In vitro evaluation of methanol extracts of edible fungi Pleurotus ostreatus and Lentinula edodes against Rhyssomatus nigerrimus Fahraeus.

The study aimed to evaluate the insecticidal activity of extracts of edible mushrooms Pleurotus ostreatus and Lentinula edodes against Rhyssomatus nigerrimus. Methanol:water extracts (70:30) of P. ostreatus and L. edodes were made and evaluated in two in vitro tests (exposure and immersion toxic effect) against R. nigerrimus. Subsequently, the toxicity test of the extracts against Artemia salina was evaluated. These extracts were subjected to colorimetric tests and gas chromatography-mass spectrometry. The results showed a mortality effect against R. nigerrimus of 50% for the P. ostreatus 2 extracts at a concentration of 20% in the immersion test. Likewise, in the toxic effect test, 90% mortality was observed after five days of exposure to a concentration of 10%. On the other hand, for the toxicity test, the extract that showed the values with the highest mortality against A. salina was P. ostreatus, starting with 80% mortality at 100µg/mL. The functional groups present in the extracts were saponins, coumarins, and alkaloids. Furthermore, the presence of more than 7 compounds in the mushroom extracts evaluated is reported. This study demonstrates the insecticidal activity of P. ostreatus and L. edodes fungal extracts and indicates the importance of using different in vitro tests to elucidate the mechanism of action for future studies.

Insecticidal effect of metabolites identified in edible mushrooms against Rhyssomatus nigerrimus Fahraeus.

Excessive use of insecticides has led to resistance of some pathogenic organisms (nematodes, bacteria and fungi), environmental contamination, and the presence of hazardous residues. Therefore, the aim of the present study was to evaluate synthetic metabolites derived from previous studies with edible mushrooms against the soybean weevil Rhyssomatus nigerrimus Fahraeus (Curculonidae) because of the relevance of pest control in an economically important crop. Furthermore, this is one of the first studies where edible fungal molecules are evaluated for the control of these insects. Initially, two in vitro tests (toxic effect and immersion) were evaluated against R. nigerrimus. In these tests, sensitivity and viability were determined in the 2% Tween control in water. For these two tests, the synthetic metabolites pentadecanoic acid (PNA), palmitic acid (PMA), stearic acid (STA), linoleic acid (LNA), ß-sitosterol (ßT) were evaluated individually as well as in combinations, "the fraction of standards (E1)". Based on the results obtained, the dip test was selected to evaluate the mixtures of two standards (1. PMA + ßT, 2. PMA + PNA, 3. PMA + LNA, 4. PMA + STA, 5. STA + ßT, 6. STA + PNA, 7. STA + LNA, 8. PNA + ßT, 9. PNA + LNA, 10. LNA + ßT), three (1. PNA + ßT + LNA, 2. PNA + ßT + STA, 3. STA + LNA + PNA and 4. STA + LNA + ßT) and four (PNA, ßT, LNA and STA). The results showed that the mixture of three standards caused a higher percentage of mortality relative to the control group: l. PNA + ßT + LNA and 2. PNA + ßT + STA with 54.44 and 48% mortality of R. nigerrimus insects exposed for 15 days. These results show the importance of evaluating mixtures of molecules against R. nigerrimus.

Induced volatiles in the interaction between soybean (Glycine max) and the Mexican soybean weevil (Rhyssomatus nigerrimus) / Voláteis induzidos na interação entre soja (Glycine max) e gorgulho da soja mexicana (Rhyssomatus nigerrimus)

