This document summarizes mechanisms of insecticide resistance in insects and its management. It discusses how resistance can develop due to behavioral adaptations, reduced penetration of insecticides, target site insensitivity, and enhanced detoxification. Target site insensitivity can occur via nerve insensitivity, acetylcholinesterase insensitivity, or reduced binding at midgut target sites. Enhanced detoxification involves increased activity of enzymes like cytochrome P450s, carboxylesterases, and glutathione S-transferases. Case studies provide examples of resistance developing in insect populations exposed to insecticides over multiple generations. Effective resistance management requires using a combination of control strategies.

1. 10/12/20151
WELCOME

2. UNIVERSITY OF AGRICULTURAL &
HORTICULTURAL SCIENCES, SHIMOGA
Seminar- I
SACHIN, U. S
Sr. M. Sc. (Hort. )
Dept. of Horticultural Entomology
COLLEGE OF HORTICULTURE, MUDIGERE
10/12/20152

3. 10/12/20153
Mechanisms of Insecticide
Resistance in insects and its
Management

4. Topic division
10/12/20154
I. Introduction
History
Insecticide resistance
Terms used
Genetics of resistance
II. Mechanisms of Resistance with case studies
III. Factors favorable to rapid development of resistance
IV. Management of Insecticide Resistance with case studies
V. Conclusion

5. Fig. 1: Dynamics of increase of the resistant species of arthropods in the
world.
10/12/2015 5
Sokolyanskaya, 2010

6. 5/8/20146
Table.1: Resistant insect and mite species according
to economic importance
Economic importance Number of species Percentage of total
Agricultural 283 56.1
Medical/ Veterinary 198 39.3
Beneficial 23 4.6
Total 504
Simon, 2008

7. Table.2: Occurrence of resistance in insects and mites according to
pesticide chemical group
10/12/20157
Chemical group Number of species Percentage of total
Cyclodiene 291 57.7
DDT 263 52.2
Organophosphate 260 51.6
Carbamate 85 16.9
Pyrethroid 48 9.5
Fumigant 12 2.4
Others 40 7.9
(Simon, 2008)

8. Order Chemical group
Cyclodienes DDT OP Carbamates Pyrethroids Fumigant Other
Diptera 108 107 62 11 10 - 1
Lepidoptera 41 41 34 14 10 - 2
Coleoptera 57 24 26 9 4 8 5
Hemiptera 31 22 36 14 5 3 1
Others 23 21 9 3 1 - 2
Acarina 16 18 45 13 2 - 27
Total 276 233 212 64 32 11 38
% 66 52 47 14 7 2 9
10/12/20158
Table.3: Number of species of insects and mites reported resistant
to insecticides till 1984 (chemical groupwise)
(Gour and Sridevi,

9. Insecticide Resistance
An added ability to withstand an insecticide acquired by
breeding of those individuals which survive exposures to that
particular toxicant insufficient to wipe out the whole colony.
(Hoskins and Gordon, 1956)
An inherited ability to tolerate dosage of insecticide that
would be lethal to the majority of individuals in a normal wild
populations of same species.
(WHO, 1957).
10/12/2015 9

10. Table.4: Terms used
Insecticide Insecticide is a toxic substance that kills insects or eliminates
disease-transmitting pests/vectors
Cross Resistance It refers to a type of resistance in which a pest population develops
resistance to more than one pesticide within a chemical family
(e.g., organophosphate insecticides, etc.).
Multiple
Resistance
It involves multiple, independent resistance mechanisms, which
often lead to resistance to chemicals from different families (i.e.,
organophosphate and carbamate insecticides)
10/12/2015 10
Karunamurthy and Sabesan, 2013

11. Insecticide
Resistance
Management
It is an effort to slow down or prevent the development of
resistance.
Insecticide
Combination
The use of two or more insecticide applications within a field,
instead of single.
Insecticide Mixture Two or more compounds are mixed within a single product or
formulation
Synergist A substance which does not itself have insecticidal properties, but
which, when mixed or applied with insecticides of a particular
class, considerably enhances their potency.
10/12/2015 11
Karunamurthy and Sabesan, 2013

