Effect of Afidopyropen and Dinotefuran on Elm Zigzag Sawfly Control, 2021

The goal of this trial was to assess the efficacy of two insecticides for the control of the newly invasive elm zigzag sawfly (EZS) in ornamentals. EZS larvae were collected on 7 July 2021 from a tree stand of Siberian elms in a suburban area near Winchester, VA. Additionally, several 2-ft long mature tree branches were collected from other elm trees as a source of foliage. Branches were treated with the insecticides on the same day that EZS larvae collection occurred. Treatments included, afidopyropen (Ventigra), dinotefuran (Zylam) and an untreated control check; and they were set up as a RCD with three replications, using three to four mature and insecticide-treated leaves, as experimental units. Each set of leaves was enclosed along with four similar-size EZS larvae in a 16 fl oz-plastic deli cup container and kept in an outdoor wood structure under shade. Insecticide treatments were made as foliar sprays, until run-off, using a CO₂ backpack with a TP Teejet 8003 VS nozzle at 30 PSI. Number of live larvae was counted at 1, 2, 3, and 7 days after treatment (DAT). Data from each collection date were individually subjected to an ANOVA, and means were separated using the Tukey’s HSD.

The number of live EZS larvae was significantly influenced by our experimental insecticide treatments (Table 1). Dinotefuran had the highest mortality on EZS larvae (83%) and its effect was consistent from 1 to 3 DAT. Afidopyropen failed to control EZS larvae under these experimental conditions. Mortality rates that originated from this insecticide active ingredient were not significantly different than those of the untreated check at 1–3 DAT. By 7 DAT, mortality rates were high (>50% mortality) and were not significantly different among treatments and the untreated.¹

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