Abstract The present study analyzed the volatile compounds emitted by Glycine max (cv. FT-Cristalina-RCH) soybean plants: healthy plants and plants damaged mechanically or by the Mexican soybean weevil Rhyssomatus nigerrimus. The SPME method was used to compare the volatile profile of soybean plants in four different conditions. The volatile profile of G. max plants infested by R. nigerrimus was qualitatively and quantitatively different from that of healthy and mechanically damaged plants. Emission of 59 compounds was detected in the four treatments. Of these compounds, 19 were identified by comparison of the Kovats index, mass spectrum and retention times with those of synthetic standards. An increase in concentration of the volatiles (Z)-3-hexenyl acetate and the compound 1-octen-3-ol was observed when the soybean plants were mechanically damaged. The compounds mostly produced by the soybean plant during infestation by male and female R. nigerrimus were 1-octen-3-ol, 6-methyl-5-hepten-2-one, (E)-β-ocimene, salicylaldehyde, unknown 10, linalool, methyl salicylate, (Z)-8-dodecenyl acetate (ester 5), ketone 2 and geranyl acetone. Behavioral effects of the identified compounds during the insect-plant interaction and their conspecifics are discussed.

Resumo O presente estudo analisou os compostos voláteis emitidos pelas plantas de soja Glycine max (cv. FT-Cristalina-RCH): plantas e plantas sadias danificadas mecanicamente ou pelo gorgulho da soja mexicana Rhyssomatus nigerrimus. O método SPME foi utilizado para comparar o perfil volátil de plantas de soja em quatro diferentes condições. O perfil volátil das plantas de G. max infestadas por R. nigerrimus foi qualitativa e quantitativamente diferente do das plantas saudáveis e danificadas mecanicamente. Foi detectada, nos quatro tratamentos, emissão de 59 compostos, dos quais 19 foram identificados por comparação do índice de Kovats, espectro de massa e tempos de retenção com aqueles de padrões sintéticos. Um aumento na concentração dos voláteis acetato de (Z)-3-hexil e do composto 1-octeno-3-ol foi observado quando as plantas de soja foram mecanicamente danificadas. Os compostos produzidos principalmente pela planta de soja durante a infestação por R. nigerrimus macho e fêmea foram 1-octeno-3-ol, 6-metil-5-hepteno-2-ona, (E)-β-ocimeno, salicilaldeído, desconhecido 10, linalol, salicilato de metila, acetato de (Z)-8-dodecenila (éster 5), cetona 2 e geranil acetona. Foram discutidos os efeitos comportamentais dos compostos identificados durante a interação inseto-planta e seus coespecíficos.

Induced volatiles in the interaction between soybean (Glycine max) and the Mexican soybean weevil (Rhyssomatus nigerrimus).

The present study analyzed the volatile compounds emitted by Glycine max (cv. FT-Cristalina-RCH) soybean plants: healthy plants and plants damaged mechanically or by the Mexican soybean weevil Rhyssomatus nigerrimus. The SPME method was used to compare the volatile profile of soybean plants in four different conditions. The volatile profile of G. max plants infested by R. nigerrimus was qualitatively and quantitatively different from that of healthy and mechanically damaged plants. Emission of 59 compounds was detected in the four treatments. Of these compounds, 19 were identified by comparison of the Kovats index, mass spectrum and retention times with those of synthetic standards. An increase in concentration of the volatiles (Z)-3-hexenyl acetate and the compound 1-octen-3-ol was observed when the soybean plants were mechanically damaged. The compounds mostly produced by the soybean plant during infestation by male and female R. nigerrimus were 1-octen-3-ol, 6-methyl-5-hepten-2-one, (E)-ß-ocimene, salicylaldehyde, unknown 10, linalool, methyl salicylate, (Z)-8-dodecenyl acetate (ester 5), ketone 2 and geranyl acetone. Behavioral effects of the identified compounds during the insect-plant interaction and their conspecifics are discussed.

Effectiveness of the Sex Pheromone for Monitoring Stenoma catenifer (Lepidoptera: Elachistidae) in Avocado Orchards.

