Semiochemicals are chemical substances produced by organisms such as plants and animals, such substances elicit a physiological or behavioral response in individuals of the same or another species. Semiochemicals are classified into pheromones and allelochemicals.

1. Use of Semiochemicals, Auditory stimuli and
Visual signals in Pest Management
Submitted by-
Abhishek Bhat
Admission No- H-2022-01-D
Submitted to -
Dr. Meena Thakur
Dr. Deepika Sharma

2. Introduction
• Integrated pest control may be defined as a system that in the context of the associated
environment and the population dynamics of pest species, utilizes all suitable techniques and
methods in compatible a manner as possible and maintains the pest population at level below
causing economic injury. FAO, 1967
• The concept of “Integrated Pest Management” during a time when insect- pest control was mostly
based on broad spectrum conventional insecticide such as organochlorine, organophosphate (OPs)
and carbamates, all neurotoxins. Their work on economic threshold and economic injury level
implemented within an ecological framework where chemical and biological control could thrive
together is basis for modern Integrated Pest Management concept.

3. Biorational Apporach
• The utilization of chemicals that affect insect behaviour, growth or reproduction
for supression of insect population is often reffered to as biorational Approach.
SEMIOCHEMICALS
• Chemical emitted by plants animals and other organisms that evoke a behavioural
or physiological response in individuals of the same or other species.
Semiochemicals are divided into two communication channels
• Intra-specific
• Inter-specific

4. Introduction
Semiochemicals
(law and Regnier, 1971)
Greek . Semeon - signal
Communication within species
(intra-specific)
Communication outside species
(inter-specific)
Pheromones
Karlson, and Lauscher in
1959
Allelochemicals
R H Whittaker in 1970.
Greek. Pherein - to carry
Hormon - to excite / stimulate.
Greek. Allo - Different
Primers Releasers
Allomones
Kairomones
Synomones
Apneumones

5.  They act through gustatory/taste sensilla.
 No immediate response in the recipient.
 Reproduction &
 Caste determination in social insects.
 Less importance in pest management.
 They act through olfactory/smell sensilla.
 With immediate response in the recipient organism.
 Much importance in pest management.
Primers
Releasers

6. Releaser Pheromones
Sex Aggregation
Trail Alarm
 For mating
 Mostly by females and
rarely by males
 ex. Bombykol
 From Bombyx Mori
 By A.A. Butenandt in 1959.
 Released by one or both sexes
 Bring both sex together for
 Mating, Feeding, Protection
 ex. Frontalin
 By Bark beetle
(Dendroctonus frontalis).
 To escape from enemies
(aphids and bugs) or
 To attack (ants and bees).
 By Aphids from cornicles
 By worker Bees from
mandibular gland
. By social insects termites &
hymenopterans.
 Ants used formic acid as trail
 Facilitate migration of colony
to new site in food of search

7. COMMERCIALLY USED PHEROMONE TARGETED PEST
Grandlure Cotton boll weevil
Gossyplure Pink bollworm
Trimedlure Meditarrnian fruitfly
Helilure American bollworm (Helicoverpa armigera)
Rhynchophorol American palm weevil
Litlure Tobacco cutworm (Spodoptera litura)
Geraniol Pepper weevil
Gyplure Gypsy moth
Important sex pheromones which have a potential in pest management

8. Allelochemicals
(R H Whittaker 1970)
Allomones
1. Advantage to producer (+ emitter)
Example- Flower of orchids emit allomones,
mimics sex pheromones of their bee, wasp
pollinator, now male attempt to copulate,
benefiting orchid only not male insect (less
importance in biocontrol)
1. Advantage to receiver (+ receptor)
2. Chemical substance emitted by a non-
living material
3. ex. Oatmeal
4. Ichnuemonid parasitoid , Venturia
canescens is attracted to odor of oatmeal,
which is its host’s food.
Apneumone

9. Synomones
1. Adavntage to both parties
(+ emitter and receptor)
Example- Nezara viridula feeding and oviposition induced
legumes to poduce blends of volatiles which attract
female Trissolcus basalis which is an egg parasitoid
1. Advantage to receiver (+ receptor)
Example- Anopheles gambiae, malaria mosquito use
human volatile, lactic acid, ammonia for host
orientation.
2. Heptanoic acid released from the larva of PTM
helps predador/parasitoid to attract
Kairomones
The kairomones and synomones are of greater interest in the biological
control programs for their ability to modify the behavior of the natural
enemies

10. Monito-
ring
Mating
distruption
Mass traping
Push-Pull
Four semiochemicals based methods have been
developed for pest management

