Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/15/2008
Publication Date: N/A
Interpretive Summary: No summary. See abstract.
Technical Abstract: Protection of people and their livestock from vector and nuisance mosquitoes and other biting arthropods (e.g. Phlebotomine sandflies) is complicated by logistical and operational constraints related to broad-spread insecticide applications. Little, if any attention has been directed at the use of perimeter application of residual insecticide to reduce vector infiltration by passive exposure to treated vegetation and harborage while at rest. Barrier treatment allows an insecticide to be delivered to where mosquitoes are resting and harboring. An objective of our research program is to evaluate the residual effectiveness of various insecticides applied to vegetation. This presentation will summarize our initial studies with bifenthrin (TalstarOne). Studies were conducted under semi-field (large outdoor screen cages located at USDA-ARS, CMAVE, Gainesville, FL) and natural field conditions (ricefields near Stuttgart, AR). The overall objective is to evaluate the residual effectiveness of various insecticides applied to natural vegetation. One of our goals was to develop a standardized method to evaluate various candidate insecticides under semi field conditions and then use this standardized method to evaluate effectiveness of insecticides under natural field conditions. This was accomplished by utilizing outdoor screened cages (30’ wide x 60’ long x 16’ high gabled to 18’). Three cages were dedicated to these studies. Two cages always contained a barrier of plants. The third cage sometimes contained a barrier of plants depending on the focus of the experiment. Over the course of three years a sequence of experiments were conducted. Initially, a comparison was made on the impact of having a barrier of plants versus no barrier on mosquito abundance in trap collections. Experiments which followed focused on the impact of treated versus untreated plants. These experiments were conducted with a regular backpack sprayer to determine the effect of different treatment rates. Lastly, the effect of application techniques, i.e. regular backpack sprayer versus the use of an electrostatic sprayer on efficacy and longevity of the insecticide application was evaluated. When a barrier of plants was utilized, it consisted of a 10’ x 10’ arrangement of potted southern wax myrtle plants (Myrica certifica) around a propane powered mosquito trap (Coleman MD-2500), which simulated the presence of a human. A propane powered trap was also located in the center of the cages without plants. Efficacy of treatment was determined by trap comparisons, landing counts and leaf bioassays. As already mentioned the trap utilized was the Coleman MD-2500, which produced carbon dioxide, water vapor and heat through the combustion of propane. An octenol (1-octen-3-ol) lure was added as an additional attractant. Two species of laboratory reared mosquitoes (Aedes aegypti and Ochlerotatus taeniorhynchus) were released into the cage in the late afternoon. Landing counts and trap collections were made the following morning, approximately two hours after sunrise. Trap comparisons not only included observations on the quantity of mosquitoes collected, but also on their vigor 14 h after release. Bioassays were conducted simultaneously to assess insecticidal residual activity of treated plants. Trap collections and bioassays were conducted the day before the plants were treated, the day of treatment (after the plants had dried), the day after treatment, and thereafter on a weekly basis. Leaves of treated and untreated plants were randomly removed with the exception that leaves from new growth were not used in these bioassays. Leaves were taped into Petri dishes and then laboratory reared mosquitoes were also placed into the Petri dishes to determine 1 h knockdown 4 h and 24 h mortality. Four species of mosquitoes were used in these bioassays: Ae.