Proceedings of The Royal Society B: Biological Sciences, Oct 22, 2004
Insect vector-borne diseases continue to present a major challenge to human health. Understanding... more Insect vector-borne diseases continue to present a major challenge to human health. Understanding the factors that regulate the size of mosquito populations is considered fundamental to the ability to predict disease transmission rates and for vector population control. The mosquito, Anopheles pseudopunctipennis, a vector of Plasmodium spp., breeds in riverside pools containing filamentous algae in Mesoamerica. Breeding pools along 3 km sections of the River Coatán, Chiapas, Mexico were subjected to algal extraction or left as controls in a cross-over trial extending over 2 years. Initial densities of An. pseudopunctipennis larvae were directly proportional to the prevalence of filamentous algae in each breeding site. The extraction of algae brought about a striking decline in the density of An. pseudopunctipennis larvae sustained for about six weeks, and a concurrent reduction in the adult population in both years of the study. Mark-release experiments indicated that dispersal from adjacent untreated areas was unlikely to exert an important influence on the magnitude of mosquito control that we observed. Habitat manipulation by extraction of filamentous algae offers a unique opportunity for sustainable control of this malaria vector. This technique may represent a valuable intervention, complimenting insecticide spraying of households, to minimize Plasmodium transmission rates in Mesoamerica.
Spinosad is a naturally derived biorational insecticide with an environmentally favourable toxici... more Spinosad is a naturally derived biorational insecticide with an environmentally favourable toxicity profile, so we investigated its potency against mosquito larvae (Diptera: Culicidae). By laboratory bioassays of a suspension concentrate formulation of spinosad (Tracer 1), the 24 h lethal concentration (LC 50) against Aedes aegypti (L.) third and fourth instars was estimated at 0.025 p.p.m. following logit regression. The concentration-mortality response of third-and fourth-instar Anopheles albimanus Weidemann did not conform to a logit model. The LC 50 value of spinosad in Anopheles albimanus was 0.024 p.p.m. by quadratic linear regression. A field trial in southern Mexico demonstrated that spinosad 1 p.p.m. compared with the standard temephos (Abate 1) 1% granules 100 g/m 3 water prevented Ae. aegypti breeding in plastic containers of water for 8 weeks; at 10 p.p.m. spinosad prevented breeding for > 22 weeks. In another field trial, spinosad at 5 p.p.m. and temephos both completely eliminated reproduction of Ae. aegypti for 13 weeks. In contrast, the bacterial insecticide Bacillus thuringiensis var. israelensis (Bti, Vectobac 1 AS) performed poorly with just 2 weeks of complete inhibition of Ae. aegypti breeding. Spinosad also effectively prevented breeding of Culex mosquitoes and chironomids in both trials to a degree similar to that of temephos. We conclude that spinosad merits evaluation as a replacement for organophosphate or Bti treatment of domestic water tanks in Mesoamerica. We also predict that spinosad is likely to be an effective larvicide for treatment of mosquito breeding sites.
In the sterile insect technique, it is important to measure the impact of mass-rearing and handli... more In the sterile insect technique, it is important to measure the impact of mass-rearing and handling of sterile males to allow a successful control of the target wild population. This study evaluates the effect of pre-release chilling on the survival, escape ability, and sexual competitiveness of male Aedes aegypti. To determine survival and escape ability, mosquitoes were chilled at 4 °C using four different treatments of either one exposure (25 min) or two consecutive exposures (25 + 25 min, 25 + 50 min, 25 + 100 min). For sexual competitiveness, two different treatments were evaluated, chilling for 25 min once and twice. Results showed that the longest exposure to chilling caused a significant reduction of survival time, from 67 to 54 days. Escape ability was reduced by the first chilling from 25 to 7% and with the second chilling, it was reduced from 30 to 24% in the control to 4.9, 2.0 and 0.5% for 25, 50 and 100 min, respectively. Sexual competitiveness index was reduced from 1...
1. The influence of filamentous algae on oviposition habitat selection by the mosquito Anopheles ... more 1. The influence of filamentous algae on oviposition habitat selection by the mosquito Anopheles pseudopunctipennis and the consequences of oviposition decisions on the diet, development, body size, and survival of offspring were examined. 2. A natural population of An. pseudopunctipennis in Chiapas, Mexico, oviposited almost exclusively in containers with filamentous algae. Algae represented 47% of the gut contents of mosquito larvae sampled from the natural population. Mosquito larvae fed on an exclusive diet of algae developed as quickly and achieved the same adult body size (wing length) as their conspecifics fed on a standard laboratory diet. 3. Multiple regression of survival of mosquito larvae on percentage surface area cover of algae (0-99%) and the density of predatory fish (zero to four fish per container) was best described by a second-order polynomial model. Increasing fish densities resulted in a reduction in mosquito survival in all algal treatments. The highest incidence of survival was observed at intermediate (66%) algal cover in all treatments. 4. The presence of fish significantly extended larval development times whereas algal cover had no significant effect. The presence of fish resulted in emergence of smaller adults due to reduced feeding opportunities and predator avoidance behaviour. Algal cover also affected mosquito wing length but differently at each fish density. 5. Oviposition habitat selection improves survival in the presence of predators and feeding opportunities for An. pseudopunctipennis larvae.