12. Resistance is Biphasic
Phase I- Due to selection of variants in the population according
to genetic principle, the resistance which is initially
present in the population is expressed.
Phase II- Acceleration of resistance takes place by induction of
pre-existing detoxifying enzymes towards enhanced
activity, resulting in faster breakdown of the chemicals.
10/12/2015 12
Saxena, 1996

13. 10/12/201513
Fig.2: Pesticide resistance can build up in the pest population
when a change in the genetic characteristic of the pest
population is inherited from one generation to the next.
Increased or frequent use of pesticides often hastens resistance(Goodell et al. 2001)

14. Genetics of resistance
10/12/201514
1. Preadaptation : Resistance is preadaptive
Eg: Resistance to DDT in House flies was eight times
higher than in original strain
2. Gene frequency : Low in original natural population (0.0001 to 0.01%)
High in wild & resistance population
Eg.: Mosquito in Nigeria – Dieldrin-R gene
@ 0.4-0.6%
(Simon, 2008)

15. 3. Dominance and number of genes
10/12/201515
Resistant gene can be dominant, recessive, incomplete
dominant or incomplete recessive.
Carbmates & OP’s Dominant or
incomplete dominant
DDT, Bt & Spinosyns Recessive
Dieldrin Incomplete dominant
Pyrethroid Incomplete recessive
Single gene High resistance
(Simon, 2008)

16. Table 5: Rate development of resistance to fenvalerate and Deltamethrin in
the parental field strain of Spodoptera litoralis
10/12/2015
16
Strain and
generation
tested
Fenvalerate (R-FN strain) Deltamethrin (R-DM strain)
Selecting
concentration
(mg/lit.)
LD50
a RRb Selecting
concentration
(mg/lit.)
LD50
a RRb
S-FM strain 0.46 1 0.021 1
P- strain 5 0.65 1.4 0.36 0.037 1.8
F1 5 0.54 1.2 0.36 0.032 1.5
F2 5 0.61 1.3 0.36 0.031 1.5
F3 6 0.84 1.8 0.36 0.032 1.5
F4 6 0.80 1.7 0.54 0.042 2.0
F5 6 0.88 1.4 0.54 0.045 2.1
F6 8 0.75 1.6 0.54 0.039 1.8
F7 12 1.35 2.9 0.72 0.045 2.1
F8 16 1.49 3.2 0.90 0.047 2.2
F9 20 2.27 4.9 1.44 0.088 4.2
(Riskallah et al. 1983, Egypt)
a-As μg/g body weight. b-Resistance ratio=LD50 of tested generation/ LD50 of S-FM
strain

17. Cont …….
10/12/201517
F10 30 2.31 5.0 1.80 0.091 4.3
F11 40 2.43 5.3 2.16 0.130 6.2
F12 50 2.49 5.4 2.52 0.140 6.7
F13 60 2.73 5.9 2.88 0.150 7.1
F14 70 3.18 6.9 3.24 0.180 8.6
F15 80 4.24 9.2 3.60 0.190 9.0
F16 90 4.32 9.3 3.96 0.210 10.0
F17 100 4.25 9.2 4.32 0.270 12.8
F18 120 5.93 12.9 4.68 0.320 15.2
F19 140 7.00 15.2 5.04 0.350 16.7
F20 160 10.20 22.2 5.40 0.410 19.5
F21 180 12.10 26.4 5.76 0.420 20.1
F22 200 13.20 28.8 6.12 0.440 21.0
F23 15.10 32.8 0.570 27.1
Riskallah, et al. 1983

18. 10/12/201518
Mechanisms of Resistance

19. 10/12/201519
I. Behavioral Resistance
II. Physiological Resistance
Reduced
penetration
Target site
insensitivity
Enhanced
detoxification
(Simon, 2008)

