Location: Southern Insect Management Research
2018 Annual Report
Objectives
Objective 1: Develop new approaches for the control of noctuid and hemipteran pests of southern row crops, integrating multiple control tactics into integrated pest management systems.
Sub-objective 1.A: Develop new strategies that reduce numbers of insecticide applications on soybean and cotton that are not economically justified.
Sub-objective 1.B: Develop new approaches for the control of insect pests of sweet potato.
Objective 2: Minimize negative effects of integrated pest management systems on pollinators and other beneficial arthropods.
Sub-objective 2.A. Determine the impact of current insect management strategies in corn, cotton, sweet potatoes, and soybean on populations of pollinators and beneficial insects.
Sub-objective 2.B. Examine the acute toxicity, synergistic/antagonistic interactions, and sub-lethal impacts of commonly used pesticides on honey bees using bioassay, biochemical, and molecular approaches.
Objective 3: Improve pest risk assessment by determining environmental influences that affect populations of important insect pests of southern row crops with emphasis on bollworms, tobacco budworms, tarnished plant bugs, stink bugs, and soybean loopers.
Objective 4: Develop methods to measure and manage insecticide resistance of pest populations of southern row crops with emphasis on bollworm, tobacco budworm, tarnished plant bug, and stink bugs.
Sub-objective 4.A. Measure levels of insecticide susceptibilities of tarnished plant bugs, bollworms and other important insect pests of southern row crops through laboratory bioassays.
Sub-objective 4.B. Develop within-field bioassays to determine insecticide susceptibilities of key pests of southern row crops.
Sub-objective 4.C. Examine the impact and sensitivity of resistance management options for major insect pests of southern row crops through simulated modeling.
Approach
Insect management guidelines are generally static from year to year regardless of crop prices, costs of insecticides and yield potential of the crop. We plan to summarize published information for bollworm, tarnished plant bug, and stink bugs and develop economic injury level probability distributions using Monte Carlo simulations. On-farm field evaluations across the Mississippi Delta will evaluate economic returns and environmental sustainability of different insecticidal control strategies in soybean and cotton. Commercially available and experimental sweet potato varieties will be planted annually and the economic impact of insect and nematode control in sweet potato will be examined. The impact of current insect management strategies in southern row crops on populations of pollinators and beneficial insects will be examined in production fields. The surrounding habitats of each field will be documented for plant community composition, focusing on blooming plants that may be of interest to pollinators. Each of these fields will be sampled using a combination of sampling techniques. Community structure will be compared between cropping systems, and related to insecticide applications. We plan to evaluate acute and sub-lethal toxicities and synergistic/antagonistic interactions of honey bees to commonly used pesticides. An examination of gene regulation in honey bees associated with immunity, adaptation, detoxification, digestion/metabolism, and stress-related genes will be conducted after exposure to pesticides with techniques such as real-time PCR , RNAseq or microarrays. Hemipteran and lepidopteran phytophagous pest populations are highly mobile within the landscape and use a variety of weeds and crops as host plants. To examine landscape influences on these insects, the landscape composition surrounding historic and current collection locations will be quantified using Cropland Data Layers (CDLs). Using these CDL layers, buffer zones will be generated around locations. Output data will be tabulated to produce total area of habitat type included within each buffer area and will be related to data collected on insect populations using appropriate statistical analyses. SIMRU will continue to examine susceptibilities of hemipteran and lepidopteran insect pests collected from locations across the Mississippi Delta with a variety of assay methods which may include topically treated diet, residual contact bioassays, glass vial bioassays and a feeding contact assays using floral foam. Insects from original collections will be preserved for molecular analysis using genetic markers. When colonies of any of the pest groups have reduced susceptibility to the tested insecticides, efforts will be made to preserve the colony under a selected and non-selected sequence of exposures to the insecticides of interest We propose to develop rapid bioassays to predict the effectiveness of an insecticide application on a real field population of insects. To examine predictive values of laboratory assays on actual field populations, a plot sprayer will be used to deliver a range of formulated product rates on targeted insects.