The sex pheromone of the avocado moth Stenoma catenifer Walsingham has potential use in the detection of S. catenifer males in the Antillean race avocado in Chiapas, Mexico, although the study of local parameters that influence its effectiveness is required. In this study, trap type, trap height, pheromone release rate and duration of pheromone activity were evaluated to determine the effectiveness of this pheromone in field conditions in the Antillean race avocado crops of the coast of Chiapas, Mexico. The results obtained indicate that the capture of moths with the traps Pherocon III (delta type) and Pherocon 1C (wing type) was higher than that with the boat-type traps. The frequency of capture of S. catenifer males was higher when the traps were placed 4 and 6 m above ground level than that when they were 2 m high. The septum releases 85% of the amount of pheromone during the first 4 weeks, and there were no differences between the number of moth captures during the first 3 weeks, only between the fourth and the first 2 weeks. Our results suggest that the efficiency of the pheromone in Antillean race avocado depends on trap placement height and type as well as on the time of use of the pheromone septum.

Traditional and Geometric Morphometry Analyses of Lutzomyia cruciata (Diptera: Psychodidae: Phlebotominae) Populations of Chiapas, Mexico.

The presence of Lutzomyia (Tricholateralis) cruciata (Coquillett 1907) species complex has been suggested by morphological analysis of eggs and genetic studies of females. The present work aimed to compare the diversity in morphology of four populations of Lu. cruciata from the Coast of Chiapas, Mexico, using traditional (TM) and geometric (GM) methods. Several morphological characteristics that were analyzed provided consistency to differentiate at least, three populations of Lu. cruciata. Both methods were effective to detect morphological differences associated with the geographical sites of capture. In both sexes, three and four groups were detected by TM and GM, respectively. These results suggest marked morphological differences in both sexes of Lu. cruciata that make these methods potentially useful to identify the geographical origin of any specimen of this species captured in the study region. Although the results produced by both methods are coincident, geometric morphometrics turned out to be most advantageous with respect to traditional morphometry, since the latter requires more time and effort. The consistency of our results shows that the variability of environmental conditions on the coast of Chiapas determines a high degree of phenotypic plasticity in Lu. cruciata, with the possibility of prezygotic isolation and the formation of species complex.

The singular insemination status of Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae) females during the inter-harvest season of a coffee crop.

The coffee berry borer, Hypothenemus hampei (Ferrari), can survive in residual coffee berries during the inter-harvest period, while new fructification only appears 2-3 months after the last harvest. The dispersal of colonizing females is an adaptation that enables the life cycle of the species to go ahead whenever his flight aptitude allows. This paper focuses on accurately determining the rate of inseminated females ready to reproduce when emerging from residuals berries to colonize new ones, which constitutes a characteristic of the live cycle far from common in Curculionidae. We dissected females caught in traps baited with a mixture of alcohols during the inter-harvest season, females from infested residual berries collected from branches, and virgin females obtained from pupae reared individually in the laboratory. After microscopic preparation with Giemsa stain, spermathecae were observed to identify the physiological status of each specimen. Out of the females found in the traps, 98.4% displayed recent and abundant insemination and 1.6% sporadic insemination. In contrast, in residual berries, most of females were recently inseminated (84.5%), followed by virgin females (10.5%) and older inseminated females (5%). In addition, the flight tests of the virgin females were negative. These results indicate that all colonizing females were inseminated, ready for flying and oviposition, females inside residual berries showed different physiological status, and virgin females could not migrate since they could not flight. The large number of inseminated females inside the residual berries, and the capacity of migrating females to colonize and reproduce, suggest that it is necessary to control residual berries and use traps to stop the dispersal and reproduction of this pest.

Pollinator Preferences for Floral Volatiles Emitted by Dimorphic Anthers of a Buzz-Pollinated Herb.