20. 10/12/201520
I. Behavioral Resistance
Development of ability to avoid a dose that would
prove lethal.
Stimulus dependent & matter of Hypersensitivity or
Hyperirritability
•Avoid lethal dose or treated surface
•Leg Autotomy
(Simon, 2008)

21. 10/12/201521
Legs
dropped
No. moths % Moths in each activity state
Dead Knocked
down
Active
0 94 31 12 57
1 46 20 10 70
2 30 20 7 73
3 5 0 20 80
4 1 0 0 100
1-4 82 18 10 72
Table.5:Leg-drop and activity status of diamondback adults
at 48 h after walking on fenvalrate residues (1,000
mg/cm2) for 5 min
(Moore et al.,

22. 10/12/201522
Fig.3: Scheme of potential Behavioral and physiological changes associated with
Resistance in insect (a) Susceptible insect, (b) Resistant insect
(Corbell and Guessan, 2013)

23. 10/12/201523
• Reduced penetration
• Target site insensitivity
• Enhanced detoxification
II Physiological Resistance
(Simon, 2008)

24. 10/12/201524
A. Reduced penetration
• Cuticle contains more protein and Lipid.
• Increased sclerotization.
• Binding protein and Lipid reservoir traps
insecticide in the cuticle.
• Slight resistance.
(Simon, 2008)

25. 10/12/201525
Fig.4: Means and variation in cuticle thicknesses (with 95% limits) of two
samples of An. funestus.
(Wood, et al. 2010, South Africa)

26. Fig.5: Time-to-knockdown (KDT) during exposure to permethrin
vs. mean cuticle thickness (microns).
10/12/201526 (Wood, et al. 2010, South Africa)

27. 10/12/201527
• Reduced penetration alone- low level of Resistance
Reduced penetration + Other mechanism- high level
of resistance
(Simon, 2008)

28. 10/12/201528
B. Target site insensitivity
(Simon, 2008)

29. Types
10/12/201529
• Nerve insensitivity
• AchE insensitivity
• Reduction in midgut target site binding
(Simon, 2008)

30. 10/12/201530
Structure of Neuron and Nerve transmission
Vesicles with ACh
AChE
Receptor site
axon

31. Mode of action of different chemicals
10/12/201531

32. 10/12/201532
Nerve insensitivity
• DDT and Pyrethroid Resistant strain
Insensitive Na+ channel
• Cyclodiene- Point mutation in GABA receptor
protein
(Simon, 2008)

33. 10/12/201
5
33
AChE insensitivity
• OP and carbamates resistant strains
Insensitive AChE enzyme
• Point mutation in receptor protein
(Simon, 2008)

34. Reduction in midgut target site binding
10/12/2015
34
 Reduced binding of toxin
 Disruption of Cadherin superfamily gene.
Tobacco bud worms-showed high levels of resistance to
Cry1Ac
Pink boll worm- alteration in BtR-4 gene
 Alteration of sugar structure- affects Bt toxin attachment

35. Fig.6: The resistance development to chlorantraniliprole in
the S strain of P. xylostella.
10/12/201535 (Gong, et al. 2014)

36. 10/12/201536
C. Enhanced detoxification
insecticide Detoxification of insecticides by
enzymes
Target site
(Simon, 2008)

37. 10/12/201537
• Detoxifying Enzymes
a. Hydrolases –Carboxyl Esterase (CarE)
i. Esterase gene amplification
ii. Esterase mutation
b. Mixed fuction oxidases (MFO’s)
Cytochrome P450 monoxygenases (P450)
c. Glutathion-S-transferases (GST)
(Simon, 2008)

38. 10/12/201538
Fig. 7: The three Principal types of insecticide resistance
mechanisms in cross section through susceptible and
resistant insects.
(Karunamurthy and Sabesan, 2013)

