Semiochemicals in insect control

1. CREDIT SEMINAR - ENT 591
ROLE OF SEMIOCHEMICALS IN THE CONTROL OF CROP PESTS
Dr. P.R.Mishra
Professor
Department of Entomology
COA, OUAT, BBSR
Yuvan Shankar Raja M
Adm.No: 201221617
Department of Entomology
COA, OUAT, BBSR

2. FLOW OF SEMINAR
1. Semiochemicals
2. Types of semiochemicals
3. Pest suppression strategies using semiochemicals
4. Interaction between semiochemicals with biocontrol agents
5. Case studies
6. Drawbacks
7. Summary
8. Future aspects
9. Reference
2

3. SEMIOCHEMICALS
The term semiochemicals is
derived form Greek word
“semeon”- sign or signal.
The term was given by
Law and Regnier .
Semiochemicals elicits
behavioral and physiological
responses in the receiver,
which result in the
interaction between them.
( Nordlund, 1981 )
Semiochemicals are organic
compounds used by insects
to convey specific chemical
messages that modify
behavior or physiology.
3

4.  Semiochemicals are markers or signal chemicals that transmit information either between
individuals of the same species or different species.
 Based on the interaction, semiochemicals are broadly divided into 2 types such as:
I. Pheromones (intra-specific)
II. Allelochemicals (inter-specific)
4
Types of semiochemicals

5. Semiochemicals
Interspecific
Allomone
Kairomone
Apneumone
Synomone
Antimone
Intraspecific action
Releaser
Sex
pheromone
Aggregation
Trail Marking
Recruitment
Alarm
Primer
Sexual
maturation
Development
Physiological
state
5
Ghany (2019)

6. Pheromones
Karlson and Butenandt coined the term pheromone in 1959 and also called as ecto-
hormones (Beth 1932).
Pheromone is a secreted or excreted chemical factor that triggers a social response in the
members of the same species (intraspecific communication).
Pheromones trigger a reaction in the recipient that causes changes in its behavior (Cork
2004)
Based on the responses elicited, pheromones can be classified into 2 groups as:
I. Primer
II. Releaser
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7. Primer pheromone:
They trigger physiological change in the recipient.
The most famous example of a primer pheromone is the honey bee
queen pheromone (a mixture of two fatty acids: 9-ODA and 9-HDA)
which suppresses ovary development in worker bees (Free, 1987).
Releaser pheromone:
They produce an immediate change in the behavior of the recipient
The most commonly known are sex pheromones, which are highly
species specific and serve to attract mates for reproduction.
The first sex pheromone was identified in 1959 from the silk moth
Bombyx mori (10,12-hexadecadien-1-ol) (Karlson & Butenandt,1959).
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8. Sex pheromones
Sex pheromones are involved in
reproduction by attracting the opposite sex.
 Female pheromones are used to attract male and
vice versa.
Gossyplure was the first registered pheromone
granted by the Environmental Protection Agency
(EPA) in February 1978. It was used for the
suppression of pink bollworm (Weatherston and
Minks 1995)
Many further insect sex pheromones have been
identified to date and are commercially used in
pheromone traps for pest control (Bell, 2004)
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Gossyplure
Pink bollworm

9. S.No. Insect pest Chemical structure of sex pheromones
1. Red gram pod borer
Helicoverpa armigera
(Z)-11-hexadecacenal and (Z)-9- hexadecenal(9:1)
2. Pink bollworm
Pectionophora gossypiella
(Z,Z)- 7,11hexadecadienyl acetate and (Z,E)-7,11 hexadecadienyl acetate (61:39)
3. Tobacco cutworm
Spodoptera litura
(Z,E)-9,11-tetradecadienyl acetate and (Z,E)-9,12 tetradecadienyl acetate (9:1)
4. Yellow stem borer
Scirpophaga incertulus
(Z)-9-hexadecacenal and (Z)-11-hexadecenal(1:3)
5. Pink stem borer
Sesamia inferenes
(Z)-11-hexadecacenal acetate and (Z)-11- hexadecen-1-ol and (Z)- 11-
hexadecanal(4:1:0.1)
6. Cutworm
Agrotis ipsilon
(Z)-7- dodecenyl acetate,(Z)-9- tetradecenyl acetate and (z)-11-hexadecenyl
acetate(1.79:6.12:3.66)
7. Angoumois grain moth
Sitotroga cerealella
(Z,E)- 7,11hexadecadienyl acetate and (Z,E)-7,11 hexadecadienyl acetate (9:1)
8. Brinjal fruit and shoot bore
Leucinodes orbonalis
(E)-11-hexadecenyl acetate, (E)-11- hexadecen-1-ol
9. Cabbage looper
Trichoplusia ni
(Z)-7- dodecenyl acetate
9
Ramalakshmi et al., 2020

