Number Of Adult Mosquitoes Research Articles

Current and lagged associations of meteorological variables and Aedes mosquito indices with dengue incidence in the Philippines.

Dengue is an increasing health burden that has spread throughout the tropics and sub-tropics. There is currently no effective vaccine and control is only possible through integrated vector management. Early warning systems (EWS) to alert potential dengue outbreaks are currently being explored but despite showing promise are yet to come to fruition. This study addresses the association of meteorological variables with both mosquito indices and dengue incidences and assesses the added value of additionally using mosquito indices for predicting dengue incidences. Entomological surveys were carried out monthly for 14 months in six sites spread across three environmentally different cities of the Philippines. Meteorological and dengue data were acquired. Non-linear generalized additive models were fitted to test associations of the meteorological variables with both mosquito indices and dengue cases. Rain and the diurnal temperature range (DTR) contributed most to explaining the variation in both mosquito indices and number of dengue cases. DTR and minimum temperature also explained variation in dengue cases occurring one and two months later and may offer potentially useful variables for an EWS. The number of adult mosquitoes did associate with the number of dengue cases, but contributed no additional value to meteorological variables for explaining variation in dengue cases. The use of meteorological variables to predict future risk of dengue holds promise. The lack of added value of using mosquito indices confirms several previous studies and given the onerous nature of obtaining such information, more effort should be placed on improving meteorological information at a finer scale to evaluate efficacy in early warning of dengue outbreaks.

Environmental dynamics and seasonal wing physiological changes of coastal mosquito vectors (Diptera: Culicidae) in Central Thailand

Mosquitoes (Diptera: Culicidae) are small hematophagous insects that serve as disease vectors by transmitting pathogens to humans and animals. This study was conducted on the coastline of Samut Songkhram Province in Thailand's central region to evaluate the impact of environmental factors on coastal mosquitoes, namely Anopheles epiroticus and Culex sitiens. A zero-inflated negative binomial (ZINB) regression was employed to assess the relationship between the density of larval mosquitoes and water quality factors. Spearman's rank correlation was used to examine the relationship between the number of adult mosquitoes and meteorological factors, and the geometric morphometric (GM) technique was used to study the wing size and shape of adult mosquitoes throughout different seasons. The ZINB analysis revealed a significant negative relationship (p < 0.05) between dissolved oxygen, high-range phosphate, and the number of An. epiroticus larvae. Conversely, in the case of Cx. sitiens, there was a significant positive relationship between nitrate-nitrogen and larval density (p < 0.01), while dissolved oxygen exhibited a significant negative relationship (p < 0.05). Regarding adult mosquitoes, relative humidity was positively correlated with the abundance of adult Cx. sitiens (r = 0.85, p < 0.01), whereas each meteorological parameter—temperature, relative humidity, rainfall, wind speed, and atmospheric pressure—was negatively correlated with adult An. epiroticus abundance (p < 0.05 for each). The GM analysis revealed statistically significant seasonal variations in wing shapes for both species (p < 0.05 for all seasonal comparisons), underscoring their adaptation to seasonal environmental conditions in coastal habitats.

Survival-Larval Density Relationships in the Field and Their Implications for Control of Container-Dwelling Aedes Mosquitoes.

Population density can affect survival, growth, development time, and adult size and fecundity, which are collectively known as density-dependent effects. Container Aedes larvae often attain high densities in nature, and those densities may be reduced when larval control is applied. We tested the hypothesis that density-dependent effects on survival are common and strong in nature and could result in maximal adult production at intermediate densities for Aedes aegypti, Aedes albopictus, and Aedes triseriatus. We surveyed naturally occurring densities in field containers, then introduced larvae at a similar range of densities, and censused the containers for survivors. We analyzed the survival-density relationships by nonlinear regressions, which showed that survival-density relationships vary among seasons, sites, and species. For each Aedes species, some sites and times yielded predictions that larval density reduction would yield the same (compensation), or more (overcompensation), adults than no larval density reduction. Thus, larval control targeting these Aedes species cannot always be assumed to yield a reduction in the number of adult mosquitoes. We suggest that mosquito control targeting larvae may be made more effective by: Imposing maximum mortality; targeting populations when larval abundances are low; and knowing the shape of the survival-density response of the target population.

An Evaluation of the Effectiveness of a Commercial Mechanical Trap to Reduce Abundance of Adult Nuisance Mosquito Populations

In this study, we explore the potential of a commercially available mechanical mosquito control device, the Liberty Plus Mosquito Magnet (hereafter referred to as Mosquito Magnet), to reduce the abundance of adult nuisance mosquito populations in public recreational areas. Mosquitoes were trapped on 2 replicate sites close to a campground at Brae Island Regional Park near Fort Langley, British Columbia, Canada. Each site comprised a treatment (Mosquito Magnets used) and control subsection (Mosquito Magnets not used). Mosquito numbers were assessed before and after the treatment period in both subsections at each site with Centers for Disease Control and Prevention (CDC) black light traps. Although nearly 200,000 mosquitoes from 14 different species were collected over 366 trap-nights from May 31 to July 31, 2008, the majority of those identified were Aedes sticticus (68%) and Ae. vexans (22%)-2 of the most notorious nuisance mosquito species in British Columbia. The number of mosquitoes captured by CDC black light traps increased overall during the study period due to natural seasonal variation. Nevertheless, a significant treatment effect (P = 0.0389) was associated with an average decrease of about 32% in the average number of adult mosquitoes collected per day. These results strongly suggest that Mosquito Magnets can reduce the abundance of nuisance mosquitoes, potentially reducing the biting pressure on the public, and providing another tool in mosquito control operations.

Field Evaluation of Mosquito Control Devices in Southern Louisiana

The effect of 2 mosquito traps and 2 repellent systems on the catch of adult mosquitoes in American Biophysics Corporation (ABC) light traps was evaluated over a 14-month period at 3 locations in Louisiana. Devices evaluated included 1) ABC Mosquito Magnet with dry ice and octanol; 2) the BioSensory 500 cc Dragonfly Biting Insect Trap with CO2, octenol, and Mosquito Cognito, which uses Conceal inhibitor; 3) the SC Johnson OFF! Mosquito Lantern; and 4) the ThermaCell cordless mosquito repellent system. The number of adult mosquitoes caught in the ABC light traps, at the SC Johnson OFF! Mosquito Lantern, and ThermaCell cordless mosquito repellent treatment sites was significantly lower than the number collected at the ABC Mosquito Magnet or the Dragonfly/Mosquito Cognito trap system sites. When the 2 repellent devices were placed in combination with the ABC traps, mosquito numbers were significantly reduced when compared with sites with ABC traps alone. These data indicate that the SC Johnson OFF! Mosquito Lantern and ThermaCell cordless mosquito system may reduce attack from biting mosquitoes due to the reduction in their numbers. In the same study, the mosquito counts of the trapping devices also were reported.

畜舎内微気象と昼間滞留蚊個体数との関係(第 11 回大会講演要旨)

畜舎内微気象と昼間滞留蚊個体数との関係(第 11 回大会講演要旨)