Mosquito Production in Built-in Containers at Condominiums and Apartments

Transcription

1 Mosquito Production in Built-in Containers at Condominiums and Apartments Ryan L. Harrison Forsyth County Department Public Health and Bruce A. Harrison

2 Study designed to determine: - significance of built-in containers in mosquito production (examples) - numbers of built-in containers that can be accessed and produce mosquitoes - mosquito diversity in these containers at 3 sites - abundance of potential/real vector species - any major differences in the 3 sites

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4 Caveat Water was collected from black pipes ONLY where it was visible. We tried to use siphon pumps to extract unseen water underground, however this method proved to be next to impossible as the tubing on the siphons naturally curled upwards. We know there is an abundance of water underground as albo s are regularly seen flying out of dry pipes.

5 Tabor View

6 Tabor View 40 units, with 128 black pipes 38 (29.6%)of them had visible water 8 sampled pipes yielded 70 larvae 54% Ae. albopictus WN, LAC, 12% Oc. japonicus WN, LAC? 2% Oc. triseriatus LAC, WN, EEE 22% Cx. pipiens complex WN, SLE 10% Cx. restuans WN, EEE, SLE

7 Bethania Oaks

8 Bethania Oaks 22 Apt/Condo units 29 black pipes 10 (34.5%) black pipes with visible water All ten black pipes had larvae, and a total of 40 larvae were collected 100% of the larvae found in black pipes were Ae. albopictus. 5 French drain openings (next slide) were found. A total of 55 larvae were collected from these drains, and yeilded a mix of 55% Cx. pipiens complex, 27% Ae. albopictus, and 18% Cx. restuans. [Hmmm - grass clipping's attracting the Culex??] Various other containers had larvae as well: Kiddy pool (Cx. restuans) and bird bath (Cx. restuans)

9 French Drains

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12 Sherwood West

13 Sherwood West 44 buildings with 165 black pipes 59 (35.8%) black pipes had visible water 90 trash cans held water, 41 (45%) had larvae On a later date we returned and randomly collected larvae from 10 black pipes and 10 trash cans. Mosquitoes from the black pipes were: 90% Ae. albopictus and 8% Oc. japonicus, 2% Oc. triseriatus LAC, WN, EEE The trash cans contained a mix of 45% Cx. pipiens complex, 28% Ae. albopictus, 15% Oc. japonicus, 7% Cx. restuans, and 5% Oc. triseriatus. WN, SLE, LAC, and EEE.

14 This pipe was perforated, but we still got 2.5 gallons of water and over 50 larvae of albos and japos out of it (not included on the previous slides).

15 Condo and Apartment Findings Built-in containers are common and provide good habitats for mosquitoes that are vectors of human pathogens. A range of 29.6% to 35.8% (average-one third) of the black pipes had visible water and could be collected. Five species in three genera were collected, and all are known or potential vectors of human pathogens. The black pipes favor Aedes and Ochlerotatus species, while French drains and garbage cans favor Culex species.

16 Containers associated with La Crosse encephalitis patients in Transylvania County in 2005

17 TWO KNOWN AND ONE SUSPECTED MOSQUITO VECTORS Ochlerotatus triseriatus, the tree hole mosquito Photo by James Gathany SUSPECTED VECTOR Ochlerotatus japonicus Aedes albopictus, the Asian Tiger mosquito Photo by Mike Sardelis Photo by James Gathany

18 La Crosse amplifying hosts Chipmunks & Squirrels

19 Results of habitat evaluation surveys at residences of La Crosse encephalitis cases Site Distance Treeholes Squirrels Containers Mosq. # to forest visible Chipmunks Perm:Disp Larvae* 1 10 m yes yes yes 2 5 m yes no 7 94 yes* 3 70 m yes yes 7 16 no* 4 25 m no yes 8 7 no* 6 5 m yes no no* 8a** 5 m yes no yes 8b** 5 m yes yes no* *Containers disposed of or water dumped 2 weeks before survey. **Patient 8 had two residences.

20 Residence 02 (= 101 containers)

21 CONTAINERS POSITIVE FOR LARVAE DATE CONTAINER Ae. albopictus Oc. japonicus Oc. triseriatus 27 Sept truck liner x-mas tree holder bowl bucket black-gum treehole Oct tarp on boat tarp on ground old sink Oct top of propane tank Oct pet dish metal trough plastic garbage can plastic garbage can used tires

22 Treehole Communities Aedes albopictus Ochlerotatus triseriatus Ochlerotatus japonicus Orthopodomyia signifera Toxorhynchites rutilus Anopheles barberi

23 Acknowledgements for workers assisting in Transylvania Co. - Brian Byrd - Parker Whitt - Gene Powell