Floral scents attract pollinators to plant rewards; in nectarless flowers, pollen grains are the only reward. Thus, pollen not only fertilizes ovules, but also feeds pollinators. This dilemma is resolved by specialization of anthers (i.e., heteranthery): feeding anthers that feed pollinators and pollinating anthers for fertilization. We hypothesized that the chemical composition of floral volatiles differs between the two types of anther and influences pollination preference for feeding anthers. We used Solanum rostratum as a study model because its heterantherous flowers produce a floral scent that suggests a close association with their pollinators. The main aim of this study was to determine the chemical composition of the two types of anther and to investigate how they influence foraging behaviour of pollinators. To characterize this composition, we used solid phase microextraction and hexane extraction followed by gas chromatography-mass spectrometry. We registered 12 volatile compounds in S. rostratum floral extracts, mainly aromatic and sesquiterpene compounds. The proportion of these compounds differed between feeding and pollinating anthers. Some of these compounds were probably emitted by osmophores located in both anther types. Also, we used electroantennography to investigate Melipona solani antennal response to floral volatiles. The M. solani antennae are receptive to the highest floral extract dose tested. Finally, we conducted two behavioural bioassays to test bee attraction for each type of floral extract: a) multiple-choice in a feeding arena using M. solani and b) Y-olfactometer bioassay using Bombus impatiens. Both bee species preferred feeding anthers in bioassays. In conclusion, heteranthery involves chemical differentiation (i.e., proportion of volatiles compounds) in anther specialization that influences bee preference for feeding anthers over pollinating anthers.

Behavioural and electrophysiological responses of Triatoma dimidiata nymphs to conspecific faecal volatiles.

The behavioural and electrophysiological (electroantennography) responses of the first two instars of Triatoma dimidiata (Hemiptera: Reduviidae) Latreille to fresh and dry faecal headspace volatile extracts from fifth instar conspecific nymphs and synthetic compounds were analysed in this study. Recently emerged nymphs (3-5 days) aggregated around filter paper impregnated with dry faeces and around filter paper impregnated with extracts from both fresh and dry faeces. Older first instars (10-15 days) and second instars aggregated around filter paper impregnated with fresh and dry faeces, and their respective headspace extracts. Dry faecal volatile extracts elicited the strongest antennal responses, followed by fresh faecal extracts. Gas chromatography-mass spectrometry analysis of dried faecal headspace volatiles demonstrated the presence of 12 compounds: 2-ethyl-1-hexanol, 1,2,4-trimethylbenzene, n-octadecane, n-nonadecane, n-eicosane, n-heneicosane, n-tricosane, n-pentaeicosane, n-hexaeicosane, n-octaeicosane, nonanal, and 4-methyl quinazoline. In fresh faecal headspace extracts, only nonanal was clearly detected, although there were other trace compounds, including several unidentified sesquiterpenes. Four of the 11 compounds tested individually elicited aggregation behaviour at concentrations of 100 ng/µL and 1 µg/µL. A blend containing these four components also mediated the aggregation of nymphs. These volatiles may be valuable for developing monitoring methods and designing sensitive strategies to detect and measure T. dimidiata infestation.

Short-distance dispersal of Hypothenemus hampei (Ferrari) females (Coleoptera: Curculionidae: Scolytidae) during the coffee tree fruiting period.

The coffee berry borer (CBB), Hypothenemus hampei (Ferrari), is a multivoltine species closely associated with coffee crops worldwide, causing severe damage to the bean. In Mexico, as in all tropical regions, CBB survives during the inter-harvest period in residual berries on the ground or in dry berries remaining on the branches, and then disperses in search of the first suitable berries. In this study, we investigated how CBB dispersed from the first infested nodes during the fruiting period of Coffea canephora Pierre, which provides a favourable trophic level for this insect. Forty-five branches equally distributed in 15 coffee trees, with one infested node and four uninfested nodes, were selected. The branches were subjected to three treatments over nine weeks: 1) glue between nodes with full protection, 2) glue between nodes without protection, and 3) no glue and no protection. In addition, 45 CBB-free branches were selected and subjected to the same three treatments. CBB colonization can occur in three ways: 1) from an infested node to an uninfested node on the same branch, 2) from infested berries to uninfested berries within the nodes, 3) from branches to other branches. We also found that CBB dispersal between nodes of the same branches never occurred by walking but by flying. Thus, in this context of coffee berry development and ripening, and unlike the phenological situation of the inter-harvest period, CBB continuously travels very short distances, thus limiting its control.

