Vector Control Method Research Articles

Knowledge regarding dengue disease among people in an urban area: a cross sectional study

Background: Vector borne diseases are one of the major public health problems worldwide. There is significant disease burden contributed to morbidity and mortality due to Dengue. Vector control is the ideal way to control dengue. But vector control methods can be successful with community participation. Hence it becomes important to assess the community’s knowledge regarding the disease. The objective of the study was to assess the knowledge regarding the dengue disease among people in an urban area.Methods: A community based cross sectional study was conducted among 400 participants. Participants were selected by using systematic random sampling method. Data was collected by house to house visit using predesigned questionnaire.Results: Majority of them (87.75%) identified fever as a cardinal symptom of dengue fever. Only 32.25% knew that dengue fever is transmitted by Aedes mosquitoes. 42% of participants had good knowledge of dengue The main source of information on dengue was from the television.Conclusions: Key finding of this study is that knowledge is poor among the study participants although majority of people had clear understanding of fever, headache, joint pain as common signs and symptoms of dengue fever.

Baseline Characterization of Dengue Epidemiology in Yogyakarta City, Indonesia, before a Randomized Controlled Trial of Wolbachia for Arboviral Disease Control.

.Dengue is endemic in Indonesia. Here, we describe the epidemiology of dengue in the city of Yogyakarta, Central Java, as a prelude to implementation of a cluster-randomized trial of Wolbachia for the biocontrol of arboviral transmission. Surveillance records from 2006 to 2016 demonstrate seasonal oscillations of dengue incidence with varying magnitude. Two lines of evidence demonstrate a high force of infection; the hospitalized case burden of patients diagnosed with dengue hemorrhagic fever or dengue shock syndrome over the last decade consisted predominantly of children/adolescents, and a serosurvey of 314 healthy children aged 1–10 years found 68% possessed dengue virus–neutralizing antibodies. Finally, a mobility survey indicated children aged 1–10 years, and particularly 1–5 year-olds, spent most of their daytime hours at home. These findings inform the design of clinical trials to measure the impact of novel vector control methods such as Wolbachia introgression into Aedes aegypti mosquitoes, by providing baseline data on disease incidence and identifying subpopulations for recruitment into prospective studies of dengue virus infection and disease. The mobility survey findings indicate that in cluster trials of interventions applied at the community level, young children can reasonably be expected to spend most of their exposure time, in epidemiological terms, within the treatment arm to which they were randomized.

Training of Convolutional Neural Network using Transfer Learning for Aedes Aegypti Larvae

The flavivirus epidemiology has reached an alarming rate which haunts the world population including Malaysia. World Health Organization has proposed and practised various methods of vector control through environmental management, chemical and biological orientations. However, from the listed control vectors, the most crucial part to be heeded are non-accessible places like water storage and artificial container. The objective of the study was to acquire and compare various accuracies and cross-entropy errors of the training sets within different learning rates in water storage tank environment which was essential for detection. This experiment performed transfer learning where Inception-V3 was implemented. About 534 images were trained to classify between Aedes Aegypti larvae and float valve within 3 different learning rates. For training accuracy and validation accuracy, learning rates were 0.1; 99.98%, 99.90% and 0.01; 99.91%, 99.77% and 0.001; 99.10%, 99.93%. Cross-entropy errors for training and validation for 0.1 were 0.0021, 0.0184 whereas for 0.01 were 0.0091, 0.0121 and 0.001; 0.0513, 0.0330. Various accuracies and cross-entropy errors of the training sets within the different learning rates were successfully acquired and compared.

