Recipient Organization
VIRGINIA POLYTECHNIC INSTITUTE
(N/A)
BLACKSBURG,VA 24061
Performing Department
Entomology
Non Technical Summary
Diseases transmitted by vectors, such as ticks and mosquitoes are resurgent and spreading into new environments. Southwest Virginia, for example, has become an emerging focus of virus activity (e.g., LAC V) in recent years, and research shows an increase prevalence of deer ticks carrying the bacteria for Lyme disease. These trends suggest an increased risk of tick and mosquito-borne diseases to residents of the region and throughout the state. This proposal seeks to narrow the knowledge gaps in our understanding of the prevalence of Lyme disease in Virginia by evaluating the potential of using white-tailed deer as a surrogate measure for the risk of Lyme disease to humans. With the close association between white-tailed deer and ticks, it is expected that many deer will be infected with pathogens transmitted by ticks. In Virginia, a large number of deer are killed annually throughout the state so an ample supply of blood is available for testing for antibodies to the Lyme disease pathogen.In addition to studies on ticks, the research also seeks to determine whether common mosquito species in the region are competent vectors of two emerging viruses, Zika and Cache Valley. Repellents such as DEET are expected to provide protection to humans against mosquito bites. Previous studies have shown that virus infection can affect mosquito feeding behavior. However, a question remains about whether infection also alters host-seeking behavior, particularly in the presence of repellants. The research will compare the host-seeking and biting behaviors of virus-infected and uninfected mosquitoes to determine whether the ability of repellents to protect individuals is altered by the virus infection state of the mosquito. Finally, a key component of any insect management/control program is surveillance (sampling). Surveillance methods for mosquitoes have focused on either the immature (larval/pupal) or adult stage with adult sampling considered to be more useful for assessing changes in population size and the effectiveness of the control programs. Ethical and labor concerns limit the use of some adult sampling methods, such as human landing catches and backpack aspirator collections, which leaves adult trapping as the next best alternative. The efficacy of adult trapping can be affected by several factors including the stage of female mosquitoes, i.e., host seeking or gravid. Some traps are better at capturing gravid females, while others are more attractive to host-seeking females. We are developing a multifunctional 3D printed mosquito trap that can be used for capturing both gravid and host-seeking females, simultaneously, thus eliminating the need to deploy different type of traps.
Animal Health Component
40%
Research Effort Categories
Basic
50%
Applied
40%
Developmental
10%
Goals / Objectives
Integrated tick management and community-centered approaches, including understanding the biology and ecology of novel and emerging tick-borne pathogens
Ae. albopictus and Ae. aegypti, with a focus on surveillance, invasion ecology, genetics
New Control Tools, including socio-ecological approaches
Project Methods
In Virginia, the hunting season for white-tailed deer is usually from mid-fall to early winter. During this period, approximately 180, 121 deer are killed throughout the state, providing an ample supply of blood samples that could be tested for antibodies reactive to Borrelia spp. We will visit local butchers to obtain blood samples from hunter-killed white-tailed deer, which will be centrifuged and the serum collected. We will use the SNAP 4Dx test, an enzyme-linked immunosorbent assay specified for use in the veterinary field, to test for the presence of the B. burgdorferi [Murdock et al. 2009,Distribution of Antibodies Reactive to Borrelia lonestari and Borrelia burgdorferi in White-Tailed Deer (Odocoileus virginianus) Populations in the Eastern United States. Vector-Borne and Zoonotic Diseases 9 (6): 729-736].Mosquitoes from a lab-reared colony will be provided with a sheep blood and virus mixture in an artificial blood feeder to simulate the consumption of an infected blood meal. Individuals that take a full blood meal will be removed and placed into a separate cage, and will be maintained in an insectary with 10% sugar water at 24C, 75% relative humidity, and a photoperiod of 16:8 (L:D) for 14 days. At least 1mL of the virus-blood mixture will be retained to determine the virus titer of the blood meal.After the 14-day period, we will extract saliva from the blood-fed mosquitoes to test for the presence of the virus using Vero cells. For the repellent study, mosquitoes will be injected with virus and infection will be verified. After seven days, the mosquitoes will be exposed to repellent-treated or untreated membranes on an artificial blood feeder. The number of mosquitoes landing, probing, and blood feeding will be recorded. The effects of virus infection on glutathione S-transferase activity in mosquitoes will also be tested. Female mosquitoes will be injected with virus and maintained in an insectary with 10% sugar water at 24C, 75% relative humidity, and a photoperiod of 16:8 (L:D). Ten mosquitoes will be removed at 3, 7, and 10 days post-infection and placed into a -80 °C freezer. A standard GST spectrophotometric assay will be performed using reduced glutathione and 1,2-dichloro-4-nitrobenzene, and absorbance will be measured using a microplate spectrophotometer.3D printing is a novel technology that holds much potential for development of small devices such as mosquito traps. The plastics used in printing are relatively cheap ($20 to $30 for 2 Kg = 1 spool) and can be easily recycled. We will use 3D printing to develop a multifunctional mosquito trap that can function as a standalone host-seeking or gravid trap, or that can perform both functions simultaneously. Our initial tests of the trap will be conducted in a large outdoor flight cage. Live adult insects will be released at the center of a 48 m2 (4 x 12 m) screened enclosure constructed within a polycarbon greenhouse with a 5 x 15 m floor space. The double enclosed system will provide a controlled environment for testing the traps and will help to contain the insects within the facility.