Susceptibility of Tarnished Plant Bug to Select Insecticides and Development of Diagnostic Doses

To determine baseline susceptibility of Lygus lineolaris (Palisot de Beauvois) to conventional and reduced-risk insecticides, serial dilutions of dicrotophos, dicrotophos+bifenthrin, bifenthrin, acetamiprid, acephate, zeta-cypermethrin, dimethoate, cyantraniliprole, imidacloprid+bifenthrin and sulfoxaflor and others  were each prepared from a 1000ppm stock solution. A petri dish was sprayed to 100% coverage with each representative solution using a Crown Spray-Tool system (Woodstock, Illinois) and allowed to dry.  A green bean was dipped into solution with 0.25% Silwet L-77 surfactant, allowed to dry, and added to the petri dish.  Fifteen adult plant bugs were added to each petri dish, the dish was sealed with parafilm to prevent escape and held at 26.8±2ºC, 70% RH, 14:10(L:D). Mortality was assessed after 48h. Probit mortality lines for three diagnostic doses, LD₅₀, LD₇₅, and LD_95, for each chemical were estimated using POLO (LeOra Software, 2007).

            The developed diagnostic doses determined thus far are: acetamiprid: 19.39, 33.72, 74.74ppm; imidacloprid+bifenthrin: 10.32, 16.78, 33.77 ppm; cyantranilioprole: 735.09, 1141.84, 1697.27 ppm; dimethoate: 9.55, 23.79, 88.35 ppm; and zeta-cypermethrin: 1.29, 3.16, 11.48 ppm; sulfoxaflor: 0.05, 0.62, 5.90 ppm; dicrotophos+bifenthrin: 5.31, 7.47, 10.15 ppm; dicrotophos: 3.96, 7.86, 14.56 ppm; bifenthrin: 0.39, 4.22, 35.97 ppm; acephate: 0.62, 5.09, 33.86 ppm, respectively.  Diagnostic doses (LD50, LD75, and LD90) have been determined and tested on a susceptible lab colony for acetamiprid, imidacloprid+bifenthrin, dimethoate and zeta-cypermethrin.   Determination of diagnostic doses are still pending for indoxacarb,and novaluron. A tank mix of acephate and bifenthrin will be tested for synergism using PoloMix program once their individual dose response curves are determined.