MISSISSIPPI SOYBEAN PROMOTION BOARD PROJECT NO. …...Objective 4: This objective will be conducted...
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MISSISSIPPI SOYBEAN PROMOTION BOARD PROJECT NO. 37-2013 (YEAR 1) ANNUAL REPORT Title: Characterization of the Resistance Potential for the Diamide Insecticides, Belt (flubendiamide) and Prevathon (chlorantraniliprole). PI: Jeff Gore, [email protected] CO-PI's: Angus Catchot, Don Cook, Natraj "Krish" Krishnan, and Trent Irby EXECUTIVE SUMMARY Bollworm, tobacco budworm, fall armyworm, and beet armyworm populations remain highly susceptible to the diamide class of chemistry, and no tolerant populations were found. In general, all populations and species were more susceptible to Prevathon than Belt. With beet armyworm, colonies are being selected at three concentrations of Belt that represent low, moderate, and high doses to determine the influence of selection pressure on the evolution of resistance. Currently, five generations have been selected. To date, none of the selections have resulted in a resistant colony. Prevathon moved into new plant tissue and provided better systemic control of bollworm than did Benevia and Belt at all rating intervals. Prevathon provided excellent systemic control out to 32 DAT. Benevia appeared to provide systemic control as well, but control declined at each subsequent rating interval. Based on these data, Belt does not appear to move into new plant parts like Prevathon. At 25 DAT, all of the insecticides resulted in greater than 90% mortality. At 32 DAT, Prevathon still provided 100% mortality, while mortality declined with Benevia and Belt. However, Benevia and Belt both provided very good residual control at 32 DAT. BACKGROUND AND OBJECTIVES This is a graduate student project to gain a better understanding of bollworm and other caterpillar pest resistance to the diamide insecticides, Belt and Prevathon. This is a new class of chemistry that provides unprecedented knockdown and residual control of caterpillar pests. As a result of their long residual control, it appears that there is a high probability of resistance development to this class of insecticides. Basic and applied research is needed to understand the biological properties of these insecticides to ensure their longevity in soybean production systems in Mississippi. Additionally, research is needed to determine their optimum use strategies in Mississippi soybean production systems. Objective 1: To quantify the variation in the response of bollworm to the diamide insecticides.
Transcript of MISSISSIPPI SOYBEAN PROMOTION BOARD PROJECT NO. …...Objective 4: This objective will be conducted...
MISSISSIPPI SOYBEAN PROMOTION BOARD
PROJECT NO. 37-2013 (YEAR 1)
ANNUAL REPORT
Title: Characterization of the Resistance Potential for the Diamide Insecticides, Belt
(flubendiamide) and Prevathon (chlorantraniliprole).
PI: Jeff Gore, [email protected]
CO-PI's: Angus Catchot, Don Cook, Natraj "Krish" Krishnan, and Trent Irby
EXECUTIVE SUMMARY
Bollworm, tobacco budworm, fall armyworm, and beet armyworm populations remain highly
susceptible to the diamide class of chemistry, and no tolerant populations were found.
In general, all populations and species were more susceptible to Prevathon than Belt.
With beet armyworm, colonies are being selected at three concentrations of Belt that represent low,
moderate, and high doses to determine the influence of selection pressure on the evolution of
resistance. Currently, five generations have been selected. To date, none of the selections have
resulted in a resistant colony.
Prevathon moved into new plant tissue and provided better systemic control of bollworm than did
Benevia and Belt at all rating intervals. Prevathon provided excellent systemic control out to 32
DAT. Benevia appeared to provide systemic control as well, but control declined at each
subsequent rating interval. Based on these data, Belt does not appear to move into new plant parts
like Prevathon.
At 25 DAT, all of the insecticides resulted in greater than 90% mortality. At 32 DAT, Prevathon
still provided 100% mortality, while mortality declined with Benevia and Belt. However, Benevia
and Belt both provided very good residual control at 32 DAT.
BACKGROUND AND OBJECTIVES
This is a graduate student project to gain a better understanding of bollworm and other caterpillar
pest resistance to the diamide insecticides, Belt and Prevathon. This is a new class of chemistry that
provides unprecedented knockdown and residual control of caterpillar pests. As a result of their long
residual control, it appears that there is a high probability of resistance development to this class of
insecticides. Basic and applied research is needed to understand the biological properties of these
insecticides to ensure their longevity in soybean production systems in Mississippi. Additionally,
research is needed to determine their optimum use strategies in Mississippi soybean production
systems.
