RESUMEN

Aedes mosquito-borne viruses (ABVs) place a substantial strain on public health resources in the Americas. Vector control of Aedes mosquitoes is an important public health strategy to decrease or prevent spread of ABVs. The ongoing Targeted Indoor Residual Spraying (TIRS) trial is an NIH-sponsored clinical trial to study the efficacy of a novel, proactive vector control technique to prevent dengue virus (DENV), Zika virus (ZIKV), and chikungunya virus (CHIKV) infections in the endemic city of Merida, Yucatan, Mexico. The primary outcome of the trial is laboratory-confirmed ABV infections in neighborhood clusters. Despite the difficulties caused by the COVID-19 pandemic, by early 2021 the TIRS trial completed enrollment of 4,792 children aged 2-15 years in 50 neighborhood clusters which were allocated to control or intervention arms via a covariate-constrained randomization algorithm. Here, we describe the makeup and ABV seroprevalence of participants and mosquito population characteristics in both arms before TIRS administration. Baseline surveys showed similar distribution of age, sex, and socio-economic factors between the arms. Serum samples from 1,399 children were tested by commercially available ELISAs for presence of anti-ABV antibodies. We found that 45.1% of children were seropositive for one or more flaviviruses and 24.0% were seropositive for CHIKV. Of the flavivirus-positive participants, most were positive for ZIKV-neutralizing antibodies by focus reduction neutralization testing which indicated a higher proportion of participants with previous ZIKV than DENV infections within the cohort. Both study arms had statistically similar seroprevalence for all viruses tested, similar socio-demographic compositions, similar levels of Ae. aegypti infestation, and similar observed mosquito susceptibility to insecticides. These findings describe a population with a high rate of previous exposure to ZIKV and lower titers of neutralizing antibodies against DENV serotypes, suggesting susceptibility to future outbreaks of flaviviruses is possible, but proactive vector control may mitigate these risks.

Asunto(s)

Aedes , Dengue , Insecticidas , Control de Mosquitos , Mosquitos Vectores , Humanos , Niño , Aedes/virología , Animales , México/epidemiología , Adolescente , Preescolar , Femenino , Control de Mosquitos/métodos , Masculino , Mosquitos Vectores/virología , Dengue/epidemiología , Dengue/prevención & control , Dengue/virología , Estudios Seroepidemiológicos , Infección por el Virus Zika/epidemiología , Infección por el Virus Zika/prevención & control , Virus Zika/inmunología , Virus Zika/aislamiento & purificación , Fiebre Chikungunya/epidemiología , Fiebre Chikungunya/prevención & control , Virus del Dengue/inmunología , Virus del Dengue/aislamiento & purificación , Virus Chikungunya/inmunología

RESUMEN

BACKGROUND: The combination of Wolbachia-based incompatible insect technique (IIT) and radiation-based sterile insect technique (SIT) can be used for population suppression of Aedes aegypti. Our main objective was to evaluate whether open-field mass-releases of wAlbB-infected Ae. aegypti males, as part of an Integrated Vector Management (IVM) plan led by the Mexican Ministry of Health, could suppress natural populations of Ae. aegypti in urbanized settings in south Mexico. METHODOLOGY/PRINCIPAL FINDINGS: We implemented a controlled before-and-after quasi-experimental study in two suburban localities of Yucatan (Mexico): San Pedro Chimay (SPC), which received IIT-SIT, and San Antonio Tahdzibichén used as control. Release of wAlbB Ae. aegypti males at SPC extended for 6 months (July-December 2019), covering the period of higher Ae. aegypti abundance. Entomological indicators included egg hatching rates and outdoor/indoor adult females collected at the release and control sites. Approximately 1,270,000 lab-produced wAlbB-infected Ae. aegypti males were released in the 50-ha treatment area (2,000 wAlbB Ae. aegypti males per hectare twice a week in two different release days, totaling 200,000 male mosquitoes per week). The efficacy of IIT-SIT in suppressing indoor female Ae. aegypti density (quantified from a generalized linear mixed model showing a statistically significant reduction in treatment versus control areas) was 90.9% a month after initiation of the suppression phase, 47.7% two months after (when number of released males was reduced in 50% to match local abundance), 61.4% four months after (when initial number of released males was re-established), 88.4% five months after and 89.4% at six months after the initiation of the suppression phase. A proportional, but lower, reduction in outdoor female Ae. aegypti was also quantified (range, 50.0-75.2% suppression). CONCLUSIONS/SIGNIFICANCE: Our study, the first open-field pilot implementation of Wolbachia IIT-SIT in Mexico and Latin-America, confirms that inundative male releases can significantly reduce natural populations of Ae. aegypti. More importantly, we present successful pilot results of the integration of Wolbachia IIT-SIT within a IVM plan implemented by Ministry of Health personnel.

