Effects of trap design and CO2 presentation on the measurement of adult mosquito abundance using centers for disease control-style miniature light traps

Centers for Disease Control miniature light traps augmented with CO2 provid e an effective method of monitoring Culex abundance and may provide a usefu l supplement to New Jersey light traps used by the California Mosquito Surv eillance Program. To assist in standardizing sampling protocols, the presen t research compared the catch of adult mosquitoes collected using 4 trap de signs and 3 CO2 presentation methods. When augmented with dry ice, the Arbo virus Field Station (AFS) trap (consisting of a 3-in. fan mounted into a wh ite polyvinyl chloride pipe and operated without a light source or rain shi eld) collected as many or more Culex females than similar traps purchased f rom John W. Hock and American Biophysics, or a trap with a 4.25-in. 2-blade d fan constructed by the Orange County Vector Control District (similar to the Encephalitis Virus Surveillance model distributed by Bioquip). Few bloo ded or gravid females and males were collected, indicating that CO2 release d from the dry ice and not light probably was the primary attractant. Catch of Culex tarsalis females in traps baited with CO2 released at 0.5-1.5 lit ers/min from gas cylinders was significantly greater than in traps baited w ith dry ice, even though the CO2 release rates from the dry ice at dusk pro bably were comparable to that released from the cylinders and averaged 0.4- 0.5 liters/min for the night. Traps baited with 0.5 liters/ min of CO2 gas released in 15 3- or 2-sec bursts per hour collected the fewest mosquitoes. In all experiments, trap location effects were significant and accounted f or as much Variability in catch size as trap design or CO2 presentation. Sa mpling efficiency of all trap designs or CO2 presentations were consistent over time, space, and different levels of mosquito abundance.