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Rice is one of the most important crops in Louisiana and Texas, USA. It is subjected to various insect pests throughout the growing season. Lepidopteran stem-boring pests including the Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), are increasing in economic importance as insect pests in rice production, particularly in southwest Louisiana, USA. Field trials were conducted in Louisiana and Texas to examine the efficacy of foliar-applied insecticides (chlorantraniliprole and the pyrethroids ζ-cypermethrin and λ-cyhalothrin) and chlorantraniliprole seed treatment for control of rice stemborers during 2018 and 2019. Furthermore, a diet incorporation assay assessed the toxicity of chlorantraniliprole to laboratory-reared E. loftini. Results of field experiments in Louisiana showed foliar applications of chlorantraniliprole, at 22 to 35 d after permanent flood was established, reduced stemborer injury to rice by 57.9 to 96.5% in 2018 and 73.9 to 87.5% in 2019 compared to nontreated or pyrethroid-treated field plots. However, rice yields in 2019 did not vary among insecticide-treated and nontreated plots. In the Texas field experiments, chlorantraniliprole applied as seed treatment reduced stemborer injury, but was not effective in reducing injury when sprayed directly to soil after planting or when applied at permanent flood. The LC50 and LC90 (lethal concentration that produced 50% and 90% mortality, respectively) of chlorantraniliprole on third-instar E. loftini were 0.09 ± 0.03 and 0.53 ± 0.17 µg a.i. mL-1, respectively, at 6 d after exposure. At 10 d after exposure, LC50 and LC90 were 0.04 ± 0.02 and 0.16 ± 0.04 µg a.i. mL-1, respectively. In addition to chlorantraniliprole seed treatment, foliar application of chlorantraniliprole in rice could provide a new tool for management of damaging stemborer infestations. [ABSTRACT FROM AUTHOR]

The rice water weevil, Lissorhoptrus oryzophilus Kuschel, is the most important economic pest of rice in the United States with the ability to substantially reduce rice yields. Stem borers, including the Mexican rice borer, Eoreuma loftini (Dyar), are emerging as more consistent pests in Louisiana and Texas, but the relationship between blanked panicles (whiteheads) caused by stem borer feeding and yield loss is not well understood. A series of field trials was conducted in Louisiana from 2019 to 2020 to determine the relative yield loss by manipulating infestations of both pests with selective insecticides. Results indicate losses from L. oryzophilus infestations are greater than those for E. loftini in early planted rice. In contrast, relative yield losses were approximately equal in later planted rice in 2019, in which E. loftini infestations were high. Additive impacts of the root-feeding L. oryzophilus and the stem-feeding E. loftini were not observed in our study. Linear regression revealed that each increase of one whitehead per square meter is associated with a 1.7% loss in yield. Results from ratoon rice suggest that protection from L. oryzophilus in the main crop also improves yield in the second crop. Collectively, results demonstrate the continued need for effective L. oryzophilus management programs to prevent economic losses. Conversely, findings suggest that benefits of E. loftini control may be minimal in many instances. Control of E. loftini is most likely to be economical under conditions where high populations are anticipated such as in late-planted fields or regions that previously had high infestations. [ABSTRACT FROM AUTHOR]

The use of multiple insecticidal seed treatments in combination to control a greater spectrum of pests has been increasing in rice production in the U.S. Mid-South. The economic benefits of individual seed treatments in rice are well documented, but returns on investment (ROI) on combinations are unknown. Efficacy and economic returns of insecticidal seed treatments alone and in combination were evaluated through a series of five field trials conducted in Louisiana from 2018 to 2020. In all trials, treatments containing chlorantraniliprole or cyantraniliprole provided the best control of rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), and control was not significantly improved by the addition of a second insecticide. Insecticidal control of L. oryzophilus by all seed treatments was reduced in late-planted rice fields relative to rice planted within the recommended planting window. Control of the Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), did not improve rice yields. Fungicidal seed treatments generally protected rice yields over treatments without fungicides despite having no effect on early-season plant populations. All seed treatments provided returns on investment which ranged from $94.30 (fungicide only 2018) to $519.75/ha (chlorantraniliprole + thiamethoxam + fungicides in 2019–2020). Increased yields resulting from the use of multiple insecticides in combination appears to justify the added expense. Collectively, results demonstrate the immense value of insecticidal seed treatments to rice production in Louisiana and throughout the U.S. Mid-South. Future research efforts should aim to assess returns on seed treatments across a range of rice production conditions and to quantify the impacts of sporadic pests on rice yields. • The use of insecticidal and fungicidal seed treatments is economically justified in rice production in the southern U.S. • Economic returns on seed treatments result primarily from control of the rice water weevil, Lissorhoptrus oryzophilus. • The use of multiple seed treatments in combination may improve economic returns over the use of single treatments alone. [ABSTRACT FROM AUTHOR]