39. 10/12/201539
Resistance
profile
OPs Carbaryl,
methomyl &
Propoxur
Carbofuran Synthetic
pyrethroids
IGRs
Resistance
mechanism
involved
Multifactorial Monofactorial Monofactorial Monofactorial Monofact
orial
Responsible
biochemical
entities
Insensitivity,
AChE,
Carboxylesterase
MFO’s MFO’s MFO’s MFO’s
Resistance
amplitude
medium high high high high
Table.7: Important mechanisms in DBM insecticide
resistance
(Cheng et al. 1998)

40. 10/12/201540
Enzyme Strain Enzyme activity Rate
P450 S 33.12± 4.48 a 1.00
GDLZ- R 35.94± 1.77 a 1.08
CarE S 37.52± 2.16 a 1.00
GDLZ- R 42.74± 10.06 a 1.14
GST S 10.20± 0.39 a 1.00
GDLZ- R 34.12± 9.69 b 3.34
Table.8: Activities of detoxification enzymes in different strains
of P. xylostella L. against chlorantraniliprole
(Zhen-di et al., 2014, China)

41. 10/12/2015
41
Fig.8a: P450 activity of control and chlorantraniliprole exposed P.xylostella L. larvae after
6 h, 12h and 24h exposure. Data represent the mean ±SE of three replicates. “*”
indicate significant difference from control and chlorantraniliprole exposure for 6
h, 12 h in S strain where *α=0.05.
(Zhen-di, et al. 2014)

42. 10/12/201542
Fig. 8b: CarE activity of control and chlorantraniliprole exposed P.xylostella L. larvae after
6 h, 12 h and 24 h exposure. Data represent the mean ±SE of three replicates.
“*”indicate significant difference from control and chlorantraniliprole exposure for
6 h in S strain where *α=0.05.
(Zhen-di, et al. 2014)

43. 10/12/201543
Fig.8c : GST activity of control and chlorantraniliprole exposed P.xylostella L. larvae after 6
h, 12 h and 24 h exposure. Data represent the mean ±SE of three replicates. “*”
indicate significant difference from control and chlorantraniliprole exposure for 6 h
in susceptible strain and 12 h, 24 h in GDLZ-R strain where *α=0.05.
(Zhen-di, et al. 2014)

44. Table.9: Mode of resistance and number of cytochrome P450s,
carboxylesterases, esterases and transferases among
the genomes of blood-feeding insects
10/12/201544
Mode of
resistance
Pediculus
humanus
Anopheles
gambiae
Culex
quinquefasciatus
Aedes
aegypti
Cimex
lectularius *
TSR MR & TSR MR & TSR MR & TSR MR & TSR
P450 37 106 172 158 73#
CES Not
reported
25 47 30 -
EST 17 15 17 19 -
TRA 13 31 37 32 14#
MR = metabolic resistance; TSR=target sensitivity resistance; P450 = cytochrome
P450s; CES = carboxylesterases; EST = esterases; TRA = transferases; # =
occurrences; * as per 454 pyrosequencing data, not complete genome of the bed
bug
(Mamidala, et al. 2011)

45. Table.10: Comparison of EST, GST and AChE activities in nine different
populations of Oxya chinensis (Orthoptera: Acrididae)
10/12/201545
Population EST specific activitya
(μ mol/min/mg protein)
GST specific activitya
(μ mol/min/mg protein)
AChE specific activityb
(μ mol/min/mg protein)
XY 0.17±0.04e 79.19±41.22bcd 9.34±3.48a
JY 0.36±0.10ab 83.68±46.11bcd 9.26±1.61a
BDG 0.30±0.07c 96.37±45.40b 8.32±1.77a
YC 0.10±0.01f 52.64±9.44d 4.83±0.78bc
XX 0.25±0.06d 89.28±55.14bc 9.02±3.30a
HZ 0.33±0.03bc 67.11±15.43bcd 2.80±0.70c
BD 0.32±0.04bc 166.95±31.88a 2.18±0.46c
CA 0.12±0.04f 81.42±32.52bcd 7.00±1.54ab
JN 0.37±0.08a 73.83±48.67bcd 3.49±0.60c
(Haihua, et al. 2007, China)
a Average of 64 individual thoraxes, each with triplicate analyses.
b Average of four groups of heads, each with triplicate analyses.