Progress Report
In collaboration with other ARS scientists, reviews of the early-season insect pests targeted for control with neonicotinoid insecticide-treated seed in corn, cotton, soybean, and wheat were published. These review articles examined the nature and severity that these insects can cause to seed or seedling pests, aspects about their biology that characterize dynamics of early-season infestation, frequency and severity of early-season infestations, local and regional factors that increase risk, and general management options available to farmers. This information aids in making the decision to use preventative seed treatments and aims to reduce the uncertainty of our knowledge of economic damage from these early-season insect pests that can infest these crops.
Participated in the 2017 and 2018 sweet potato variety trials at the Alcorn State University Research Farm in Mound Bayou, Mississippi. The yield and quality of ten sweet potato varieties grown in the Mississippi Delta were compared. The compatibility of lines from Louisiana and North Carolina were examined for their compatibility to the growing conditions of the Mississippi Delta. This information is being used by local sweet potato producers and others in the southern U.S.
Collections of native bees were continued in a variety of agricultural produced commodities including commercial fields of corn, cotton, sorghum, sunflowers, and soybean located across the Mississippi Delta. Additional specimens were collected form selected non-agricultural areas including fallow fields, roadside ditches, and National Wildlife Refuges in the Mississippi Delta. Samples were collected with a combination of collection techniques including modified pan traps (bee bowls), malaise traps, and net sampling to document species richness and abundance. Additional specimens were added from bycatch of other studies including moth pheromone traps. Over 30,000 specimens have been cleaned, pinned, and mounted, and entered into a database. Specimens of species new to the state or of particular significance have been deposited with regional and national entomological museums. There is little or no existing information pertaining to the native bees present in the Mississippi Delta, especially in agricultural systems. This baseline information is being used to examine potential impacts of local agricultural production practices on these insects.
The influence of the insecticide, acephate, alone and in mixtures with other commonly used pesticides on honey bee survival and detoxification enzyme activities were examined. Honey bee workers treated with acephate at residue concentrations did not show increased mortality, but esterase activity was significantly suppressed. Similarly, bees treated with mixtures of acephate with six different pesticides consistently showed decreased esterase activity and body weight.
Responses of honey bees to lethal and sublethal doses of the insecticide, clothianidin, alone and in mixtures did not decrease adult survivorship, but all treatments caused reduced body weight compared to control treatments. Most mixtures at residue levels showed minor additive effects or no interaction on body weigh loss, and synergistic interactions were only detected for the mixture of clothianidin and lambda-cyhalothrin. In long-term risk assessments, spray treatments twice a week for 52 days with low concentrations (up to 1 mg/L) of imidacloprid showed no adverse effect on bee survival, but concentrations > 80 mg/L significantly reduced bee survival. This information is being used to examine the impact of a range of insecticide doses on long-term honey bee health.
Two laboratory bioassay methods were used to examine susceptibilities of field populations of tarnished plant bugs to five different classes of insecticides commonly used in the Mississippi Delta. Over 100 field populations were tested using either a diet-overlay method or exposure to an insecticide in a glass vial. Insecticides tested included: acephate, permethrin, imidacloprid, thiamethoxam, and sulfoxaflor. These methods are being examined to determine the best predictor of tarnished plant bug field control on cotton and to detect populations that may develop decreased susceptibilities or potential resistance to these insecticides. Additionally, the residual activity on cotton leaves of several commonly used insecticides use for tarnished plant bug was examined.
Current insecticide susceptibilities of lepidopteran pests of the Mississippi Delta were continued. Assays included insecticide mixed with artificial diet (diet-incorporated), and direct applications of one ul droplets to 3rd instar larvae (topical). Insect populations were collected from wild and cultivated host plants Insecticides tested included lambda-cyhalothrin, chlorantraniliprole, and acephate. The tobacco budworm continues to show a much higher tolerance to pyrethroid insecticides compared to bollworms, but response to chlorantraniliprole is similar. The risk of development of insecticide resistance to diamide insecticides by bollworms and tobacco budworms under different usage scenarios is being explored through computer model simulations. This information will be used to present optimal usage to preserve the longevity of these insecticides as a means of control.
Accomplishments
1. Survey of native bees in agricultural production fields. Currently, there is little or no information regarding native bee communities in agricultural environments across the Mississippi Delta. Through a variety of sampling techniques, baseline information regarding the species richness and abundance of native bees inhabiting the Mississippi Delta were collected by ARS scientists at Stoneville, Mississippi. Several species of bees not previously reported in our area, including large range expansions have been recorded. This baseline information will be used to evaluate impacts of various agricultural practices on populations of these insects.
