1. Host Finding Behaviour of Different Insects
&
Role of Learning , Kairomonal Signals and Sensory
Physiology in Host Finding Behaviour
Department of Agriculture Entomology Bahauddin Zakariya University, Multan

2. What is behavior … ?
What animals do.
• Organisms adjusts and interacts with its total environment
• Any action that an individual carries out in response to a stimulus or its
environment.
Insect Behavior
• How an insect takes information from its environment, processes that
information, and acts. (Hoy, M. A. 2013)

3. Host Finding Behaviour
• All the movement of insects for the finding of something.
• Movements of insects are considered as searching activities.
Objects needed
by Insects
Food
Medium for
oviposition
Find a mate
Shelter

4. • Depends on the internal and external condition of insects.
 State of hunger
 Maturation of ovaries
• For finding, powers of movement and perception are necessary (Laing, J.1997).
Questions arise in this topic are
 How does the parasite find the area in which the host occur?
 How does the parasite find the host when both are within the same limited
area?

5. Persistent change in behavior that occurs as a result of experience.
Two types of learning
i. Learned
ii. Innate
Learned
Acquires new skills and knowledge through trial and error, observation
of other individuals, or memory of past events.
Learning

6. Example
• The parasitic wasp Trogus pennator attacks larva of two genera of
Papilionidae, Eurytides and Papilio on plants.
• T. pennator females showed no preferences when offered either a choice
between two food plants or a choice between a food plant and a plant not
used for food by Papilionidae.
• After experience with hosts in the presence of a
particular food plant, however, wasps preferred
that plant. (Sime, 2002 )
Sime, K.R. 2005

7. Innate behavior
• Controlled by genes with little or no environmental effect.
• Occur naturally in all members of a species
• Experience during the immature stage affect adult behavior and habitat
selection.
• First behaviors entirely innate.
• Newborn nymph or larva has no prior experience Adult actively seeks the
habitat that it has experienced as a young.
• This phenomenon has also been called hopkin’s host selection principle.

8. Example
• Polyphagous Spodoptera littoralis were reared on different host plants.
• After pupation, the oviposition preference of the emerging females was
tested.
• In four of the five plants tested, females prefer to feed on the diet
which they were fed at larval stage. (Thoming et al. 2013).

9. Interspecific chemical communication substances that benefit the receiver but
disadvantage the producer.
Example 1
• Aphid alarm pheromone (E)- 𝛽-farnesene (EBF) also used by natural
enemies as a host finding.
• Cues from aphids are most reliable, compared to host plants, they are often
hard to detect. (Stephan, 1996)
Role of Kairomones in Host Finding Behaviour

10. • Most aphid species respond to EBF dosages less than 20 ng.
• Natural enemies are attracted to EBF amounts higher than 1 μg.
• More than 50 times higher than the detection for most aphid species (Vosteen,
2016).
http://bioplanet.eu/392/
John E. Aphids on Minnesota trees and
shrubs. University of Minnesota.

11. Example 2
• Hyssopus pallidus, a larval parasitoid of Cydia pomonella.
• Wasp enters into the infested apples through the tunnel
made by the host larvae and parasitize them.
• Host frass contains a host location kairomone (Mattiacci, 1999).

12. Role of Induced Plant Volatiles in Host Finding
• Herbivore-induced plant volatiles (HIPV) are involved in plant
communication with natural enemies of the herbivores, neighboring plants,
and different parts of the damaged plant.
• HIPVs are released from leaves, flowers, and fruits into the air or soil from
roots in response to herbivore attack.
Aartsma, Y. 2017. Herbivore‐induced plant volatiles and
tritrophic interactions across spatial scales. New
Phytologist. Volume 216, 1054-1063

13. Example 1
• Corn seedlings release large amounts of terpenoid volatiles after fed by
Spodoptera exigua.
• Females of the parasitic wasp Cotesia marginiventris take advantage of plant
produced volatiles to locate hosts.
• The terpenoids may be produced in defense against herbivores but may
also serve a secondary function in attracting the natural enemies. (Turlings, 1991)
Example 2
• Damage by corn rootworm, Diabrotica virgifera larvae in maize roots induces
the release of (E)-β- caryophyllene, which attracts the nematode,
Heterorhabditis megidis that feed on the larvae of D. virgifera. (Rashid, 2011)

