Evaluation of foliar insecticides for control of rice stink bug in Texas rice, 2023

The rice stink bug (RSB) is a significant insect pest affecting rice. Feeding by both adult and nymph RSBs on developing rice grains not only leads to a decrease in overall yield but more significantly reduces grain quality, resulting in the development of pecky rice. In 2023, the efficacy of selected foliar insecticides for the management of RSB-infested rice panicles was evaluated in 2 field locations. Those field trials were conducted at the Texas A&M AgriLife Research Center at Beaumont and at the David R. Wintermann Rice Research Station at Eagle Lake, TX. Plots were 4.1 ft wide by 16 ft long (Beaumont) and 3.75 ft by 16 ft (Eagle Lake). A long-grain rice variety ‘Trinity’ was planted at a seeding rate of 80 pounds per acre on 4 May and 30 May at Beaumont and Eagle Lake, respectively. Plots were maintained according to 2023 Texas Rice Production Guidelines. Four insecticide treatments including 2 rates of Endigo ZCX (AI: thiamethoxam and lambda-cyhalothrin), Tenchu 20SG (AI: dinotefuran), Belay (AI: clothianidin), and an untreated check were evaluated in an RCBD with 4 blocks. At the milk to soft dough stage, pretreatment data of RSB were sampled from each trial on 24 Aug (Beaumont) and 8 Sep (Eagle Lake) before insecticide application. On sampling dates, RSB nymphs were not found at Beaumont, while both nymphs and adults of RSB were present at Eagle Lake. On 25 Aug and 8 Sep, foliar insecticides were applied at Beaumont and Eagle Lake, respectively, using a hand-held CO₂-pressurized 3-nozzle spray rig (800067 tips, 50 mesh screens, 28 gpa final spray volume).

The efficacy of insecticides was determined by sampling each plot using a 15-inch sweep net at 3, 7, and 10 days after treatment (DAT) at Eagle Lake and 3, 7, and 11 DAT at Beaumont. Densities of RSBs were measured by recording the total number of adults and nymphs per 10 sweeps in each plot. Data from each sampling date were analyzed separately using analysis of variance (ANOVA) (PROC ANOVA, SAS ver.9.4). Means were separated using Fisher’s least significant difference (α = 0.05).

At Beaumont, differences among treatments were detected on 3 DAT only (Table 1). Insecticide treatments decreased RSB densities by 63%–86% compared with the untreated check 3 DAT. However, there were no significant differences in RSB densities among treatments 7 and 11 DAT. A similar trend was observed at Eagle Lake where the total number of RSBs was only significantly reduced at 3 DAT by all insecticide treatments compared with the untreated check (Table 2). Two rates of Endigo ZCX and Tenchu 20SG exhibited a reduction in RSB densities, ranging from 83% to 100%, compared to the untreated check, while Belay demonstrated a 50% reduction at 3 DAT. Throughout the experiment, the populations of RSBs recorded in all plots at Eagle Lake remained below the economic threshold of 5 RSBs per 10 sweeps during the heading or milk stage of rice.¹

Footnotes