Utility of new synthetic molecules for the management of plant parasitic nematodes ✓How noval chemical molecules are better than old nematicides ✓Their function & mode of action

1. Presented by
Aman Sahoo (2020A51M)
M.Sc
Department of Nematology
CCS Haryana Agricultural University, Hisar

2. Title
Utility of new synthetic molecules for the
management of plant parasitic nematodes

3. Index
Introduction
History of Nematicides
Classification of nematicides
Mode of action of nematicides
Restriction on old nematicides
Next-Generation Nematicides
Case Studies
Future Prospects

4. Introduction
 PPNs -leading biotics causing yield losses in different crops
 Small about 0.5 to 3 mm unsegmented worms
 Can affect the crops in different ways
Altering normal root cell division
Modifying plant cells for nutrient transfer
Transmittng viruses and creating wounds
 Crop loss estimated about Us $173 billion annually
Plant parasitic nematodes
hidden enemies

5. Nematode Management Methods
Nematode
managment
Cultural
control
Physical
control
Chemical
control
Host
resistance
Regulator
y
Biological
control

6. Why chemical is best method ?
Among all the methods of nematode control, chemical
control methods are :
More reliable
Effective
Quick in action
can be used when and where required

7. Chemical control
 Involves use of Nematicides or Nematocides
 Pre-requisites
 When Pi is very high
 Crop is valuable
 Quick results are warranted

8. • NEMATICIDES:
A nematicide is a type of chemical pesticide used to kill
plant-parasitic nematodes.
Nematicides
Nematostatic
immobilize the
nematode activity
Nematicidal
kill the nematodes

9. History of Nematicides
ANCIENT
HISTORY
MEDIEVAL
HISTORY
MODERN
HISTORY

10. Ancient history
 The sugarbeet nematode, Heterodera schachtii, was first
reported in sugarbeets by Schacht (1859)
 Kuhn reported experiments with carbon bisulphide for its
control in 1871

11. Medieval history
 Chloropicrin was reported by Mathew (1919) on pineapple in
Hawaii effective against most fungi and insects
 Smedly (1936) reported nematicidal properties of
isothiocyanate compounds
 Hurst and Franklin (1938) reported nematicidal properties of
cyanide
 In 1940, Christie and Cobb reported an experiment with the
insecticide methyl bromide for control of chrysanthemum
foliar nematode

12. Modern history
• Carter (1943) discovered D-D mixture and Christie (1945)
discovered EDB and reported their efficacy against plant
parasitic nematodes
• Mc. Berth (1954) reported the nematicidal property of DBCP
(1,2, Dibromo-chloropropane) which is comparatively less
volatile used as an emulsion in irrigation water
• Dazomet and Metham sodium were introduced by Stauffr
chemical company in1952 & 1956
• Several chemicals of organophosphate and organocarbamate
groups (mostly insecticides) were screened for their
nematicidal values
• Several chemicals like carbofuran, aldicarb, ethoprop, phorate
etc. showed good nematicidal response

13. Common Name Commercial Name Manufacturer Fumigant/Nonfu
migant
Aldicarb TEMIK Union Carbide Nonfumigant
Carbofuran FURADAN Niagra Chemical Nonfumigant
Chloropicrin CHLOR-O-PIC Great Lakes Fumigant
1,3-D TELONE Dow Chemical Fumigant
DD Mixture D-D, VIDDEN - D Shell Chemical Fumigant
EDB DOWFUME W-85 Dow Chemical Fumigant
Ethoprop MOCAP Mobil Chemical Nonfumigant
Fenamiphos NEMACUR Chemagro (Mobay) Nonfumigant
Fensulfothion DASANIT Chemagro (Mobay) Nonfumigant
MBr DOWFUME MC-2 Dow Chemical Fumigant
Oxamyl VYDATE Dupont de Nemours Nonfumigant
Nematicides commonly found in world markets

14. Need for Nematicides
 Nematode becoming a major pest in agriculture
 Losses due to a nematode attack are crossing billions
year by year
 Nematode cuticle is permeable to a wide range of
organic compounds

15. Classification of nematicides
Fumigant
(VOLATILE SOIL FUMIGANTS)
Halogenated
hydrocarbons
Methyl bromide &
(EDB)
Methyl
isothiocyanate
Metham sodium
(vapam)
Non-fumigant
(Contact and systemic)
Organophos-
phates
Phenamiphos
Organocarba-
mates
Aldicarb,
Carbofuran

16. Fumigants
• Highly volatile halogenated hydrocarbons
• Upon application into soil, turn into gaseous phase and
diffuse through soil pore spaces
• Kill nematodes due to blocking enzymes by substitution with
halogen moieties
• Used extensively during I950-60s
• Examples
Dichloropropane and dichloropropene
EDB - Ethylene dibromide
MBr — Methyl bromide
1,3 D — 1,3 dichloropropene
DBCP — Dibromochloropropene