11. • Monitoring - Monitoring methods based on the use of semiochemical baited traps consists in detecting
the presence of pests, and keeping track of pest population dynamics.
Example - In the case of Bruchus rufimanus affecting beans (Coleoptera: Chrysomelidae) the
determination of economic threshold is currently based on the surveillance of temperatures.
•Two consecutive days of sunny weather manifesting maximum temperatures above 20 ◦C at the time of
first pod setting is economic threshold. These meteorological conditions, ask grower to enable
semiochemical traps to detect and monitor pest populations for further chemical spray.
•Mating Disruption- In this method pheromones helps to manipulate or disrupt the natural mating
behaviours of insects to reduce pest population. This is done by blocking of communication channel
between individuals of both sexes by flooding the environment with sex pheromones.
•Mass trapping - It is a similar method to monitoring, except that it does not relies on pesticides, but it
rather aims to catch as many individuals as possible to reduce or eradicate pest population.
•Example - In B. rufimanus control, pods kairomones have the particular advantage of attracting females
offering better chances for avoiding oviposition

12. Also called “attract and kill”, “male annihilation”, “bait sprays” or “attracticide”, consists in
combining a pesticide/sterilant/pathogenic agent with an attractant in order to kill/sterilize/infect the
insect.
Example - Host plant kairomones containing entomopathogenic fungi to infect insects by contact with
conidia. The infected insects could then disseminate the pathogen to other members of their population
and killing maximum of pest population.
• Push Pull – It is another implementable semiochemical control method of pest consisting in regulating
the insect behavior by “pushing” it from protected crops, using repellent or deterrent from
associated plants or synthetic compounds, and “pulling” it to the perimeter of the crop where it will
develop on other plants. Ideally, the pushing effect also attracts natural enemies such as predators or
parasitoids, and pulling plants reduce population with innate defense.
• Example - Botanical oils of Artemisia campestris and mustard were identified as having efficient
repellence/oviposition-deterring/insecticidal effects on B. rufimanus.

13. Table 1. List of host insect kairomones and entomophages
Host insect Kairomone Entomophage References
Nezara viridula
(green stink bug)
Hydrocarbons
(Egg wash)
Trissolcus basalis
(egg parasitoid)
(Colazza et al., 2003)
Chilo partellus
(maize stem borer)
Tricosane, Docosane,
(Egg wash)
T. chilonis (Paramasivam et al.,
2004)
Helicoverpa
armigera,
Corcyra cephalonica
Hexane
(body wash)
Trichogramma
chilonis
(Kumar et al., 2005)
Earias vittella,
Spodoptera litura
Tricosane,
Pentacosane
(egg wash)
Trichogramma
brasiliensis
(Maruthadurai et al.,
2011)
Euschistus heros
(Stink bug)
Hydrocarbons
(Egg wash)
Telonomus podisi
(egg parasitoid)
(Paz-Neto et al.,
2015)

14. Synomones (HIPVs) as tools for biocontrol
 Plant volatiles play an important role to influence the tri-
trophic level interaction.
These interactions involving, plants (1st trophic level),
herbivores (2nd trophic level) and the natural enemies of
herbivores (predators and parasitoids) (3rd trophic level)
The defense of plant to pest attack may be direct (chemicals
which retard the growth or cause the death of herbivores) or
indirect (through the production of HIPVs which act as
recruiting agents for the natural enemies).

15. Pictorial representation of tri–trophic level interaction
Fig.A Fig.B
Peter price and collaborators gave emphasize to tri-trophic interaction Price et al., 1980

16. Some examples of chemical manipulation of natural
enemy behaviour.
• Increased egg parasitism rates of H. zea by Trichogramma spp. from
13% to 22% by spraying an extract from the host (moth) scales or
synthetic kairomones on to soybean plants
• The moth scales contain tricosane, which was found to be the main
source of attraction
• Volatiles from the ovipositor gland of female H. zea, which contains
the moth sex pheromone, are also attaract Trichogramma spp.
• Laboratory reared Aphytis melinus, a parasitoid of the California red
scale Aonidiella aurantii, more readily parasitized hosts when exposed
to the kairomone Ocaffeoyl tyrosine prior to being released in the
field.