Asunto(s)

Aedes , Infertilidad Masculina , Wolbachia , Animales , Femenino , Humanos , Insectos , Masculino , México , Control de Mosquitos/métodos , Mosquitos Vectores , Proyectos Piloto

RESUMEN

OBJECTIVE: To evaluate the protective effect of house screening (HS) on indoor Aedes aegypti infestation, abundance and arboviral infection in Merida, Mexico. METHODS: In 2019, we performed a cluster randomised controlled trial (6 control and 6 intervention areas: 100 households/area). Intervention clusters received permanently fixed fiberglass HS on all windows and doors. The study included two cross-sectional entomologic surveys, one baseline (dry season in May 2019) and one post-intervention (PI, rainy season between September and October 2019). The presence and number of indoor Aedes females and blood-fed females (indoor mosquito infestation) as well as arboviral infections with dengue (DENV) and Zika (ZIKV) viruses were evaluated in a subsample of 30 houses within each cluster. RESULTS: HS houses had significantly lower risk for having Aedes aegypti female mosquitoes (odds ratio [OR] = 0.56, 95% CI 0.33-0.97, p = 0.04) and blood-fed females (OR = 0.53, 95% CI 0.28-0.97, p = 0.04) than unscreened households from the control arm. Compared to control houses, HS houses had significantly lower indoor Ae. aegypti abundance (rate ratio [RR] = 0.50, 95% CI 0.30-0.83, p = 0.01), blood-fed Ae. aegypti females (RR = 0.48, 95% CI 0.27-0.85, p = 0.01) and female Ae. aegypti positive for arboviruses (OR = 0.29, 95% CI 0.10-0.86, p = 0.02). The estimated intervention efficacy in reducing Ae. aegypti arbovirus infection was 71%. CONCLUSIONS: These results provide evidence supporting the use of HS as an effective pesticide-free method to control house infestations with Aedes aegypti and reduce the transmission of Aedes-transmitted viruses such as DENV, chikungunya (CHIKV) and ZIKV.

Asunto(s)

Aedes/fisiología , Vivienda , Control de Mosquitos/métodos , Aedes/virología , Animales , Análisis por Conglomerados , Estudios Transversales , Virus del Dengue/aislamiento & purificación , Femenino , Interacciones Huésped-Patógeno , Humanos , México , Virus Zika/aislamiento & purificación

RESUMEN

We conducted a baseline characterization of the abundance and seasonality of Aedes aegypti (Linnaeus, 1762)-a vector of dengue, chikungunya, and Zika-in two suburban localities of Yucatan, Mexico, as the first step in the implementation of an integrated vector management (IVM) plan combining 'traditional Aedes control' (source reduction/truck-mounted ultra-low volume [ULV] spraying) and incompatible insect technique/sterile insect technique for population suppression in Yucatan, Mexico. Weekly entomological collections with ovitraps and BG-sentinel traps were performed in 1-ha quadrants of both localities for 1 yr. Three distinct periods/phases were identified, closely associated with precipitation: 1) a phase of low population abundance during the dry season (weekly average of Aedes eggs per ovitrap and adults per BG trap = 15.51 ± 0.71 and 10.07 ± 0.88, respectively); 2) a phase of population growth and greatest abundance of Aedes (49.03 ± 1.48 eggs and 25.69 ± 1.31 adults) during the rainy season; and finally 3) a phase of decline among populations (20.91 ± 0.97 eggs and 3.24 ± 0.21 adults) after the peak of the rainy season. Seasonal abundance and dynamics of Ae. aegypti populations suggest that it is feasible to develop and implement time-specific actions as part of an IVM approach incorporating integrating novel technologies (such as rear-and-release of Wolbachia-infected males) with classic (insecticide-based) approaches implemented routinely for vector control. In agreement with the local vector control program, we propose a pilot IVM strategy structured in a preparation phase, an attack phase with traditional vector control, and a suppression phase with inundative releases, which are described in this paper.

