title: Paraffin wax emulsion for increased rainfastness of insecticidal bait to control Rhagoletis pomonella (Diptera: Tephritidae).
abstract: In regions with a humid summer climate, the use of water-soluble bait to control apple maggot is often limited by rainfall. We studied increasing the rainfastness of GF-120 fruit fly bait by adding paraffin wax emulsion. First, we verified that adding 10% wax to a mixture containing 16.7% GF-120 did not reduce the mortality of female apple maggot compared with GF-120 without wax. In addition, we determined that fly mortality caused by GF-120 plus wax subjected to simulated rain was similar to that caused by GF-120 without wax not subjected to rain. Other assays showed that higher fly mortality resulted from increasing the proportion of wax from 10 to 15%, and lower mortality resulted from decreasing GF-120 from 16.7 to 10 or 5%. The availability of spinosad on or near droplets of a mixture consisting of 5, 10, or 15% GF-120 and 15% wax was determined before and after the droplets were subjected to three 15-min periods of simulated rain. We found an initial steep decline in dislodgeable spinosad and smaller decreases after subsequent periods of rain. In a small-plot field trial, fruit infestation by apple maggot in plots treated with a mixture consisting of 16.7% GF-120 and 19.2% wax was less than in plots treated with 16.7% GF-120 without wax but not less than in control plots. Overall, we found that adding paraffin wax emulsion to GF-120 increased rainfastness in laboratory bioassays, and specifically that it retained the active ingredient spinosad. However, our field data suggest that optimal rainfastness requires the development of mixtures with > 19.2% wax, which may preclude application using standard spray equipment.
authors.affiliation: Department of Entomology, Michigan State University, East Lansing, MI 48824, USA. teixei10@msu.edu
authors.forename: Luís A F
authors.initials: LA
authors.lastname: Teixeira
authors.forename: John C
authors.initials: JC
authors.lastname: Wise
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Gut
authors.forename: Rufus
authors.initials: R
authors.lastname: Isaacs
mesh_terms: D000818:Animals; D005260:Female; D006813:Humidity; D007300:Insect Control / Q000295:instrumentation* / Q000379:methods*; D007306:Insecticides / Q000633:toxicity; D007814:Larva / Q000187:drug effects / Q000502:physiology; D008824:Michigan; D010232:Paraffin; D033621:Tephritidae / Q000187:drug effects* / Q000502:physiology
chemical_list: D007306:Insecticides; D010232:Paraffin