10. Aggregation pheromones
Aggregation pheromones are used to congregate large numbers of
the same species irrespective of sex.
It is used in IPM for monitoring pest and attract parasitoid.
Recently, aggregation pheromone of Holotrichia consanguinea
was identified as methoxy benzene.
The ICAR-NBAIR, Bengaluru has developed a slow release
nanogel formulation of methoxy benzene and the technology was
tested in white grub endemic areas of Rajasthan in groundnut and
perfected.
(Source: ICAR- National Bureau of Agricultural Insect Resources,
Bengaluru)
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11. Alarm pheromones
Alarm pheromones are used to alert the other members of the
same species about imminent danger.
β-farnesene -(alarm pheromone released by aphid upon
predation) Arabidopsis thaliana- repels aphids but attracts the
parasitoid Diaeretiella rapae (Hymenoptera: Ichneumonidae)
(Vandermoten et al., 2012).
It is considered to be the second most common pheromone
produced by insects, after sex pheromones.
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Alarm pheromone released from cornicles

12. Trail pheromones
Foraging ants, termites and larvae of
some lepidopteran insects produces
trail pheromones.
They are used by insect to indicate
sources of food to other members of
the colony.
A high concentration of trail
pheromone disrupts trail following
therefore, synthetic trail pheromones
could be a novel control agent for pest
ants (Mashay et al. 2012).
12
Recruitment
pheromones
• Recruitment pheromones induce nest
mates to leave the nest and migrate to a
work site or vice versa (Meer and
Preston, 2008).
• An important model to illustrate the
recruitment mechanism is the red fire
ant, Solenopsis invicta. The process
begins when a foraging scout worker
discovers a food source too large for it
to carry back to the colony
Trail pheromones
Recruitment behavior

13. Oviposition-deterrent
pheromones
This pheromone discourage females from laying
eggs in the same source of another female’s
oviposition site.
Several fruit flies e.g. Rhagoletis pomonella mark
the surface of fruit after oviposition to prevent egg
laying by other female flies (Prokopy et al. 1982).
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• Recently identified from subterranean royal
termites as a wax-like hydro-carbon called
“heneicosane”.
• This pheromone enables workers to
recognize patronage (kings and queens),
there by maintaining the reproductive
division (Funaro et al. 2018)
Royal pheromones

14. Allelochemicals
Substances which transmit chemical messages between different species, known as interspecific
communication.
Fundamentally, these are substances which are primarily emitted by individuals of one species and are
understood by individuals of a different species.
They have been divided into five categories:
I. Allomones,
II. Kairomones,
III. Synomones,
IV. Antimones and
V. Apneumones (Vilela and Della Lucia, 2001)
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15. Allomones
Allomones released from one organism stimulate deterrent response in
an individual of another species. The response is beneficial to the emitter.
Glandular trichomes which cover plant leaves and stems release
herbivore insect-deterring allomones under stress conditions as a defense
process (e.g. nicotine from tobacco plant).
15
Joris J. Glas
Glandular trichomes

16. Kairomones are emitted by one organism that
stimulate beneficial response in an individual of
another species.
Spraying of kairomones extracted from the frass of
Cnaphalocrocis medinalis on rice plants in the field
increased 15-25% of the parasitization by Apanteles
cypris (Hu and Chen, 1987).
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Kairomones
Apanteles cypris
Rice leaf folder