Asunto(s)

Aedes , Infertilidad Masculina/microbiología , Control de Mosquitos/métodos , Wolbachia , Aedes/microbiología , Aedes/fisiología , Animales , Infecciones por Arbovirus/prevención & control , Infecciones por Arbovirus/transmisión , Masculino , México/epidemiología , Mosquitos Vectores/microbiología , Mosquitos Vectores/fisiología , Regulación de la Población/métodos , Estaciones del Año

RESUMEN

BACKGROUND: The integration of house-screening and long-lasting insecticidal nets, known as insecticide-treated screening (ITS), can provide simple, safe, and low-tech Aedes aegypti control. Cluster randomised controlled trials in two endemic localities for Ae. aegypti of south Mexico, showed that ITS conferred both, immediate and sustained (~2 yr) impact on indoor-female Ae. aegypti infestations. Such encouraging results require further validation with studies quantifying more epidemiologically-related endpoints, including arbovirus infection in Ae. aegypti. We evaluated the efficacy of protecting houses with ITS on Ae. aegypti infestation and arbovirus infection during a Zika outbreak in Merida, Yucatan, Mexico. METHODOLOGY/PRINCIPAL FINDINGS: A two-arm cluster-randomised controlled trial evaluated the entomological efficacy of ITS compared to the absence of ITS (with both arms able to receive routine arbovirus vector control) in the neighbourhood Juan Pablo II of Merida. Cross-sectional entomological surveys quantified indoor adult mosquito infestation and arbovirus infection at baseline (pre-ITS installation) and throughout two post-intervention (PI) surveys spaced at 6-month intervals corresponding to dry/rainy seasons over one year (2016-2017). Household-surveys assessed the social reception of the intervention. Houses with ITS were 79-85% less infested with Aedes females than control houses up to one-year PI. A similar significant trend was observed for blood-fed Ae. aegypti females (76-82%). Houses with ITS had significantly less infected female Ae. aegypti than controls during the peak of the epidemic (OR = 0.15, 95%CI: 0.08-0.29), an effect that was significant up to a year PI (OR = 0.24, 0.15-0.39). Communities strongly accepted the intervention, due to its perceived mode of action, the prevalent risk for Aedes-borne diseases in the area, and the positive feedback from neighbours receiving ITS. CONCLUSIONS/SIGNIFICANCE: We show evidence of the protective efficacy of ITS against an arboviral disease of major relevance, and discuss the relevance of our findings for intervention adoption.

Asunto(s)

Aedes/virología , Control de Mosquitos/métodos , Mosquiteros/estadística & datos numéricos , Infección por el Virus Zika/prevención & control , Animales , Virus Chikungunya/aislamiento & purificación , Virus del Dengue , Femenino , Vivienda , Humanos , Mordeduras y Picaduras de Insectos/prevención & control , Insecticidas , México , Mosquitos Vectores , Virus Zika/aislamiento & purificación , Infección por el Virus Zika/epidemiología

RESUMEN

Fitting long-lasting insecticidal nets (LLIN) as screens on doors/windows has a significant impact on indoor-adult Aedes aegypti (L.), with entomological reductions measured in a previous study being significant for up to 2 yr post-installation, even in the presence of pyrethroid-resistant Aedes populations. To better understand the mode of LLIN protection, bioassays were performed to evaluate the effects of field deployment (0, 6, and 12 mo) and damage type (none, central, lateral, and multiple) on LLIN efficacy. Contact bioassays confirmed that LLIN residual activity (median knockdown time, in minutes, or MKDT) decreased significantly over time: 6.95 (95% confidence interval [CI]: 5.32-8.58) to 9.24 (95% CI: 8.69-9.79) MKDT at 0- and 12-mo age, respectively, using a pyrethroid-susceptible Aedes strain. Tunnel tests (exposing human forearm for 40 min as attractant) showed that deployment time affected negatively Aedes passage inhibition from 54.9% (95% CI: 43.5-66.2) at 0 mo to 35.7% (95% CI: 16.3-55.1) at 12 mo and blood-feeding inhibition from 65.2% (95% CI: 54.2-76.2) to 48.9% (95% CI: 26.4-71.3), respectively; both the passage/blood-feeding inhibition increased by a factor of 1.8-2.9 on LLINs with multiple and central damages compared with nets with lateral damage. Mosquito mortality was 74.6% (95% CI: 65.3-83.9) at 0 mo, 72.3% (95% CI: 64.1-80.5) at 6 mo, and 59% (95% CI: 46.7-71.3) at 12 mo. Despite the LLIN physical integrity could be compromised over time, we demonstrate that the remaining chemical effect after field conditions would still contribute to killing/repelling mosquitoes.

