Location: Southern Insect Management Research
2020 Annual Report
Objectives
Objective 1: Determine key factors that naturally regulate tarnished plant bug (TPB) population increases and develop new tools for managing tarnished plant bug, including bio-control strategies.
Sub-objective 1.A. Quantify the impact of biological control on TPB seasonal abundance and distribution.
Sub-objective 1.B. Identify and develop new biological control options (including entomopathogens, entomophagous insects, host manipulation and behavioral modification) as possible regulators of TPB population growth.
Sub-objective 1.C. Identify sampling methods for TPB that are cost and time effective for landscape level monitoring, evaluate their use as tools in TPB population management, and link information about seasonal habitat changes to population dynamics.
Objective 2: Develop novel alternative ways to deploy tarnished plant bug control agents, and evaluate effectiveness of these deployment methods in large-scale field experiments.
Sub-objective 2. A. Determine if sprays of the NI8 strain of Beauverua (B.) bassiana applied alone and in combination with novaluron will suppress TPB populations colonizing adjacent cotton.
Sub-objective 2. B. Measure impacts of NI8 and new biological control agent identified in Sub-objective 1B on TPB populations infesting wild hosts and crops in the Mississippi Delta.
Approach
The key factors that naturally regulate tarnished plant bug (TPB) population will be determined by collecting feral population from wild host plants, and when available, in cultivated crops at different locations within the Mississippi Delta. TPB nymphs and adults will be collected at each location. Collected insects will be used for microbial and parasitoids identification, molecular identification studies, life table construction, and stable carbon isotope study. Potential entomopathogenic fungi will be bioassayed in replicated laboratory tests and compered with NI8. The most effective fungus will be tested in large-scale field experiments.
Progress Report
This is the final report and approved this project for merger with ARS Research Project Number: 6066-22000-084-00D, "Integrated Insect Pest and Resistance Management on Corn, Cotton, Sorghum, Soybean, and Sweet Potato."
Laboratory assays continued being conducted to evaluate the effect of 5 more potential native entomopathogenic fungi (NI16, NI17, NI18, NI19, and NI20) of B. bassiana strains isolated from tarnished plant bug (TPB) samples collected in the Mississippi delta from 2015 and 2016. Each strain was screened based on virulence with 1 to 4 days mortality after exposure and 2 to 4 days sporulation after dead, which is the standard measurement for NI8 activity. The median lethal concentration, sporulation and doses of the seven native strains of B. bassiana including the Mississippi Delta native NI8 ARSEF8889 were estimated on lab colonies of mixed-sex 2 d old TPB adults (3 groups of 30 adults/strain). Serial dilutions of four test concentrations of NI8 and the 13 strains (n x 107, n x 106, n x 105, n x 104 spores/ mL) were prepared to treat TPB adults. All treatments were applied using a specially designed spray tower. After application, adults were released in an insect observation cage to let them dry and then transferred individually into solo cup with diet. Insects were held in an environmental room at 27ºC, 65%RH, and 12L: 12D photoperiod and examined daily for five day for mortality. Differences in mortality and sporulation were found among strains. No differences in mortality and sporulation were found in TPB treated with B. bassiana strains NI8 and NI15.
A second-year field experiments were carried out to evaluate mortality of TPB using the entomopathogenic fungus B. bassiana strain NI8 alone and in conjunction with the growth regulator novaluron. Both the fungus and growth regulator were evaluated for compatibility and compared to a conventional treatment. Twenty plots, sixteen rows wide and 400’ long (0.465 acres) were planted with BGII cotton. Each treatment (Untreated control, NI8, novaluron, NI8+novaluron, and conventional) was replicated four times. Treatments were randomized within each replication and a plot of 4 rows of corn were planted between cotton plots to avoid contamination among treatments. Concentration of B. bassiana was 6x1012 (spores/acre). All sprays included 1.5 ml of Tween-80 per gallon of spray. Insect assessment were made by employing four sets of ten sweeps per plot at 1 day before spray and 3, 7, and 14 days after treatment. The number of TPB adults and nymphs for each plot and rating were recorded. No broadcast applications of compounds for the control of TPB or any other insects were made during the duration of the test. Similarly, to the first year no significant differences were found in lint yield between treatments. However, the conventional, Diamond, and NI8+Diamond treatments resulted in a higher lint yield than the control and B. bassiana alone.