Teknik Serangga Mandul Nyamuk Culex quinquefasciatus sebagai Upaya Pengendalian Vektor Filariasis di Kota Pekalongan

Filariasis is a disease caused by infection filarial worms and transmitted by the bite of female mosquitoes. Controls of filariasis are still limited to the treatment of patients and prevent secondary infection, whereas the control of mosquitoes is not optimal yet. Sterile insect technique is a vector control method that environmentally friendly, effective, and potential. The study design is quasi-experimental design with pre-posttest control group design. The location of the research is in the Village of Padukuhan Kraton, District of North Pekalongan, Pekalongan City. Sterile insect technique can be made by irradiation of the male mosquitoes in the laboratory (BATAN) with dose (0 Gy, 60 Gy, 65 Gy, 70 Gy, 75 Gy and 80 Gy). The male mosquitoes exposed to irradiation testing sterility, survival, matting competitiveness and flight distance test. The male mosquitoes of Culex quinquefasciatus are derived from laboratory of Balai Litbang P2B2 Banjarnegara. Post-irradiation dose of 60 Gy, 65 Gy, 70 Gy, 75 Gy and 80 Gy obtained high sterility figures between 95.35%-98.53%, which means a chance to breed only 1.5-4.5%. The age of mosquitoes’ post-irradiation without matting about 35 days, the matting competitiveness with laboratory scale is almost close to normal (0.7-0.8), the matting competitiveness with field spring scale is lower than normal mosquito (0.04-0.2), mosquito flight range was only caught in the radius 100 m. The utilization of gamma irradiation to sterilizing Culex quinquefasciatus is effective at dose 70 Gy and can be done to intervention control of Culex quinquefasciatus in limited scope

Comparing Effectiveness of Hay Infusion and Sugar Fermentation Solution as Ovitrap's Attractans to Aedes aegypti

Dengue Hemorrhagic Fever (DHF) is still one of the major public health problems in the world and Indonesia. There are several methods of mosquito vector control, one of them is the use of ovitrap and the addition of attractants which is a compound that may attract gravid mosquitoes to lay eggs. Some examples of attractants are hay infusion and sugar fermentation solution. This research aimed to compare effectiveness of hay infusion and sugar fermentation solution as Aedes aegypti attractants. This research type was true experimental laboratory with complete randomized design which is divided into 3 groups of ovitrap containing aquades as control, 20% hay infusion and 20% sugar fermentation solution. Ovitraps with those attractants were put into a mosquito coop containing 25 gravid female mosquitoes. Mosquito’s eggs counting was done after 2 days with 9 times repetition. The data were then analyzed using Kruskal-Wallis and Mann-Whitney test. It was found that the difference of mosquito’s eggs number in the ovitrap containing the fermentation solution of sugar and hay infusion had a significance value of 0.000 (p> 0,05). It means that hay infusion is more effective compared with sugar fermentation. Keywords : DHF, ovitrap, attractant, hay infusion, sugar fermentation solution

A cross-sectional analysis of ITN and IRS coverage in Namibia in 2013

BackgroundAchieving vector control targets is a key step towards malaria elimination. Because of variations in reporting of progress towards vector control targets in 2013, the coverage of these vector control interventions in Namibia was assessed.MethodsData on 9846 households, representing 41,314 people, collected in the 2013 nationally-representative Namibia Demographic and Health Survey were used to explore the coverage of two vector control methods: indoor residual spraying (IRS) and insecticide-treated nets (ITNs). Regional data on Plasmodium falciparum parasite rate in those aged 2–10 years (PfPR2–10), obtained from the Malaria Atlas Project, were used to provide information on malaria transmission intensity. Poisson regression analyses were carried out exploring the relationship between household interventions and PfPR2–10, with fully adjusted models adjusting for wealth and residence type and accounting for regional and enumeration area clustering. Additionally, the coverage as a function of government intervention zones was explored and models were compared using log-likelihood ratio tests.ResultsIntervention coverage was greatest in the highest transmission areas (PfPR2–10 ≥ 5%), but was still below target levels of 95% coverage in these regions, with 27.6% of households covered by IRS, 32.3% with an ITN and 49.0% with at least one intervention (ITN and/or IRS). In fully adjusted models, PfPR2–10 ≥ 5% was strongly associated with IRS (RR 14.54; 95% CI 5.56–38.02; p < 0.001), ITN ownership (RR 5.70; 95% CI 2.84–11.45; p < 0.001) and ITN and/or IRS coverage (RR 5.32; 95% CI 3.09–9.16; p < 0.001).ConclusionsThe prevalence of IRS and ITN interventions in 2013 did not reflect the Namibian government intervention targets. As such, there is a need to include quantitative monitoring of such interventions to reliably inform intervention strategies for malaria elimination in Namibia.