46. Table.11: Metabolic enzyme activities of fourth instars from the
SZ strain and the Fipronil-resistant SZ-F strain of
Plutella xylostella.
10/12/201546
Detoxification enzyme Specific activity (Mean ± SE)
SZ strain
(susceptible)
SZ-F strain
(resistant)
Ratio (SZ-F/SZ)
Oxidases (pmol/min/mg protein)
PNOD 0.26±0.06 0.28±0.04 1.07
ECOD 1.63±0.51 1.83±0.34 1.12
MCOD 4.52±1.1 4.71±0.59 1.04
Esterases (nmol/min/mg protein)
α-NA esterase 102.2±12 108.5±4.1 1.06
GSTs (nmol/min/mg protein)
CDNB conjugation 179.1±58 191.6±7.7 1.07
DCNB conjugation 5.06±0.3 5.74±0.31 1.13
P > 0.05; t- test
(Ageng et al. 2006, China)

47. Table.12:Resistance levels of Plutella xylostella
strains to Acephate
10/12/201547
Strain n LC50(mg/L) 95%CL RR
SS 288 16.8 14.0-20.3 1
OR 215 3316.7 2683.3-4253.6 197.4
KU-10 165 581.5 439.6-787.5 34.6
SMN 43 255.0 51.1-754.4 15.2
WH 252 90.2 59.3-129.1 5.4
BJ1-10 333 308.0 195.5-488.3 18.3
BJ3 91 1307.2 894.0-2092.8 77.8
RR: resistant ratio= LC50 of strains tested/LC50 of SS strain.
(Sonoda, et al. 2014)

48. Table.13: Mean resistance frequency * (%) to different chemistries in
H. armigera population of Tamilnadu (a comparision
among the three locations)
10/12/201548
Insecticides Coimbatore Poluvampatty Madukarai
Fenvalerate 95.0 97.2 93.4
Cypermethrin 96.7 97.4 93.3
Deltamethrin 91.9 95.4 88.9
Lamdacyhalothrin 91.5 91.9 86.3
Betacyfluthrin 81.8 89.4 81.4
Quinalphos 49.2 34.4 38.9
Chlorpyrifos 49.3 46.6 44.0
Profenofos 35.4 24.5 27.8
Endosulfan 36.5 26.0 29.4
Thiodicarb 36.2 32.1 33.3
Spinosad 0.0 0.0 0.0
*Mean of resistance frequency data obtained for 49 weeks (June 2002- April 2003)
(Ramasubramaniam and Ragupathy, 2004, Coimbatore)

49. 10/12/201549
• Prolonged exposure to a single insecticide
• High selection pressure
• Large coverage area
• Immigration or Migratory
• Insects multiplying by asexual means
• Short life cycle of insect
• Selection at every stage of insect life cycle

50. Table.14: Biological, genetic, and operational factors in resistance
development.
10/12/2015
50
Factor
Potential for resistance development
Lower Higher
Biological factors
Population size Small Large
Reproductive potential Low High
Generation turnover One or less generations
per year
Many generations per year
Pesticide metabolism Difficult Easy
Number of target sites of
the pesticide
Multiple sites Single
Specific Pest host range Narrow Wide
International Code of Conduct on the Distribution and Use of Pesticides, 2012.

51. 10/12/201551
Factor
Potential for resistance development
Lower Higher
Genetic factors
Occurrence of resistance
genes
Absent Present
Number of resistance
mechanisms
One Several
Gene frequency Low High
Dominance of resistance
genes
Recessive Dominant
Fitness of “R” individuals Poor Good
Cross resistance Negative or none Positive
Modifying genes Absent Present
International Code of Conduct on the Distribution and Use of Pesticides, 2012.

