Osborn F. 2002. First report of a parasitic microsporidium of Hylesia metabus Cramer, 1775 larvae... more Osborn F. 2002. First report of a parasitic microsporidium of Hylesia metabus Cramer, 1775 larvae (Lepidoptera: Saturniidae). Entomotropica 17(2):185-188. A first report is made of a microsporidium from Hylesia metabus Crammer, 1775 larvae, collected from mangrove swamps close to the village of Yaguaraparo, Municipio Cajigal, Sucre state. The microsporidium shares some characteristics with Orthosomella: they are uninuclear and in direct contact with the host cytoplasm, the spore is cylindrical and the polar filament is isofilar. Nevertheless, information about the type of sporogeny is lacking, which is diagnostic for Orthosomella. I therefore propose that the species be placed as "near" Orthosomella.
Coevolution may be defined as an evolutionary change in a trait of one species in response to a c... more Coevolution may be defined as an evolutionary change in a trait of one species in response to a change in a trait of a second species, followed by an evolutionary response by the second species to the changes in the first. Yet, more complex evolutionary relationships are known to occur, such as Batesian mimicry, where three or more separate species interact along their evolutionary history. Do these complex interactions involve coevolution? In order to explore possible answers to this question, we built an agent based simulation model in which we monitored the evolution of the characteristics of individuals in a Batesian mimicry system consisting of predators, noxious prey or toxic models, non-noxious prey mimicking the toxic model, and non-mimic nonnoxious prey or alternate prey. The evolutionary game consisted in Predators evolving genetic mechanisms for avoiding preying on Toxic Models, in Toxic Models evolving anti-predator toxins and signals for Predators, and in Mimics evolving mimic anti-predator signals, taking as a modeling reference the case of the evolution of harmless look-alikes of venomous coral snakes is taken as a reference. Results showed that a likely evolutionary scenario for Batesian mimicry is a mutual selective pressure between Predators and Toxic Models (i.e. Predators and Models coevolve), a selective pressure acting from Predators on Mimics, and a "dilution effect" exerted by Mimics and Alternative Prey upon the Predator-Model interaction. Alternative genetic mechanisms by Predators to avoid toxins in Models (resistance), slows Predator-Model coevolution. The simulations provide for the following testable predictions: Mimics will not coevolve with Predators nor Models but evolves in response of selective pressure from Predators without affecting the evolution of Predators nor Models. Predators and Models have to affect each others population significantly in order for a Batesian ring to get established. Deterrents in Models have to be very toxic against Predators in order to allow the establishment of a Batesian mimicry ring.
Hylesia metabus es una mariposa nocturna distribuida principalmente en el nor-oeste de Venezuela.... more Hylesia metabus es una mariposa nocturna distribuida principalmente en el nor-oeste de Venezuela. Las hembras adultas usan sus vellos abdominales para cubrir y proteger los huevecillos de parásitos y depredadores. Estos vellos tienen propiedades urticantes, causando una dermatitis severa entre la población humana, cuyos síntomas se acentúan al usar jabón y se mejoran al aplicar soluciones de un pH ligeramente bajo tal como el vinagre. Sin embargo los vellos de los machos adultos no causan síntoma alguna. En el presente estudio se aisló y caracterizó en forma parcial una proteasa con propiedades parecidas a la calicreina de los vellos presentes en el abdomen de las hembras adultas. El material protéico de las posturas, constituidas por los vellos abdominales de la hembra, fue extraído en tampón Tris-Salino pH 8.5. El extracto fue centrifugado y luego cromatografiado en una columna de exclusión molecular (Sephadex G-75). La actividad biológica de los picos obtenidos fue determinada midiendo la actividad amidolítica con el sustrato cromogénico S-2288 (diseñado para serinaproteasas de amplio espectro) y S-2302 (diseñado para calicreina). Las fracciones con actividad en sustrato S-2302 fueron concentradas mediante ultrafiltración y usadas para otros experimentos. La medición de especificidad a substratos cromogénicos mostró una preferencia para el substrato S-2302 seguido por S-2288. La actividad enzimática tuvo su máximo a pH 9, mientras que por debajo de pH 5 no hubo actividad. Los resultados del presente estudio apoyan la idea de que esta sustancia puede tener importancia en las lesiones cutáneas observadas en personas expuestas a las posturas o las hembras adultas.