Induced volatiles in the interaction between soybean (Glycine max) and the Mexican soybean weevil (Rhyssomatus nigerrimus)

Abstract The present study analyzed the volatile compounds emitted by Glycine max (cv. FT-Cristalina-RCH) soybean plants: healthy plants and plants damaged mechanically or by the Mexican soybean weevil Rhyssomatus nigerrimus. The SPME method was used to compare the volatile profile of soybean plants in four different conditions. The volatile profile of G. max plants infested by R. nigerrimus was qualitatively and quantitatively different from that of healthy and mechanically damaged plants. Emission of 59 compounds was detected in the four treatments. Of these compounds, 19 were identified by comparison of the Kovats index, mass spectrum and retention times with those of synthetic standards. An increase in concentration of the volatiles (Z)-3-hexenyl acetate and the compound 1-octen-3-ol was observed when the soybean plants were mechanically damaged. The compounds mostly produced by the soybean plant during infestation by male and female R. nigerrimus were 1-octen-3-ol, 6-methyl-5-hepten-2-one, (E)--ocimene, salicylaldehyde, unknown 10, linalool, methyl salicylate, (Z)-8-dodecenyl acetate (ester 5), ketone 2 and geranyl acetone. Behavioral effects of the identified compounds during the insect-plant interaction and their conspecifics are discussed.

Resumo O presente estudo analisou os compostos voláteis emitidos pelas plantas de soja Glycine max (cv. FT-Cristalina-RCH): plantas e plantas sadias danificadas mecanicamente ou pelo gorgulho da soja mexicana Rhyssomatus nigerrimus. O método SPME foi utilizado para comparar o perfil volátil de plantas de soja em quatro diferentes condições. O perfil volátil das plantas de G. max infestadas por R. nigerrimus foi qualitativa e quantitativamente diferente do das plantas saudáveis e danificadas mecanicamente. Foi detectada, nos quatro tratamentos, emissão de 59 compostos, dos quais 19 foram identificados por comparação do índice de Kovats, espectro de massa e tempos de retenção com aqueles de padrões sintéticos. Um aumento na concentração dos voláteis acetato de (Z)-3-hexil e do composto 1-octeno-3-ol foi observado quando as plantas de soja foram mecanicamente danificadas. Os compostos produzidos principalmente pela planta de soja durante a infestação por R. nigerrimus macho e fêmea foram 1-octeno-3-ol, 6-metil-5-hepteno-2-ona, (E)--ocimeno, salicilaldeído, desconhecido 10, linalol, salicilato de metila, acetato de (Z)-8-dodecenila (éster 5), cetona 2 e geranil acetona. Foram discutidos os efeitos comportamentais dos compostos identificados durante a interação inseto-planta e seus coespecíficos.

Presence of Putative Male-Produced Sex Pheromone in Lutzomyia cruciata (Diptera: Psychodidae), Vector of Leishmania mexicana.

Lutzomyia cruciata (Coquillet) is a vector of cutaneous leishmaniasis in Mexico and Central America. However, several aspects of its ecology and behavior are unknown, including whether a male pheromone partially mediates the sexual behavior of this sand fly. In this study, we evaluated the behavioral response of females to male abdominal extracts in a Y-tube olfactometer. The volatile compounds from male abdominal extracts were identified by gas chromatography-mass spectrometry and compared with those of female abdominal extracts. Finally, the disseminating structures of the putative sex pheromone were examined by scanning electron microscopy in the male abdomen. Females were more attracted to male abdominal extract than to the hexane control, suggesting the presence of male-produced sex pheromone. The male abdominal extracts were characterized by the presence of 12 sesquiterpene compounds. The major component, an unknown sesquiterpene with an abundance of 60%, had a mass spectrum with molecular ion of m/z 262. In contrast, the abdominal female extracts contained saturated fatty acids. Finally, we detected the presence of small "papules" with a mammiform morphology distributed on the abdominal surface of tergites IV-VII of male Lu. cruciata These structures are not present in females. We conclude that Lu. cruciata males likely produce a pheromone involved in attracting or courting females.

