The document discusses the diamondback moth (DBM), Plutella xylostella, which is the most destructive pest of cabbage in the Philippines. It notes that DBM has developed high levels of resistance to most insecticides used for its control. It provides background on various diamide insecticides such as flubendiamide and chlorantraniliprole that have been used against DBM. However, field failures have been reported shortly after their introduction, indicating the development of resistance. The document emphasizes the importance of monitoring baseline susceptibility and implementing insecticide resistance management strategies to preserve the effectiveness of new insecticide classes.

2. INTRODUCTION
Crucifer crops like cabbage, Brassica oleracea L., Chinese
cabbage, Brassica campestris (L.) sp. pekinensis, and
radish, Raphanus sativus L., are the most important
vegetables in the Philippines after tomato and eggplant
(Bureau of Agricultural Statistics).
Diamondback moth (DBM), Plutella xylostella (L.)
(Lepidoptera: Yponomeutidae), is the
most destructive pest of cabbage.
In Southeast Asia DBM is highly resistant to most insecticides
used for its control (Perng and Sun 1987). In the Philippines
growth-regulator insecticides (based on teflubenzuron) was
successful for about 2 years. A reduced efficacy of even
Bacillus thuringiensis Berliner is reported from the DBM
strain of North Luzon.

3. Cabbage Growing
Areas
15,000 ha or 85% in
highland areas.
117,000 MT per
year.
25-30% production
Cost (pesticide).

4. Cabbage Production
YEAR ACTIVITY
1920’s Crop introduction
1960’s Production boomed
1970’s Area Expansion
1980’s Product quality
1990’s Product quality
2000 Product quality

5. The Filipino DBM
YEAR ACTIVITY
1927 First record
1965 First recorded outbreak
1967 First trial on insecticides
1970 First record on resistance
1974 Multiple Resistance recorded
1990 2nd outbreak (Cyanide Scare)

6. The Filipino DBM
YEAR ACTIVITY
1950’s Slight damage, Class A
1960’s Severe, no marketable
1970’s Severe, no marketable
1990’s Severe, no marketable

7. Resistance to Insecticides
YEAR ACTIVITY
1974 1974 First report on resistance
To Mevinphos
1976 1976 First report on multiple resistance
to, Carbaryl, Mevinphos,
Malathion, Methyl Parathion,
Diazinon and Dichlorvos
1982 Cypermethrin, Triazophos, Bt,
Cartap, Fenvalerate, Deltamethrin
1994 IGR’s (Nomolt, Diaract. Atabron)
2005 Fipronil (Ascend)

8. Pesticide Usage
91% use
pesticides
85% use >2
kinds
/season
1 kind
after
another
7-21 days
interval

9. Other Practices
Potato
43%
Carrot
17%
Others
15%
Percentage

10. Preferences
Fenos,
Prevathon,
Voliam
Flexi
Success
(Spinosad)
Tamaron
(Methamidophos)

11. Other Insecticides Used
Brand Name Active Ingredient
Ascend Fipronil
Decis Deltametrin
Hostathion Triazophos
Kafil Cypermethrin
Kutetso Chlorphenapyr
Matador Methamidophos
Malathion Malathion)
Padan Cartap
Pegasus Diafenthiuron
Sumicidin Fenvalerate
Thuricide Bt
Vegetox Cartap

12. Diamide Insecticide
Resistance of DBM
Diamide insecticides, such as flubendiamide and
chlorantraniliprole, are a new class of insecticide with a
novel mode of action, selectively activating the insect
ryanodine receptor (RyR).
They are particularly active against lepidopteran
pests of cruciferous vegetable crops, including the
diamondback moth, Plutella xylostella.
However, within a relatively short period following their
commercialization, a comparatively large number of control
failures have been reported in the field.