17. Synomones
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 Synomones are beneficial to both the releaser
and receiver. Examples include scents used by
flowers to attract pollinating insects.
 The field elm (Ulmus minor) releases volatiles
(synomones) that attract the egg parasitoid
Oomyzus gallerucae on oviposition by the elm
leaf beetle Xanthogaleruca luteola (Meiners
and Hilker, 2000).
Antimones: mal-adaptive for both the
releaser and receiver.
These substances are produced or
acquired by an organism that activate a
repellent response in both the receiving
individuals and emitting individuals.
Antimones

18. Apneumones
Apneumones (from Greek word “apneum” = breathless or lifeless)
They are emitted by a non-living source, causing a favorable behavioral or physiological
reaction to a receiving organism (Nordlund and Lewis, 1976).
Rare cases of these allelochemicals, eg. hexanal and 2-methyl-2-butanol released from rabbit
stools attracts sand-fly females for oviposition (Dougherty et al. 1995).
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19. Pest Suppression Strategies using
semiochemicals
The most successful method using the semiochemicals in the pest suppression is to monitor the
pest population activity or to regulate the density of an insect population to take the need base
control measures.
Various control strategies of insects based on semiochemicals used in IPM programs include:
I. Monitoring,
II. Mass trapping,
III. Lure and kill (attract-annihilate),
IV. Mating disruption, and
V. Push-pull strategy (stimulo-deterrent diversion)
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20. Monitoring
These pheromone traps are used to detect the density of the
population, and also for monitoring the presence of invasive species
and prevent its establishment and spread (Trematerra, 2012).
The monitoring system is helpful in making the decision for control
measure to keep the pest population below the economic threshold
level.
Currently sex pheromones, aggregation pheromones and kairomones
employed to monitor insect activity.
5 traps per ha are used to monitor yellow stem borer in the rice
(Integrated pest management package for rice, NIPHM 2014).
20
Delta trap

21. Monitoring can be useful in following ways
1. Detection of pest
2. Measurement of pest density
3. Assessment of density of natural enemies
4. Assessment of pest phenology
5. Assessment of effectiveness of mating disruption
6. Monitoring insecticide resistance
7. Decision support
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22. Mass Trapping Strategy
Mass trapping aims at catching significant proportion of a pest
population before mating, oviposition or feeding and thus
stopping the damage to the crop.
Success with this technique involves the combination of very
attractive lure and a highly efficient trap.
This trapping based on aggregation pheromone aims to reduce
both sexes population before eggs are laid or damage is done by
feeding adults.
For mass trapping 12 traps per ha was used against yellow stem
borer and moth population (Integrated pest management package
for rice, NIPHM 2014).
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Funnel trap

