Performing Department
Biological Sciences
Non Technical Summary
This work centers on the ecology of mosquitoes and ticks that transmit human pathogens.Our first aim is to understand what environmental and landscape factors allow invasive mosquitoes to establish and spread in Rhode Island. Successful invasions are quite rare, and it is estimated that only 10% of introduced species successfully invade and establish. The Zika vector Aedes albopictus exemplifies a tremendously successful ecological invasion in the United States. Surveillance has allowed public health officials to track the course of the invasion, yet there is limited information on the constraints governing the distribution of this organism. The current and potential range of this vector has recently been characterized and mapped based on surveillance data and global temperatures, but beyond temperature the forces that facilitate the invasion, persistence, and establishment of populations remain poorly understood. Our proposed work aims to improve our understanding of the invasion ecology of Ae. albopictus and predict how the current distribution of this Zika vector will expand in the years to come.Our second aim focuses on controlling mosquito populations through the application of carnivorous aquatic plants, commonly known as bladderworts, that naturally occur in ponds throughout US that can consume mosquito larvae, but also grow without mosquitoes present. Despite centuries of biological research on mosquito vectors, there is very little known about the role plants play in regulating mosquito populations. New methods for the control of mosquitoes are needed that are effective but also do not harm non-target insects such as beneficial pollinators. Few studies have experimentally studied the application of bladderworts as a biological control measure for mosquito larvae. We will examine the impacts of placing plants in backyards on local mosquito populations.
Animal Health Component
100%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Goals / Objectives
Develop and strengthen effective surveillance and monitoring of disease vectors at local and regional scales, including the development and testing of novel trapping and vector/pathogen identification techniques. Under this objective, project participants will leverage and strengthen existing surveillance programs in a coordinated fashion to yield robust comparable data across large geographic scales.
Determine the ecology and geographic distribution of invasive and native disease vectors under changing environmental conditions to enhance our ability to predict conditions leading to existing and novel animal and human diseases.
Project Methods
Project 1To obtain baseline oviposition data and to provide wild type Ae. albopictus females for laboratory experiments we will set oviposition traps consisting of black cups partially filled with water and an oak leaf infusion. The eggs are laid on a small piece of germination paper partially submerged in the cup. We are planning to install oviposition traps positioned in transects extending through the sampling site. The collections will be done weekly in the mosquito surveillance months of June to September. Oviposition cups will be changed at the same time. The germination paper with eggs will be brought to the RI DEM laboratory, hatched, the larvae counted, and identified to the species. To obtain baseline adult population data to determine the presence of current populations and the abundance over the study period we will use two methods, conventional BG Sentinel traps and the Prokopack hand held mosquito aspirator (Vazquez-Prokopec et al. 2009), weekly at each site. The Prokopack aspirates adult mosquitoes at rest into a collection cup using a motor that is attached to a hand-held pole in order to allow targeted collections around resting habitat (i.e. tire dumps, around homes, underside of leaves in bushes, etc.). We will test this recently developed tool in mosquito collection, the Prokoack, against the conventional BG Sentinel trap.Currently there are 4 weather monitor stations in the state of Rhode Island. We will place HOBO data loggers that monitor temperature, humidity, and light level at sampling sites for the duration of the sampling season. To analyze these data we will use a combination of statistical modeling and geographic information systems to create predictive models of the invasion potential of Ae. albopictus for RI based on the sampling data collected, experimentally estimated cold tolerance of the introduced Ae. albopictus eggs found in sampling, weather monitoring data, and spatial data on points of entry and calculated rates of spread for Ae. albopictus. We will develop a predictive spatio-temporal model of the invasion of the Zika vector for Rhode Island. This model will have broad applications for use in areas in the United States that are along the northern edge of the distribution of Ae. albopictus.Project 2Lab: To experimentally evaluate larval survival Aedine mosquitoes with and without bladderworts we propose an experiment to measure direct predation of bladderwort on larval survival of Ae. albopictus, Ae. aegypti, and Ae. japonicus. Larval survival will be evaluated by placing larvae at each instar stage into cups with bladderwort plant cuttings. The number of bladder traps, though the diet added daily will vary based on previous findings of conditions that range from poor to favorable for Ae. aegypti (Couret et al. 2014). Preliminary results show that in Ae. albopictus, 20 first instar larvae were fully predated within 3-5 days for most cups. This experiment will be repeated for each species individually and interspecific combinations in the laboratory. In the summer of 2018 experiments will be repeated in semi-natural field conditions at URI at the East Farm Agricultural Experiment Station in Kingston, RI A lux meter and a HOBO data logger will be used to evaluate differences in environmental conditions across semi-natural field sites.Field: We will test bladderwort-enhanced-trapping of mosquitoes compared to traditional-trapping at control sites without bladderworts. Bladderwort-enhanced-traps are those with plant cuttings either placed in gravid solution or in water with crush leaves for gravid and oviposition traps respectively. During the mosquito surveillance season in RI, a Couret lab research assistant will set bladderwort-enhanced traps at 10 sites around the state. Traditional-trapping will be done by RI state collaborators, RI Department of Environmental Management (RIDEM) Mosquito Abatement. RIDEM has 28 long-term mosquito trap sites, and a subset of 10 sites have gravid traps, light traps, and oviposition traps. Based, in part, on the results from the oviposition experiments in Objective 1, aspects of the traps will be refined, including the length of plant and number of bladders. Mosquito abundance, species distribution, and oviposition will be measured weekly across sites. Field: Based on the results from laboratory experiments we will evaluate bladderwort for biocontrol in semi-natural backyard conditions. We expect that this will be a pilot experiment in the first year. Recruiting households in urban and suburban neighborhoods, we will place bladderwort plants in backyard bird baths or artificial stagnant ponds. Rather than emptying birdbaths, as is the general recommendation, backyard larval habitats will be maintained with water throughout a 2 week period study period during which pupae will be removed. Based on our 2017 surveillance data this is the peak month for mosquito populations in Rhode Island. Backyards will be chosen based on the presence of an artificial larval habitat such as a bird bath, the number of additional larval habitats based on Breteau indices. Yards treated with bladderwort will be compared to control yards without bladderwort.