FIRST REPORT ON OTOTOXICITY OF MEGLUMINE ANTIMONIATE

Aedes aegypti is one of the main vectors in the transmission of dengue fever. Its abundance may cause the spread of the disease to be more intense. In the study of its biological life cycle, temperature was found to increase the development rate of each stage of this species and thus, accelerate the process of the development from egg to adult. In this paper, a Lefkovitch matrix model will be used to study the stage-structured population dynamics of Aedes aegypti. In constructing the transition matrix, temperature will be taken into account. As a case study, temperature recorded at the Subang Meteorological Station for year 2006 until 2010 will be used. Population dynamics of Aedes aegypti at maximum, average and minimum temperature for each year will be simulated and compared. It is expected that the higher the temperature, the faster the mosquito will breed. The result will be compared to the number of dengue fever incidences to see their relationship.

Acta Tropica, 2011

This study was conducted to determine the effects of increased water temperatures on the development of Aedes aegypti immatures under laboratory conditions in Trinidad, West Indies using temperature regulated water baths to cover a range of temperatures from 24-25 • C to 34-35 • C at a relative humidity of 80%. Two experiments were designed: (1) at constant temperature regimens and (2) under diurnal temperature regimens ranging from 24-25 • C to 34-35 • C. At 24-25 • C egg hatching success was 98% at 48 h, however at 34-35 • C egg hatching rates declined to 1.6% after 48 h. Ae. aegypti larvae reared under constant temperature regimens showed pupation on day 4 with highest pupation occurring at 30 • C (78.4%) However, under diurnal temperature regimens, pupation began on day 4 but only at the higher temperatures of 30-35 • C. Under diurnal temperature regimens ranging from 24 • C to 35 • C significantly more females emerged at higher temperatures, than males. In contrast, at constant temperatures of 24-35 • C no significant difference in M/F ratios were observed. The body size of Ae. aegypti reared at constant temperature regimens was significantly larger than males and females larvae reared under diurnal temperature regimens of 25-30 • C. The results of this study are discussed in the context of changing or increasing water temperatures, seasonal changes in vector populations and vector competence. Using these key factors control strategies are recommended to manage vector populations as expected increases in temperatures impact the Caribbean region.

Neotropical Entomology, 2019

Aedes albopictus (Skuse 1894) is prevalent in the urban/peri-urban Port Blair, posing a public health threat, during past outbreaks of chikungunya ( ) and dengue (2010). Despite its vector potential, information on the biology is scanty. Therefore, impact of temperature on survival of immature stages, under laboratory conditions, was studied on F 1 population of Andamans. Ae. albopictus larvae were exposed to static temperatures viz. 37°C, 39°C, 41°C, 43°C and 45°C, and the lethal time to cause 50% (LT 50 ) and 90% mortality (LT 90 ) was computed. To assess adaptive thermotolerance, larvae exposed (37°C and 39°C) were re-exposed to higher temperatures (43°C and 45°C). All larvae survived at 37°C and 39°C for the entire exposure period of 420 min, while variable mortality was observed at 41°C, 43°C and 45°C. Larvae re-exposed to 43°C and 45°C showed an increase in thermotolerance with respect to non-adapted larvae. The results are discussed in the context of survival, development and distribution.

Medical and Veterinary Entomology, 2000

Immature development times, survival rates and adult size (winglengths) of the mosquito Aedes aegypti (L.) (Diptera: Culicidae) were studied in the laboratory at temperatures of 10±40°C. The duration of development from egg eclosion (hatching of the ®rst instar) to adult was inversely related to temperature, ranging from 7.2 6 0.2 days at 35°C to 39.7 6 2.3 days at 15°C. The minimum temperature threshold for development (t) was determined as 8.3 6 3.6°C and the thermal constant (K) was 181.2 6 36.1 day-degrees above the threshold. Maximum survival rates of 88±93% were obtained between 20 and 30°C. Wing-length was inversely related to temperature. The sex ratio (X:Y) was 1 : 1 at all temperatures tested (15, 20, 25 and 35°C) except 30°C (4 : 3). Under ®eld conditions at Townsville and Charters Towers, north Queensland, the duration of immature development varied according to the container position (i.e. shaded or exposed) and the availability of food resources, as well as inversely with temperature. These data indicate that containers with an abundance of organic matter (e.g. those used for striking plant cuttings) or those amongst foliage or under trees (e.g. discarded plastic tubs and tyres) tended to produce the largest adult Ae. aegypti, which had faster development and better immature survival. As such progeny have been linked to a greater risk of dengue transmission, it would seem important to focus on control of such containers.