Asunto(s)

Aedes , Mosquiteros Tratados con Insecticida/estadística & datos numéricos , Insecticidas , Control de Mosquitos , Piretrinas , Animales , Femenino , México , Control de Mosquitos/estadística & datos numéricos

RESUMEN

Abstract:The expanded use of macrocyclic lactones (ML) to treat endo- and ectoparasites in cattle in tropical regions, can reduce dung beetle populations, and thus interrupt the dung removal process in cattle pasture ecosystems. During the reproductive period (the rainy season) of two functional groups of dung beetles (paracoprid and telocoprid Scarabaeinae), we compared dung removal amount in ranches where ML are and are not used in Yucatan, Mexico, through exclusion traps baited with 500 g of ML-free cow dung. On each ranch, two transects (separated by 500 m) with six traps each, were set up for 24 hours. After this time, all the dung remnants in each trap were obtained and weighed in order to record the dung removal. Results showed that dung removal amounts were similar in ranches with and without ML use. Dung beetles removed 40.1 % of all cow dung weighed. Paracoprids removed 87.46 % and telocoprids 12.54 % of all the dung that was removed. Our results indicated that the ecological function of dung beetles in the pastures studied, does not seem to be affected by the ML use, and that paracoprid species removed most of the dung. For both types of ranch, further studies that take into account the population dynamics and movement of the most important dung beetle species in the region are required, coupled with laboratory studies evaluating the effect of ML on their reproductive success. This could give some light on the effect of ML on the ecological function of this important insect group in the sustainability of cattle production systems. Rev. Biol. Trop. 64 (3): 945-954. Epub 2016 September 01.

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ResumenLa expansión en el uso de lactonas macrocíclicas (LM) para el tratamiento de endo y ectoparásitos del ganado en las regiones tropicales puede reducir las poblaciones de escarabajos del estiércol, interrumpiendo así el proceso de eliminación de estiércol de ganado en los pastizales. Durante el período reproductivo (época de lluvias) de dos grupos funcionales de escarabajos coprófagos (paracópridos y telecópridos), se comparó la cantidad removida de estiércol usando trampas de exclusión cebadas con 500 g de estiércol de vaca libre de LM en dos ranchos donde se usan y en dos donde no se usan LM, en la península de Yucatán, México. En cada rancho se establecieron dos transectos (separados por 500 m) con seis trampas cada uno, las cuales estuvieron activas durante 24 horas. Después de este tiempo, todos los restos de estiércol en cada trampa se pesaron para registrar la remoción. Los resultados mostraron que las cantidades de remoción fueron similares en ranchos con y sin uso de LM. Los escarabajos estercoleros removieron 40.1 % del peso total del excremento. Los paracópridos removieron 87.46 % y los telecópridos 12.54 % del total de excremento removido. Los resultados indican que la función ecológica de los escarabajos estercoleros en los potreros estudiados no parece verse afectada por el uso de LM y que las especies paracórpidas remueven la mayor parte del excremento. Se requiere hacer más estudios en ambos tipos de ranchos, en los que se tome en cuenta la dinámica poblacional y el movimiento de las especies más importantes de la región, acoplados a estudios de laboratorio que evalúen el efecto de las LM sobre el éxito reproductivo, y de esta manera esclarecer el efecto de las LM sobre la función ecológica de este grupo de insectos tan importante para la sustentabilidad de los sistemas ganaderos.

Asunto(s)

Animales , Escarabajos/efectos de los fármacos , Escarabajos/fisiología , Compuestos Macrocíclicos/farmacología , Lactonas/farmacología , Estiércol , Antiparasitarios/farmacología , Lluvia , Estaciones del Año , Especificidad de la Especie , Factores de Tiempo , Bovinos , México