Volatile compounds emitted by Triatoma dimidiata, a vector of Chagas disease: chemical analysis and behavioural evaluation.

In this study, we evaluated the responses of Triatoma dimidiata Latreille (Hemiptera: Reduviidae) to volatiles emitted by conspecific females, males, mating pairs and metasternal gland (MG) extracts with a Y-tube olfactometer. The volatile compounds released by mating pairs and MGs of T. dimidiata were identified using solid-phase microextraction and coupled gas chromatography-mass spectrometry (GC-MS). Females were not attracted to volatiles emitted by males or MG extracts; however, they preferred clean air to their own volatiles or those from mating pairs. Males were attracted to volatiles emitted by males, females, mating pairs, pairs in which the male had the MG orifices occluded or MG extracts of both sexes. However, males were not attracted to volatiles emitted by pairs in which the female had the MG orifices occluded. The chemical analyses showed that 14 and 15 compounds were detected in the headspace of mating pairs and MG, respectively. Most of the compounds identified from MG except for isobutyric acid were also detected in the headspace of mating pairs. Both females and males were attracted to octanal and 6-methyl-5-hepten-2-one, and males were attracted to 3,5-dimethyl-2-hexanol. Males but not females were attracted to a seven-compound blend, formulated from compounds identified in attractive MG extracts.

Effect of biotic factors on the spatial distribution of stingless bees (Hymenoptera: Apidae, Meliponini) in fragmented neotropical habitats.

We recorded stingless bee colony abundance and nesting habits in three sites with different anthropogenic activities in the Soconusco region of Chiapas, Mexico: (1) agroforestry (7 hacacao crop), (2) grassland (12 ha), and (3) urban area (3 ha). A total of 67 nests were found, representing five stingless bee species, Tetragonisca angustula angustula (Lepeletier), Trigona fulviventris (Guérin), Scaptotrigona mexicana (Guérin), Scaptotrigona pectoralis (Dalla Torre), and Oxytrigona mediorufa (Cockerell). The most abundant stingless bee in each site was T. angustula angustula (>50%). The primary tree species used by the bees were Ficus spp. (Moraceae, 37.8%) and Cordia alliodora (Boraginaceae, 13.5%). The nest entrance height of T. angustula angustula (96 ± 19 cm) was different than the other species, and this bee was the only one that used all different nesting sites. Volatiles analyzed by gas chromatography from pollen collected by the stingless bees differed between bee species, but were highly similar in respect to the fragrances of the pollen collected by the same species at any site. Our data indicate that T. angustula angustula experienced low heterospecific and high intraspecific foraging overlap especially in the urban site. We observed cluster spatial distribution in grassland and in agroforestry sites. In the urban site, T. angustula angustula presented random distribution tended to disperse. Trigona fulviventris was the only overdispersed and solitary species.

Effect of temperature on pupa development and sexual maturity of laboratory Anastrepha obliqua adults.