13. Background of Flubendiamide
Flubendiamide is an extremely effective insecticide against P.
xylostella, especially when used as a larvicide. The parent
compound structure was discovered by Nihon Nohyaku Co., Ltd
during their pyrazine- dicarboxamide herbicide development
program conducted in the
early 1990s.
The discovery of more potent substituents led to the
synthesis, in 1998, of a phthalic acid diamide insecticide,
later named flubendiamide, co-developed by Nihon Nohyaku
and Bayer CropScience.
However, within a relatively short period
following their commercialization, a
comparatively large number of control failures
have been reported in the field.

14. Background of Flubendiamide
Flubendiamide is an extremely effective insecticide against P. xylostella,
especially when used as a larvicide. The parent compound structure was
discovered by Nihon Nohyaku Co., Ltd during their pyrazine-
dicarboxamide herbicide development program conducted in the
early 1990s.
The discovery of more potent substituents led to the synthesis, in 1998, of
a phthalic acid diamide insecticide, later named flubendiamide, co-
developed by Nihon Nohyaku and Bayer CropScience.
However, within a relatively short period following their
commercialization, a comparatively large number of
control failures have been reported in the field.

15. Chlorantraniliprole or Rynaxypyr® (Dupont,
USA), is another insecticide in the IRAC
Mode of Action Group 28 family.
Chlorantraniliprole was the first member of
the anthranilic diamides, and, as with
flubendiamide, is particularly effective for
control of insects in the order Lepidoptera.
Background of Chlorantraniliprole

16. √ Chlorantraniliprole is relatively harmless to
beneficial arthropods and was not found to
exhibit cross resistance with existing
insecticides.
√ This insecticide is currently sold under the
trade names Acelepryn®, Altacor®,
Coragen®, Dermacor®, Prevathon®, Flexi
and Voliam® Xpress Durivo® and Virtako®.
Background of Chlorantraniliprole

17. √ Cyantraniliprole or Cyazypyr™
- Products containing cyantraniliprole were
launched in selected countries from 2012
under the trade names Exirel®, Verimark®,
Ference®, Fortenza Duo®, Benevia® and
Spinner®.
Background of Cyantraniliprole or
Cyazypyr™

18. The LC50 value (lethal concentration that
provides 50% mortality) of a particular
insecticide can be used to establish a baseline
susceptibility for a target population. This
can then be used as a baseline reference in
future monitoring surveys to determine if
the susceptibility of the target population has
shifted after the population has been exposed
to the insecticide.
Baseline susceptibility monitoring for
diamide insecticides

19. Actual LC50 values can be compared between
populations by examining the 95%
confidence intervals, whereby if the upper
and lower limits do not overlap then it is
likely that the population has experienced a
significant loss of susceptibility. Such a
change could be indicative of a resistance
problem and should trigger further
investigation.
Baseline susceptibility monitoring for
diamide insecticides

20. • Baseline monitoring for P. xylostella
susceptibility to chlorantraniliprole was
conducted by DuPont in the Philippines
from 2006 to 2008, at locations in Benguet
Province (Buguias and La Trinidad) and
Laguna Province (Calauan and Liliw). The
field populations surveyed showed high
sensitivity to the diagnostic dose rates of 1
ppm (LC95) and 5 ppm (5X LC95) (Edralin et
al., 2011).
Baseline susceptibility monitoring for
diamide insecticides

21. Cabbage Planters in Benguet
Cabbage Planters in
Mantalongon,Cebu

22. • A future shift to significant survivorship (i.e.
>20%) at the higher rate would indicate incipient
problems and a greater risk of resistance
developing. Similar baseline monitoring for both
chlorantraniliprole and flubendiamide were
conducted in Thailand from 2008 to 2010
(Sukonthabhirom et al., 2011), with susceptible
field populations from Tub Berg, Petchabun
Province, displaying approximately similar LC50
values to those reported in the Philippines survey.
Baseline susceptibility monitoring for
diamide insecticides

23. Diamondback moth larvae are historically
notorious for the speed at which they can
develop resistance to new products. This is
probably due to their genetic plasticity, a
rapid generation time, high fecundity, and
the fact that new chemistry is often heavily
used, creating high selection pressure in the
field.
Diamide resistance development