52. 10/12/2015
52
Factor
Potential for resistance development
Lower Higher
Operational factors
Activity spectrum of the
pesticide
Narrow spectrum Broad spectrum
Pesticide application rate Less More
Presence of secondary
pests
Absent (only the target
pest is treated)
Present (non targeted
(potential) pests are also
treated)
Pest control tactics Multiple control tactics
(chemical, biological,
cultural)
Continuous use of single
method or compound
International Code of Conduct on the Distribution and Use of Pesticides, 2012.

53. 10/12/201553
Management of Insecticide Resistance
 Integrated pest management
• Grow trap crops
• Inundative release of Biological agents
• Swabbing & stem banding
• Judicious use of insecticides (Need based & Recommended
dose)
• The use of insecticide synergists
• Window system of pesticide application
• Insecticide rotation
• Area wide management

54. Table.15: Phases of resistance monitoring and management for a new
pesticide
10/12/201554
Timing Resistance detection
and monitoring
activities
Other management
activities
1-2 years before start of
sales
Establish sampling and
testing methods &
Survey for initial
sensitivity data
Assess risk
During years of use Monitor randomly in
treated areas for
resistance, if justified by
risk assessment of special
importance of crop/pest
Implement the RMP;
watch practical
performance of the
pesticide closely
International Code of Conduct on the Distribution and Use of Pesticides, 2012.

55. 10/12/201555
As soon as signs of
resistance have been
detected
Monitor to determine the
extent and practical
significance of resistance
Study cross resistance,
fitness of variants of
resistant organisms,
assess other factors
affecting the
development of
resistance
If resistance problem is
confirmed, review and
modify RMP
Subsequently Monitor rate of spread or
decline of resistance
Watch pesticide
performance; review
RMPs
International Code of Conduct on the Distribution and Use of Pesticides, 2012.

56. Figure. 11: Swabbing with mineral oil &
10/12/2015
56
(Ayyasamy & Regupathy, 2010, Tamil
Nadu)
Stem banding with black
polythene sheet

57. Table.16: Mean synergistic suppression (%) of insecticide
resistance by MFO and CE inhibitors
Insecticides Piperonyl
butoxide (50 μg)
Pungam oil
(50 μg)
Profenofos
(0.1 μg)
Fenvalerate 57.9 46.0 24.4
Cypermethrin 52.2 45.8 19.7
Endosulfan 14.2 2.1 19.5
Thiodicarb 0.6 -------- 2.9
10/12/2015 57
(Ramasubramaniam and Ragupathy, 2004, Coimbatore)

58. Table.17: Combination products in pest management in different
crop eco-system
10/12/201558
Combination products Dose (per ha) Target pest
Bhendi
Polytrin C 44EC (40%
profenofos+ 4% cypermethrin)
2lit. Erias spp., Aphis gossypii
Glover, Tetranychus
cinnabarinus Boisdual,
Amrasca devastans (Dist.)
Cypermethrin+Chlorpyrifos 100+1000g a.i Erias vittella and
Helicoverpa armigera
Brinjal
Polytrin C 44EC 0.044% Bemisia tabaci
Spark 36 EC (35% of
Triazophos+ 1% of
Deltamethrin)
1.25 lit. Leucinodus orbonalis
Guenee
Carbosulfan + Quinalphos 1ml each/lit. Leucinodus orbonalis
(Ragupathy, et al. 2004,

59. Cont…
10/12/201559
Tomato
Polytrin C 44 EC (40%
profenofos+ 4%
cypermethrin)
1 lit. Helicoverpa armigera
Spark 36 EC (35% of
Triazophos+ 1% of
Deltamethrin)
1 lit. Helicoverpa armigera
Lethal super 2 lit. Helicoverpa armigera
Mango
Nurelle D 505 1.5 ml/lit Amritodes atkinsoni L.
Sugar beet
Nagata 45 EC 675 g a.i Spodoptera litura F.
Cabbage
Spark 36 EC 1.25 lit. Plutella xylostella (L.)
(Ragupathy, et al. 2004)