Sustainable and effective control of dengue is hampered due to a number of factors, including the... more Sustainable and effective control of dengue is hampered due to a number of factors, including the lack of evidence-based, locally relevant interventions; insuf-
Sterile males of Aedes aegypti were released once a week for 8 weeks to evaluate the dispersal ef... more Sterile males of Aedes aegypti were released once a week for 8 weeks to evaluate the dispersal efficiency of ground and aerial drone release methods in a rural village of 26 Ha in southern Mexico. Indoor and outdoor BG-Sentinel traps were placed in 13–16 houses distributed throughout the village. The BG traps were activated 48 h after the release of the sterile males and functioned for a 24 h period following each release. Over the 8-week period of simultaneous ground and aerial releases, an average of 85,117 ± 6457 sterile males/week were released at ground level and 86,724 ± 6474 sterile males/week were released using an aerial drone. The ground release method resulted in higher numbers of captured males (mean = 5.1 ± 1.4, range 1.1–15.7 sterile males/trap) compared with the aerial release method (mean = 2.6 ± 0.8, range 0.5–7.3 sterile males/trap) (p < 0.05). Similarly, the prevalence of traps that captured at least one sterile male was significantly higher for ground release ...
Background: A genetically-engineered strain of the dengue mosquito vector Aedes aegypti, designat... more Background: A genetically-engineered strain of the dengue mosquito vector Aedes aegypti, designated OX3604C, was evaluated in large outdoor cage trials for its potential to improve dengue prevention efforts by inducing population suppression. OX3604C is engineered with a repressible genetic construct that causes a female-specific flightless phenotype. Wild-type females that mate with homozygous OX3604C males will not produce reproductive female offspring. Weekly introductions of OX3604C males eliminated all three targeted Ae. aegypti populations after 10–20 weeks in a previous laboratory cage experiment. As part of the phased, progressive evaluation of this technology, we carried out an assessment in large outdoor field enclosures in dengue endemic southern Mexico. Methodology/Principal Findings: OX3604C males were introduced weekly into field cages containing stable target populations, initially at 10:1 ratios. Statistically significant target population decreases were detected in ...
Dengue and other Aedes-borne diseases have dramatically increased over the last decades. The Ster... more Dengue and other Aedes-borne diseases have dramatically increased over the last decades. The Sterile Insect Technique (SIT) has been successfully used as part of integrated pest strategies to control populations of insect-plant and livestock pests and is currently being tested as a potential method to reduce mosquito populations in an environmentally friendly approach. However, during the mass rearing steps needed to produce millions of mosquitoes, egg storage and preservation are essential for a certain amount of time. Eggs of Aedes aegypti have a chorionic pad that functions as a sticky substance to glue them onto the inner walls of larval breeding sites. The chorionic pad is chemically made of hyaluronic acid, a hygroscopic compound, responsible to protect them from desiccation over time. Two commercial products with hygroscopic properties, hydrolyzed collagen, and Hyalurosmooth®, both were tested to assess their ability to prolong egg life storage for A. aegypti and A. albopictu...
Simple Summary Aedes aegypti and Ae. albopictus are the most important mosquito vectors of dengue... more Simple Summary Aedes aegypti and Ae. albopictus are the most important mosquito vectors of dengue, chikungunya and Zika virus. There is growing interest in the control of these vectors using the sterile insect technique in which large numbers of sterilized males are released and compete with wild fertile males for mates. Females that mate with sterile males do not produce viable offspring. A study was performed on the population fluctuations of Ae. aegypti and Ae. albopictus using egg traps in two rural villages with a history of dengue in Chiapas, southern Mexico. Higher numbers of Aedes eggs were recorded in Hidalgo village compared with the village of Río Florido. In contrast, higher number of eggs were collected in areas surrounding Río Florido, compared with those around Hidalgo. Aedes aegypti was the dominant species during the dry season and at the start of the rainy season in both villages. Aedes albopictus populations were lower for most of the dry season, but increased dur...