17. Table 2. List of HIPV (Synomones) and Entomophages
Host plant HIPVs Target pest Entomophage References
cotton Hexenal,
Hexenol
Spodopteran
larva
Cotesia marginiventris
(larval parasitoid)
(Turlings et al.,
1995)
Pine tree Cis-3-hexen -1-
o1
massson pine
caterpilar
Phytoseiulus persimilis
(predatory mite)
(Xu et al., 2006).
Tea Methyl
salicylate
Ectrophis olique
(geometrid
moth)
Apanteles sp.
(larval parasitoid)
(Huang et al.,
2009)
Rice (E)-2-hexenal,
methyl salicylate
Tibraca
limbativentris
(rice stem bug)
Trissolcus basalis
(egg parasitoid)
(Machado et al.,
2014)

18.  Food supplements :- providing suitable food
supplements will enhance the natural enemy
population and encouraged, immigration of natural
enemies to pest containing areas that increase the
natality and reduce the mortality of natural enemies.
ex. Highest density of coccinelids and chrysopids
occurred in alfafa plots sprayed with a mixture of
sucrose and wheat.

19. Play an important role in biocontrol.
Eco-friendly in nature (no pollution).
No problem of bio-magnification (through food chain).
Less human efforts (Spray/reaching target place).
Best at forest insect pest management.
No/less cost, with long run.
Availability of synthetic semiochemicals.
Merits of semiochemicals

20. Visual signals
• Visual stimuli are used most frequently in combination with chemical stimuli, enhancing the
efficacy of a method over the use of either stimulus type alone.
Example -Tsetse (Glossina spp.), which are the vectors of the protozoans that cause, sleeping
sickness, provide one of the best examples of the use of both visual and chemical stimuli in an
attract-annihilate method.
• The host-finding behavior of tsetse is influenced by visual stimuli, including shape,
orientation, brightness, contrast, movement, and color. Traps using only visual stimuli, such as
the biconical trap, are used for control of these flies. Tsetse also respond to host odors.
Attractive components of which include, butanone, acetone, and various phenols. The
addition of odor (acetone and CO2) to the biconical trap doubled catches over a non-odor-
baited trap.
• An elegant variant of the attract-annihilate method has been devised for control of the apple
maggot fly, Rhagoletis pomonella. Females of this species find host trees and suitable
oviposition sites on apples using a combination of host odors and visual stimuli.

21. • Also insect primarily use two methods of visual communications: body colour patterns and light
signals (bioluminescence).
• Some insect use bright colour eyespots or other distinctive patterns to scare away preadators.
• Example – Commom owl butterfly (Caligo Memnon) with its spots that resemble two big owl eye
and which allow them to drive away preadators.
• Most visual communication are effective during daylight, but some insect can generate their own
light and use visual signals that can be seen at night.
Example – The male firefly (Photinus consimilis) during a rising flight movement emits a series of
3.5 short flashes and a female responds after a double flash

22. • Acouistic communication can be made to vary in frequency, amplitude and frequency. Since sound wave
moves rapidly through air these can be quickly started, stopped or modified to send a time sensitive
message. Such signals are readily detected by wide range of predators.
• Example- (1)Toxic tiger moth (Arctiidae) send loud return sounds to approaching insectivorous bats.
• (2) One more study showed that airborne sounds of 200 Hz picked up by plants were able to interrupt the
mating communication of a leafhopper and a planthopper, Amrasca devastans and Nilaparvata lugens.
They suggested that music could be used for mating disruption.
• (3) Use of acoustic technology with visual surveys and pitfall traps can help managers to identify and target
infestations within their warehouses, enabling them to reduce postharvest losses. Storage grain pests of
greatest economic importance, Sitophilus zeamais, maize weevil and Prostephanus truncates, large grain
borer can be managed by background noise considerations
• In this study acoustic sensor installationis done in commercial and strategic warehouses for grain storage,
and make sure sources of background noise and mitigate their effects. Pitfall traps contained various
postharvest pest species at different infestation levels.
Auditory stimuli

23. • (A) Vibrational- The oscillatory movement of the wings of an insect sets up regions of
compression and rarefaction and a vibrational sound is produced.
Example- The flight sound, made by wings, in swarming mosquitoes is considered to be used for
species-specific recognition.
• Wings vibration is also used in the courtship dances of Drosophila species.
• (B) Percussion- Striking one part of the body against another as a communication system for pair
formation
• Example- In Australian moth, males produce ultrasonic acoustical long distance signals to attract
sexually receptive females and to establish territorial residency in competition with other males.
• (C)Stridulation- It consist of sound produced by frictional mechanism, involving the movement
of two specialized body parts against each other in systematics patterns manner
Example- In orthoptera, insect respond to stridulation from the receptive female orientation towards
their locomotion to male.
Categories of sound producing mechanism