23. Mating Disruption Strategy
Mating disruption technique in which release synthetic pheromones into
pest habitat to reduce the ability of a male to locate the female and thereby
affecting chance of reproduction, hence reduces the incidence of the insect in
the next generation.
Comparatively lower damage percentage in bolls and higher yield in PB
rope plots compared with control and yield of 24.95q/ha from PB rope
treated block where as 22.45q/ha in control block (Radhika and Reddy,
2006).
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24. Interaction of host kairomone and
parasitoid
The kairomones secreted from the host body indicate the suitability of the host for parasitoid progeny
and are represented by amino acids and salts in the hemolymph
Higher levels of docosane and heneicosane, from female whole-body extract of Spodoptera litura,
attracted more Trichogramma chilonis (Murali-Baskaran et al., 2018)
While whole-body extract of Earias vittella , which contained heneicosane, tricosane, pentacosane,
hexacosane, octacosane, and nonacosane, was also attractive to T. chilonis (Murali-Baskaran et al.,
2018)
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25. Interaction of host kairomone and
parasitoid
.
The hydrocarbons heneicosane and hexacosane, isolated from the whole-body extract of females of Spodoptera
exigua and Chilo auricilius create a significant attraction in the parasitoid T. chilonis. (Murali-Baskaran et al.,
2018)
(Z)-jasmone (a compound released from cotton leaves and flowers when fed on by various lepidopteran
larvae), Wheat plants when sprayed with (Z)-jasmone they became less attractive to aphids and instead
attracted more parasitoids, thus due to increased parasitism, the aphid population declined. (Birkett et al.,
2000)
The scales, silk, and frass of larvae and adults of Opisina arenosella elicited attraction from several
parasitoid species, such as Trichogramma evanescens, Goniozus nephantidis , Brachymeria
nephantidis, and Elasmus nephantidis.
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26. Semiochemicals and predators
Plant volatiles play a major role in mediating tritrophic relationships among pest insects,
their host plants, and the predators.
When using predators, augmentation biological control can be a viable pest management
technique in enclosed environments, but in field conditions, is less effective due to the rapid
dispersal of predators.
Similar to parasitoids, the frass of prey insects also plays a role in attracting predators, as
shown in the case of the bark beetle Dendroctonus micans, whose predator Rhizophagus
grandis is attracted to the bark beetle’s frass, present in the tree. (Wyatt et al., 1993)
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27. Plant pest pathogen interaction
Plant pathogens also create complex tritrophic relationships between host plants
and phytophagous insects and their parasitoids, by manipulating a host plant to
produce volatiles that attract their vector and also parasitoids.
Candidatus liberibacter asiaticus induces citrus trees to release methyl salicylate,
which attracts its vector, Diaphorina citri and also a its parasitoid , Tamarixia
radiata. (Murali-Baskaran et al., 2018)
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28. Lure-and-Infect:
Lure and infect system is a combination of an attractive lure with an entomo-pathogen. This
technique is also called “autodissemination”.
The insects that arrive at the source are not killed, but are inoculated with pathogen to magnify
the treatment by spreading the disease to other individuals.
Different pathogens could be used with slightly different pathways including viruses, bacteria,
fungi and nematodes.
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29. Semiochemicals and Entomopathogenic
microbes:
Fungi
Semio-chemicals are being used to increase the rates of entomopathogenic fungal infection in several
insects.
Successful examples of the use of combinations of semiochemicals and entomopathogenic fungi
include Cosmopolites sordidus ,moths (Plutella xylostella) (Gonzalez et al., 2016)
 Increased control of the diamondback moth, Plutella xylostella (Linnaeus), on cabbage when
inoculated with an endophytic strain of Acremonium strictum along with semiochemical(Raps and
Vidal 1998)
Endophytic Beauveria bassiana in banana (Musa spp.) increases reduction in banana weevil
(Cosmopolites sordidus) damage when inoculated with semiochemicals (Akello et al., 2008)
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30. Virus
Most known entomopathogenic viruses are baculoviruses (four genera: Alpha-, Beta-, Gamma-,
and Deltabaculoviruses), Reoviridae, Parvoviridae, or Nudiviruses)
Combination of apple-associated yeasts and codling moth granulovirus (CpGV) increased the
mortality of the codling moth (Cydia pomonella) under both laboratory and field conditions.
(Knight et al., 2013)
In 1992, sex pheromone baited traps was first used to auto-disseminate the Baculoviruses
[nucleopolyhedrovirus (NPV)] against Heliothis virescens. (Vega et al., 2007)
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31. Nematode
Volatiles secreted by parasitic nematodes also attract EPNs
The application of infected cadavers with EPNs proved to be more effective than the direct
spraying of infective juveniles
When an extract of the infected cadavers was applied along with the aqueous suspension
of Heterorhabditis bacteriophora (Poinar) Hb strain, it was also found to be more infective
than direct spraying to Galleria mellonella (Shapiro et al., 1999)
Pheromone extracts from Steinernema carpocapsae , when tested on Tenebrio molitor
larvae, showed an improved dispersal and efficacy of nematode. (Wu et al., 2018)
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32. Push-pull strategy
It is a combination of deterred or repellent from the intercrops (push strategy) and attractive
stimuli by lures (pull strategy), that control the insect pests by trapping or killing tactics.
The push-pull strategy for maize stemborers in comprises trapping stem borers on highly
attractant trap plants (pull) such as Napier grass (Pennisetum purpureum), while driving them
away from the main crop using repellent intercrops desmodium (Desmodium uncinatum and
Desmodium intortum).
 Molasses grass when intercropped with maize, not only reduced infestation of the maize by
stemborers, but also increased stemborer parasitism by a natural enemy, Cotesia sesamiae (Khan
and Pickett 2004).
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33. 33