The sterile insect technique may prove useful for the suppression of mosquito vectors of medical ... more The sterile insect technique may prove useful for the suppression of mosquito vectors of medical importance in regions where arboviruses pose a serious public health threat. In the present study, we examined the effects of sterilizing irradiation doses across different ratios of fertile:irradiated males on the mating competitiveness of Ae. aegypti and Ae. albopictus under laboratory and field-cage conditions. For both species, the percentage of females inseminated and the number of eggs laid over two gonotrophic cycles varied significantly in mating treatments involving 1:1, 1:5, and 1:10 fertile:irradiated males compared to controls of entirely fertile or entirely irradiated males but was not generally affected by the irradiation dose. Egg hatching was negatively affected in females exposed to increasing proportions of irradiated males in both laboratory and field cages. Male competitiveness (Fried’s index) values varied from 0.19 to 0.58 in the laboratory and were between 0.09 and...
Objective. To compare the efficacy of three modern larvicides with the organophosphate temephos ... more Objective. To compare the efficacy of three modern larvicides with the organophosphate temephos for control of Aedes aegypti in water tanks in Chiapas. Materials and methods. Trials were performed to compare the efficacy of pyriproxyfen, novaluron, two formulations of spinosad (granules and tablets) and temephos in oviposition traps and domestic water tanks. Results. Pyriproxyfen and temephos provided 2-3 weeks of complete control of larvae in oviposition traps, whereas spinosad granules and novaluron provided 7-12 weeks of control. Treatment of water tanks resulted in a significant reduction in oviposition by Ae. aegypti in houses (p<0.001). Higher numbers of larvae were present in temephos and pyriproxyfen-treated water tanks compared to novaluron and spinosad tablet treatments during most of the study. Conclusion. Spinosad formulations and novaluron were effective larvicides in this region. The poor performance of temephos may be indicative of reduced susceptibility in Ae. a...
Objective. To determine the species distribution, abundance, and diversity of culicids in the Yuc... more Objective. To determine the species distribution, abundance, and diversity of culicids in the Yucatan Peninsula (YP); their potential distribution, using ecological niche modeling (ENM), and the risk of contact with urban and rural populations. Materials and methods. A cross-sectional study was carried out through the YP. The diversity of species was determined with the Shannon index. The potential distribution of the culicids was determined through the ENM, as well as the risk of urban and rural populations through contact with vectors. Results. A total of 10 699 specimens, 15 genera and 52 species were registered. Campeche and the Biosphere Reserve of Calakmul exhibited the highest diversity. Conclusions. The ENM predict a high suitability in all the YP of Ae. aegypti, An. albimanus, An. pseudopuntipennis, Cx. coronator, and Cx. quinquefasciatus. The vector species that exhibited the highest risk of contact in the YP were Cx. quinquefasciatus, Ae. aegypti and Ae. albopictus.
The Sterile Insect Technique (SIT) is a pest control method where large numbers of sterile males ... more The Sterile Insect Technique (SIT) is a pest control method where large numbers of sterile males are released to induce sterility in wild populations. Since a successful SIT application depends on the released sterile males being competitive with wild males, standard quality control tests are a necessary component of any SIT program. Flight ability (ability to fly out from a device) is a reliable indicator of insect quality. Based on previous studies, we developed four new tubular devices constructed with locally available materials to explore their potential as flight test devices for Aedes aegypti (L.) mass-reared males. Males were allowed to fly upwards through a vertical tube, the ones that flew out were considered successful. The effect of male age (0 to 21 d old), test time interval (30 min to 24 h), and the design of the device (40 and 80 cm height and 2 and 3.5 cm diameter) were evaluated. Our devices determined differences in the flight ability of Ae. aegypti males of diffe...
Journal of the American Mosquito Control Association
The invasive mosquito Aedes albopictus is currently distributed in most of the southern Mexican r... more The invasive mosquito Aedes albopictus is currently distributed in most of the southern Mexican region. Since the species was first recorded in the state of Tamaulipas, in northeastern Mexico in 1988, it has expanded its distribution throughout the Sierra Madre Oriental and Gulf of Mexico to the Neotropical region of the country. Currently the species occurs in the states of Tamaulipas, Coahuila, Nuevo Leon, Veracruz, Chiapas, Morelos, Quintana Roo, Sinaloa, San Luis Potosi, and Hidalgo. This is the first report of the mosquito in the states of Tabasco and Yucatan and the confirmation of its presence in Quintana Roo state. Aedes albopictus has been incriminated as a secondary vector of diseases such as those caused by dengue, chikungunya, and Zika viruses, which have caused epidemic outbreaks in most tropical and subtropical regions of Mexico; therefore, surveillance for the detection of Ae. albopictus is paramount so that targeted control strategies can be implemented for its contr...