Hylesia metabus is a species of moth, distributed principally in North Eastern Venezuela. Adult f... more Hylesia metabus is a species of moth, distributed principally in North Eastern Venezuela. Adult females use their abdominal hairs to cover and protect the eggs from predators and parasites. These hairs have urticating properties, causing a severe dermatitis in humans, whose symptoms worsen using soap and are alleviated by slightly acid substances e.g. vinegar. The hairs from male moths however
We estimated the diversity and abundance of ants and nymphalid butterflies on the ground and in t... more We estimated the diversity and abundance of ants and nymphalid butterflies on the ground and in the canopy; and of plants in six different forest sites in Venezuela. Statistical analysis using eight different diversity indices for each species group revealed large variations among them. Ground ants appeared to be the most reliable bioindicators, even when only the five most common species are sampled. Results showed in addition that ground ant diversity is correlated to that of canopy ants and that vegetational diversity is linked to butterfly diversity but not to that of canopy ants. Ant species diversity in the canopy was always less than that of the ground. We conclude that no simple index or taxon describes completely complex ecosystems, thus, biodiversity assessments require tools still to be developed.
The symptoms of Anopheles aquasalis larvae naturally infected by a microsporidium, and the ultra ... more The symptoms of Anopheles aquasalis larvae naturally infected by a microsporidium, and the ultra - structure of the infecting spores is described. The larvae were maintained under laboratory conditions in salt con - centrations of 10 g/l and 20 g/l of water. Daily recordings of the mortality of the larvae were made and the dates of change of instar were
The symptoms of Anopheles aquasalis larvae naturally infected by a microsporidium, and the ultras... more The symptoms of Anopheles aquasalis larvae naturally infected by a microsporidium, and the ultrastructure of the infecting spores is described. The larvae were maintained under laboratory conditions in salt concentrations of 10 g/l and 20 g/l of water. Daily recordings of the mortality of the larvae were made and the dates of change of instar were noted. Infected larvae were processed for transmission electronic microscopy using conventional methods at pH 7.2 and 260 mOsm/l. The infection by the microsporidia was positively correlated with an increase in the mean duration of the fourth instar of 2.88 to 6.33 days in 10 g/l of salt and of 2.47 to 6.14 days in 20 g/l of salt. Larval mortality also increased by approximately 50% during this instar in both salt concentrations. Development time and survival were not affected during the other immature stages. The mature spores found in the intestines of infected larvae were barrel shaped and measured approximately 2.6 x 2.4 mm. The exospo...
Journal of the American Mosquito Control Association, 2006
Anopheles aquasalis is the main malaria vector in Sucre State, Venezuela. The larvae of this spec... more Anopheles aquasalis is the main malaria vector in Sucre State, Venezuela. The larvae of this species are saltwater tolerant. The effects of different concentrations of salt on oviposition preference and egg survival were studied under laboratory conditions. Choice experiments with salt concentrations of 0, 10, 20, 30, and 40% in bottled water were set up for individual adult females and the number of eggs laid in each salt concentration was noted. Egg survival, as inferred by the number of hatched larvae also was determined for each salt concentration. Females preferred to oviposit in freshwater and rejected water salt concentrations of 40%, but they were neither attracted nor repelled by water with 10-30% of salt. Eggs hatched more quickly in the lower salt concentrations, but egg survival was not affected by salt concentrations of up to 20%. Thus, female oviposition preference in An. aquasalis determines egg survival.
Studies on Neotropical Fauna and Environment, 1998
The recovery of ecosystems after disturbance in the tropics is of interest for future programs of... more The recovery of ecosystems after disturbance in the tropics is of interest for future programs of sustainable development. The dynamics of ecosystem recovery in 26 sites in Venezuela was evaluated using various methods. The ant and plant biodiversity of disturbed forest and surrounding savanna sites at different stages of recovery were compared with those for nearby primary vegetation. We estimated the species composition for ants, the number of species and equitability for ants and plants, and the plant coverage at each site. Of these indices, percentage of plant cover showed the most rapid return to pre-disturbance values. In a few cases, full return of all indices to pre-disturbance values occurred after around 25 years in both savanna and forest. A multiple factorial analysis of ant composition showed that species structure in old recovered sites converged sometimes, but not always, to that in surrounding natural habitats. Our results suggest that ant diversity indices provide for quantitative estimates of ecosystem recovery. They also suggest that even small scale human intervention may have irreversible effects on neotropical habitats. The estimated time constant for forest recovery could serve to estimate human carrying capacity of forest sites for eventual sustainable use of these ecosystems in the neotropics.
