Thyrinteina arnobia (Stoll) (Lepidoptera: Geometridae) reared on Psidium guajava and Eucalyptus grandis host-plant leaves and on artificial diet

This work was carried out to determine and compare the effects of three diets (Psidium guajava and Eucalyptus grandis host-plant leaves and artificial diet) on the calling behavior and on thetemporal pattern of calling behavior of Thyrinteina arnobia (Stoll). All activities of virgin females during six scotophases were observed in the laboratory at 5min. intervals until the females stoppedcalling in the following photophase, at 22 ± 1oC, 70 ± 5% RH and 10h scotophase. The diets affected the calling behavior of T. arnobia. Two positions of calling were observed. Calling of female virgins started in the first hour immediately after emergence. The calling pattern was characteristic of the continuous pattern. The type of diet affected the mean onset of calling time (pre-calling) and the total time calling ofT. arnobia. Older females called earlier than younger after the onset of scotophase. The diets affected the color of pheromone gland.

Este estudo teve como objetivos determinar e comparar o efeito de três dietas: Psidium guajava, Eucalyptus grandis e dieta artificial no comportamento de chamamento e no padrão temporal do comportamento de chamamento de fêmeas virgens de Thyrinteina arnobia (Stoll). Foram analisados os parâmetros: tempo médio para o início do chamamento, número médio de chamamento, tempo médiode cada chamamento e tempo médio total de chamamento. Os bioensaios relacionados ao comportamento de chamamento de fêmeas virgens foram realizados durante seis escotofases consecutivas e as observações tomadas a cada 5 min., a 22 ± 1oC, 70 ± 5% de UR e 10h de escotofase. As fêmeas,independente da dieta analisada, apresentaram duas posições diferentes de chamamento. A maioria das fêmeas virgens iniciou o chamamento na 1a hora da 1a escotofase. O padrão de chamamento da fêmea individualizada foi característico de um padrão contínuo. O tipo de dieta oferecida na fase larvalinfluenciou o início do comportamento de chamamento (pré-chamamento) e o tempo médio total de chamamento. O tipo de dieta também alterou a coloração da glândula de feromônio.

Electrophysiological responses of female and male Hypsipyla grandella (Zeller) to Swietenia macrophylla essential oils.

The mahogany shoot borer, Hypsipyla grandella, is one of the most economically important Neotropical forest pest insects because it attacks valuable timber of the Meliaceae. Despite detailed information on the life cycle of H. grandella, factors influencing attack by the shoot borer are not well known. Electroantennogram studies of borer antennae indicate that both female and male moths elicited significant antennal responses to essential oil of the terminal shoots, mature and senescent leaves, in three concentrations. Gamma-himachalene, germacrene D, germacrene A, cadina-1,4-diene, hexadecanoic acid, and ethyl hexadecanoate appeared in all essential oils from Swietenia macrophylla. Germacrene-D and gamma-himachalene were also present in the active essential oil of Cedrela odorata and Toona ciliata. These findings suggest that these compounds play a role in attracting H. grandella to oviposit on the leaves of these plants. The GC-EAD of essential oil from S. macrophylla mature leaves to female H. grandella antennae led to the identification of beta-caryophyllene as the main constituent responsible for the antennae response.

Electrophysiological studies and identification of possible sex pheromone components of Brazilian populations of the sugarcane borer, Diatraea saccharalis.

Virgin female gland extracts of sugarcane moth Diatraea saccharalis (Fabricius) (Lepidoptera: Pyralidae), from three locations in Brazil, have been analyzed. By GC-MS analysis and comparison of the chromatographic retention time of the components of the pheromone gland with those retention times of synthetic standards, we observed the presence of (Z)-hexadec-11-enal (1), hexadecanal (2), (9E,11Z)-hexadecadienal (4), (9Z,11Z)-hexadecadienal (5) and (9E,11E)-hexadecadienal (6), as minor components besides the major constituent (9Z,11E)-hexadecadienal (3) already reported. We found no variations in the composition of the gland extracts deriving from the three Brazilian populations and only two compounds, (Z)-hexadec-11-enal (1) and (9Z,11E)-hexadecadienal (3), elicited antennal responses (GC-EAD). In electroantennography (EAG), however, pure compounds 1 and 3, a binary mixture containing 1 and 3, and a mixture containing all of the six synthetic compounds 1-6 elicited a depolarization in male antennae of D. saccharalis, without any statistically different delay. The EAG responses to the other isomers of 9,11-hexadecadienal were small and not significantly different from the control, except for the (9Z,11Z)-isomer (5) which showed an relatively strong electroantennal activity.

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.