Journal of the American Mosquito Control Association
Collections of mosquitoes were conducted for the surveillance of species of medical importance in... more Collections of mosquitoes were conducted for the surveillance of species of medical importance in the state of Quintana Roo, Mexico, in June of 2017. Species collected included Psorophora (Psorophora) cilipes and Culex (Melanoconion) theobaldi, both new records for the state. Psorophora cilipes was previously recorded in Mexico State and Cx. theobaldi in Chiapas State. With the addition of these species, the mosquito fauna of Quintana Roo State now includes 81 species. Quintana Roo and Tamaulipas State with 82 species are the most mosquito-rich states in Mexico, based on currently available records. The specimens collected in this study were deposited in the Culicidae collection of the Universidad Autónoma Agraria Antonio Narro Unidad Laguna.
The sterile insect technique (SIT) may offer a means to control the transmission of mosquito born... more The sterile insect technique (SIT) may offer a means to control the transmission of mosquito borne diseases. SIT involves the release of male insects that have been sterilized by exposure to ionizing radiation. We determined the effects of different doses of radiation on the survival and reproductive capacity of local strains of Aedes aegypti and Ae. albopictus in southern Mexico. The survival of irradiated pupae was invariably greater than 90% and did not differ significantly in either sex for either species. Irradiation had no significant adverse effects on the flight ability (capacity to fly out of a test device) of male mosquitoes, which consistently exceeded 91% in Ae. aegypti and 96% in Ae. albopictus. The average number of eggs laid per female was significantly reduced in Ae. aegypti at doses of 15 and 30 Gy and no eggs were laid by females that had been exposed to 50 Gy. Similarly, in Ae. albopictus, egg production was reduced at doses of 15 and 25 Gy and was eliminated at 35 Gy. In Ae. aegypti, fertility in males was eliminated at 70 Gy and was eliminated at 30 Gy in females, whereas in Ae. albopictus, the fertility of males that mated with untreated females was almost zero (0.1%) in the 50 Gy treatment and female fertility was eliminated at 35 Gy. Irradiation treatments resulted in reduced ovary length and fewer follicles in both species. The adult median survival time of both species was reduced by irradiation in a dose-dependent manner. However, sterilizing doses of 35 Gy and 50 Gy resulted in little reduction in survival times of males of Ae. albopictus and Ae. aegypti, respectively, indicating that these doses should be suitable for future evaluations of SIT-based control of these species. The results of the present study will be applied to studies of male sexual competitiveness and to stepwise evaluations of the sterile insect technique for population suppression of these vectors in Mexico.
Many countries in Latin America have recently experienced outbreaks of Zika and chikungunya fever... more Many countries in Latin America have recently experienced outbreaks of Zika and chikungunya fever, in additional to the usual burden imposed by dengue, all of which are transmitted by Aedes aegypti in this region. To identify potential larvicides, we determined the toxicity of eight modern insecticides to A. aegypti larvae from a colony that originated from field-collected insects in southern Mexico. The most toxic compounds were pyriproxyfen (which prevented adult emergence) and λ-cyhalothrin, followed by spinetoram, imidacloprid, thiamethoxam, and acetamiprid, with chlorantraniliprole and spiromesifen the least toxic products. Field trails performed in an urban cemetery during a chikungunya epidemic revealed that insecticide-treated ovitraps were completely protected from the presence of Aedes larvae and pupae for 6 and 7 weeks in spinosad (Natular G30) and λ-cyhalothrin-treated traps in both seasons, respectively, compared to 5-6 weeks for temephos granule-treated ovitraps, but w...