60. Table.18: Insecticide resistance management guidelines for beet
army-worm (March 2001).
10/12/201560
Insecticide class Early season(April
to mid-june)
Mid season (Mid-
June through July)
Late season
(August and
September)
Bacillus
thuringiensis
Various products Various products
Organophosphate Lorsban or
Curacron
Lorsban
Carbamate Lannate Lannate
Miscellaneous Steward
Success
Conform
Success Steward
Conform
Pyrethroid Capture
Asana
Goodell, et al. 2001

61. Table.19: Insecticide resistance management guidelines for Silver
leaf whitefly (March 2001).
10/12/201561
Chemical class Initial build up Gradual invasion Heavy migration
Insect growth regulator
Chitin synthesis inhibitor
Applaud
Insect growth regulator
Metamorphosis inhibitor
Knack
Chloronicotinyl Provado
Amidene Ovasyn
Pyrethroid Capture
Pyrethroid+ organochlorin Pyrethroid+ Endosulfan
Pyrethroid+
organophosphate/carbamate
Denitol+Orthene/Curac
ron/Lannate/Vydate
Goodell, et al. 2001

62. 10/12/2015 62
Rotation Number of WFT adults per plant Cumulative
number of WFT
adult
2DAA1 3DAA2 2DAA3 2DAA4
Untreated 14.1a 23.0a 44.8a 123.6a 205.5a
Radiant/ Movento 0.8b 11.3b 40.4abc 16.8bcd 69.3bc
Radiant/ Assail 1.5b 7.3b 31.7abcd 17.9bcd 58.4cd
Radiant/ Venom 1.1b 8.6b 26.0cd 11.1cd 46.8de
Radiant/ Beleaf 0.9b 13.1b 43.3ab 26.2b 83.5b
Radiant / Requiem 1.2b 10.8b 36.5abc 15.5bcd 64.0cd
Radiant/ Eco+ Req 1.4b 13.6b 30.7abcd 13.0cd 58.7cd
Radiant/ Agri- Mek 1.4b 6.5b 18.9d 8.2d 35.0e
Radiant/M- Pede 1.4b 12.2b 26.6bcd 22.7bc 62.9cd
Table.20: Effect of several insecticide rotations on WFT on adult
numbers (onion trial; Fresno, CA), 2009
(James et al., 2010)
2DAA1 = 2 days after the first application

63. 10/12/201563
Rotation Number of WFT larvae per plant Cumulative
number of
WFT larvae
2DAA1 3DAA2 2DAA3 2DAA4
Untreated 72.6 a 118.0 a 127.1 a 305.1 a 624.0 a
Radiant/ Movento 9.0 b 16.1 b 106.0 ab 36.3 b 168.0 bcd
Radiant/ Assail 16.9 b 7.7 b 50.5 c 45.8 b 120.0 de
Radiant/ Venom 11.1 b 12.7 b 43.4 c 62.0 b 128.0 cd
Radiant/ Beleaf 10.2 b 11.5 b 83.5 b 50.3 b 156.0 bcd
Radiant / Requiem 10.1 b 18.2 b 113.2 ab 63.3 b 204.0 b
Radiant/ Eco+ Req 15.8 b 18.1 b 110.7 ab 38.2 b 184.0 bc
Radiant/ Agri+
Mek
13.6 b 9.4 b 14.9 d 29.6 b 68.0 e
Radiant- Pede 14.0 b 21.6 b 104.5 ab 51.1 b 192.0 b
Table.21: Effect of several insecticide rotations on WFT on larval
numbers (onion trial; Fresno, CA), 2009.
(James et al., 2010)
2DAA1 = 2 days after the first application

64. 10/12/201564
conclusion

65. 10/12/201565