# Presentation: 663173

## Studies in the Cambridge rainforest

- Paul Reiter
- CDC West Nile Project
- Harvard School of Public Health

## A collaborative study

- Harvard School of Public Health
- Massachusetts State Laboratory Institute
- Cambridge Public Health Department
- East Middlesex Mosquito Control Project
- Central Massachusetts Mosquito Control Project

- CDC Division of Vector-Borne Infectious Diseases, and:

## Egg-rafts in natural sites

## Cx.restuans egg-rafts, Memphis, 1981

## Hay infusion

## On the road

## The trap is laid

## Convenient collecting vessel

## Species identification in the 1st instar

- egg-breaker

## Egg rafts, Memphis,1982

## Memphis, 1983, Cx. restuans eggs

## Gravid mosquitoes, 1983

## 1983, Cx. restuans, gravid females

## What is the impact of ULV treatments on Culex pipiens and Cx. restuans?

## Bioassay Cages

## Memphis, Resmethrin, 0.0062 lb/acre

- 1

- 2

- 3

- 4

- 5

- 6

- 7

- 8

- 9

- 10

- 11

- 12

- 0

- 10

- 20

- 30

- 40

- 50

- 60

- egg-rafts per site

- day of trial

## Memphis, mean % change, 4 trials

## Summary of observations, Memphis

- Springtime* restuans* and enzootic transmission coincide
- Dramatic early summer disappearance of *restuans*
- Dramatic fall reappearance of *restuans*
- Principal* Cx. pipiens* activity _after_ *restuans *dormancy
- ULV resmethrin effective against *Culex* species

## Egg-raft collections, Boston, 2001

- 0.00

- 5

- 10

- 15

- 20

- 25

- 30

- 35

- 40

- 45

- 1-Jun

- 1-Jul

- 1-Aug

- 1-Sep

- 1-Oct

- 1-Nov

- 1-Dec

- 1-Jan

- egg-rafts per pan

- date

## Culex larval infestation rates

- Cambridge
- Yards:		27% positive (n = 30)
- Jamaica Plain
- Catch basins:	38% positive (n = 100)

## Burlington, resmethrin,  0.001 lb/acre

- egg-rafts per site

## Framingham, Resmethrin, 0.00175 lb/acre

## Tewksbury, Resmethrin, 0.007 lb/acre

- 4-Sep

- 5-Sep

- 6-Sep

- 7-Sep

- 8-Sep

- 9-Sep

- 10-Sep

- 11-Sep

- 12-Sep

- 13-Sep

- 0

- 2

- 4

- 6

- 8

- 10

- 12

- 14

- egg-rafts per site

- date

## Why was ULV resmethrin effective against Culex spp in Memphis ... but not in Massachusetts ... ?

## Possible reasons?

- Application rate?
- Street plan?
- Vegetation?
- Weather variables?
- Mosquitoes behavior?

## Egg-raft collections, after August 1

## Egg-raft collections in fall

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 20-Aug

- 27-Aug

- 3-Sep

- 10-Sep

- 17-Sep

- 0

- 5

- 10

- 15

- 20

- egg rafts per site

- week

*p* = 0.94

## Bird-baited trap

## Urban Culex are canopy feeders?

- Ground

- Canopy

- 840

## Decline of Culex adults in autumn

- Decline of* Culex *adults in autumn

- September

- October

## Parous rate of blood-feeding Culex

- These mosquitoes ecloded before August 10th?

- Mosq.

- Parous

- %

- 7

- 77.8

- 10

- 100.0

- 22

- 95.7

- 11

- 100.0

- 4

- 100.0

- 4

- 100.0

- 4

- 100.0

- 6

- 100.0

- 16

- 88.9

- 1

- 100.0

- 9

- 100.0

- 13

- 100.0

- 6

- 100.0

- 9

- 6

- 100.0

**124**

**119**

**97.3**

- Sep 20

## Questing at caged starling, Sept 10-11

## Questing at caged starling, Sept 11-12

## Questing at caged starling, Sept 12-13

## Flight at oviposition site, Aug 21-22

## Flight at oviposition site

- Mean of 4 nights data

## Overwintering

## Survival in overwintering Culex

- Cold winter

*El Niño* winter

## Conclusions (Boston): background data

*Cx restuans *and *Cx pipiens* are abundant
- Source is not clear
- Catch basins may not be significant as source

## Blood feeding

*Cx. restuans* and* pipiens* feed in tree canopy
- Questing occurs throughout the night

## Oviposition

- Flight over sites mainly in early night
- Oviposition mainly late in night

## After early August ...

- Pre-diapause adults feed and oviposit
- Diapausing adults do not feed
- Survival rate of pre-diapause adults is high
- Adulticides: major impact on transmission?
- Survival of overwintering adults is high

## Acknowledgements

- Duane Gubler
- Andy Spielman
- Richard Pollack
- Tony Kiczewski
- Chris Mores
- Sam Telford
- Mike Reddy
- TJ Lepore
- Sejal Shah
- Matthew Garland
- Brian Spencer
- Patrick Barton
- Nina Kishore
- Henry Goldfarb
- David Goldfarb

- Ralph Timperi
- Barbara Werner
- Sam Lipson
- David Henley
- Tim Deschamps
- Gary Alpert
- James Willcox
- Larry Acosta
- Paul Meyvaert
- Curtis Brown & Diane Allen
- About 120 householders