The arrival of chikungunya fever (CHIKF) in Latin American countries has been expected to trigger... more The arrival of chikungunya fever (CHIKF) in Latin American countries has been expected to trigger epidemics and challenge health systems. Historically considered as dengue-endemic countries, abundant Aedes aegypti populations make this region highly vulnerable to chikungunya virus (CHIKV) circulation. This review describes the current dengue and CHIKF epidemiological situations, as well as the role of uncontrolled Ae. aegypti and Ae. albopictus vectors in spreading the emerging CHIKV. Comments are included relating to the vector competence of both species and failures of surveillance and vector control measures. Dengue endemicity is a reflection of these abundant and persistent Aedes populations that are now spreading CHIKV in the Americas. This article forms part of a symposium in Antiviral Research on &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;Chikungunya discovers the New World.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;
Proceedings of The Royal Society B: Biological Sciences, Oct 22, 2004
Insect vector-borne diseases continue to present a major challenge to human health. Understanding... more Insect vector-borne diseases continue to present a major challenge to human health. Understanding the factors that regulate the size of mosquito populations is considered fundamental to the ability to predict disease transmission rates and for vector population control. The mosquito, Anopheles pseudopunctipennis, a vector of Plasmodium spp., breeds in riverside pools containing filamentous algae in Mesoamerica. Breeding pools along 3 km sections of the River Coatán, Chiapas, Mexico were subjected to algal extraction or left as controls in a cross-over trial extending over 2 years. Initial densities of An. pseudopunctipennis larvae were directly proportional to the prevalence of filamentous algae in each breeding site. The extraction of algae brought about a striking decline in the density of An. pseudopunctipennis larvae sustained for about six weeks, and a concurrent reduction in the adult population in both years of the study. Mark-release experiments indicated that dispersal from adjacent untreated areas was unlikely to exert an important influence on the magnitude of mosquito control that we observed. Habitat manipulation by extraction of filamentous algae offers a unique opportunity for sustainable control of this malaria vector. This technique may represent a valuable intervention, complimenting insecticide spraying of households, to minimize Plasmodium transmission rates in Mesoamerica.
Spinosad is a naturally derived biorational insecticide with an environmentally favourable toxici... more Spinosad is a naturally derived biorational insecticide with an environmentally favourable toxicity profile, so we investigated its potency against mosquito larvae (Diptera: Culicidae). By laboratory bioassays of a suspension concentrate formulation of spinosad (Tracer 1), the 24 h lethal concentration (LC 50) against Aedes aegypti (L.) third and fourth instars was estimated at 0.025 p.p.m. following logit regression. The concentration-mortality response of third-and fourth-instar Anopheles albimanus Weidemann did not conform to a logit model. The LC 50 value of spinosad in Anopheles albimanus was 0.024 p.p.m. by quadratic linear regression. A field trial in southern Mexico demonstrated that spinosad 1 p.p.m. compared with the standard temephos (Abate 1) 1% granules 100 g/m 3 water prevented Ae. aegypti breeding in plastic containers of water for 8 weeks; at 10 p.p.m. spinosad prevented breeding for > 22 weeks. In another field trial, spinosad at 5 p.p.m. and temephos both completely eliminated reproduction of Ae. aegypti for 13 weeks. In contrast, the bacterial insecticide Bacillus thuringiensis var. israelensis (Bti, Vectobac 1 AS) performed poorly with just 2 weeks of complete inhibition of Ae. aegypti breeding. Spinosad also effectively prevented breeding of Culex mosquitoes and chironomids in both trials to a degree similar to that of temephos. We conclude that spinosad merits evaluation as a replacement for organophosphate or Bti treatment of domestic water tanks in Mesoamerica. We also predict that spinosad is likely to be an effective larvicide for treatment of mosquito breeding sites.
In the sterile insect technique, it is important to measure the impact of mass-rearing and handli... more In the sterile insect technique, it is important to measure the impact of mass-rearing and handling of sterile males to allow a successful control of the target wild population. This study evaluates the effect of pre-release chilling on the survival, escape ability, and sexual competitiveness of male Aedes aegypti. To determine survival and escape ability, mosquitoes were chilled at 4 °C using four different treatments of either one exposure (25 min) or two consecutive exposures (25 + 25 min, 25 + 50 min, 25 + 100 min). For sexual competitiveness, two different treatments were evaluated, chilling for 25 min once and twice. Results showed that the longest exposure to chilling caused a significant reduction of survival time, from 67 to 54 days. Escape ability was reduced by the first chilling from 25 to 7% and with the second chilling, it was reduced from 30 to 24% in the control to 4.9, 2.0 and 0.5% for 25, 50 and 100 min, respectively. Sexual competitiveness index was reduced from 1...
1. The influence of filamentous algae on oviposition habitat selection by the mosquito Anopheles ... more 1. The influence of filamentous algae on oviposition habitat selection by the mosquito Anopheles pseudopunctipennis and the consequences of oviposition decisions on the diet, development, body size, and survival of offspring were examined. 2. A natural population of An. pseudopunctipennis in Chiapas, Mexico, oviposited almost exclusively in containers with filamentous algae. Algae represented 47% of the gut contents of mosquito larvae sampled from the natural population. Mosquito larvae fed on an exclusive diet of algae developed as quickly and achieved the same adult body size (wing length) as their conspecifics fed on a standard laboratory diet. 3. Multiple regression of survival of mosquito larvae on percentage surface area cover of algae (0-99%) and the density of predatory fish (zero to four fish per container) was best described by a second-order polynomial model. Increasing fish densities resulted in a reduction in mosquito survival in all algal treatments. The highest incidence of survival was observed at intermediate (66%) algal cover in all treatments. 4. The presence of fish significantly extended larval development times whereas algal cover had no significant effect. The presence of fish resulted in emergence of smaller adults due to reduced feeding opportunities and predator avoidance behaviour. Algal cover also affected mosquito wing length but differently at each fish density. 5. Oviposition habitat selection improves survival in the presence of predators and feeding opportunities for An. pseudopunctipennis larvae.