Studies on Neotropical Fauna and Environment, 1999
We estimated the diversity and abundance of ants and nymphalid butterflies on the ground and in t... more We estimated the diversity and abundance of ants and nymphalid butterflies on the ground and in the canopy; and of plants in six different forest sites in Venezuela. Statistical analysis using eight different diversity indices for each species group revealed large variations among them. Ground ants appeared to be the most reliable bioindicators, even when only the five most common species are sampled. Results showed in addition that ground ant diversity is correlated to that of canopy ants and that vegetational diversity is linked to butterfly diversity but not to that of canopy ants. Ant species diversity in the canopy was always less than that of the ground. We conclude that no simple index or taxon describes completely complex ecosystems, thus, biodiversity assessments require tools still to be developed.
RESUMEN-Hylesia metabus Cramer es una polilla considerada un problema de salud pública debido a q... more RESUMEN-Hylesia metabus Cramer es una polilla considerada un problema de salud pública debido a que las hembras adultas liberan setas urticantes produciendo dermatitis y prurito intenso en el hombre. En la región nororiental de Venezuela, en dos localidades ( ...
Anopheles aquasalis larvae are salt water tolerant, preferring concentrations between 10 and 20 p... more Anopheles aquasalis larvae are salt water tolerant, preferring concentrations between 10 and 20 parts per thousand (ppt). The larvicidal efficacy of two formulations of Bacillus thuringiensis var. israelensis (Vectobac-12AS ® and Bactivec ® ), was investigated against An. aquasalis at salinities of 0, 10, and 20 ppt. A probit analysis was used to calculate the lethal concentrations (LC 50 and LC 95 ) for each product at each salinity. The LC 50 and LC 95 were higher for Bactivec ® than Vectobac-12AS ® , and for Bactivec ® , the LC 50 and LC 95 increased with salinity. Vectobac-12AS ® should thus be preferred to Bactivec ® for An. aquasalis control, especially in saline breeding habitats.
Hylesia metabus larvae are susceptible to several pathogens indigenous to the area in which they ... more Hylesia metabus larvae are susceptible to several pathogens indigenous to the area in which they are found. Some larvae show symptoms characteristic of bacterial infection; they become flaccid and lethargic, and show a marked loss of appetite. We isolated and identified 29 bacterial strains from live, dead and experimentally infected H. metabus larvae, and evaluated their pathogenic activity. The bacteria which caused mortality in the larvae were: Pseudomonas aeruginosa (60-93.3%), Proteus vulgaris (20%), Alcaligenes faecalis, Planococcus sp. and Bacillus megaterium (10%), at doses of 3-4 x 10(7). Although P. aeruginosa is a well-known insect pathogen, this is the first report of its pathogenic activity on H. metabus. The potential risk to humans and low virulence make it unlikely that P. aeruginosa could be used in an augmentative biological control programme. However its natural incidence may be enhanced using parasites and predators of H. metabus as carriers.
Hylesia metabus is a species of moth, distributed principally in northeastern Venezuela. Female m... more Hylesia metabus is a species of moth, distributed principally in northeastern Venezuela. Female moths use their abdominal setae to cover their egg masses. Contact with these setae can cause a severe dermatitis in humans. Setae from males do not produce these symptoms. The external morphology of the abdominal setae in male and female moths was described and the effect of the setae on ant behavior was studied. We classified the setae into four types, S1, S2, S3 and S4. In females, two of these types were found in the dorsal region; S1 and S2 show a porous structure and measure 2000 µm and 155 µm in length, respectively. In the ventral part of the abdomen we observed three setae types, S1, S3 which are 190 µm long and have small barbs along their length directed towards the apex, and S4 which have numerous barbs at the base, but further up flatten out, with barbs along both sides, before tapering off at the apex. S4 also were found in the lateral zones of the abdomen and were the predominant type of setae covering the egg masses. Only S1 setae were found in males. Egg masses not covered by setae were examined and transported by Pheidole ants, whereas covered eggs were largely avoided. The morphology of the S3 and S4 setae types suggests that these may be related to the urticating properties reported for the moth. Ant avoidance of setae covered eggs suggests that these protect the eggs from at least some predators.