RESUMEN

The expanded use of macrocyclic lactones (ML) to treat endo- and ectoparasites in cattle in tropical regions, can reduce dung beetle populations, and thus interrupt the dung removal process in cattle pasture ecosystems. During the reproductive period (the rainy season) of two functional groups of dung beetles (paracoprid and telocoprid Scarabaeinae), we compared dung removal amount in ranches where ML are and are not used in Yucatan, Mexico, through exclusion traps baited with 500 g of ML-free cow dung. On each ranch, two transects (separated by 500 m) with six traps each, were set up for 24 hours. After this time, all the dung remnants in each trap were obtained and weighed in order to record the dung removal. Results showed that dung removal amounts were similar in ranches with and without ML use. Dung beetles removed 40.1 % of all cow dung weighed. Paracoprids removed 87.46 % and telocoprids 12.54 % of all the dung that was removed. Our results indicated that the ecological function of dung beetles in the pastures studied, does not seem to be affected by the ML use, and that paracoprid species removed most of the dung. For both types of ranch, further studies that take into account the population dynamics and movement of the most important dung beetle species in the region are required, coupled with laboratory studies evaluating the effect of ML on their reproductive success. This could give some light on the effect of ML on the ecological function of this important insect group in the sustainability of cattle production systems.

Asunto(s)

Antiparasitarios/farmacología , Escarabajos/efectos de los fármacos , Escarabajos/fisiología , Lactonas/farmacología , Compuestos Macrocíclicos/farmacología , Estiércol , Animales , Bovinos , México , Lluvia , Estaciones del Año , Especificidad de la Especie , Factores de Tiempo

RESUMEN

New distribution records of 22 braconid species belonging to Agathidinae, Braconinae, Helconinae, Homolobinae and Rogadinae subfamilies from Brazil, Chile, Costa Rica, Guatemala, Mexico and Panama are presented. Agathirsia ninesevenci Pucci & Sharkey is reported for the first time from Mexico; Homolobus acares van Achterberg, H. antefurcalis van Achterberg and H.infumator (Lyle) from Costa Rica; Triaspis kurtogaster Martin from Brazil, Costa Rica and Panama. Sabulodes caberata Guenée (Lepidoptera: Geometridae) is recorded as a new host for Homolobus infumator (Lyle).

Asunto(s)

Avispas/clasificación , Animales , Demografía , América Latina

RESUMEN

New distribution records of 22 braconid species belonging to Agathidinae, Braconinae, Helconinae, Homolobinae and Rogadinae subfamilies from Brazil, Chile, Costa Rica, Guatemala, Mexico and Panama are presented. Agathirsia ninesevenci Pucci & Sharkey is reported for the first time from Mexico; Homolobus acares van Achterberg, H. antefurcalis van Achterberg and H.infumator (Lyle) from Costa Rica; Triaspis kurtogaster Martin from Brazil, Costa Rica and Panama. Sabulodes caberata Guenée (Lepidoptera: Geometridae) is recorded as a new host for Homolobus infumator (Lyle).

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Se proporciona nueva información de distribución geográfica para 22 especies de las subfamilias Agathidinae, Braconinae, Helconinae, Homolobinae y Rogadinae (Hymenoptera: Braconidae) de Brasil, Chile, Costa Rica, Guatemala, México y Panamá. Se reporta por primera vez a Agathirsia ninesevenci Pucci & Sharkey en México; Homolobus acares van Achterberg, H. antefurcalis van Achterberg y H. infumator (Lyle) en Costa Rica; Triaspis kurtogaster Martin en Brasil, Costa Rica y Panamá. Sabulodes caberata Guenée (Lepidoptera: Geometridae) es registrado como huésped de Homolobus infumator (Lyle).

Asunto(s)

Animales , Avispas/clasificación , Demografía , América Latina

RESUMEN

Beetles were collected from April 2002 to July 2003 from the following sites in the centre of the state of Veracruz located every 200 m along an altitudinal gradient (1000 - 1400 m asl): three fragments of cloud forest, three shaded coffee plantations, an open canopy coffee plantation, secondary forest, and a pasture. A total of 9,982 specimens were captured, belonging to the families Scarabaeidae and Trogidae, and representing 21 genera and 50 species. The genera Ataenius Harold, Onthophagus Latreille and Aphodius Illiger represented 48% of the species of Scarabaeidae. Species richness was found to decrease with increasing altitude; there were 36 species at 1000 m asl, 27 species between 1200 and 1300 m asl, and 26 species at 1400 m asl. Abundance along the altitudinal gradient follows a pattern of few abundant species and many species with few specimens. Beetle activity is related to precipitation. In the nine communities studied, species richness was observed to increase when precipitation was greater than 100 mm at the beginning of the rainy season. On the landscape scale, there were 44 species during the rainy season, 22 during the windy nortes season, and 24 during the dry season. In terms of trophic guild, 40% of the beetles captured were saprophagous that feed on decomposing organic material from plants and 60% were saprophagous that feed on decomposing organic material from animals (30% necrophagous, 26% coprophagous, 4% telio-necrophagous).

