Development Of Long-acting Biocide Bti-Block And Mosquito-borne Monitor

Background:Arbovirus transmitted by Aedes.albopictus is becoming an increasingly serious threat to global public health.With the continuous global invasion and fast emerging insecticide resistance among the Aedes.albopictus population,the limitations of traditional mosquito management strategies are increasingly apparent.It is imperative to improve the control strategies and develop new monitoring methods.Biopesticide,a contraction of biological pesticides’,is generally the natural pathogen of pests,with strict species specificity,and has little or no known direct impact on non-target vertebrates or invertebrates.Bacillus thuringiensis subsp.israelensis(Bti)is a kind of bacillus bacteria with high toxicity to mosquito larvae which has been increasingly used worldwide for mosquito control for decades.The Insecticidal crystal protein(ICP)produced by Bti can be activated in the alkaline midguts of the mosquito to kill the host,and it has been confirmed that it is not easy to result in insecticide resistance in the field application,thus achieving the objectives of protecting human health,environmental safety,and sustainable development.However,the Bti dosage forms currently have the disadvantages of a short duration of action,and spore and ICP quickly lose efficacy under the influence of adverse environmental factors,limiting the promotion and application of Bti for control of Aedes albopictus.For Aedes albopictus,the vector of dengue fever,the traditional monitoring methods include the Bretu index,Mosq-ovitrap and "Double-mosquito net",In practical application,they are usually Labor-intensive work for investigate and data collecting.In nowadays,high-speed,highly efficient mobile communication system is accessible to get.It is of great significance to develop an Internet-based mosquito density monitor to counting and recording the mosquito density in real-time,which can provide a scientific reference for the early prevention and accurate intervention of mosquito and its infectious diseases.Objectives:1.Develop a Bti formulation with simple production technology,low cost,longterm sustained release,and UV protection.2.This study evaluated the sustained release and insecticide efficacy of new formulation under laboratory,semi-field,and field research to test their efficacy in reducing the dengue vector population.3.Develop a monitoring trap that can accurately and specifically collect and count vector mosquitoes,with real-time Internet transmission functions to provide a reliable reference for mosquito vector density monitoring and early warning of infectious disease epidemics.Methods:1.Based on solid-liquid dispersion,polyethylene glycol and hexadecanol were used to form an effective polymer molecular skeleton to encapsulate Bti.The longterm sustained release of Bti in water was realized by different ratios of watersoluble carriers and non-water-soluble carriers.2.The release efficiency of the formulation was evaluated under laboratory conditions to verify and ensure the active ingredient of Bti remains.3.Develop a novel lethal trap that would effectively attract A.albopictus to lay eggs for further application.4.Explore the effect of new Bti formulation on oviposition preference of female Aedes albopictus.5.Use bioassays to assess the effectiveness and duration of validity of new formulations.6.In the field environment,the inhibited effect of the combination of new dosage forms and breeding trap on the population density of A.albopictus was tested,and the Ross-Macdonald model was used to evaluate the impact of control measures on the risk of dengue vector for the experimental area.7.Based on mosquito sensor consists of arrays of infrared LEDs and light detectors that provide reliable and sensitive detection,an Internet-based mosquito density monitor is developed.8.Test the capture efficiency,this mosquito counting traps were tested in different condition to evaluate whether they can specifically capture mosquitoes and count them according to their size.Results:1.A sustained-released formulation,named Bti-Block,was successfully developed,which can be directly used for the long-term killing of mosquito larvae in container habitats.2.Under laboratory conditions,Bti-Block effectively prolonged the efficacy duration of Bti in water to more than 188 days.3.In semi-field and field experiments,Bti-Block combined with artificial breeding trap(ABT)can effectively induce female Aedes.albopictus to lay eggs and achieve more than 90%killing effect in trap water which can be maintained for more than four weeks.The emergence of mosquito pupae can be completely inhibited.4.In the test of 40000 m2 experimental area,the combination could collect more than 10,000 eggs and killed thousands of A.albopictus larvae per month,and the adult mosquito density in the coverage area was reduced by more than 50%,according to human landing index.5.According to the Ross-Macdonald model,the R0 values were 9.297 and 0.715 before and after intervention based on gloomy prediction,which meant that the risk of dengue transmission could be minimized by 92.31 per cent.6.A mosquito vector density monitor MS 100 was successfully developed.It can automatically differentiate mosquitoes from other insects entering the trap,counts them,and wirelessly transmits the results to a cloud server with sensitivity and specificity above 90%.Conclusion:1.A sustained release formulation named Bti-Block was developed to ensure the activity of spores and toxin proteins with extending duration of larvicide efficacy for more than 180 days.2.Bti-Block based lethal traps can effectively reduce the population density of dengue vector Aedes albopictus in field applications.3.A mosquito density monitor was successfully developed to monitor the population density of A.albopictus in real time.The above results will become a powerful tool for the prevention and monitoring of dengue vector Aedes albopictus,and have a certain application prospect.