34. CASE STUDY -1:
Auto confusion technology- an innovative and novel method of use of
pheromone for management of rice yellow stem borerScirpophaga
incertulas (walker) in eastern india satpathi et al., (2016)
34

35. 35
2

36. Case study - 2
Integrated pest management of fruit flies, Bactrocera
spp., in rainy season guava in indian punjab (Sandeep
Singh , 2020)
IPM module
1. Ploughing with discs in June followed by regular removal of infested fallen fruits and
burying same in 60 cm deep pit. The pit was covered after 2-3 days.
2. Methyl eugenol based 16 traps per acre(MAT, Protein hydrolysate (0.1%) + spinosad
(0.03%).
PAU recommendation
1. Ploughing with discs in June followed by regular removal of infested fallen fruits and
burying same in 60 cm deep pit. The pit was covered after 2-3 days.
2. Spray 1250 ml Sumicidin 20 EC (fenvalerate) in 500 litres of water at weekly intervals on
ripening fruits commencing from July onwards till the rainy season crop is over.
36

37. 37

38. 38

39. Case study-3
Kairomone gel formulations enhance biocontrol efficacy of Trichogramma
japonicum Ashmead on rice yellow stem borer, Scirpophaga incertulas Walker
(Murali-baskeran et al., 2021)
39
Treatment Kairomone No. of T. japonicum released Date of release
T1 n-hexadecanoic acid @ 200 ppm 24 h after each release of wasps
(@ 50,000/ha )
32nd, 39th, 46th, 53rd days
after transplanting (DAT)
T2 n-octadecanoic acid @ 500 ppm 24 h after each release of wasps
(@ 50,000/ha)
32nd, 39th, 46th, 53rd days
after transplanting (DAT)
T3 octadecane @ 500 ppm 24 h after each release of wasps
(@ 50,000/ha )
32nd, 39th, 46th, 53rd days
after transplanting (DAT)
T4 _ release of wasps (@ 50,000/ha) 32nd, 39th, 46th, 53rd days
after transplanting (DAT)
T5 Untreated control

40. 40
 T3(octadecane @ 500 ppm along with4 release of T.japonicum) gives Maximum reduction of dead
heart over control of 77.92 % which also higher than T4 (4 release of T.japonicum)
 T3(octadecane @ 500 ppm along with 4 release of T.japonicum) gives Maximum reduction of white
ear over control of 79.44 % which also higher than T4 (4 release of T.japonicum)
 T3(octadecane @ 500 ppm alongwith 4 release of T.japonicum) gives Maximum grain yield per ha of
6.93 ton/ha and which also higher than T4 (4 release of T.japonicum)5.83 ton/ ha with minimum in
T5 (control) 5.18 ton /ha

41. Semiochemicals for many species of insect pests are still unknown.
Quick results cannot be obtained with semiochemicals, so they cannot be employed in short term
control measures.
Commercialization of semiochemicals-based products is strongly affected by the size of the
potential market, cost of registration and product’s price competitiveness
The wide-scale use of semiochemicals, such as sex pheromones of pink bollworm and tomato
pinworm raises the possibility that resistance may develop.
41
Drawbacks

42. Summary
There has been a rapid progress in the utilization of semiochemicals in pest management during
the last 2-3 decades because, these are species specific and do not cause adverse effect on non-
target organisms.
Many of semiochemicals do not persist or accumulate in the environment and therefore, do not
pose any environmental problems, Since they are used in minute quantities and kill a large
number of insects.
This approach is labour saving, since large number of insect pests could be brought from long
distances right at the door for getting destroyed.
They offer an easy means to monitor the building –up of pest populations, entry of foreign pests
into a country through its ports could be checked at the point of entry itself
42

43. Future aspect
Semiochemical identification should be extended to homopteran pests
More efficient technology for the application to control pest , based on Semiochemicals can be
studied.
Registration procedure for these products needs to be simplified
Research on controlled release systems with cost effective, non-toxic and biodegradable
semiochemicals can be carried out.
43

44. Reference
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46. Thank you
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