Objective 1: To quantify the variation in the response of bollworm to the diamide insecticides.
Objective 2: To determine the influence of selection pressure with the diamide class of insecticides
(Belt and Prevathon) on resistance development in bollworm and beet armyworm.
Objective 3: To correlate field control with diamides against resistant and susceptible populations.
Objective 4: To determine the heritability and mechanisms of resistance for the diamide
insecticides in bollworm, soybean looper, and beet armyworm.
EXPECTED OUTCOME: Improved use strategies to extend the life of the diamide class of
insecticides and develop a better understanding of their use strategies.
REPORT OF PROGRESS/ACTIVITY
Objective 1: Overall, populations of caterpillar pests were very low in Mississippi during the 2013
season. However, nine populations of bollworm, one population of tobacco budworm, two
populations of fall armyworm, and one population of beet armyworm were collected from locations
throughout Mississippi and tested to determine variation in their response to Belt and Prevathon
using concentration mortality bioassays.
An emphasis was placed on the collection and testing of H. zea, because it is a more critical pest of
soybean production in Mississippi and more readily available for collection. Based on the results of
these bioassays, bollworm, tobacco budworm, fall armyworm, and beet armyworm populations
remain highly susceptible to this class of chemistry and no tolerant populations were found. In
general, all populations and species were more susceptible to Prevathon than Belt. Doses used for
Belt ranged from 0.0078 to 0.065 parts per million (ppm). In contrast, doses used for Prevathon
ranged from 0.0039 to 0.0156 ppm.
All data for the first objective are presented in Appendix 1. Additional populations will be tested in
2014. The information generated with these bioassays will be important in future years if field
control failures occur with these insecticides.
Objective 2: This objective has been initiated with a recently collected colony of beet armyworm.
Colonies are being selected at three concentrations of Belt that represent low, moderate, and high
doses to determine the influence of selection pressure on the evolution of resistance. Currently, five
generations have been selected. To date, none of the selections have resulted in a resistant colony.
Insect susceptibility to a particular insecticide is generally based on LC50 or LC90 values. These
values represent the concentration of insecticide that will kill 50% or 90%, respectively, of a
susceptible population. After 5 generations, those values are similar to the original unselected
population. Similarly, the seventh generation was tested using a discriminating dose bioassay. All
colonies were tested at a single dose. No significant differences were observed between the selected
colonies and the non-selected colony. However, percent survival was slightly lower in the selected
colonies. All data are presented in Appendix 2.
Objective 3: No tolerant populations have been identified for this objective to date. As a
contingency, a field experiment was conducted to quantify the residual and systemic activity of Belt
and Prevathon. Plots were 25 feet long with 4 40-in. wide rows. Plots were sprayed with Belt,
Prevathon, and Benevia at the current use rates using a compressed air sprayer calibrated to deliver
10 gpa at 40 psi traveling at 3 mph using TX-8 hollow cone nozzles.
Benevia is another diamide that is not labeled in soybean. Treatments were applied on 28 August
2013 and plants were flagged at the uppermost node in order to ensure that only new leaf material
was collected for bioassays (Photo 1 & 2 in Appendix 3). Plots were irrigated on 29 August 2013
to encourage new growth. Leaves were pulled from the upper part of each plant and only newly
emerged leaves were used to ensure that they had not been directly sprayed with the insecticides.
Leaves were pulled at 11, 18, 25, and 32 days after treatment (DAT). In addition, leaves that had
been directly sprayed were removed from the bottom portion of each plant to measure residual
control at 25 and 32 DAT.
All data are presented in Appendix 3. Prevathon moved into new plant tissue and provided better
systemic control of bollworm than Benevia and Belt at all rating intervals. Prevathon provided
excellent systemic control out to 32 DAT. Benevia appeared to provide systemic control as well,
but control declined at each subsequent rating interval. Based on these data, Belt does not appear to
move into new plant parts like Prevathon.
In terms of residual activity, all of the insecticides provided good control. At 25 DAT, all of the
insecticides resulted in greater than 90% mortality. At 32 DAT, Prevathon still provided 100%
mortality, while mortality declined with Benevia and Belt. However, Benevia and Belt both
provided very good residual control at 32 DAT. This objective has been expanded to include more
work on the residual and systemic nature of these insecticides. Greenhouse experiments were
initiated in January. Additional field experiments will be done in 2014.
Objective 4: This objective will be conducted during years 2 and 3 of the project using populations
from objective 2 after multiple generations of selection.
