Evaluation of Contact and Residual Activity of Selected Insecticides for Control of Rice Stink Bug. Beaumont, TX

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1 Title: Evaluation of Contact and Residual Activity of Selected Insecticides for Control of Rice Stink Bug. Beaumont, TX Principal Investigator: M.O. Way Texas A&M University Agricultural Research and Extension Center 1509 Aggie Drive Beaumont, TX (phone) (fax) ( ) Introduction The rice stink bug (RSB), Oebalus pugnax, is a key pest of rice in Texas. USEPA may prohibit use of organophosphates and carbamates in the future. This means rice farmers may lose currently registered RSB insecticides containing carbaryl and methyl parathion. Thus, other potential RSB insecticides must be evaluated for efficacy. The objective of this experiment is to evaluate selected insecticides for contact and residual activity against the RSB. Materials and Methods Two experiments were conducted at the Texas A&M University Agricultural Research and Extension Center at Beaumont in Experiment1: This experiment was designed to evaluate the effectiveness of the treatment insecticides applied directly to adult RSB. Adult RSB were collected at the Beaumont Center on 28 Sep by sweep net from untreated rice. Insects were placed in ventilated plastic tubes which were transported to the greenhouse. In the greenhouse, 10 adult insects were placed inside a cylindrical metal screen (1/4 inch mesh) cage which was 1 inch tall and 7 5/8 inches in diameter. Each cage with 10 RSB was a replication and each treatment consisted of four replications. Treatments are described in the tables. The screen cages with insects were sprayed with the treatment insecticides on 28 Sep with a three nozzle (tip size , 50 mesh screens), hand-held spray rig pressurized with CO 2 (20-30 psi). Spray swath was about 4 ft and final spray volume was 28.8 gpa. Insects were allowed to dry for 1 hour then each group of insects in each cage was transferred to four untreated rice panicles whose severed ends were inserted in moist sand in a styrofoam cup. The panicles were in the dough stage of development. A transparent, ventilated plastic cylinder was placed over the RSB-infested panicles. This plastic cylinder served as a cage once the bottom was inserted in the sand and the top fitted with a fine mesh organdy cloth. Number of dead insects was recorded 24 and 48 hours after application of treatment insecticides. Experiment 2: This experiment was designed to evaluate the effectiveness of the treatment insecticides applied indirectly to adult RSB by caging the insects on panicles sprayed in the field. Plots were laid out in a randomized complete block design in an untreated rice field (Cocodrie) in the dough stage of development. Each plot was 20 ft x 4 ft (seven rows, 7 inches between rows). 66

2 Treatments described in the tables were replicated four times. On 11 Sep, plots were sprayed with the treatment insecticides with a three nozzle ( tip size, 50 mesh screens), hand-held spray rig pressurized with CO 2 (20-30 psi). Spray width was about 4 ft. Final spray volume was 28.8 gpa. One, 4, 7, 10 and 14 days after application, four panicles were randomly removed from each plot. Immediately after removal, severed panicles were transported to a greenhouse. Each set of four panicles was caged in a transparent plastic cylinder ventilated with screen windows and a screen top. The severed ends of panicles were inserted in moist sand contained in a styrofoam cup. The bottom of the cage was secured in the moist sand. Once panicles and cages were in place, each cage was infested with 10 adult RSB collected by sweep net from untreated ratoon crop rice. At 24 and 48 hours after infestation, cages were inspected for dead insects. For both experiments data were expressed as % mortality which was transformed using arcsine. Transformed data were then analyzed by 2-way ANOVA and means separated by DMRT. Additional Materials and Methods for rice production practices for Experiment 2: 17 May drill-planted 90 lb/acre 18 May at planting urea applied by 2/3 of 170 lb N/acre, incorporated with a rake and flushed 26 May rice emerged through soil (League) 9 d after planting; from emergence to permanent flood, plots flushed as needed 14 Jun Arrosolo 2 qt/acre, 1.5 pt/acre, Facet 0.5 lb/acre and 1 pt/acre applied with a 13 nozzle, two-person spray rig (tip size = 80015, 50 mesh screens, swath width = 21.7 ft, final spray volume = 12.3 gpa) pressurized with CO psi 15 Jun permanent flood (20 d after emergence) 3 Jul panicle differentiation urea applied by 1/3 of 170 lb N/acre (thus, 170 lb N/acre applied during entire growing season) Results Experiment 1: Due to consistently lower than expected values in replication IV (Tables 1 and 2), results from three (and not four replications) are analyzed and interpreted. Forty-eight h after treatment, the Orthene, Karate Z, F0570 (Fury), and the high rate of GF-317 treatments provided over 90% contact control of RSB (Table 8). Experiment 2: The Orthene treatment gave the best residual control; 7 d after treatment over 30% mortality was recorded (Tables 5 and 9). At 10 d after treatment, none of the test insecticides provided control (Tables 6 and 9). Karate Z, Fury and the high rate of GF-317 treatments provided 20-30% control 1 d after treatment (Tables 3 and 9). In the future, field and lab/cage residual activity tests should be conducted simultaneously. If field tests show longer activity than lab/cage tests, then insecticidal repellency may be involved. 67

