Joshua H. Temple

Species Composition and Seasonal Abundance of Stink Bugs (Hemiptera: Pentatomidae) in Louisiana Soybean

ABSTRACT In Louisiana during the last decade, the redbanded stink bug, Piezodorus guildinii (Westwood), has become a significant and yield-limiting pest of soybean. The redbanded stink bug was previously reported in the United States in 1892, but was never considered an economically important pest until recently. Soybeans representing four maturity groups (MG) III, IV, V, and VI were sampled weekly from beginning bloom (R1) to physiological maturity (R8) during 2008–2010 at five locations across Louisiana to determine the Pentatomidae composition. In total, 13,146 stink bugs were captured and subsequently identified to species. The predominant species included the redbanded stink bug (54.2%); southern green stink bug (27.1%), Nezara viridula L.; brown stink bug (6.6%), Euschistus servus (Say); and green stink bug (5.5%), Acrosternum hilare (Say). Redbanded stink bug comprised the largest percentage of the complex collected at four of the five survey sites. Numbers exceeding action thresholds of this stink bug complex were only detected during R4 to R7 growth stages. Redbanded stink bug accounted for the largest percentage of the stink bug complex in early maturing soybean varieties (MG III [86%] and IV [60%]) and declined in later maturing soybeans (MG V [54%] and VI [50%]). The redbanded stink bug was initially identified in southern Louisiana during 2000 and had been reported in all soybean producing regions in Louisiana by 2006. This survey is the first to report the redbanded stink bug as a predominant pest of soybeans from locations within the United States.

LABORATORY TOXICITY AND FIELD EFFICACY OF SELECTED INSECTICIDES AGAINST FALL ARMYWORM (LEPIDOPTERA: NOCTUIDAE) 1

ABSTRACT Fall armyworm, Spodoptera frugiperda (J. E. Smith), is an occasional but often serious pest of several row crops in the southern U.S., including cotton, field corn, and grain sorghum. The objective of these studies was to generate baseline dose-mortality responses for fall armyworm larvae in laboratory bioassays, to confirm field efficacy against natural infestations, and to determine residual efficacy of selected insecticides. These studies evaluated 4 recently developed insecticides (chlorantraniliprole, cyantraniliprole, flubendiamide, and spinetoram) and 5 commercial standards (indoxacarb, lambda-cyhalothrin, methoxyfenozide, novaluron, and spinosad). In diet-incorporated assays, the LC50 values of chlorantranilprole and spinetoram were significantly lower than the LC50s of all other insecticides. The results of a field trial against a native fall armyworm infestation in grain sorghum indicated that chlorantraniliprole reduced the number of infested whorls below that in the non-treated control and the lambda-cyhalothrin- and methoxyfenozide-treated plots at 3 d after treatment (DAT). At 7 DAT, no insecticides significantly reduced the number of infested whorls below that in the non-treated plots. In residual efficacy studies, exposure of fall armyworm larvae to chlorantraniliprole- and cyantraniliprole-treated tissue resulted in significantly greater mortality compared to those exposed to non-treated tissue and lambda-cyhalothrin-, flubendiamide-, novaluron-, and methoxyfenozide-treated tissues at 7 DAT. In addition, chlorantraniliprole and cyantraniliprole were the only compounds that resulted in >40% mortality at 28 DAT. These results indicate that newer insecticides are equal to or more efficacious against fall armyworm than traditional insecticides.

Influence of Nezara viridula Feeding on Cotton Yield, Fiber Quality, and Seed Germination

Abstract The influence of southern green stink bug, Nezara viridula (L.), adults (males and females) and fourth to fifth instars on cotton, Gossypium hirsutum L., boll abscission, seedcotton yield, fiber quality, and seed viability was evaluated in field studies conducted during 2004 and 2005. Cotton bolls representing several age classes ranging from 0–600 heat units were individually infested with a specific gender or life stage of southern green stink bug. Adults and nymphs induced abscission of bolls that accumulated 0–280 heat units after anthesis. Seedcotton yield was significantly lower in bolls infested with adults (males and females) and late instars through ≈500 heat units after anthesis. Southern green stink bug feeding on bolls significantly affected the physical fiber properties of micronaire (measure of fiber fineness or maturity), strength, uniformity, and fiber length. Discolored cotton lint in the stink bug-infested bolls was more common than in noninfested bolls. Seed germination and development of normal seedlings for seed harvested from stink bug-infested bolls that accumulated ≤500 heat units beyond anthesis were significantly lower compared with noninfested bolls. No significant differences in boll abscission, yield, fiber quality, and seed germination were detected between southern green stink bug males and females or between adults and fourth to fifth instars.