Modeling and Testing of the Multi-pole Field of a Motor for Pure Electric Vehicles

From the principles of electromechanical energy conversion and electromagnetic torque generation, our study evaluated the mathematical model of the electromagnetic torque and the vector control method of motors. An analysis of motor types indicates that the electromechanical energy conversion component is interchangeable. Three distinct types of motor structures, namely DC, induction, and synchronous, are possible, all three being commonly used in pure electric vehicles. For each motor type, simulation models were developed using Modelica, a modeling language for object-oriented multi-domain physical system. A test model of each motor type was configured in the MWorks simulation platform. With a representative motor, specifically the permanent-magnet DC motor, the asynchronous induction motor, and the permanent-magnet synchronous motor, mechanical properties were simulated and analyzed. The simulation results show that the characteristics of each motor model are consistent with the theoretical and engineering performance of the representative motor. Therefore, modeling, motor control, and performance testing of a unified multi-pole-field motor, which is used in pure electric vehicles, have been achieved.

An experimental and numerical investigation of the effect of geometric parameters on the flexible joint nonlinear behavior for thrust vector control

Solid-propellant motors are used in a variety of space systems. This type of motor requires a guidance system, and a thrust vector control to function properly. One of the most effective methods for thrust vector control can be achieved by utilizing a flexible joint system. The flexible joint is the most widely used device in advanced nozzle system, such as space shuttle boosters, Vega, and Ariane 5. This setup includes multiple layers of elastomers to provide the flexibility, and a few metallic or composite rings as the scaffold of the system. In this study, a nonlinear simulation of the flexible joint is investigated using finite element method. These results are verified by construction and hydrostatic test, and there is a good consistency between predictions and empirical data. To the best of our knowledge, contemporary architecture does not provide the optimum result. Therefore, we propose delicately designed configuration, which can be mentored in a variety of motors, to improve the functionality of the flexible joints. A detailed study on the alteration of geometric parameters has been done to unravel its effect on the behavior of the flexible joint.

A tool vector control for laser additive manufacturing in five-axis configuration

Laser additive manufacturing facilitates the manufacture of functional structures, gradient materials, and complex inner structure parts. This process, which is known for its rapid and green manufacturing capabilities, presents an important direction for the development of advanced manufacturing technologies. However, contour accuracy introduces a technical bottleneck that remains unsolved. In five-axis laser additive manufacturing, tool vector control plays a pivotal role in determining contour accuracy. Accordingly, this article proposes a method for tool vector control in five-axis laser additive manufacturing. This method utilizes a five-axis spiral milling tool path to change the vector direction for five-axis laser additive manufacturing and to improve the contour precision of complex surface parts. First, the continuous spiral tool path is obtained by using commercial CAM software. Second, based on the relationship between the additive and subtractive control vectors, the control vector of the obtained spiral tool path is converted into the tool vector control of the laser cladding. Third, the tool position point and tool vector are converted into a G code program via post processing. Fourth, the performance of the proposed method is verified by conducting a virtual simulation and a five-axis laser cladding experiment with a blade specimen.