24. It has been recorded that P. xylostella has
developed resistance to 93 insecticides
(Whalon et al., 2016) and has become one of
the most problematic pests to control in
cruciferous vegetables.
Diamide resistance development

25. • Flubendiamide (Fenos®) and
Chlorantraniliprole (Prevathon®)
insecticides were registered in the
Philippines in 2006 and 2007, respectively
and Voliam Flexi®, a premix of
chlorantraniliprole and thiamethoxam (a
neonicotinoid insecticide) in 2008.
Flubendiamide (Takumi® 20WDG) was
registered in Thailand in May, 2007.
Diamide resistance development

26. These diamides offered growers excellent
control of diamondback moth larvae in
cruciferous crops, where few other
registered products were adequately effective
(Andaloro et al., 2011).
Diamide resistance development

28. Nursery -
Transplanting
Leafy Stage Head Forming Harvest
Diamond
Back
Moth
1st Generation 2nd Generation 3rd
Generation
Option 1
Option 2
MoA 1 MoA 2 MoA 3
MoA 1 MoA 2 MoA 1
Not
recommended
MoA 1
Insecticide Application
Insecticide Resistance Management (IRM) Strategy in
Cabbage

29. Insecticide Mode of Action (MoA)
Nerve
Growth /
Development/
Molting
Excretory
+
+
+
Energy/ Muscle
+
Feeding
Respiration
Digestive
Reproduction
+
+
+
+
A specific Mode of Action will target a specific part/
function of an insect
Methomyl, Carbaryl, Fipronil, Malathion,
Beta-cyfluthrin, Thiamethoxam, Pymetrozine,
Abamectin, Spinosad, etc
Abamectin, Chlorantraniliprole,
Flubendiamide, Cyanide
Buprofezin, Teflubenzuron
Abamectin, Indoxacarb, Chlorantraniliprole,
Flubendiamide

30. MoA Group Chemical Subgroup Active ingredient
1 Organophosphates Profenophos, malathion
2B Phenyl Pyrazole Fipronil
3A Pyrethroids
Deltamethrin, Cypermethrin, Fenvalerate, Esfenvalerate,
Betacypermethrin, alphacypermethrin
4 Neonicotinoids Thiometoxam, Chlotianidin, Imidacloprid
5 Spinosyns Spinosad
6 Avermectins Abamectin
11 Bacillus Bacillus Thuringiensis (Bt)
12 Diafenthiuron Diafenthiuron
13 Chlorfenapyr Chlorfenapyr
14 Nereistoxin analogues Cartap
22A Indoxacarb Indoxacarb
28 Diamides Flubendiamide, chlorantraniliprole
Registered and Commonly Used Pesticides in
Vegetables in the Philippines: Chemical Class and MoA

31. Slide
31
Same MOA: Group 28
Resistant to Group 28 Insecticides
IPM: Chemical Control

32. • Project Management Introduction BCS Phl March 2012Page 32
Different brands may have
the same Active
Ingredient!!!
IPM: Chemical Control

33. • Project Management Introduction BCS Phl March 2012Page 33
Different brands may
have the same Active
Ingredient!!!
IPM: Chemical Control

34. • Project Management Introduction BCS Phl March 2012Page 34
Different Active Ingredients may belong to the same
MODE of ACTION!!!
IPM: Chemical Control

35. • Project Management Introduction BCS Phl March 2012Page 35
Different Active Ingredients may belong to
the same MODE of ACTION!!!
IPM: Chemical Control

36. √ In September of 2009, field representatives
covering the Cebu area of the Philippines
received reports of reduced control of P.
xylostella using diamides.
√ Subsequently, throughout 2010, further field
failures were reported.
Diamide resistance development in the
Philippines

37. √ Susceptibility monitoring from multiple
locations in Cebu Province showed low
mortality rates for both chlorantraniliprole
and flubendiamide at the highest diagnostic
dose rate of 5 ppm and cross resistance of P.
xylostella larvae to both diamide products
appeared evident.
Diamide resistance development in the
Philippines