Susceptibility of Southern Green Stink Bug and Redbanded Stink Bug to Insecticides in Soybean Field Experiments and Laboratory Bioassays

Abstract Recently the redbanded stink bug, Piezodorus guildinii (Westwood), has become a major pest of soybean, Glycine max (L.) Merrill, in Louisiana and has begun to infest soybeans throughout the Mid-South. Soybean industry and cooperative extension personnel have reported differential susceptibility between the southern green stink bug, Nezara viridula L., and redbanded stink bug treated with currently labeled insecticides in commercial production fields. To address their concern, we evaluated susceptibility of southern green stink bug and redbanded stink bug to insecticides in field and laboratory experiments. Insecticide field efficacy experiments during 5 years indicated control with pyrethroids was 94.4 ± 1.3% for southern green stink bug and 75.1 ± 1.9% for redbanded stink bug, with organophosphates, 89.8 ± 2.7% for southern green stink bug, and 84.8 ± 1.7% for redbanded stink bug, and with neonicotinoid insecticides, 78.0 ± 5.6 and 63.2 ± 6.0%, respectively. Insecticide pre-mixtures or product combinations provided 98.6 ± 0.6 and 83.8 ± 2.4% control, respectively. Bioassays of adults in vials validated results in the field. Pyrethroid and organophosphate LC50 values ranged from 0.02 to 2.36 µg per vial for southern green stink bug and 0.21 to 4.86 µg per vial for redbanded stink bug. The redbanded stink bug was four to eight-fold less susceptible to pyrethroids and two to eight-fold less susceptible to organophosphates than was the southern green stink bug.

Fall Armyworm (Lepidoptera: Noctuidae) Development, Survivorship, and Damage on Cotton Plants Expressing Insecticidal Plant-Incorporated Protectants

ABSTRACT Cotton, Gossypium hirsutum (L.), plants expressing insecticidal crystal (Cry) proteins of Bacillus thuringiensis (Bt) Berliner are planted on significant acreage across the southern region of the United States. Fall armyworm, Spodoptera frugiperda (J. E. Smith), can be a significant cotton pest in some years, but this species has not been a primary target of Bt cotton technologies. The objective of this study was to quantify fall armyworm larval survivorship and fruiting form injury on transgenic cotton lines expressing Cry1Ac (Bollgard), Cry1Ac + Cry2Ab (Bollgard II), and Cry1Ac + Cry1F (WideStrike) Bt proteins. Larval survivorship and fruiting form damage of fall armyworm on Bollgard, Bollgard II, WideStrike, and non-Bt (control) cotton lines were evaluated in no-choice field studies. Fall armyworm (third instars) were placed on flower buds (squares), white flowers, and bolls, enclosed within a nylon mesh exclusion cage, and evaluated at selected intervals after infestation. Exposure of fall armyworm larvae to Bollgard cotton lines generally resulted in no significant effects on survivorship compared with larvae exposed to the non-Bt cotton line. Survivorship and plant injury by fall armyworm on Bollgard II cotton lines was variable compared with that on non-Bt cotton lines, and significant differences between treatments were inconsistent. Fall armyworm had significantly lower survivorship and caused less plant injury on WideStrike cotton lines than on non-Bt cotton lines across all plant structures. Development and survivorship of fall armyworm larvae on these cotton lines also were evaluated in no-choice laboratory assays by offering the previously described fruiting forms to third instars. Bollgard II andWideStrike cotton lines significantly reduced fall armyworm development and survivorship compared with those larvae offered non-Bt tissue. These results suggest that differences exist among selected Bt cotton technologies in their performance against fall armyworm.

Oviposition and Sex Ratio of the Redbanded Stink Bug, Piezodorous guildinii, in Soybean.

Redbanded stink bug, Piezodorus guildinii (Westwood), is a significant soybean pest across the mid-south region of the United States. The objectives of these studies were to characterize: (1) redbanded stink bug oviposition in relationship to soybean maturity group (MG), plant structure, crop phenology, and vertical distribution within the plant canopy; and (2) redbanded stink bug adult sex ratios in relationship to soybean phenology. A total of 5645 redbanded stink bug eggs in 421 egg masses (clusters) were field collected from naturally-occurring populations in MG IV and V soybean over a three year period (2009 to 2011). The mean number of eggs within a cluster was 16.6 ± 0.3. Plant structures by MG interactions were highly significant with more egg masses oviposited on leaves in MG IV (79.4%) and more on pods in MG V (72.7%). The ratio of females to males was similar in all soybean growth stages except R5, where the sex ratio increased to 1.4:1, coinciding with peak oviposition. Only 29.9% of egg clusters in MG IV and 18.3% of egg clusters in MG V were oviposited in the upper 35 cm of the soybean canopy. Based on these results, sampling strategies and insecticide application placement for stink bugs may require modification.