Asunto(s)

Coffea/parasitología , Escarabajos/clasificación , Árboles/parasitología , Animales , México , Densidad de Población

RESUMEN

Scarabaeinae are sensitive to structural habitat changes caused by disturbance. We compared copronecrophagous beetle (Scarabaeinae) community structure in three differently managed zones within an agroeco-system of the northern Yucatan Peninsula, Mexico. We placed dung and carrion traps once a month from June 2004 through May 2005. The beetle community included 17 species from the genera Canthon, Canthidium, Deltochilum, Pseudocanthon, Malagoniella, Onthophagus, Phanaeus, Copris, Uroxys, Sisyphus and Ateuchus. The secondary vegetation had a higher beetle diversity than the other two zones. Species richness was highest in the Brosimum alicastrum plantation. The pasture had the lowest species diversity and richness, but exhibited the highest abundance of Scarabaeinae in the dry season. The two zones with extensive tree cover were the most diverse. Roller beetles were dominant over burrower species and small-sized species outnumbered large species. Our data show two important issues: beetle species in the pasture extended their activity to the beginning of the dry season, while abundances dropped in the other, unirrigated zones; and the possibility that the Scarabaeinae living in neotropical forests are opportunistic saprophages and have specialized habits for resources other than dung. The B. alicastrum plantation is beneficial to the entire ranch production system because it functions as a dispersion and development area for stenotopic species limited to tree cover.

Asunto(s)

Animales , Escarabajos/fisiología , Coprofagia , Ecosistema , Escarabajos/clasificación , Densidad de Población , Especificidad de la Especie , Estaciones del Año , México

RESUMEN

Durante 16 meses de colectas entre abril 2002 y julio 2003, en el centro del estado de Veracruz, en tres fragmentos de bosque mesófilo de montaña, tres cafetales bajo sombra, un cafetal sin sombra, un acahual y un pastizal, establecidos en un gradiente altitudinal (1000-1400 m), cada 200 m, se obtuvieron 9982 especimenes de Scarabaeidae y Trogidae que representan a 21 géneros y 50 especies. Los géneros Ataenius Harold, Onthophagus Latreilley Aphodius Illiger reúnen al 48 por ciento de las especies de Scarabaeidae. En el gradiente altitudinal se obtuvo que a mayor altitud menor riqueza específica, a los 1000 m coexisten 36 especies, entre los 1200-1300 m 27 especies y a 1400 m 26 especies. La abundancia general en el gradiente altitudinal sigue un patrón de pocas especies abundantes y muchas especies con pocos especimenes. La actividad de los escarabajos está relacionada con la precipitación, observándose con precipitaciones mayores a 100 mm al inicio de la época de lluvias un incremento en la riqueza específica en las nueve comunidades. Durante la época de lluvias coexisten 44 especies, en época de nortes 22 especies y en época de secas 24 especies. Los gremios tróficos están representados por el 40 por ciento de los saprófagos que se alimentan de materia orgánica en descomposición de origen vegetal, y por el 60 por ciento los saprófagos que se alimentan de materia orgánica en descomposición de origen animal (necrófagos 30 por ciento, coprófagos 26 por ciento, telio-necrófagos 4 por ciento).

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Beetles were collected from April 2002 to July 2003 from the following sites in the centre of the state of Veracruz located every 200 m along an altitudinal gradient (1000 - 1400 m asl): three fragments of cloud forest, three shaded coffee plantations, an open canopy coffee plantation, secondary forest, and a pasture. A total of 9,982 specimens were captured, belonging to the families Scarabaeidae and Trogidae, and representing 21 genera and 50 species. The genera Ataenius Harold, Onthophagus Latreille and Aphodius Illiger represented 48 percent of the species of Scarabaeidae. Species richness was found to decrease with increasing altitude; there were 36 species at 1000 m asl, 27 species between 1200 and 1300 m asl, and 26 species at 1400 m asl. Abundance along the altitudinal gradient follows a pattern of few abundant species and many species with few specimens. Beetle activity is related to precipitation. In the nine communities studied, species richness was observed to increase when precipitation was greater than 100 mm at the beginning of the rainy season. On the landscape scale, there were 44 species during the rainy season, 22 during the windy nortes season, and 24 during the dry season. In terms of trophic guild, 40 percent of the beetles captured were saprophagous that feed on decomposing organic material from plants and 60 percent were saprophagous that feed on decomposing organic material from animals (30 percent necrophagous, 26 percent coprophagous, 4 percent telio-necrophagous).

