Influence of Urban Landscapes on Population Dynamics in a Short-Distance Migrant Mosquito: Evidence for the Dengue Vector Aedes aegypti

Worldwide, 2.5 billion people are at risk for dengue infection, with no vaccine or treatment available. Thus dengue prevention is largely focused on controlling its mosquito vector, Aedes aegypti. Traditional mosquito control approaches typically include insecticide applications and breeding site source reduction. Presently, novel dengue control measures including the sterile insect technique and population replacement with dengue-incompetent transgenic mosquitoes are also being considered. Success of all population control programs is in part dependent upon understanding mosquito population ecology, including how anthropogenic effects on the urban landscape influence dispersal and expansion. We conducted a two year population genetic study examining how a major metropolitan highway impacts mosquito dispersal in Trinidad, West Indies. As evidenced by significant differentiation using both nuclear and mitochondrial DNA sequences, the highway acted as a significant barrier to dispersal. Our results suggest that anthropogenic landscape features can be used effectively to enhance population suppression/replacement measures by defining mosquito control zones along recognized landscape barriers that limit population dispersal

Comparing vector and human surveillance strategies to detect arbovirus transmission: A simulation study for Zika virus detection in Puerto Rico.

BACKGROUND:Detecting and monitoring the transmission of arboviruses such as Zika virus (ZIKV), dengue virus, and chikungunya virus is critical for prevention and control activities. Previous work has compared the ability of different human-focused surveillance strategies to detect ZIKV transmission in U.S. counties where no known transmission had occurred, but whether virological surveillance in mosquitoes could represent an effective surveillance system is unclear. OBJECTIVES:We leveraged a unique set of data from human and virological surveillance in Ae. aegypti during the 2016 ZIKV epidemic in Caguas, Puerto Rico, to compare alternative strategies for detecting and monitoring ZIKV activity. METHODS:We developed a simulation model for mosquito and human surveillance strategies and simulated different transmission scenarios with varying infection rates and mosquito trap densities. We then calculated the expected weekly number of detected infections, the probability of detecting transmission, and the number of tests needed and compared the simulations with observed data from Caguas. RESULTS:In simulated high transmission scenarios (1 infection per 1,000 people per week), the models demonstrated that both approaches had estimated probabilities of detection of greater than 78%. In simulated low incidence scenarios, vector surveillance had higher sensitivity than human surveillance and sensitivity increased with more traps, more trapping effort, and testing. In contrast, the actual data from Caguas indicated that human virological surveillance was more sensitive than vector virological surveillance during periods of both high and low transmission. CONCLUSION:In scenarios where human surveillance is not possible or when transmission intensity is very low, virological surveillance in Ae. aegypti may be able to detect and monitor ZIKV epidemic activity. However, surveillance for humans seeking care for Zika-like symptoms likely provides an equivalent or more sensitive indicator of transmission intensity in most circumstances

Summary of variation at 9 microsatellite and 2 SNP loci by collection.

<p>N, number of individuals; F_IS, inbreeding coefficient.</p><p>Bold denotes significant departure from HW after Bonferroni correction.</p><p>*denotes SNPs.</p

Distribution of alleles for microsatellite locus AG2 in 2006 and 2007.

<p>*Denotes private alleles with a frequency of >5%.</p

Analysis of molecular variance using nuclear microsatellite and SNP markers.

<p>*<i>P</i><0.05,</p><p>**<i>P</i><0.01,</p><p>***<i>P</i><0.001.</p

Analysis of molecular variance using mtDNA CO1 haplotypes.

<p>Probability (random value ≥ observed value) (10,100 permutations).</p><p>†0.00040+/−0.00019.</p><p>*0.00000+/−0.00000.</p><p>♦0.06891+/−0.00250.</p><p>‡0.00238+/−0.00051.</p

Distribution of alleles for microsatellite locus AG7 in 2006 and 2007.

<p>Distribution of alleles for microsatellite locus AG7 in 2006 and 2007.</p

Collection sites were located along Uriah Butler Highway in the Charlieville neighborhood of Chagaunas, Trinidad, West Indies.

<p>This is the major north-south highway from Port of Spain to San Fernando.</p

Distribution of alleles for microsatellite locus CT2 in in 2006 and 2007.

<p>*Denotes private alleles with a frequency of >5%.</p