Memórias do Instituto Oswaldo Cruz, 2009

Despite its vector importance little attention is given to Aedes aegypti embryonic development. In this study, temperature influence on time course of Ae. aegypti larvae hatching and egg viability were evaluated. The dormancy state at the end of embryogenesis could be interrupted with a proper stimulus. Temperatures tested ranged between 12-36 degrees C; the maximum temperature limit is 35 degrees C and the minimum one is below 12 degrees C. Egg viability between 16-31 degrees C was above 80%. The definition of physiological embryonic parameters at this temperature range corroborates Ae. aegypti presence on tropical and subtropical world regions.

Journal of Biological Researches, 2000

Spherefix bioinsecticide is microbial agent of Bacillus sphaericus H-5a5b (VCRC B24) showing high potency for vector control. The bioinsecticide specific to target insect, and do not produce any adverse environmental impact, so the bioinsecticide would be very promising agent for vector control, especially vector of dengue haemorrhagic fever in Indonesia. The present studies aimed at observing the toxicity persistence of Spherefix on the larvae Aedesaegypti L. in some types of water container, and recycling potencies in the breeding places of A.aegypti. Two steps of the studies were carried out under laboratory conditions. Firststeps were reared mosquitos in the laboratory to supply larvae of Aedes aegypti. Second step testing of Spherefix toxicity persistence in the cemented, clay, and plastic containiers. The bioinsecticides were preparated by Vector Control Research Centre (VCRC), India. The toxicity persistence of Spherefix on the larvae of A. aegypti L. in some types of water c...

Journal of Insect Physiology, 2012

Physiological processes mediate the impact of ecological conditions on the life histories of insect vectors. For the dengue/chikungunya mosquito, Aedes aegypti, three life history traits that are critical to urban population dynamics and control are: size, development rate and starvation mortality. In this paper we make use of prior laboratory experiments on each of these traits at 2°C intervals between 20 and 30°C, in conjunction with eco-evolutionary theory and studies on A. aegypti physiology, in order to develop a conceptual and mathematical framework that can predict their thermal sensitivity. Our model of reserve dependent growth (RDG), which considers a potential tradeoff between the accumulation of reserves and structural biomass, was able to robustly predict laboratory observations, providing a qualitative improvement over the approach most commonly used in other A. aegypti models. RDG predictions of reduced size at higher temperatures, but increased reserves relative to size, are supported by the available evidence in Aedes spp. We offer the potentially general hypothesis that temperature-size patterns in mosquitoes are driven by a net benefit of finishing the growing stage with proportionally greater reserves relative to structure at warmer temperatures. By relating basic energy flows to three fundamental life history traits, we provide a mechanistic framework for A. aegypti development to which ecological complexity can be added. Ultimately, this could provide a framework for developing and field testing hypotheses on how processes such as climate variation, density dependent regulation, human behavior or control strategies may influence A. aegypti population dynamics and disease risk.

PLOS ONE, 2018

The increasing range of Aedes aegypti, vector for Zika, dengue, chikungunya, and other viruses, has brought attention to the need to understand the population and transmission dynamics of this mosquito. It is well understood that environmental factors and breeding site characteristics play a role in organismal development and the potential to transmit pathogens. In this study, we observe the impact of larval density in combination with diurnal temperature on the time to pupation, emergence, and mortality of Aedes aegypti. Experiments were conducted at two diurnal temperature ranges based on 10 years of historical temperatures of Houston, Texas (21-32˚C and 26.5-37.5˚C). Experiments at constant temperatures (26.5˚C, 32˚C) were also conducted for comparison. At each temperature setting, five larval densities were observed (0.2, 1, 2, 4, 5 larvae per mL of water). Data collected shows significant differences in time to first pupation, time of first emergence, maximum rate of pupation, time of maximum rate of pupation, maximum rate of emergence, time of maximum rate of emergence, final average proportion of adult emergence, and average proportion of larval mortality. Further, data indicates a significant interactive effect between temperature fluctuation and larval density on these measures. Thus, wild population estimates should account for temperature fluctuations, larval density, and their interaction in low-volume containers.

