A comparison of two ultra-low-volume spray nozzle systems by using a multiple swath scenario for the aerial application of fenthion against adult mosquitoes.
Two hydraulic spray nozzle systems, a flat fan and a high-pressure hollow cone, were used for ultra-low-volume application of the mosquito adulticide fenthion under a multiple swath scheme. Eight swaths at 322-m intervals were applied from a height of 91 m to simulate operational conditions. Deposition, effects on nontarget organisms (fiddler crabs), aerial flux, and mosquito (Ochlerotatus taeniorhynchus) mortality were monitored for 8,230 m downwind, including the area under all 8 swaths. The flat-fan nozzle system deposited 88 times the amount of fenthion deposited by the high-pressure system in a lightly vegetated zone directly beneath the application area (0-2,134 m). Further downwind (2,286-4,420 m) in the 2nd semiopen urban zone, 10.5 times more chemical was deposited with the flat-fan nozzles than with the high-pressure nozzles, and in the 3rd highly vegetated zone (4,572-8,230 m), 25 times more was deposited compared with high-pressure nozzles. The corresponding nontarget mortalities with the flat-fan nozzle were 80, 12, and 17% at 2,438, 3,658, and 4,572 m, respectively. No treatment-induced mortality was observed with high-pressure nozzles. Similar amounts of fenthion residue were recovered from yarn samples for both nozzle systems, with the exception of the zone directly under the flight paths, where the flat-fan system deposited 2.5 times the amount recovered with the high-pressure system. Mosquito mortality was similar between the 2 nozzle types except in the farthest zone, where the average mortalities for the high-pressure system and the flat-fan system were 73.4 and 34.8%, respectively. Regression analysis of the mosquito mortality and yarn samples showed that the high-pressure hollow-cone application could control mosquitoes with half the amount of chemical compared to flat-fan nozzles.
Dukes
James
J
John A. Mulrennan, Sr., Public Health Entomology Research and Education Center, College of Engineering Sciences, Technology and Agriculture, Florida A&M University, 4000 Frankford Avenue, Panama City, FL 32405, USA.
Zhong
He
H
Greer
Mike
M
Hester
Phil
P
Hogan
Donald
D
Barber
Jane A S
JA
D000336:Aerosols; D000818:Animals; D003386:Brachyura / Q000187:drug effects; D005284:Fenthion / Q000008:administration & dosage*; D007306:Insecticides / Q000008:administration & dosage*; D009032:Mosquito Control / Q000379:methods*; D044969:Ochlerotatus; D010573:Pesticide Residues
D000336:Aerosols; D007306:Insecticides; D010573:Pesticide Residues; D005284:Fenthion