IMPACTS AND BENEFITS TO MISSISSIPPI SOYBEAN PRODUCERS
The diamide insecticides are a remarkable chemistry that provide long residual control of caterpillar
pests. The residual activity of these insecticides make them especially susceptible to resistance
because multiple generations can be exposed from a single application. Because of their importance
for insect control in Mississippi soybean, it is important to understand the development,
mechanisms, and heritability of resistance in key insect pests. This research will help identify factors
to be used to detect, manage, and mitigate resistant populations in the future. Additionally, the field
results will help identify the optimum use strategies for these insecticides in Mississippi soybeans.
END PRODUCTS
Results from this research have been presented by the student at numerous scientific meetings,
including the Mississippi Entomological Association, Entomological Society of America National
and Southeastern Branch meetings, and the Beltwide Cotton Conferences.
Laboratory and field results have been presented by MSU research and extension personnel at
numerous field days, workshops, and consultant and grower meetings.
Multiple papers will be published by the graduate student in refereed journals.
At least one extension publication will be published at the end of the project.
Multiple posts pertaining to this research will be included on the Mississippi Crop Situation Blog
(www.mississippi-crops.com).
Appendix 1: Results of bioassays conducted with Prevathon and Belt against corn earworm,
beet armyworm, fall armyworm, and tobacco budworm. Doses used for Belt ranged from
0.0078 to 0.065 parts per million (ppm). In contrast, doses used for Prevathon ranged from
0.0039 to 0.0156 ppm.
Objective 1
• To quantify the variation in the
response of bollworm to the diamide
insecticides.
CEW – Prevathon 2013
0
0.005
0.01
0.015
0.02
0.025
CEW-Stoneville Corn
CEW-STARK 1 CEW-Milo CEW-Garbanzo
LC50 LC90
CEW – Belt 2013
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
CEW-Stoneville Corn CEW-STARK 1 CEW-STARK 3 CEW-Milo
LC50 LC90
FAW – Prevathon 2013
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
FAW-SUSC FAW-Sorghum FAW-Corn
LC50 LC90
FAW – Belt 2013
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
FAW-SUSC FAW-Sorghum FAW-Corn
LC50 LC90
BAW – Prevathon 2013
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
BAW-SUSC BAW-FIELD
LC50 LC90
BAW – Belt 2013
0
0.005
0.01
0.015
0.02
0.025
0.03
BAW-SUSC BAW-Field
LC50 LC90
Appendix 2
Results of selection pressure experiment to study resistance to diamide insecticides.
Objective 2
• To determine the influence of selection pressure with
the diamide class of insecticides (Belt) on resistance
development in beet armyworm
Selection Colony – 5 generations
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
0.05
LC0 LC30 LC60 LC90
LC 50 LC90
Discriminating Dose LC807 Generations
80
82
84
86
88
90
92
94
96
98
100
102
LC0 LC30 LC60 LC90
Perc
en
t M
ort
ali
ty
Appendix 3
Results of a field experiment to determine the systemic and residual control of corn earworm
(bollworm) in soybeans.
Objective 5
• To determine the systemic nature and longevity of
chlorantraniliprole against corn earworm
Systemic Mortality 11 DAT
0
10
20
30
40
50
60
70
80
90
100
110
Prevathon 14 oz Benevia 14 oz Belt 2 oz Non-Treated
P < 0.01a
c
b
c
% C
on
tro
l
Systemic Mortality 18 DAT
0
10
20
30
40
50
60
70
80
90
Prevathon 14 oz Benevia 14 oz Belt 2 oz Non-Treated
a
b
c
c
% C
on
tro
l
P < 0.01
Systemic Mortality 25 DAT
0
10
20
30
40
50
60
70
80
90
100
Prevathon 14 oz Benevia 14 oz Belt 2 oz Non-Treated
a
b
cc
% C
on
tro
l
P < 0.01
Systemic Mortality 32 DAT
0
10
20
30
40
50
60
70
80
90
100
Prevathon 14 oz Benevia 14 oz Non-Treated
P < 0.01a
bcc
% C
on
tro
l
Residual Efficacy 25 DAT
0
10
20
30
40
50
60
70
80
90
100
110
Prevathon 14 oz Benevia 14 oz Belt 2 oz Non-Treated
a ab
c
% C
on
tro
l
P < 0.01
Residual Efficacy 32 DAT
0
10
20
30
40
50
60
70
80
90
100
110
Prevathon 14 oz Benevia 14 oz Belt 2 oz Non-Treated
a
b
ab
% C
on
tro
l
c
P < 0.01