Sustainable and effective control of dengue is hampered due to a number of factors, including the... more Sustainable and effective control of dengue is hampered due to a number of factors, including the lack of evidence-based, locally relevant interventions; insuf-
Sterile males of Aedes aegypti were released once a week for 8 weeks to evaluate the dispersal ef... more Sterile males of Aedes aegypti were released once a week for 8 weeks to evaluate the dispersal efficiency of ground and aerial drone release methods in a rural village of 26 Ha in southern Mexico. Indoor and outdoor BG-Sentinel traps were placed in 13–16 houses distributed throughout the village. The BG traps were activated 48 h after the release of the sterile males and functioned for a 24 h period following each release. Over the 8-week period of simultaneous ground and aerial releases, an average of 85,117 ± 6457 sterile males/week were released at ground level and 86,724 ± 6474 sterile males/week were released using an aerial drone. The ground release method resulted in higher numbers of captured males (mean = 5.1 ± 1.4, range 1.1–15.7 sterile males/trap) compared with the aerial release method (mean = 2.6 ± 0.8, range 0.5–7.3 sterile males/trap) (p < 0.05). Similarly, the prevalence of traps that captured at least one sterile male was significantly higher for ground release ...
Background: A genetically-engineered strain of the dengue mosquito vector Aedes aegypti, designat... more Background: A genetically-engineered strain of the dengue mosquito vector Aedes aegypti, designated OX3604C, was evaluated in large outdoor cage trials for its potential to improve dengue prevention efforts by inducing population suppression. OX3604C is engineered with a repressible genetic construct that causes a female-specific flightless phenotype. Wild-type females that mate with homozygous OX3604C males will not produce reproductive female offspring. Weekly introductions of OX3604C males eliminated all three targeted Ae. aegypti populations after 10–20 weeks in a previous laboratory cage experiment. As part of the phased, progressive evaluation of this technology, we carried out an assessment in large outdoor field enclosures in dengue endemic southern Mexico. Methodology/Principal Findings: OX3604C males were introduced weekly into field cages containing stable target populations, initially at 10:1 ratios. Statistically significant target population decreases were detected in ...
Dengue and other Aedes-borne diseases have dramatically increased over the last decades. The Ster... more Dengue and other Aedes-borne diseases have dramatically increased over the last decades. The Sterile Insect Technique (SIT) has been successfully used as part of integrated pest strategies to control populations of insect-plant and livestock pests and is currently being tested as a potential method to reduce mosquito populations in an environmentally friendly approach. However, during the mass rearing steps needed to produce millions of mosquitoes, egg storage and preservation are essential for a certain amount of time. Eggs of Aedes aegypti have a chorionic pad that functions as a sticky substance to glue them onto the inner walls of larval breeding sites. The chorionic pad is chemically made of hyaluronic acid, a hygroscopic compound, responsible to protect them from desiccation over time. Two commercial products with hygroscopic properties, hydrolyzed collagen, and Hyalurosmooth®, both were tested to assess their ability to prolong egg life storage for A. aegypti and A. albopictu...
Simple Summary Aedes aegypti and Ae. albopictus are the most important mosquito vectors of dengue... more Simple Summary Aedes aegypti and Ae. albopictus are the most important mosquito vectors of dengue, chikungunya and Zika virus. There is growing interest in the control of these vectors using the sterile insect technique in which large numbers of sterilized males are released and compete with wild fertile males for mates. Females that mate with sterile males do not produce viable offspring. A study was performed on the population fluctuations of Ae. aegypti and Ae. albopictus using egg traps in two rural villages with a history of dengue in Chiapas, southern Mexico. Higher numbers of Aedes eggs were recorded in Hidalgo village compared with the village of Río Florido. In contrast, higher number of eggs were collected in areas surrounding Río Florido, compared with those around Hidalgo. Aedes aegypti was the dominant species during the dry season and at the start of the rainy season in both villages. Aedes albopictus populations were lower for most of the dry season, but increased dur...