The development of high resolution maps of tsetse abundance to guide interventions against human African trypanosomiasis in northern Uganda

BackgroundVector control is emerging as an important component of global efforts to control Gambian sleeping sickness (human African trypanosomiasis, HAT). The deployment of insecticide-treated targets (“Tiny Targets”) to attract and kill riverine tsetse, the vectors of Trypanosoma brucei gambiense, has been shown to be particularly cost-effective. As this method of vector control continues to be implemented across larger areas, knowledge of the abundance of tsetse to guide the deployment of “Tiny Targets” will be of increasing value. In this paper, we use a geostatistical modelling framework to produce maps of estimated tsetse abundance under two scenarios: (i) when accurate data on the local river network are available; and (ii) when river information is sparse.MethodsTsetse abundance data were obtained from a pre-intervention survey conducted in northern Uganda in 2010. River network data obtained from either digitised maps or derived from 30 m resolution digital elevation model (DEM) data as a proxy for ground truth data. Other environmental variables were derived from publicly-available resolution remotely sensed data (e.g. Landsat, 30 m resolution). Zero-inflated negative binomial geostatistical models were fitted to the abundance data using an integrated nested Laplace approximation approach, and maps of estimated tsetse abundance were produced.ResultsRestricting the analysis to traps located within 100 m of any river, positive associations were identified between the length of river and the minimum soil/vegetation moisture content of the surrounding area and daily fly catches, whereas negative associations were identified with elevation and distance to the river. The resulting models could accurately distinguish between traps with high and low fly catches (e.g. < 5 or > 5 flies/day), with a ROC-AUC (receiver-operating characteristic - area under the curve) greater than 0.9. Whilst the precise course of the river was not well approximated using the DEM data, the models fitted using DEM-derived river data performed similarly to those that incorporated the more accurate local river information.ConclusionsThese models can now be used to assist in the design, implementation and monitoring of tsetse control operations in northern Uganda and further can be used as a framework by which to undertake similar studies in other areas where Glossina fuscipes fuscipes spreads Gambian sleeping sickness.

Vector Control of Piezoelectric Transducers and Ultrasonic Actuators

This paper presents the implementation of a novel vibration amplitude control and resonant frequency tracking for piezoelectric transducers (PTs) and ultrasonic motors (USMs). It is based on a generalization of the vector control method to the PT and the USM, which is explained in the first part. We show that two independent controllers with a similar structure are required: one tracks the resonant frequency and the second controls the amplitude. We then present the implementation into a low-cost digital signal processing controller with a sampling period of 200 $\mu$ s. Experimental results on a Langevin transducer achieved a time response of 20 ms approximately, and the generality of the method is further demonstrated on a 2-D tactile stimulator at the end of this paper.

Associated patterns of insecticide resistance in field populations of malaria vectors across Africa

The development of insecticide resistance in African malaria vectors threatens the continued efficacy of important vector control methods that rely on a limited set of insecticides. To understand the operational significance of resistance we require quantitative information about levels of resistance in field populations to the suite of vector control insecticides. Estimation of resistance is complicated by the sparsity of observations in field populations, variation in resistance over time and space at local and regional scales, and cross-resistance between different insecticide types. Using observations of the prevalence of resistance in mosquito species from the Anopheles gambiae complex sampled from 1,183 locations throughout Africa, we applied Bayesian geostatistical models to quantify patterns of covariation in resistance phenotypes across different insecticides. For resistance to the three pyrethroids tested, deltamethrin, permethrin, and λ-cyhalothrin, we found consistent forms of covariation across sub-Saharan Africa and covariation between resistance to these pyrethroids and resistance to DDT. We found no evidence of resistance interactions between carbamate and organophosphate insecticides or between these insecticides and those from other classes. For pyrethroids and DDT we found significant associations between predicted mean resistance and the observed frequency of kdr mutations in the Vgsc gene in field mosquito samples, with DDT showing the strongest association. These results improve our capacity to understand and predict resistance patterns throughout Africa and can guide the development of monitoring strategies.

A spatial genetics approach to inform vector control of tsetse flies (Glossina fuscipes fuscipes) in Northern Uganda.