We analyzed the behavioral responses of the ants Camponotus rufipes and Solenopsis geminata towar... more We analyzed the behavioral responses of the ants Camponotus rufipes and Solenopsis geminata towards all instars of Dione junio and Abananote hylonome (Lepidoptera: Nymphalidae). We also analyzed ant behavior towards hexane extracts of larvae and extracts of the spines and neck glands of the fifth instars of both species and identified the chemical compounds present. Larvae of both species were repellent to ants from the first instar onward. Later instars survived ant attacks better than earlier instars. The spines and neck glands of the larvae influenced the behavior of C. rufipes. The chemical compounds contained in the hexane extracts of whole first and fifth instars, and in the spines and neck glands of fifth instars, were principally carboxylic acids and terpenes. Further bioassays confirmed the repellent effect of some of these acids toward ants.
20 Flower ecology in the neotropics: a flower-ant love-hate relationship Klaus Jaffe, Jose Vicent... more 20 Flower ecology in the neotropics: a flower-ant love-hate relationship Klaus Jaffe, Jose Vicente Hernandez, William Goitia, Anais Osio, Frances Osborn, Hugo ... 1 Ruiz i Ptrrogrsirr {livrncr 2 § ,"^^ 1,- «s U"«S-* § ZB^^ 9 14 9 fi-^ -3*^ J3^-3 u g 3: 3 1 .; 15.00-17.00 is ...
F Fr ra an nc ce es s O Os sb bo or rn n, , L Lu uz z B Be et tt ti in na a V Vi il ll la al lo o... more F Fr ra an nc ce es s O Os sb bo or rn n, , L Lu uz z B Be et tt ti in na a V Vi il ll la al lo ob bo os s, , L Lu uz z M Ma ar ri in na a R Ro oj ja as s, , M Ma ar rc co os s D De e D Do on na at to o, , R Ra aq qu ue el l S Sa al la az za ar r y y Z Zh ha ay yd da a D Du ur rá án n
Osborn F. 2002. First report of a parasitic microsporidium of Hylesia metabus Cramer, 1775 larvae... more Osborn F. 2002. First report of a parasitic microsporidium of Hylesia metabus Cramer, 1775 larvae (Lepidoptera: Saturniidae). Entomotropica 17(2):185-188. A first report is made of a microsporidium from Hylesia metabus Crammer, 1775 larvae, collected from mangrove swamps close to the village of Yaguaraparo, Municipio Cajigal, Sucre state. The microsporidium shares some characteristics with Orthosomella: they are uninuclear and in direct contact with the host cytoplasm, the spore is cylindrical and the polar filament is isofilar. Nevertheless, information about the type of sporogeny is lacking, which is diagnostic for Orthosomella. I therefore propose that the species be placed as "near" Orthosomella.
Coevolution may be defined as an evolutionary change in a trait of one species in response to a c... more Coevolution may be defined as an evolutionary change in a trait of one species in response to a change in a trait of a second species, followed by an evolutionary response by the second species to the changes in the first. Yet, more complex evolutionary relationships are known to occur, such as Batesian mimicry, where three or more separate species interact along their evolutionary history. Do these complex interactions involve coevolution? In order to explore possible answers to this question, we built an agent based simulation model in which we monitored the evolution of the characteristics of individuals in a Batesian mimicry system consisting of predators, noxious prey or toxic models, non-noxious prey mimicking the toxic model, and non-mimic nonnoxious prey or alternate prey. The evolutionary game consisted in Predators evolving genetic mechanisms for avoiding preying on Toxic Models, in Toxic Models evolving anti-predator toxins and signals for Predators, and in Mimics evolving mimic anti-predator signals, taking as a modeling reference the case of the evolution of harmless look-alikes of venomous coral snakes is taken as a reference. Results showed that a likely evolutionary scenario for Batesian mimicry is a mutual selective pressure between Predators and Toxic Models (i.e. Predators and Models coevolve), a selective pressure acting from Predators on Mimics, and a "dilution effect" exerted by Mimics and Alternative Prey upon the Predator-Model interaction. Alternative genetic mechanisms by Predators to avoid toxins in Models (resistance), slows Predator-Model coevolution. The simulations provide for the following testable predictions: Mimics will not coevolve with Predators nor Models but evolves in response of selective pressure from Predators without affecting the evolution of Predators nor Models. Predators and Models have to affect each others population significantly in order for a Batesian ring to get established. Deterrents in Models have to be very toxic against Predators in order to allow the establishment of a Batesian mimicry ring.