The sterile insect technique may prove useful for the suppression of mosquito vectors of medical ... more The sterile insect technique may prove useful for the suppression of mosquito vectors of medical importance in regions where arboviruses pose a serious public health threat. In the present study, we examined the effects of sterilizing irradiation doses across different ratios of fertile:irradiated males on the mating competitiveness of Ae. aegypti and Ae. albopictus under laboratory and field-cage conditions. For both species, the percentage of females inseminated and the number of eggs laid over two gonotrophic cycles varied significantly in mating treatments involving 1:1, 1:5, and 1:10 fertile:irradiated males compared to controls of entirely fertile or entirely irradiated males but was not generally affected by the irradiation dose. Egg hatching was negatively affected in females exposed to increasing proportions of irradiated males in both laboratory and field cages. Male competitiveness (Fried’s index) values varied from 0.19 to 0.58 in the laboratory and were between 0.09 and...
Objective. To compare the efficacy of three modern larvicides with the organophosphate temephos ... more Objective. To compare the efficacy of three modern larvicides with the organophosphate temephos for control of Aedes aegypti in water tanks in Chiapas. Materials and methods. Trials were performed to compare the efficacy of pyriproxyfen, novaluron, two formulations of spinosad (granules and tablets) and temephos in oviposition traps and domestic water tanks. Results. Pyriproxyfen and temephos provided 2-3 weeks of complete control of larvae in oviposition traps, whereas spinosad granules and novaluron provided 7-12 weeks of control. Treatment of water tanks resulted in a significant reduction in oviposition by Ae. aegypti in houses (p<0.001). Higher numbers of larvae were present in temephos and pyriproxyfen-treated water tanks compared to novaluron and spinosad tablet treatments during most of the study. Conclusion. Spinosad formulations and novaluron were effective larvicides in this region. The poor performance of temephos may be indicative of reduced susceptibility in Ae. a...
Objective. To determine the species distribution, abundance, and diversity of culicids in the Yuc... more Objective. To determine the species distribution, abundance, and diversity of culicids in the Yucatan Peninsula (YP); their potential distribution, using ecological niche modeling (ENM), and the risk of contact with urban and rural populations. Materials and methods. A cross-sectional study was carried out through the YP. The diversity of species was determined with the Shannon index. The potential distribution of the culicids was determined through the ENM, as well as the risk of urban and rural populations through contact with vectors. Results. A total of 10 699 specimens, 15 genera and 52 species were registered. Campeche and the Biosphere Reserve of Calakmul exhibited the highest diversity. Conclusions. The ENM predict a high suitability in all the YP of Ae. aegypti, An. albimanus, An. pseudopuntipennis, Cx. coronator, and Cx. quinquefasciatus. The vector species that exhibited the highest risk of contact in the YP were Cx. quinquefasciatus, Ae. aegypti and Ae. albopictus.
The Sterile Insect Technique (SIT) is a pest control method where large numbers of sterile males ... more The Sterile Insect Technique (SIT) is a pest control method where large numbers of sterile males are released to induce sterility in wild populations. Since a successful SIT application depends on the released sterile males being competitive with wild males, standard quality control tests are a necessary component of any SIT program. Flight ability (ability to fly out from a device) is a reliable indicator of insect quality. Based on previous studies, we developed four new tubular devices constructed with locally available materials to explore their potential as flight test devices for Aedes aegypti (L.) mass-reared males. Males were allowed to fly upwards through a vertical tube, the ones that flew out were considered successful. The effect of male age (0 to 21 d old), test time interval (30 min to 24 h), and the design of the device (40 and 80 cm height and 2 and 3.5 cm diameter) were evaluated. Our devices determined differences in the flight ability of Ae. aegypti males of diffe...
Journal of the American Mosquito Control Association
The invasive mosquito Aedes albopictus is currently distributed in most of the southern Mexican r... more The invasive mosquito Aedes albopictus is currently distributed in most of the southern Mexican region. Since the species was first recorded in the state of Tamaulipas, in northeastern Mexico in 1988, it has expanded its distribution throughout the Sierra Madre Oriental and Gulf of Mexico to the Neotropical region of the country. Currently the species occurs in the states of Tamaulipas, Coahuila, Nuevo Leon, Veracruz, Chiapas, Morelos, Quintana Roo, Sinaloa, San Luis Potosi, and Hidalgo. This is the first report of the mosquito in the states of Tabasco and Yucatan and the confirmation of its presence in Quintana Roo state. Aedes albopictus has been incriminated as a secondary vector of diseases such as those caused by dengue, chikungunya, and Zika viruses, which have caused epidemic outbreaks in most tropical and subtropical regions of Mexico; therefore, surveillance for the detection of Ae. albopictus is paramount so that targeted control strategies can be implemented for its contr...