3 Table 1. Contact activity (24 h after treatment) of selected insecticides vs rice stink bug. Beaumont, TX % mortality (24 h after treatment) Description [lb (AI)/acre] I II III IV 0 a Karate Z ab F EC ab F EC b V EC c V EC b Orthene 97PE a GF = 3.37 g (AI)/ha ab GF = 6.73 g (AI)/ha b Untreated d % mortality (24 h after treatment) Description [lb (AI)/acre] I II III 0 a Karate Z ab F EC b F EC ab V EC c V EC ab Orthene 97PE a GF = 3.37 g (AI)/ha b GF = 6.73 g (AI)/ha b Untreated d a Means in a column followed by the same or no letter are not significantly different at the 5% level 68

4 Table 2. Contact activity (48 h after treatment) of selected insecticides vs rice stink bug. Beaumont, TX % mortality (48 h after treatment) Description [lb (AI)acre] I II III IV 0 a Karate Z a F EC ab F EC abc V EC c V EC bc Orthene 97PE a GF = 3.37 g (AI)/ha abc GF = 6.73 g (AI)/ha abc Untreated d % mortality (48 h after treatment) Description [lb (AI)/acre] I II III 0 a Karate Z ab F EC ab F EC ab V EC c V EC bc Orthene 97PE a GF = 3.37 g (AI)/ha bc GF = 6.73 g (AI)/ha abc Untreated d a Means in a column followed by the same or no letter are not significantly different at the 5% level 69

5 Table 3. Residual activity (1 d after treatment) of selected insecticides vs rice stink bug. Beaumont, TX Sample date = 1 day after treatment % mortality (24 h exposure to panicles) Karate Z b F EC b F EC b V EC cd V EC cd Orthene 97PE a GF cd GF bc Untreated d Sample date = 1 day after treatment % mortality (48 h exposure to panicles) Karate Z b F EC b F EC b V EC d V EC cd Orthene 97PE a GF cd GF bc Untreated d a Means in a column followed by the same or no letter are not significantly different at the 5% level 70

6 Table 4. Residual activity (4 d after treatment) of selected insecticides vs rice stink bug. Beaumont, TX Sample date = 4 days after treatment % mortality (24 h exposure to panicles) Karate Z b F EC b F EC b V EC b V EC b Orthene 97PE a GF b GF b Untreated b Sample date = 4 days after treatment % mortality (48 h exposure to panicles) Karate Z b F EC b F EC b V EC b V EC b Orthene 97PE a GF b GF b Untreated b a Means in a column followed by the same or no letter are not significantly different at the 5% level 71

7 Table 5. Residual activity (7 d after treatment) of selected insecticides vs rice stink bug. Beaumont, TX Sample date = 7 days after treatment % mortality (24 h exposure to panicles) Karate Z b F EC b F EC b V EC b V EC b Orthene 97PE a GF b GF b Untreated b Sample date = 7 days after treatment % mortality (48 h exposure to panicles) Karate Z b F EC b F EC b V EC b V EC b Orthene 97PE a GF b GF b Untreated b a Means in a column followed by the same or no letter are not significantly different at the 5% level 72

8 Table 6. Residual activity (10 d after treatment) of selected insecticides vs rice stink bug. Beaumont, TX Sample date = 10 days after treatment % mortality (24 h exposure to panicles) Karate Z F EC F EC V EC V EC Orthene 97PE GF GF Untreated Sample date = 10 days after treatment % mortality (48 h exposure to panicles) NS Karate Z a F EC F EC V EC V EC Orthene 97PE GF GF Untreated NS a Means in a column followed by the same or no letter are not significantly different at the 5% level 73

9 Table 7. Residual activity (14 d after treatment) of selected insecticides vs rice stink bug. Beaumont, TX Sample date = 14 days after treatment % mortality (24 h exposure to panicles) Karate Z F EC F EC V EC V EC Orthene 97PE GF GF Untreated NS Sample date = 14 days after treatment % mortality (48 h exposure to panicles) Karate Z b F EC b F EC b V EC a V EC b Orthene 97PE a GF b GF b Untreated b a Means in a column followed by the same or no letter are not significantly different at the 5% level 74

10 Table 8 (Summary of Tables 1 and 2). Contact activity of selected insecticides vs rice stink bug (RSB). Beaumont, TX % mortality (h after treatment) a Treatment [lb (AI)/acre] Karate Z ab 93.3 ab F EC b 93.3 ab F EC ab 96.7 ab V EC c 73.1 c V EC ab 83.3 bc Orthene 97PE a 100 a GF b 78.3 bc GF b 90 abc Untreated - 0 d 6.7 d a Means in a column followed by the same or no letter are not significantly different at the 5% level Table 9 (Summary of Tables 3-7). Residual activity of selected insecticides vs rice stink bug (RSB). Beaumont, TX Days after treatment b Description [lb (AI)/acre] 1 a 4 a 7 a 10 a 14 a Karate Z b 7.5 b 0 b b F EC b 10.0 b 0 b b F EC b 5.0 b 0 b b V EC d 2.5 b 0 b a V EC cd 0 b 2.5 b b Orthene 97PE a 45.0 a 32.5 a a GF cd 5.0 b 2.5 b 0 0 b GF bc 0 b 0 b b Untreated - 0 d 0 b 5.0 b b NS a Means in a column followed by the same or no letter are not significantly different at the 5% level b Mortality recorded 48 h after RSB exposed to panicles. 75