EVALUATION OF SULFOXAFLOR (GF-2372) AGAINST TARNISHED PLANT BUGS IN COTTON, 2010

Insecticide efficacy trials were conducted during 2010 at the Northeast Research Station (NERS) near St. Joseph, LA (Tensas Parish) and the Macon Ridge Research Station (MRRS) near Winnsboro, LA (Franklin Parish). Cotton seed (DP 555 BG/RR) was planted into a Commerce silt loam on 25 May at NERS (trial 1) and a Gigger silt loam on 1 Jun at MRRS (trials 2 and 3). Plot size was four to eight rows (40-inches on row centers) X 50 ft with four replications. Insecticides were applied with a highclearance sprayer and compressed air system calibrated to deliver 12 GPA through TeeJet TX-10 hollow cone nozzles (2/row) at 48 psi at NERS and at 9.5 GPA through TeeJet TX-8 hollow cone nozzles (2/row) at 50 psi at MRRS. In trial 1, insecticides were applied on 20 and 29 Jul, and post-treatment evaluations were made on 3, 7 DAT1, and 2, 7, 12 DAT2. In trial 2, insecticides were applied on 3 Aug and post-treatment evaluations were made on 3, 8, 10, 14 DAT. In trial 3, insecticides were applied on 25 Aug and post-treatment evaluations were made on 3, 7, 10 DAT. Plots were sampled with a standard 2.5 x 2.5 ft black cloth shake sheet by taking two samples on two-four rows (10 row ft total) of each plot. Data were subjected to ANOVA and means separated according to DNMRT. Rainfall of 7.61, 1.46, and 0.4 inches occurred during trials 1, 2, and 3, respectively.

EVALUATION OF INSECTICIDE EFFICACY AGAINST SOYBEAN LOOPER IN SOYBEANS, 2010

A field trial evaluated selected foliar treatments against soybean looper (SBL) on R5.5 stage soybeans at the Macon Ridge Research Station (Franklin Parish). Soybean seed were planted into a Gigger-Gilbert silt loam soil on 15 Apr. Plot size was four rows (40inches on centers) X 45 ft. Treatments were arranged in a RCB design with four replications. Insecticides were applied with a highclearance sprayer and compressed air system calibrated to deliver 6 gpa through TeeJet TX-8 hollow cone nozzles (2/row) at 50 psi. Insecticides were applied on 13 Aug, and post-treatment evaluations were performed at 3, 7 and 11 DAT. Insecticide efficacy was measured by taking 25 sweep-samples with a sweep net (15 inches diameter) in each plot and recording the number of SBL larvae > 1⁄2 inch. Data were subjected to ANOVA and means separated according to DNMRT. Total rainfall of 0.76 inches occurred during the trial period.

EVALUATION OF SELECTED INSECTICIDES FOR CONTROL OF SOYBEAN LOOPER AND STINK BUG, 2007

Selected insecticides were evaluated for control of SBL and a stink bug complex (SBC) in two tests at the Macon Ridge Research Station (Franklin Parish). Soybean seed (Asgrow 5501) were planted into a Gigger silt loam soil on 11 Jun in Tests 1 and 2. Plot size was four rows (40-inches on centers) x 50 ft. Treatments were placed in a RCB design with four replications in both tests. Insecticides were applied on 21 Aug in Test 1 and 27 Aug in Test 2 with a John Deere high clearance sprayer and CO2-charged system calibrated to deliver 6 gpa through Teejet TX-6 hollow cone nozzles (2/row) at 48 psi. Treatment efficacy against SBL and SBC was determined at 2, 6, and 9 DAT in Test 1 and 2, 4, and 8 DAT in Test 2 using a standard (15 inches diameter) sweep net and taking a 25 sweep sample in each plot. Data were subjected to ANOVA and means separated according to DMRT. No rainfall occurred during these tests.

EVALUATION OF SELECTED INSECTICIDES FOR CONTROL OF RED BANDED STINKBUGS AND THREECORNERED ALFALFA HOPPERS, 2006

Selected insecticides were evaluated for control of RBSB (adults) and TCAH (adults and nymphs) in soybean at the LSU Agricultural Center’s Sweet Potato Research Station (Franklin Parish). Soybean seed were planted into a Gigger silt loam soil on May 19, 2006. Plot size consisted of eight rows centered on 40-inches and 50 ft in length. Treatments were placed in a RCB design with five replications. Insecticides were applied on 11 Aug with a John Deere high clearance sprayer and CO2-charged system calibrated to deliver 6 gpa through Teejet TX-8 hollow cone nozzles (2/row) at 60 psi. Treatment efficacy against RBSB and TCAH was determined at 3, 5, and 7 DAT using a standard (15 inches diameter) sweep net and taking a 25 sweep samples in each plot. Data were subjected to ANOVA and means separated according to DMRT. No rainfall occurred during these tests.