We completed to screen two strains of a microbial control agent composed of the fungus B. bassiana, against red banded stink bugs, a species of increasing economic concern in regional soybean production. Four concentrations of both a strain native to the Mississippi Delta (NI8) and a currently commercially available formulation (GHA) were tested against field-collected red banded stink bug adults in the laboratory, and evaluated at four time points (3, 5, 10, and 15 days after application). Application methods simulated in-field sprays. Both isolates were pathogenic to red banded stink bugs in the lab, though the commercially available strain known as GHA outperformed the native NI8 strain. Unlike other control options, B. bassiana has a short re-entry interval and no harvest interval, making it a potentially attractive and environmentally benign alternative to conventional synthetic insecticides for control this important pest. Further testing on juvenile life stages and field testing is needed to evaluate the potential for in-field control.
Two strains of B. bassiana were evaluated for potential control of immature stages of southern green stink bug, SGSB by contact. Four concentrations (7 x 104, 7 x 105, 7 x 106, 7 x 107) of both a Mississippi Delta native strain (NI8) and a commercially available formulation (GHA) were tested against lab colony of juvenile life stages of SGSB and evaluated at five time points (3, 5, 10, 15, and 20 days). All treatments were applied directly to the diet cup using a specially designed spray tower. After application, adults were released individually into each solo cup with diet at specific concentration. Insects were held in an environmental room at 27ºC, 65%RH, and 12L: 12D photoperiod and examined daily for twenty day for mortality. Differences in mortality and sporulation were found among strains and concentrations.
Microbial control agents continued being codified and identified from field samples collected in Mississippi Delta during 2016-2018. Spore powder of new microbial agents have been produced and used in bioassays to evaluate the pathogenicity on tarnished plant bugs and other pestiferous insects of southern crops and potential impact on beneficial insect populations. Using biological control agents is the major goal addressed in this investigation. Result indicated that the Mississippi Delta native strain NI8 may be suitable for control of TPB, not only because of its high pathogenicity against targeted pest, but also for its selectivity against some beneficial arthropods. This further refines our knowledge in the development of field application strategies of B. bassiana for Lygus and other cotton pest managements.
Accomplishments
1. Field efficacy of B. bassiana for control of the tarnished plant bug and other insect pests. Microbial insecticides are an important component of many insect pest management programs. ARS researchers in Stoneville, Mississippi, continued field experiments that determined mortalities and estimate lethal doses of potential microbial insecticides including the native Delta strain NI8 and the commercial strain GHA on feral tarnished plant bug populations and red banded stink bug on cotton and soybean, respectively were completed and published. Results indicated that B. bassiana applications resulted in decreased survival of tarnished plant bugs by >50% regardless of the isolate by direct spray or contact under field conditions. These studies will impact the development of non-chemical control methods used in cotton integrated pest management systems across the southern United States.
Review Publications
Parys, K.A., Portilla, M. 2020. Effectiveness of Beauveria bassiana against Piezodorus guildinii (Hemiptera: Pentatomidae), a key pest of soybeans in the Neotropics. Biocontrol Science and Technology. 30:5 451-461. https://doi.org/10.1080/09583157.2020.1731426.
Sharma, A., Sandhi, R.K., Reddy, G.V. 2019. A review of interactions between insect biological control agents and semiochemicals. Insects. 10(12):439. https://doi.org/10.3390/insects10120439.
Reddy, G.V., Sharma, A., Guerrero, A. 2020. Advances in the use of semiochemicals in integrated pest management: Pheromones. Biopesticides for Sustainable Agriculture. Cambridge, UK: Burleigh Doddds Science Publishing Limited. 30 p. https://doi.org/10.19103/AS.2020.0073.12.
Maniania, N.K., Portilla, M., Amnulla, F.M., Darie, A., Ghiman, G., Rao, I.M. 2020. NoVil: Hunt for weevil control: Update! IOBC/WPRS Bulletin (Abstract for Conference Proceedings). 150:33-38.
Ghaemmaghami, E., Fathipour, Y., Bagheri, A., Talebi, A., Reddy, G.V. 2020. Quality control of the parasitoid wasp Trichogramma brassicae (Hymenoptera: Trichogrammatidae) over 45 generations of rearing on Sitotroga cerealella . Insect Science. 28(1):180-190. https://doi.org/10.1111/1744-7917.12757.
Portilla, M. 2020. A laboratory diet-overlay bioassay to monitor resistance in Lygus lineolaris (Hemiptera: Miridae) to insecticide commonly used in the Mississippi Delta. Journal of Insect Science. 20:4;1-13. https://doi.org/10.1093/jisesa/ieaa067.
Wang, L., Gao, F., Reddy, G.V., Zhao, Z. 2020. Optimization of nitrogen fertilizer application enhances biocontrol function and net income. Journal of Economic Entomology. https://doi.org/10.1093/jee/toaa112.