Tsetse flies (genus Glossina) are the only vector for the parasitic trypanosomes responsible for sleeping sickness and nagana across sub‐Saharan Africa. In Uganda, the tsetse fly Glossina fuscipes fuscipes is responsible for transmission of the parasite in 90% of sleeping sickness cases, and co‐occurrence of both forms of human‐infective trypanosomes makes vector control a priority. We use population genetic data from 38 samples from northern Uganda in a novel methodological pipeline that integrates genetic data, remotely sensed environmental data, and hundreds of field‐survey observations. This methodological pipeline identifies isolated habitat by first identifying environmental parameters correlated with genetic differentiation, second, predicting spatial connectivity using field‐survey observations and the most predictive environmental parameter(s), and third, overlaying the connectivity surface onto a habitat suitability map. Results from this pipeline indicated that net photosynthesis was the strongest predictor of genetic differentiation in G. f. fuscipes in northern Uganda. The resulting connectivity surface identified a large area of well‐connected habitat in northwestern Uganda, and twenty‐four isolated patches on the northeastern margin of the G. f. fuscipes distribution. We tested this novel methodological pipeline by completing an ad hoc sample and genetic screen of G. f. fuscipes samples from a model‐predicted isolated patch, and evaluated whether the ad hoc sample was in fact as genetically isolated as predicted. Results indicated that genetic isolation of the ad hoc sample was as genetically isolated as predicted, with differentiation well above estimates made in samples from within well‐connected habitat separated by similar geographic distances. This work has important practical implications for the control of tsetse and other disease vectors, because it provides a way to identify isolated populations where it will be safer and easier to implement vector control and that should be prioritized as study sites during the development and improvement of vector control methods.

Analisis Faktor Keberadaan Vektor Penular DBD Melalui Identifikasi Tempat Potensial Perkembangbiakan Nyamuk Aedes Sp. di Desa Gergunung, Kabupaten Klaten, Jawa Tengah

The presence of potential breeding places can be used to measure the risk of DHF transmission in Klaten. This result can be used by the community to eridication of mosquito breeding place on terget and can improve to early warning system through effective methods for vector control. Type of study was analytic with cross-sectional study. The study was conducted in 104 households with simple random sampling technique. Data analysis used three stages: univariate, bivariate (Chi-square, Kolmogorov Smirnov, Spearman rank) and multivariate test with α=5%. The density of larvae based on the value of CI, HI, and BI amounted to 1.6%, 19.2%, 27.9%. The potential place for larvae breed based on Maya Index of 76%. Containers of open wells with groundwater sources, the volume of water is more than 1 liter and the material from cement can be the preferred place for mosquitoes to breed. Multivariate analysis shows that open wells are strongly related and has a risk of 1,556 (CI: 1,199-2,019) increasing the density of larvae compared with other variables.The density of larvae based on BI is a high category, HI is a moderate category and CI is a low category. This condition is influenced by the presence of open wells made of cement and can hold water in large quantities. Improve to early warning system of DHF transmission through identification of the presence of potential breading places in this area are to close the wells at the household level and conduct regular monitoring on the Controllable Sites.

Changing distribution and abundance of the malaria vector Anopheles merus in Mpumalanga Province, South Africa.

Background: The malaria vector Anopheles merus occurs in the Mpumalanga Province of South Africa. As its contribution to malaria transmission in South Africa has yet to be ascertained, an intensification of surveillance is necessary to provide baseline information on this species. The aim of this study was therefore to map An. merus breeding sites in the Ehlanzeni District of Mpumalanga Province and to assess qualitative trends in the distribution and relative abundance of this species over a 9-year period. Methods: The study was carried out during the period 2005-2014 in the four high-risk municipalities of Ehlanzeni District. Fifty-two breeding sites were chosen from all water bodies that produced anopheline mosquitoes. The study data were extracted from historical entomological records that are captured monthly. Results: Of the 15 058 Anopheles mosquitoes collected, 64% were An. merus. The abundance and distribution of An. merus increased throughout the four municipalities in Ehlanzeni District during the study period. Conclusion: The expanded distribution and increased abundance of An. merus in the Ehlanzeni District may contribute significantly to locally acquired malaria in Mpumalanga Province, likely necessitating the incorporation of additional vector control methods specifically directed against populations of this species.