2. Impact of sublethal and long-term concentrations of insecticides on honey bee survival. Understanding the impact of pesticides (through both direct and residue contact) is important in developing strategies to mitigate their impact on honey bees. Feeding treatments with the insecticide, chlothianidin, alone or in mixtures with five different insecticide classes at residue concentrations did not influence adult survivorship but did reduce adult body weight. Long-term spray treatments with imidacloprid at low rates showed no adverse effect on bee survival, but higher concentrations (>80mg/L) significantly reduced bee survival. Results from these studies by ARS scientist at Stoneville, Mississippi, are being used to determine impacts of different insecticide concentrations on honey bee health.
3. Determination of insecticide resistance status of caterpillar pests of Mississippi Delta. Two of the most important insect pests of row crops in the Mississippi Delta are the bollworm and tobacco budworm. They have historically developed resistance to insecticides commonly used for their control. Through collections of population from cultivated and wild host plants, their current susceptibilities have been examined. Neither have shown signs of increased survival in response to use of the diamide insecticide class. This information from ARS scientist at Stoneville, Mississippi, is being used to detect potential shifts in susceptibility and to develop plans for economical and judicious use of insecticide deployment to prolong the longevity for this class of insecticide.
Review Publications
Yao, J., Zhu, Y., Adamczyk Jr, J.J., Luttrell, R.G. 2018. Influences of acephate and mixtures with other commonly used pesticides on honey bee (Apis mellifera) survival and detoxification enzyme activities. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology. 209:9-17. https://doi.org/10.1016/j.cbpc.2018.03.005.
Parys, K.A., Luttrell, R.G., Snodgrass, G.L., Portilla, M. 2018. Patterns of tarnished plant bug (Heteroptera: Miridae) resistance to pyrethroid insecticides in the lower Mississippi Delta for 2008-2015: Linkage to pyrethroid use and cotton insect management. Journal of Insect Science. 18(2):29. https://doi.org/10.1093/jisesa/iey015.
Papiernik, S.K., Sappington, T.W., Luttrell, R.G., Hesler, L.S., Allen, K.C. 2018. Overview: Risk factors and historic levels of pressure from insect pests of seedling corn, cotton, soybean, and wheat in the U.S. Journal of Integrated Pest Management. 9:1. https://doi.org/10.1093/jipm/pmx026.
Parys, K.A., Luttrell, R.G., Snodgrass, G.L., Portilla, M., Copes, J. 2017. Longitudinal measurements of tarnished plant bug (Hemiptera: Miridae) susceptibility to insecticides in Arkansas, Louisiana and Mississippi: Associations with insecticide use and insect control recommendations. Insects. 8(4),109. https://doi.org/10.3390/insects8040109.
Allen, K.C., Luttrell, R.G., Sappington, T.W., Hesler, L.S., Papiernik, S.K. 2018. Frequency and abundance of selected early season insect pests of cotton. Journal of Integrated Pest Management. 9(1):20;-1-11. https://doi.org/10.1093/jipm/pmy010.
Parys, K.A., Griswold, T.L., Ikerd, H.W., Orr, M.C. 2018. New records and range extensions of several species of native bees (Hymenoptera: Apoidea) from Mississippi. Biodiversity Data Journal. 6:e25230. https://doi.org/10.3897/BDJ.6.e25230.
Rashid, M., Ahmed, N., Jahan, M., Islam, K., Nansen, C., Willers, J.L., Ali, M. 2017. Higher fertilizer inputs increase fitness traits of brown planthopper in rice. Scientific Reports. 7:4719. doi:10.1038/s41598-017-05023-7.
Tang, G., Yao, J., Li, D., He, Y., Zhu, Y., Zhang, X., Zhu, K. 2017. Cytochrome P450 genes from the aquatic midge Chironomus tentans: Atrazine-induced up-regulation of CtCYP6EX3 contributing to oxidative activation of chlorpyrifos. Chemosphere. 186: 68-77. https://doi.org/10.1016/j.chemosphere.2017.07.137.
Yao, J., Zhu, Y., Adamczyk Jr, J.J. 2018. Responses of honey bees to lethal and sublethal doses of formulated clothianidin alone and mixtures. Journal of Economic Entomology. 1-9. https://doi.org/10.1093/jee/toy140.