Medical and Veterinary Entomology, 2012

We asked whether climate change might affect the geographic distributions of Aedes aegypti (L.) and Aedes albopictus (Skuse) (Diptera: Culicidae). We tested the effects of temperature, diet and the presence of congeneric species on the performance of immature stages of these two aedine species in the laboratory. Mosquitoes in three different species-density combinations were reared at four constant temperatures (20 • C, 25 • C, 30 • C, 35 • C) on low-or high-level diets. Of the four temperatures tested, mortality increased only at 35 • C in both species. Mortality was higher on the high-level diet than on the low-level diet at 35 • C, but not at other temperatures. The presence of congeneric species had a significant positive effect on mortality in Ae. albopictus, but not in Ae. aegypti. Both species developed more quickly at higher temperatures within the range of 20-30 • C; development was not enhanced at 35 • C. Population growth of Ae. albopictus was more stable, regardless of diet and temperature; that of Ae. aegypti varied more according to these two factors. These species-specific attributes may help to explain the latitudinal distribution of the mosquitoes and degree of species dominance where they are sympatric.

Neotropical Entomology, 2007

Eclosão, Desenvolvimento e Sobrevivência de Aedes albopictus (Skuse) (Diptera: Culicidae) sob Diferentes Condições de Temperatura da Água RESUMO-Em áreas tropicais, onde as populações de insetos vetores são particularmente abundantes, as temperatura usualmente variam entre 25°C e 35°C. Considerando a importância dessa variação na determinação da dinâmica populacional de mosquitos, neste trabalho, desenvolvimento e as taxas de eclosão e sobrevivência dos estágios imaturos de Aedes albopictus (Skuse) foram comparados sob temperaturas constantes de 25, 30 e 35°C (em câmaras climatizadas) e ambientes (25°C a 29°C). A taxa de eclosão foi considerada como o total de larvas obtidas após 24h. O período de desenvolvimento, assim como a taxa de sobrevivência larval e pupal foram avaliados diariamente. A taxa de eclosão foi signifi cativamente mais elevada sob temperatura ambiente comparada às constantes, sugerindo que a variação da temperatura pode ser um fator estimulante da eclosão. O tempo médio de eclosão aumentou com a temperatura, variando de 2,8h (25ºC) a 5,2h (35ºC). A duração do período larval apresentou grande variabilidade dentro de cada grupo, embora não tenha diferido signifi cativamente entre os mesmos (11,0 ± 4,19 dias), tendo sido mais longo para indivíduos mantidos na água a 35°C (12,0 ± 4,95 dias) e temperatura ambiente (13,6 ± 5,98 dias). Ao contrário, a sobrevivência das larvas foi fortemente afetada na temperatura mais elevada, onde apenas um indivíduo alcançou o estágio adulto. Esses resultados sugerem que a população de Ae. albopictus de Recife pode estar em processo de adaptação ao aumento de temperatura e que o limite para o desenvolvimento de estágios larvais se encontra próximo a 35°C. PALAVRAS-CHAVE: Biologia, vetor, ciclo de vida, limite térmico ABSTRACT-In tropical areas, where vector insects populations are particularly numerous, temperature usually range between 25°C and 35°C. Considering the importance of such temperature variation in determining mosquitoes population dynamics, in this work the developmental, eclosion and survival rates of the immature stages of Aedes albopictus (Skuse) were compared under constant 25, 30 and 35°C (using acclimatized chambers) and environmental (25°C to 29°C) temperatures. The hatching rate was considered as total number of larvae recovered after 24h. The development period as well as larval and pupal survival rate were evaluated daily. Eclosion rate was signifi cantly higher under environmental temperature than under the studied constant temperatures, suggesting that temperature variation may be an eclosion-stimulating factor. The mean eclosion time increased with the temperature, ranging from 2.8h (25°C) to 5.2h (35°C). The larval period was greatly variable inside each group, although it did not differ signifi cantly amongst groups (11.0 ± 4.19 days), with individuals showing longer larval stages in water at 35°C (12.0 ± 4.95 days) and environmental temperature (13.6 ± 5.98 days). Oppositely, survival was strongly affected by the higher temperature, where only one individual lived through to adult phase. The results suggest that population of Ae. albopictus from Recife may be adapting to increasing of environmental temperatures and that the limiting temperature to larval development is around 35°C.