Nightly Biting Cycles of Anopheles Species in Rural Northwestern Burkina Faso.

The biting behavior of anophelines is an important determinant of malaria transmission. Understanding the local vector host-seeking behavior, its outdoor/ indoor biting preference, and nocturnal biting periods is essential for effectively applying and improving vector control methods, such as Long Lasting Insecticidal Nets (LLINs) and personal protective measures. To better understand the biting and host-seeking patterns of Anopheles mosquitoes in Northwestern Burkina Faso, we performed biweekly Human Landing Catches (HLC) in six villages during the period of highest mosquito abundance and malaria transmission. We applied a negative binomial regression framework to statistically analyze the host-seeking activities of Anopheles species and test for differences across hours, months, and villages, as well as for differences between indoor and outdoor capture points. Anopheles gambiae s.l. was identified as the main malaria vector in this region, representing about 90% of the total anopheline population. Biting activity was significantly different across hours and showed a peaked plateau between 2000 and 0200 hours. Differences in the pattern of biting cycles were observed between the early and late rainy season. This study shows that anopheline biting activity in Northwest Burkina Faso is high throughout the night, at indoor and outdoor posts alike. Consequently, bed nets alone may not provide sufficient protection against early biting anophelines and should be complemented with additional strategies such as indoor residual spraying (IRS) and larval source management (LSM) to meet the WHO’s ambitious goals that are reflected in the global technical malaria strategy for 2030.

The use of driving endonuclease genes to suppress mosquito vectors of malaria in temporally variable environments

BackgroundThe use of gene drive systems to manipulate populations of malaria vectors is currently being investigated as a method of malaria control. One potential system uses driving endonuclease genes (DEGs) to spread genes that impose a genetic load. Previously, models have shown that the introduction of DEG-bearing mosquitoes could suppress or even extinguish vector populations in spatially-heterogeneous environments which were constant over time. In this study, a stochastic spatially-explicit model of mosquito ecology is combined with a rainfall model which enables the generation of a variety of daily precipitation patterns. The model is then used to investigate how releases of a DEG that cause a bias in population sex ratios towards males are affected by seasonal or random rainfall patterns. The parameters of the rainfall model are then fitted using data from Bamako, Mali, and Mbita, Kenya, to evaluate release strategies in similar climatic conditions.ResultsIn landscapes with abundant resources and large mosquito populations the spread of a DEG is reliable, irrespective of variability in rainfall. This study thus focuses mainly on landscapes with low density mosquito populations where the spread of a DEG may be sensitive to variation in rainfall. It is found that an introduced DEG will spread into its target population more reliably in wet conditions, yet an established DEG will have more impact in dry conditions. In strongly seasonal environments, it is thus preferable to release DEGs at the onset of a wet season to maximize their spread before the following dry season. If the variability in rainfall has a substantial random component, there is a net increase in the probability that a DEG release will lead to population extinction, due to the increased impact of a DEG which manages to establish in these conditions. For Bamako, where annual rainfall patterns are characterized by a long dry season, it is optimal to release a DEG at the start of the wet season, where the population is growing fastest. By contrast release timing is of lower importance for the less seasonal Mbita.ConclusionThis analysis suggests that DEG based methods of malaria vector control can be effective in a wide range of climates. In environments with substantial temporal variation in rainfall, careful timing of releases which accounts for the temporal variation in population density can substantially improve the probability of mosquito suppression or extinction.