Asunto(s)

Animales , Escarabajos/clasificación , Coffea/parasitología , Árboles/parasitología , México , Densidad de Población

RESUMEN

Scarabaeinae are sensitive to structural habitat changes caused by disturbance. We compared copronecrophagous beetle (Scarabaeinae) community structure in three differently managed zones within an agroeco-system of the northern Yucatan Peninsula, Mexico. We placed dung and carrion traps once a month from June 2004 through May 2005. The beetle community included 17 species from the genera Canthon, Canthidium, Deltochilum, Pseudocanthon, Malagoniella, Onthophagus, Phanaeus, Copris, Uroxys, Sisyphus and Ateuchus. The secondary vegetation had a higher beetle diversity than the other two zones. Species richness was highest in the Brosimum alicastrum plantation. The pasture had the lowest species diversity and richness, but exhibited the highest abundance of Scarabaeinae in the dry season. The two zones with extensive tree cover were the most diverse. Roller beetles were dominant over burrower species and small-sized species outnumbered large species. Our data show two important issues: beetle species in the pasture extended their activity to the beginning of the dry season, while abundances dropped in the other, unirrigated zones; and the possibility that the Scarabaeinae living in neotropical forests are opportunistic saprophages and have specialized habits for resources other than dung. The B. alicastrum plantation is beneficial to the entire ranch production system because it functions as a dispersion and development area for stenotopic species limited to tree cover.

Asunto(s)

Escarabajos/fisiología , Coprofagia , Ecosistema , Animales , Escarabajos/clasificación , México , Densidad de Población , Estaciones del Año , Especificidad de la Especie

RESUMEN

Introducción. En muchas de las zonas urbanas de México persisten temores infundados hacia los alacranes. El presente estudio tuvo como objetivo el conocer la fauna de alacranes sinantrópicos de Mérida, Yucatán, México y describir de manera preliminar la fauna de alacranes sinantrópicos de Mérida Yucatán, México y describir de manera preliminar a la fenología e importancia médica de las especies encontradas. Material y Métodos. Los ejemplares recolectados fueron obtenidos de donaciones y recolectas durante los años 1992-1998. El material entomológico recolectado fue determinado y depositado en la colección Entomológica Regional de la Facultad de Médicina Veterinaria y Zootecnia, Universidad Autonóma de Yucatán. Resultados y conclusión. Se obtuvieron 107 ejemplares de alacranes adultos pertenecientes a dos familias y cuatro especies: Centruroides gracilis, C. ochraceus (Buthidae) y Diplocentrus sp1 t sp2 (Diplocentridae), ninguna de las cuales pertenece a las especies altamente tóxicas. Se observó un periodo de mayor abundancia relativa de las especies de marzo a julio

Asunto(s)

Animales , Entomología , Escorpiones

RESUMEN

Objetivo. Determinar el desarrollo, mortalidad y supervivencia de las etapas inmaduras del mosquito Aedes aegypti en neumáticos, en Mérida, Yucatán, México. Material y Métodos. Se construyeron tablas de vida para hacer estimaciones de tasas de mortalidad y supervivencia específicas para las edades o estadios. Resultados. La duración promedio del ciclo de vida Ae. aegypti en neumáticos fue de 11.15 días (ñ2.68 sd). La etapa de larva con sus distintos estadios ocupa un total de 8.1 días (ñ2.40 sd), mientras que la etapa de pupa dura 3.05 días (ñ1.09 sd). Del número inicial de individuos (larvas de primer estadio) solamente emergió el 9 por ciento, es decir, que la mortalidad total de las etapas inmaduras fue del 91 por ciento. La mayor tasa de mortalidad se observó en la etapa de pupa (18 por ciento). La proporción de sexos de los adultos emergidos fue de 1:1. Conclusión. Los valores ajustados de mortalidad larvaria y pupal de Ae. aegypti en neumáticos y bajo condiciones seminaturales, corresponden a una curva de sobrevivencia tipo II

Asunto(s)

Masculino , Femenino , Aedes/crecimiento & desarrollo , Larva/crecimiento & desarrollo , Tablas de Vida , Residuos Sólidos , México/epidemiología