Journal of the American Mosquito Control Association
Collections of mosquitoes were conducted for the surveillance of species of medical importance in... more Collections of mosquitoes were conducted for the surveillance of species of medical importance in the state of Quintana Roo, Mexico, in June of 2017. Species collected included Psorophora (Psorophora) cilipes and Culex (Melanoconion) theobaldi, both new records for the state. Psorophora cilipes was previously recorded in Mexico State and Cx. theobaldi in Chiapas State. With the addition of these species, the mosquito fauna of Quintana Roo State now includes 81 species. Quintana Roo and Tamaulipas State with 82 species are the most mosquito-rich states in Mexico, based on currently available records. The specimens collected in this study were deposited in the Culicidae collection of the Universidad Autónoma Agraria Antonio Narro Unidad Laguna.
The sterile insect technique (SIT) may offer a means to control the transmission of mosquito born... more The sterile insect technique (SIT) may offer a means to control the transmission of mosquito borne diseases. SIT involves the release of male insects that have been sterilized by exposure to ionizing radiation. We determined the effects of different doses of radiation on the survival and reproductive capacity of local strains of Aedes aegypti and Ae. albopictus in southern Mexico. The survival of irradiated pupae was invariably greater than 90% and did not differ significantly in either sex for either species. Irradiation had no significant adverse effects on the flight ability (capacity to fly out of a test device) of male mosquitoes, which consistently exceeded 91% in Ae. aegypti and 96% in Ae. albopictus. The average number of eggs laid per female was significantly reduced in Ae. aegypti at doses of 15 and 30 Gy and no eggs were laid by females that had been exposed to 50 Gy. Similarly, in Ae. albopictus, egg production was reduced at doses of 15 and 25 Gy and was eliminated at 35 Gy. In Ae. aegypti, fertility in males was eliminated at 70 Gy and was eliminated at 30 Gy in females, whereas in Ae. albopictus, the fertility of males that mated with untreated females was almost zero (0.1%) in the 50 Gy treatment and female fertility was eliminated at 35 Gy. Irradiation treatments resulted in reduced ovary length and fewer follicles in both species. The adult median survival time of both species was reduced by irradiation in a dose-dependent manner. However, sterilizing doses of 35 Gy and 50 Gy resulted in little reduction in survival times of males of Ae. albopictus and Ae. aegypti, respectively, indicating that these doses should be suitable for future evaluations of SIT-based control of these species. The results of the present study will be applied to studies of male sexual competitiveness and to stepwise evaluations of the sterile insect technique for population suppression of these vectors in Mexico.
Many countries in Latin America have recently experienced outbreaks of Zika and chikungunya fever... more Many countries in Latin America have recently experienced outbreaks of Zika and chikungunya fever, in additional to the usual burden imposed by dengue, all of which are transmitted by Aedes aegypti in this region. To identify potential larvicides, we determined the toxicity of eight modern insecticides to A. aegypti larvae from a colony that originated from field-collected insects in southern Mexico. The most toxic compounds were pyriproxyfen (which prevented adult emergence) and λ-cyhalothrin, followed by spinetoram, imidacloprid, thiamethoxam, and acetamiprid, with chlorantraniliprole and spiromesifen the least toxic products. Field trails performed in an urban cemetery during a chikungunya epidemic revealed that insecticide-treated ovitraps were completely protected from the presence of Aedes larvae and pupae for 6 and 7 weeks in spinosad (Natular G30) and λ-cyhalothrin-treated traps in both seasons, respectively, compared to 5-6 weeks for temephos granule-treated ovitraps, but w...
The arrival of chikungunya fever (CHIKF) in Latin American countries has been expected to trigger... more The arrival of chikungunya fever (CHIKF) in Latin American countries has been expected to trigger epidemics and challenge health systems. Historically considered as dengue-endemic countries, abundant Aedes aegypti populations make this region highly vulnerable to chikungunya virus (CHIKV) circulation. This review describes the current dengue and CHIKF epidemiological situations, as well as the role of uncontrolled Ae. aegypti and Ae. albopictus vectors in spreading the emerging CHIKV. Comments are included relating to the vector competence of both species and failures of surveillance and vector control measures. Dengue endemicity is a reflection of these abundant and persistent Aedes populations that are now spreading CHIKV in the Americas. This article forms part of a symposium in Antiviral Research on &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;Chikungunya discovers the New World.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;
Uploads
Papers by Guillermo Bond