14. Role of Olfaction in Host Seeking Behaviour
• Host seeking behavior of blood feeding insects find host from a distance.
• For short distance, body temperature and moisture are important.
• At greater distance, visual and olfactory cues are involved.
• Almost all hematophagous insect respond CO2.
• Specific CO2 receptors located on the maxillary palps and lactic acid
sensitive receptor on the antennae of Ae. Aegypti. (Takken, W. 1991)

15. Zwiebel, L.J. 2006 Antennal sensilla of two female Anopheline
sibling species with differing host ranges Article. Malaria
Journal

16. • The best odorous products are present in human sweat produced by eccrine
sudoriferous glands distributed over the entire body surface.
• Most abundant on the palms of the hands, the soles of the feet and the
forehead.
• 1-octen-3-ol is also attractive for several species of mosquitoes that feed
on animals such as cattle and deer.
• Urine contains diphenols and steroids to which mosquitoes are attracted.

17. Vision
Role of Vision in Host Finding Behaviour
• Ability to perceive spatial patterns and true image formation.
• In insects, this is possible only in the compound eyes.
• Ocelli, found in moths, are poor image formers.
 Only have the ability to detect light and dark expanses.
• Moths are nocturnal and locomotory activity may change by the change in
light intensity
• Low intensity and short wavelengths of light reflected from the field act
as stimuli for moths to attract them for oviposition or feed.

18. Example
• In the day-flying hummingbird hawkmoth, Hemaris sp., egg-laying
females are attracted by the colour green, visit yellow as well, but neglect
bluish green.
Example
• In the case of night fliers, Helicoverpa zea approached areas on the
oviposition substrate with shorter wavelength light.
• Wavelengths of 365 nm and 480-575 nm may be the most effective light
stimuli for H. zea and Heliothis virescens. (Ramaswamy, 1988)

19. • In a study of a night flier, Trichoplusia ni females preferred to approach
and lay more eggs on yellow than on other colours. (Shorey, 1964)
• Eoreuma loftini laid more eggs on vertical rather than horizontal leaves.
(Van Leerdam, 1984)

20. References
 Hoy, M.A. 2013 Molecular Genetics of Insect Behavior, Insect Molecular Genetics. 3rd Edition
 Laing, J. 1997. Host-Finding by Insect Parasites. Journal of Animal Ecology, Vol. 6, pp. 298-317
 Sime, K.R. 2002 . Experimental Studies of The Host-finding Behavior of Trogus Pennator, A Parasitoid of Swallowtail Butterflies. Journal
of chemical ecology, vol. 28
 Thoming et al. 2013. Comparison of Plant Preference Hierarchies of Male and Female Moths and The Impact of Larval Rearing Hosts.
Ecological Society of America. Vol. 8, pp. 1744–1752
 Vosteen, I. 2016. Is There any Evidence That Aphid Alarm Pheromones Work As Prey and Host Finding Kairomones for Natural
Enemies?. Ecological Entomology. 41, 1–12
 Stephan G. 1996. Aphid Alarm Pheromone (E)-p-farnesene: A Host Finding Kairomone for The Aphid Primary Parasitoid Aphidius
Uzbekistanicus (Hymenoptera: Aphidiinae). Chemoecology Vol. 7:132-139

21.  Mattiacci, L., 1999. Host Location of Hyssopus pallidus, a Larval Parasitoid of the Codling Moth, Cydia pomonella. Institute of Plant
Science/Applied Entomology, Swiss Federal Institute of Technology 15, 241–251
 Takken, W. 1991. The Role of Olfaction In Host-seeking of Mosquitoes: A Review. Insect Sci. Applic. Vol. 12, No. 1/2/3, pp. 287-295
 Ramaswamy S.B, 1988. Host Finding By Moths: Sensory Modalities and Behaviours. Insect Physiology. Vol. 34, pp. 235-249.
 Leerdam M. B., 1984. ) Effects of substrate physical characteristics and orientation on oviposition by Eoreuma loftini (Lepidoptera:
Pyralidae). Environmental Entomology. 13, 500-802
 Turlings, T.C. 1991. Larval-damaged plants: source of volatile synomones that guide the parasitoid Cotesia marginiventris to the
micro-habitat of its hosts. Entomol. exp. appl. 58: 75-82, Kluwer Academic Publishers. Printed in Belgium.
 Warab, A.R. 2011. Herbivore induced plant volatiles: Their role in plant defence for pest management. Plant Signaling &
Behavior, 6:12, 1973-1978