17. Trade names of Fumigants
Common name Trade name
Methyl bromide Bromomethane
Ethylene dibromide EXTOXNET PIP
1,3 dichloropropene (1,3-D) Telone II
96.5-99% chloropicrin Chlor-O-Pic
Metam sodium Vapam
Metam potassium K-Pam
Dimethyl Disulfide Paladin

18. Problems involved with Fumigants
• Require high doses which are phytotoxic, hence need pre-
plant application
• Waiting period of 3-5 weeks
• Need special applicators
• Need soil surface sealing with covers
• Need special field preparations
• Efficacy dependant upon edaphic factors
• Some proved carcinogenic and leave
residue in fruits

19. Non-fumigants
• Mostly systemic in nature
• Relatively non-volatile
• Effective at low dosages
• Easy to apply and handle
• Less phytotoxic an can be
applied to standing crops

20. Organophosphates
Common name Trade name
Organophosphates
Ethoprop Mocap
Fensulfothion Dasanit
Phenamiphos Nemacur
Phorate Thimet
Thonazin Nemaphos
Organocarbamates
Aldicarb Temik
Carbofuran Furadan
Metham sodium Vapam
Oxamyl Vydate

21. action
of
Mode

22. Mode of action of nematicides
• The death of nematodes by these
chemicals takes place due to
oxidation of iron (Fe++) centers
in the cytochrome chain and
blocks the respiration process
Fumigant
nematicides
• These chemicals inhibit acetyl
cholenestrase enzyme at
cholinergic site in the nervous
system of the nematodes leads to
paralyze and kill nematodes
Non-
Fumigant
nematicides

23. Toxicity

24. Effect of Carbofuran against CCN in Wheat

25. Characteristics of the ideal nematicide
•
•
•
Grower perspective Regulator
perspective
Intrinsic
activitiy
Broad-spectrum, control
all parasitic nematodes
Selectivity (safe to
non-target beneficial
organisms)
Soil behavior Good soil movement and
long soil residual activity
No leaching and low
soil Persistence
Plant behavior Systemic activity, low
phytotoxicity
No crop residues, no
negative impact on
produce quality
Application Flexibility, low rates Safe to handlers, low
human toxicity

27. List of Nematicides Banned in India
Chemical Name Banned on
Aldicarb 08.08.2018
Carbofuron 50% SP 17th July 2001
Diazinon 08.08.2018
Dibromochloropropane
(DBCP)
25th July 1989
Ethylene Dibromide (EDB) 17th July 2001
Phorate 08.08.2018
Dazomet 31st Dec, 2008
Methyl Bromide 2016 (completely)
(As on 01.07.2021)

28. Restriction on use of old-generation
nematicides
o High toxicity to humans and other non-target organisms
o Environmental pollution
o Residue problems in edible parts
o Resurgence of pest problems
o Cost considerations
o Decreased nematicidal activity after repeated applications of
the same nematicide to the same field
The Main reasons are…..

29. Recent Nematicidal Active Compounds
Active Compounds Examples
Amides Fluopyram & fluopimomide
Esters Furocoumarin & Tulipaline
Ketones 4-nitroacetophenone, 2,4′
dichloroacetophenone,and 2-methoxy-α-
bromoacetophenone
Thioethers allicin,pyrithiobac-sodium, and temefos
Sulfones Fluensulfone, fluorosulfone & Fluazaindolizine
Hydrazones Drazoxolon, metaflumizone, hydramethylnon,
and ferimzone
Tioxazafen
Analogues.
tioxazafen
Chemical Nematicides: Recent
Research Progress (2020)

30. Next-Generation Nematicides
• A few new compounds with a very promising efficacy have
been developed and released in recent years namely
fluensulfone, fluopyram, and fluazaindolizine
• These compounds contain trifluoromethyl (-CF3). Therefore,
they are called 3F or fluorinated nematicides
• Spirotetramat is a relatively new systemic
nematicide/insecticide that can be applied by foliar spraying
• Tioxazafen is about to be released for the seed treatment of
soybean,cotton, and corn against several nematodes
• Silver nanoparticles (AgNP) as a potential nematicide
against root knot nematodes

31. 3F or fluorinated nematicides

32. Characteristics
Fluensulfone Fluopyram Fluazaindolizine
Chemical group Fluoroalkenyl sulfone Pyridinyl-ethyl-
benzamide
Imidazopyridine
Commercial name Nimitz Velum, Verango,
ILeVo,Indemnify, etc.
Salibro
Manufacturer Adama Bayer CropScience Corteva Agriscience
Discovery (year) 2004 2009 (as nematicide) 2017 (reported)
Release (year) 2014 2014 (as nematicide) Not yet
LD50 (mg/kg) 671 >2000 >1187
Applicaton Dose 1.9–3.3 kg/ha 0.2 kg/ha 0.25–2.0 kg/ha
Registered crops tomato, cucumber,
squash, potato,
cabbage, broccoli,
strawberry, melon,
lettuce and turf
Tomato, carrots and
cucumber
No commercial
product

33. Mode of action of Fluopyram
Fluopyram is the first SDHI nematicide, which selectively
inhibits complex II of the mitochondrial respiratory chain,
causing rapid depletion of energy in the nematode cells and
ultimately leading to nematode death