38. √ Additional monitoring at locations in Negros
Oriental also showed reduced susceptibility
at 1 and 5 ppm compared to earlier assays
conducted from the northern islands
(Edralin et al., 2011).
Diamide resistance development in the
Philippines

39. √ However, more than 2 years after being
introduced, flubendiamide and chloran-
traniliprole were still providing good control
against P. xylostella in the highlands of
Benguet (Edralin et al., 2011).
Diamide resistance development in the
Philippines

40. This may have been because the climatic
conditions of the two locations differ
considerably: the highlands of Benguet have
a mean temperature range of 18.5–23 C,
whereas for the midlands of Cebu the main
crop production areas have warmer mean
temperatures of 25– 28 C.
Diamide resistance development in the
Philippines

41. • Under warmer temperatures the total life cycle of P.
xylostella tends to be shorter (Talekar and Shelton,
1993), leading to higher selection pressures.
• In Cebu province an over-dependency of growers on
Fenos and Prevathon, continuous planting of related
cruciferous crops, the presence of alternate hosts
throughout the year, over and under – dosing and a
lack of crop rotation were some of the key factors
that were identified as having contributed to the
development of diamide resistance in the Philippines.
Diamide resistance development in the
Philippines

42. • Flubendiamide and chlorantraniliprole act
by selective activation of the ryanodine
receptor (RyR) in the endoplasmic reticulum
of insects.
• The function of these specialized channels is
the rapid release of Ca2+ from intracellular
stores, which is necessary for muscle
contraction.
Mode of action of diamides

43. • Diamide insecticides induce ryanodine-
sensitive cytosolic Ca2+ transients
independent of the extracellular Ca2+
concentration.
• This potent activation of RyRs results in a
fast initial efficacy in the insect larvae, with
an unique symptomology of irreversible
muscle contraction paralysis and
characteristic feeding cessation
Mode of action of diamides

44. Diamide resistance is a growing problem globally. This
review has focused on the diamondback moth P.
xylostella, which was the first insect pest to develop
resistance to diamides and where the molecular basis
of the resistance has been most extensively studied.
However, there are still significant gaps in our under-
standing of resistance in this species. Target site
mutations on the RyR are clearly involved in
conferring resistance to diamides and there are also
indications that there may be a metabolic component
contributing to the resistant phenotypes. Subsequent
to these studies, control failures relating to diamides
have also been reported in other lepidopteran pests.
SUMMARY

45. Edralin, O.D., et al., 2011. Update on DBM diamide resistance from the Philippines: causal factors and
learnings. AVRDC – The World Vegetable Center, Abstracts from the Sixth International Workshop on
Management of the Diamondback Moth and Other Crucifer Insect Pests. AVRDC-The World AVRDC
Publication, Kasetsart University, Nakhon Pathom, Thailand No. 11-746.
Nauen, R., 2006. Insecticide mode of action: return of the ryanodine receptor. Pest Manage. Sci. 62, 690–692.
doi:http://dx.doi.org/10.1002/ps.1254.
Nishimatsu, T., et al., 2005. A novel insecticide agent, flubendiamide, for controlling lepidopterous insect
pests. International Conference on Pesticides, Kuala Lumpur, Malaysia.
Tohnishi, M., et al., 2005. Flubendiamide, a novel insecticide highly active against lepidopterous insect pests. J.
Pestic. Sci. 30, 354–360.
Troczka, B., et al., 2012. Resistance to diamide insecticides in diamondback moth, Plutella xylostella
(Lepidoptera: Plutellidae) is associated with a mutation in the membrane-spanning domain of the ryanodine
receptor. Insect Biochem. Mol. Biol. 42, 873–880. doi:http://dx.doi.org/10.1016/j.ibmb.2012.09.001.
Zalucki, M.P., et al., 2012. Estimating the economic cost of one of the world’s major insect pests, Plutella
xylostella (Lepidoptera: Plutellidae): just how long is a piece of string? J. Econ. Entomol. 105, 1115–1129.
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References