Hylesia metabus es una mariposa nocturna distribuida principalmente en el nor-oeste de Venezuela.... more Hylesia metabus es una mariposa nocturna distribuida principalmente en el nor-oeste de Venezuela. Las hembras adultas usan sus vellos abdominales para cubrir y proteger los huevecillos de parásitos y depredadores. Estos vellos tienen propiedades urticantes, causando una dermatitis severa entre la población humana, cuyos síntomas se acentúan al usar jabón y se mejoran al aplicar soluciones de un pH ligeramente bajo tal como el vinagre. Sin embargo los vellos de los machos adultos no causan síntoma alguna. En el presente estudio se aisló y caracterizó en forma parcial una proteasa con propiedades parecidas a la calicreina de los vellos presentes en el abdomen de las hembras adultas. El material protéico de las posturas, constituidas por los vellos abdominales de la hembra, fue extraído en tampón Tris-Salino pH 8.5. El extracto fue centrifugado y luego cromatografiado en una columna de exclusión molecular (Sephadex G-75). La actividad biológica de los picos obtenidos fue determinada midiendo la actividad amidolítica con el sustrato cromogénico S-2288 (diseñado para serinaproteasas de amplio espectro) y S-2302 (diseñado para calicreina). Las fracciones con actividad en sustrato S-2302 fueron concentradas mediante ultrafiltración y usadas para otros experimentos. La medición de especificidad a substratos cromogénicos mostró una preferencia para el substrato S-2302 seguido por S-2288. La actividad enzimática tuvo su máximo a pH 9, mientras que por debajo de pH 5 no hubo actividad. Los resultados del presente estudio apoyan la idea de que esta sustancia puede tener importancia en las lesiones cutáneas observadas en personas expuestas a las posturas o las hembras adultas.
Hylesia metabus is a species of moth, distributed principally in North Eastern Venezuela. Adult f... more Hylesia metabus is a species of moth, distributed principally in North Eastern Venezuela. Adult females use their abdominal hairs to cover and protect the eggs from predators and parasites. These hairs have urticating properties, causing a severe dermatitis in humans, whose symptoms worsen using soap and are alleviated by slightly acid substances e.g. vinegar. The hairs from male moths however
We estimated the diversity and abundance of ants and nymphalid butterflies on the ground and in t... more We estimated the diversity and abundance of ants and nymphalid butterflies on the ground and in the canopy; and of plants in six different forest sites in Venezuela. Statistical analysis using eight different diversity indices for each species group revealed large variations among them. Ground ants appeared to be the most reliable bioindicators, even when only the five most common species are sampled. Results showed in addition that ground ant diversity is correlated to that of canopy ants and that vegetational diversity is linked to butterfly diversity but not to that of canopy ants. Ant species diversity in the canopy was always less than that of the ground. We conclude that no simple index or taxon describes completely complex ecosystems, thus, biodiversity assessments require tools still to be developed.
The symptoms of Anopheles aquasalis larvae naturally infected by a microsporidium, and the ultra ... more The symptoms of Anopheles aquasalis larvae naturally infected by a microsporidium, and the ultra - structure of the infecting spores is described. The larvae were maintained under laboratory conditions in salt con - centrations of 10 g/l and 20 g/l of water. Daily recordings of the mortality of the larvae were made and the dates of change of instar were
The symptoms of Anopheles aquasalis larvae naturally infected by a microsporidium, and the ultras... more The symptoms of Anopheles aquasalis larvae naturally infected by a microsporidium, and the ultrastructure of the infecting spores is described. The larvae were maintained under laboratory conditions in salt concentrations of 10 g/l and 20 g/l of water. Daily recordings of the mortality of the larvae were made and the dates of change of instar were noted. Infected larvae were processed for transmission electronic microscopy using conventional methods at pH 7.2 and 260 mOsm/l. The infection by the microsporidia was positively correlated with an increase in the mean duration of the fourth instar of 2.88 to 6.33 days in 10 g/l of salt and of 2.47 to 6.14 days in 20 g/l of salt. Larval mortality also increased by approximately 50% during this instar in both salt concentrations. Development time and survival were not affected during the other immature stages. The mature spores found in the intestines of infected larvae were barrel shaped and measured approximately 2.6 x 2.4 mm. The exospo...