34. ATP Production

35. Mode of action
It can gradually cause
metabolic damage to the
nematode and eventually
cause the nematode to fail
to obtain lipid storage and
die, but its target is not yet
clear
The catalytic action of
fluorescent carbon nitride
can combine with special
sites of ryanodine receptors
(RyRs) to activate calcium
ion channels, destroy the
stability of the calcium ion
environment in the
cytoplasm, affect the
movement of striated
muscle , cause paralysis and
death of nematodes
Fluorosulfone
Fluazaindolizine
Chemical Nematicides: Recent
Research Preogress (2020)

36. Fluopyram Systemic upward
Xylem-mobile
(Systemic upward)

38.  Two greenhouse trials (GH 1, GH 2)
GH 1 in 2015 & GH2 in 2016
factorial design
Experimental units - plastic pots
Two untreated lima bean seeds were
planted in each pot
RKN inoculum ( 6,000, and 30,000
eggs/pot) (Meloidogyne incognita )
treatments were applied the same day as
RKN egg inoculation
Harvested- 32 (GH 1) and 30 DAP (GH 2)
Microplot experiment
Conducted in 2015
random complete block
designs
RKN inoculum- 3,450 (J2) per
microplot
planted with 20 seeds of the
lima bean
Harvested - 82 DAP
Greenhouse experiments
Jones et al., 2017

39. Results
Greenhouse experiments

40. Mean densities of Meloidogyne incognita (J2) and eggs per
gram lima bean root fresh weight, as affected by nematicide
treatment
Nematicide Treatment RKN J2
(#per 100cc soil)
RKN Eggs
(# per gram root weight)
Control 16,669 ± 1542 aa 39.9 ± 17.2 cde
Fluopyram 1,943 ± 1542 d 81.4 ± 17.2 ab
Ethoprophos 121 ± 1542 e 116.9 ± 17.2 a
Fluensulfone (2.34 L a.i. ha-1) 2,603 ± 1542 d 44.7 ± 17.2 bc
Fluensulfone (1.64 L a.i. ha-1) 5995 ± 1542 bc 38.1 ± 17.2 cd
Fluopyram + spirotetramat 2,165 ± 1542 bc 37.0 ± 17.2 cd
Spirotetramat (2x) 11,780 ± 1542 ab 20.9 ± 17.2 e
Oxamyl 3522 ± 1542 cd 23.1 ± 17.2 de
a LS means ± standard error of five replicates. Any means within the same column not connected by the
same letter are considered significantly different according to Protected LSD (a ¼ 0.05). Analysis
performed on square root transformed data
Microplot experiment

41. Population used -M. incognita and M. javanica
Experiment - in vitro at Israel in 2018
Chemicals used - fluensulfone and fluopyram
Each plate was filled with 0.5mL of nematicide solution
and 0.5 mL of a nematode suspension containing ∼120 J2
Replication- four replicates
 J2 were exposed for 17 h (short-exposure
experiment) or 48 h (long-exposure experiment)
Oka and Saroya , 2019

42. Meloidogyne incognita M. javanica
Results
Values are means ± SD of four replicates. NS indicates no significant difference (P >0.05)
between the nematicides at each concentration by Student’s t-test.

43. Nematode Motility Bioassays
Conducted – in vitro at Greece in
2019
50 J2s of Meloidogyne javanica
were used per treatment
exposed to fluopyram and oxamyl
solutions
Experiment – twice & replicated 5
times
Observed after 24, and 48h
Effect on Entomopathogenic
Nematodes
Steinernema feltiae and
Heterorhabditis becteriophora
were used as non-target organisms
50 j2 used
Distilled water served
as control
Observed after 24, 48 and 96h
Giannakou & Kamaras., 2021

44. Effect of different concentrations of fluopyram or oxamyl on
the motility of second-stage juveniles of Meloidogyne
javanica
24 h
48 h
Results

45. Percentage of dead third-stage instars of Steinernema feltiae
and Heterhorhabditis bacteriophora affected by different
concentrations of fluopyram or oxamyl
Numbers in the same line followed by the same lowercase letters are not significantly different at
p < 0.05.

46. Future Prospects
• The future of the new nematicides will depend on: their Efficacy, residual
activity, selectivity ,cost and safety.
• Nematicides which had been in the market for over 20 years is no longer
manufactured, this influence the future of nematicides. Perhaps it is the
begging of a new era.
• The new nematicides are very different from previous products: (i) they
are more selective, often only targeting nematodes, and (ii) they are less
toxic, and safer to use.
• The loss of traditional nematicides, combined with a lack of replacement
products and awareness of the damage that nematodes can cause, has
not only raised concern among growers, but has also created new
opportunities for the crop protection industry.
• The economic cost of research and registration of new chemicals is an
enormous hurdle for a new chemical nematicide to overcome.
• Few nematicides like Fluensulfone, fluopyram, and fluazaindolizine ,their
trails are going on , they are not used for commercial purpose yet.

47. SYMBOL OF TRUST