Sliding Mode Variable Structure Vector Control of Permanent Magnet Synchronous Machine Servo System for Side Scan Sonar

To control the distance between the side scan sonar and the seabed, a permanent magnet synchronous machine(PMSM) servo system is designed, and the overall structure of the system and the design scheme of each part are presented. The maximum torque per ampere (MTPA) vector control method is adopted to enhance the power factor and dynamic performances of the system, and based on MTPA vector control method, according to the harmful effects of the dynamic load in the servo control of sonar, the sliding mode variable structure (SMVS) vector control method is proposed, and the robustness of the servo system is effectively improved. The mechanism of the MTPA and SMVS vector control method is demonstrated in detail, and their effectiveness is verified.

Pyrethroid resistance persists after ten years without usage against Aedes aegypti in governmental campaigns: Lessons from São Paulo State, Brazil.

BackgroundAedes aegypti, vector of dengue, chikungunya and Zika viruses, is found at high densities in tropical urban areas. The dissemination of this vector is partially the consequence of failures in current vector control methods, still mainly relying upon insecticides. In the State of São Paulo (SP), Brazil, public health managers employed pyrethroids against Ae. aegypti adults from 1989 to 2000, when a robust insecticide resistance monitoring system detected resistance to pyrethroids in several Ae. aegypti populations. However, pyrethroids are also the preferred compounds engaged in household applications due to their rapid knockdown effect, lower toxicity to mammals and less irritating smell.Methodology/Principal findingsWe evaluated pyrethroid resistance in Ae. aegypti populations over the course of a decade, from 2004 to 2015, after interruption of pyrethroid public applications in SP. Qualitative bioassays with papers impregnated with a deltamethrin diagnostic dose (DD) performed with insects from seven SP municipalities and evaluated yearly from 2006 to 2014, detected resistance in most of the cases. Quantitative bioassays were also carried out with four populations in 2011, suggesting a positive correlation between resistance level and survivorship in the DD bioassays. Biochemical tests conducted with seven insect populations in 2006 and 2015, detected increasing metabolic alterations of all major classes of detoxifying enzymes, mostly of mixed function oxidases. Genotyping of the voltage-gated sodium channel (AaNaV, the pyrethroid target-site) with a TaqMan real time PCR based technique was performed from 2004 to 2014 in all seven localities. The two kdr mutations, Val1016Ile and Phe1534Cys, known to be spread throughout Brazil, were always present with a severe decrease of the susceptible allele over time.Conclusions/SignificanceThese results are discussed in the context of public and domestic insecticide use, the necessity of implementation of a strong integrated vector control strategy and the conceptual misunderstanding between 'vector control' and 'chemical control of vectors'.

Population dynamics of engineered underdominance and killer-rescue gene drives in the control of disease vectors.

A number of different genetics-based vector control methods have been proposed. Two approaches currently under development in Aedes aegypti mosquitoes are the two-locus engineered underdominance and killer-rescue gene drive systems. Each of these is theoretically capable of increasing in frequency within a population, thus spreading associated desirable genetic traits. Thus they have gained attention for their potential to aid in the fight against various mosquito-vectored diseases. In the case of engineered underdominance, introduced transgenes are theoretically capable of persisting indefinitely (i.e. it is self-sustaining) whilst in the killer-rescue system the rescue component should initially increase in frequency (while the lethal component (killer) is common) before eventually declining (when the killer is rare) and being eliminated (i.e. it is temporally self-limiting). The population genetics of both systems have been explored using discrete generation mathematical models. The effects of various ecological factors on these two systems have also been considered using alternative modelling methodologies. Here we formulate and analyse new mathematical models combining the population dynamics and population genetics of these two classes of gene drive that incorporate ecological factors not previously studied and are simple enough to allow the effects of each to be disentangled. In particular, we focus on the potential effects that may be obtained as a result of differing ecological factors such as strengths of larval competition; numbers of breeding sites; and the relative fitness of transgenic mosquitoes compared with their wild-type counterparts. We also extend our models to consider population dynamics in two demes in order to explore the effects of dispersal between neighbouring populations on the outcome of UD and KR gene drive systems.