The sugarcane borer, Diatraea saccharalis (Lepidoptera: Crambidae), is the primary pest of sugarcane, Saccharum spp., in much of North and South America. Control of D. saccharalis can be obtained through judicious application of insecticides, but more research is needed to optimize chemical control strategies. A series of field trials evaluated the duration of protection and influence of application water volume on D. saccharalis control in Louisiana sugarcane from 2018 to 2020. Results across trials demonstrated superior control was achieved with chlorantraniliprole over novaluron and tebufenozide. Analysis of insecticide concentrations present in leaf sheath tissue of the target internode suggests chlorantraniliprole and novaluron are achieving systemic activity, but not tebufenozide. Chlorantraniliprole concentrations remained above lethal levels for more than 8 wk after application. The percentage of bored internodes was 1.3- and 1.9-fold greater following applications with a water volume of 18.7 L/ha relative to those made with 46.7 and 186.8 L/ha, respectively, across insecticides. Collectively, results suggest chlorantraniliprole applied early in the season with sufficient water volume can provide nearly season-long protection of sugarcane against D. saccharalis injury. • Chlorantraniliprole and novaluron are systemic in sugarcane. • Chlorantraniliprole provides up to eight weeks of protection from Diatraea saccharalis injury in sugarcane. • Efficacy of insecticide applications in sugarcane is reduced at low water volumes. [ABSTRACT FROM AUTHOR]

Field populations of soybean looper, Chrysodeixis includens (Walker) (Noctuidae), were collected from soybean, Glycine max (L.) Merr., fields in Mississippi and Louisiana during 2010 and 2011 to determine their susceptibility to novel insecticides. Flubendiamide and chlorantraniliprole are diamide insecticides that have recently been registered for use in field crops. Baseline data were collected for each of these insecticides as well as for methoxyfenozide, which has been the recommended insecticide for soybean looper in Mississippi soybeans prior to the introduction of these new novel insecticides. Mean LC50 values for flubendiamide and chlorantraniliprole were similar among the populations tested, and susceptibility was higher for methoxyfenozide compared to flubendiamide and chlorantraniliprole. Diet incorporated assays determined a 9.4-fold variation in susceptibility to flubendiamide among the 7 soybean looper populations tested. Variation to chlorantraniliprole was 6.25-fold and variation for methoxyfenozide was 5.37-fold. Variation in the diamide insecticides was higher than methoxyfenozide with less exposure to soybean looper populations. Documenting variability along with baseline data will be useful in the future for resistance monitoring of soybean loopers to diamide insecticides. [ABSTRACT FROM AUTHOR]

Current pest management practices for the rice water weevil (Lissorhoptrus oryzophilus Kuschel) and the Mexican rice borer (Eoreuma loftini Dyar) in U.S. rice rely heavily on a small number of insecticides. Thus, additional products are needed to delay resistance development and replace products no longer available to farmers. Evaluation of novel and widely used insecticidal seed treatments was conducted in eight small plot field trials from 2015 to 2019 in Louisiana and Texas. Treatments evaluated included the insecticides cyantraniliprole, chlorantraniliprole, thiamethoxam, and clothianidin. Seed treated with chlorantraniliprole and seed treated with both cyantraniliprole and thiamethoxam together provided the best control of L. oryzophilus across trials. Thiamethoxam and clothianidin seed treatments did not provide satisfactory control of L. oryzophilus. Only chlorantraniliprole seed treatment controlled E. loftini. Improved yield was recorded from plots treated with chlorantraniliprole or cyantraniliprole + thiamethoxam across trials from 2017 to 2019 over fungicide only controls. Yield differences among treatments were not detected in 2015–2016 trials. Registration of cyantraniliprole seed treatment for use in U.S. rice provides a new tool for diversification of pest management practices and insecticide resistance management. • Cyantraniliprole seed treatment effectively controlled Lissorhoptrus oryzophilus. • Improved control was achieved by cyantraniliprole together with thiamethoxam. • Cyantraniliprole was not effective against the stem borer, Eoreuma loftini. • Registration of cyantraniliprole provides U.S. rice farmers a new pest management tool. [ABSTRACT FROM AUTHOR]

Field experiments assessed control of the stem borers, Diatraea saccharalis (F.) and Eoreuma loftini (Dyar), in sugarcane (Saccharum spp.) with selected insect growth regulators and diamide insecticides. Tebufenozide, novaluron, chlorantraniliprole, and flubendiamide were evaluated for D. saccharalis control in four field experiments in Louisiana between 2009 and 2014. Aerial application of the same insecticides was evaluated for control of E. loftini in commercial sugarcane fields in southern Texas in 2012 and 2015. Stalk injury from D. saccharalis in nontreated plots ranged from 7.4-28.1% bored internodes across the four experiments. All insecticides reduced D. saccharalis injury compared with nontreated plots (39.1-99.4% reduction). Better control was achieved with novaluron, flubendiamide, and chlorantraniliprole than with tebufenozide. Pheromone trap-assisted scouting for E. loftini in Texas sugarcane helped to time insecticide applications. Reduced E. loftini injury was observed in diamide-treated plots (3.6-4.7% bored internodes) compared with nontreated controls (13.1%), but not in novaluron- (6.0%) or tebufenozide-treated (8.3%) plots in the 2012 experiment. Significant E. loftini injury was present prior to the aerial insecticide application in 2015, and differences in overall injury were not detected among treatments. However, chlorantraniliprole reduced injury to the top portion of sugarcane stalks. None of the insecticides improved sugar yields in 2012 or 2015. Results suggest insect growth regulators and diamide insecticides fit well in D. saccharalis management programs in Louisiana sugarcane. These chemistries also have potential to improve control of E. loftini, but more research into application strategies is needed to achieve consistent efficacy., (© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)