Journal of the American Mosquito Control Association, 2006
Anopheles aquasalis is the main malaria vector in Sucre State, Venezuela. The larvae of this spec... more Anopheles aquasalis is the main malaria vector in Sucre State, Venezuela. The larvae of this species are saltwater tolerant. The effects of different concentrations of salt on oviposition preference and egg survival were studied under laboratory conditions. Choice experiments with salt concentrations of 0, 10, 20, 30, and 40% in bottled water were set up for individual adult females and the number of eggs laid in each salt concentration was noted. Egg survival, as inferred by the number of hatched larvae also was determined for each salt concentration. Females preferred to oviposit in freshwater and rejected water salt concentrations of 40%, but they were neither attracted nor repelled by water with 10-30% of salt. Eggs hatched more quickly in the lower salt concentrations, but egg survival was not affected by salt concentrations of up to 20%. Thus, female oviposition preference in An. aquasalis determines egg survival.
Studies on Neotropical Fauna and Environment, 1998
The recovery of ecosystems after disturbance in the tropics is of interest for future programs of... more The recovery of ecosystems after disturbance in the tropics is of interest for future programs of sustainable development. The dynamics of ecosystem recovery in 26 sites in Venezuela was evaluated using various methods. The ant and plant biodiversity of disturbed forest and surrounding savanna sites at different stages of recovery were compared with those for nearby primary vegetation. We estimated the species composition for ants, the number of species and equitability for ants and plants, and the plant coverage at each site. Of these indices, percentage of plant cover showed the most rapid return to pre-disturbance values. In a few cases, full return of all indices to pre-disturbance values occurred after around 25 years in both savanna and forest. A multiple factorial analysis of ant composition showed that species structure in old recovered sites converged sometimes, but not always, to that in surrounding natural habitats. Our results suggest that ant diversity indices provide for quantitative estimates of ecosystem recovery. They also suggest that even small scale human intervention may have irreversible effects on neotropical habitats. The estimated time constant for forest recovery could serve to estimate human carrying capacity of forest sites for eventual sustainable use of these ecosystems in the neotropics.
Studies on Neotropical Fauna and Environment, 1999
We estimated the diversity and abundance of ants and nymphalid butterflies on the ground and in t... more We estimated the diversity and abundance of ants and nymphalid butterflies on the ground and in the canopy; and of plants in six different forest sites in Venezuela. Statistical analysis using eight different diversity indices for each species group revealed large variations among them. Ground ants appeared to be the most reliable bioindicators, even when only the five most common species are sampled. Results showed in addition that ground ant diversity is correlated to that of canopy ants and that vegetational diversity is linked to butterfly diversity but not to that of canopy ants. Ant species diversity in the canopy was always less than that of the ground. We conclude that no simple index or taxon describes completely complex ecosystems, thus, biodiversity assessments require tools still to be developed.
RESUMEN-Hylesia metabus Cramer es una polilla considerada un problema de salud pública debido a q... more RESUMEN-Hylesia metabus Cramer es una polilla considerada un problema de salud pública debido a que las hembras adultas liberan setas urticantes produciendo dermatitis y prurito intenso en el hombre. En la región nororiental de Venezuela, en dos localidades ( ...
Anopheles aquasalis larvae are salt water tolerant, preferring concentrations between 10 and 20 p... more Anopheles aquasalis larvae are salt water tolerant, preferring concentrations between 10 and 20 parts per thousand (ppt). The larvicidal efficacy of two formulations of Bacillus thuringiensis var. israelensis (Vectobac-12AS ® and Bactivec ® ), was investigated against An. aquasalis at salinities of 0, 10, and 20 ppt. A probit analysis was used to calculate the lethal concentrations (LC 50 and LC 95 ) for each product at each salinity. The LC 50 and LC 95 were higher for Bactivec ® than Vectobac-12AS ® , and for Bactivec ® , the LC 50 and LC 95 increased with salinity. Vectobac-12AS ® should thus be preferred to Bactivec ® for An. aquasalis control, especially in saline breeding habitats.