The effect of four temperatures (18, 20, 25 and 30°C) on pupa development and sexual maturity of Anastrepha obliqua adults was investigated under laboratory conditions. The results showed that the duration of the pupal stage decreased with an increase in temperature (29, 25, 13 and 12 days, respectively), and maintaining the pupae at 18°C and 20°C results in a low percentage of pupation, pupa weight loss and lesser flying ability. However, it significantly favored sexual behavior, a higher proportion of sexual calls and matings. While enhanced pupa development was observed at a temperature of 30°C, adults had low sexual efficiency, as well as a lower proportion of calls and matings. Gas chromatography-mass spectrometry (GC-MS) analysis of male volatiles showed that the amount of (Z,E)-α-farnesene did not vary among males from pupae reared at different temperatures; however, less (E,E)-α-farnesene was emitted by males obtain from pupa reared at 30°C. Male flies kept at 30°C during their larval stage had more (Z)-3-nonenol and, also, an unknown compound was detected. The fecundity of the females was higher at low temperatures. Regarding fertility, no significant differences were found between temperatures. The optimal temperature on pupa development was 25°C when males displayed ideal attributes for rearing purposes.

Removal of chlorothalonil, methyl parathion and methamidophos from water by the Fenton reaction.

The efficiency of a dark Fenton system (H2O2/Fe2+) to remove chlorothalonil from water, alone and in the presence of the organophosphorous pesticides methyl parathion and methamidophos, was evaluated. Here we show that the process is rapid and efficient. Nearly complete degradation of chlorothalonil and methyl parathion (98%) was observed in less than 10 min whereas methamidophos showed similar levels of efficiency only after 40 to 90 min. Formulating agents did not appear to impair the degradation of active ingredients. Interactions during the degradation of mixtures of the three pesticides only appeared to affect methamidophos degradation.

Electroantennography in the study of two stingless bee species (Hymenoptera: meliponini)

Relatam-se aqui os resultados preliminares de estudos eletroantenográficos realizados com duas espécies de Frieseomellita brasileira. Os experimentos com F. silvestrii e F. varia mostraram que as antenas respondem aos extratos obtidos com hexano das cabeças e dos abdômens das duas espécies e da tíbia posterior de F. silvestrii (que transporta resinas coletadas de plantas). Respondem também aos compostos puros, 2-heptanol e 2-nonanol, e aos terpenos, a-cubebeno, humuleno e b-cariofileno, encontrados nas tíbias e no cerume de seus próprios ninhos.

Electroantennography in the study of two stingless bee species (Hymenoptera: Meliponini).

The first recorded electroantennographic preliminary studies on stingless bees have been performed using two species of Frieseomelitta from Brazil. Experiments with F. silvestrii and F. varia showed that antennae respond to hexane extracts of heads and abdomens of both species and posterior tibia of F. silvestrii (which carry plant resin), as well as to the pure compounds 2-heptanol and 2-nonanol, which occur in the mandibular glands of both species, and to the terpenes alpha-cubebene, humulene, and beta-caryophyllene found on their tibia and in the cerumen of their nests.

Secretions of stingless bees: cephalic secretions of two Frieseomelitta species.

Gas chromatographic and mass spectrometric analysis of the volatile compounds in the mandibular glands of Frieseomelitta varia and the heads of Frieseomelitta silvestrii have revealed relatively simple or more complex mixtures of volatile oxygenated compounds. 2-Alkanols were found to be important components for both species. In F. varia the composition was essentially the same in samples from two widely separated areas and there were small differences between callows and mature, foraging bees. The first electroantennographic studies on stingless bees, using hexane extracts of heads of both species, have demonstrated a response in the workers' antennae to these, as well as to the pure compounds 2-heptanol and 2-nonanol.

Secretions of stingless bees: the Dufour gland of Nannotrigona testaceicornis.

The Dufour gland of Nannotrigona testaceicornis is a large, wide, pear-shaped sac. The gland secretion consists chiefly of the diterpene ester all-trans-geranylgeranyl acetate (64% of the total), together with a complex mixture of small amounts of cyclic ketals; mono-, sesqui-, and diterpene compounds; acetates; and other oxygenated compounds. Samples of N. testaceicornis collected at two sites in Brazil and one in México shared the same composition of their glands, suggesting that the species is uniform over this wide geographical area.