Hylesia metabus larvae are susceptible to several pathogens indigenous to the area in which they ... more Hylesia metabus larvae are susceptible to several pathogens indigenous to the area in which they are found. Some larvae show symptoms characteristic of bacterial infection; they become flaccid and lethargic, and show a marked loss of appetite. We isolated and identified 29 bacterial strains from live, dead and experimentally infected H. metabus larvae, and evaluated their pathogenic activity. The bacteria which caused mortality in the larvae were: Pseudomonas aeruginosa (60-93.3%), Proteus vulgaris (20%), Alcaligenes faecalis, Planococcus sp. and Bacillus megaterium (10%), at doses of 3-4 x 10(7). Although P. aeruginosa is a well-known insect pathogen, this is the first report of its pathogenic activity on H. metabus. The potential risk to humans and low virulence make it unlikely that P. aeruginosa could be used in an augmentative biological control programme. However its natural incidence may be enhanced using parasites and predators of H. metabus as carriers.
Hylesia metabus is a species of moth, distributed principally in northeastern Venezuela. Female m... more Hylesia metabus is a species of moth, distributed principally in northeastern Venezuela. Female moths use their abdominal setae to cover their egg masses. Contact with these setae can cause a severe dermatitis in humans. Setae from males do not produce these symptoms. The external morphology of the abdominal setae in male and female moths was described and the effect of the setae on ant behavior was studied. We classified the setae into four types, S1, S2, S3 and S4. In females, two of these types were found in the dorsal region; S1 and S2 show a porous structure and measure 2000 µm and 155 µm in length, respectively. In the ventral part of the abdomen we observed three setae types, S1, S3 which are 190 µm long and have small barbs along their length directed towards the apex, and S4 which have numerous barbs at the base, but further up flatten out, with barbs along both sides, before tapering off at the apex. S4 also were found in the lateral zones of the abdomen and were the predominant type of setae covering the egg masses. Only S1 setae were found in males. Egg masses not covered by setae were examined and transported by Pheidole ants, whereas covered eggs were largely avoided. The morphology of the S3 and S4 setae types suggests that these may be related to the urticating properties reported for the moth. Ant avoidance of setae covered eggs suggests that these protect the eggs from at least some predators.
We analyzed the behavioral responses of the ants Camponotus rufipes and Solenopsis geminata towar... more We analyzed the behavioral responses of the ants Camponotus rufipes and Solenopsis geminata towards all instars of Dione junio and Abananote hylonome (Lepidoptera: Nymphalidae). We also analyzed ant behavior towards hexane extracts of larvae and extracts of the spines and neck glands of the fifth instars of both species and identified the chemical compounds present. Larvae of both species were repellent to ants from the first instar onward. Later instars survived ant attacks better than earlier instars. The spines and neck glands of the larvae influenced the behavior of C. rufipes. The chemical compounds contained in the hexane extracts of whole first and fifth instars, and in the spines and neck glands of fifth instars, were principally carboxylic acids and terpenes. Further bioassays confirmed the repellent effect of some of these acids toward ants.
20 Flower ecology in the neotropics: a flower-ant love-hate relationship Klaus Jaffe, Jose Vicent... more 20 Flower ecology in the neotropics: a flower-ant love-hate relationship Klaus Jaffe, Jose Vicente Hernandez, William Goitia, Anais Osio, Frances Osborn, Hugo ... 1 Ruiz i Ptrrogrsirr {livrncr 2 § ,"^^ 1,- «s U"«S-* § ZB^^ 9 14 9 fi-^ -3*^ J3^-3 u g 3: 3 1 .; 15.00-17.00 is ...
F Fr ra an nc ce es s O Os sb bo or rn n, , L Lu uz z B Be et tt ti in na a V Vi il ll la al lo o... more F Fr ra an nc ce es s O Os sb bo or rn n, , L Lu uz z B Be et tt ti in na a V Vi il ll la al lo ob bo os s, , L Lu uz z M Ma ar ri in na a R Ro oj ja as s, , M Ma ar rc co os s D De e D Do on na at to o, , R Ra aq qu ue el l S Sa al la az za ar r y y Z Zh ha ay yd da a D Du ur rá án n
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