Chemical communication involves the production, transmission and perception of odors. Most adult insects rely on chemical signals and cues to locate food resources, oviposition sites or reproductive partners and consequently, numerous odors provide a vital source of information. Insects detect these odors with receptors mosty located on the antennae, and the diverse shapes and sizes of these antennal sensilla are both astonishing and puzzling: what selective pressures are responsible for these different solutions to the same problem- to perceive signals and cues? It gives a brief idea about the selection pressure derived from chemical communication that are responsible for shaping the diversity of insect antennal morphology. In particular, some sorts of new technologies and techniques that offer exciting opportunities for addressing this surprisingly neglected but yet crucial component of chemical communication, are highlighted.
FUNGICIDES COMPATIABILITY WITH AGRO-CHEMICALSsubhashB10
In this presentation you will come to learn (or) you will learn about the different types of fungicides and its application towards plants in the Sevier infestation of the plant diseases in an particular crop. and also you will come to learn about the different AGRO-CHEMICALS used for eradication of the particular plant diseases. and also you will come to know about the different FUNGICIDES mixtures & AGRO-CHEMICAL mixtures used for curing an particular plant disease or an diseases as a whole.
Predators are one of the most important aspects of biologial control of crop pests. The predators may be insects or mites or nematodes or any other living organisms. Like the parasitoids, predators also follow a typical prey selection strategy. It includes Prey Habitat Selection, Prey Finding, Prey Acceptance and Prey Suitability. Prey Habitat Selection can be obtained by different plant odors or prey odors (like- honeydew, prey frass etc) or herbivore induced plant volatiles (HIPV). The HIPV is the most of important and reliable one to select the prey species by the predators. Actually when a plant is attacked by the pest species, the defense system is activated and it includes production of de novo or phytoalexins or secondary plant metabolites of various odors which actually attract the predators. Like- the bean plants attacked by Tetranychid mites, are attracted by the predatory Phytoseiid mites. Besides plants attacked under pests, release Methyl Salicylate like molecules which also attracts predators like Chrysopa spp. After habitat finding, the predators forage for suitable prey and if initial inspection of the habitat leads to evidence of prey in the local area, the predator is likely to engage in Intensified Local Search (ILS). ILS includes frequent turning, sinous search paths and slower walking. Theere are a number of factors which influence the efficiency of ILS. These include- Host Plant Architecture, Surface Texture of Plants, Hunger Status of Predators, Visual Cues, Patch Quality and Prey Products. Like- Larvae of some ladybirds foage less frequently for aphids on highly branched varieties than on normal branched varieties of crops. Similarly waxy surfaces can reduce their foragig efficiency and some of the predators are entrapped and died within the trichomes. Native adults of Harmonia axyridis are more attracted to yellow colour as compared to green colour. They are also attracted to the surface treated with prey products like honeydew to search for the preys while there are lots of exceptions regarding this. After a prey has been contacted, the age and experience of the predator, size of the prey and prey's defensive actions can influence the success of attack. The acceptance of prey depends on certain features like- food habit of the prey, chemical composition of prey cuticle, warning colourations and gregarious nature of prey species. After the acceptance, the suitability of prey is important to determine. This depends on- whether it supports both developement and reproduction or only developement or unpalatable. Suitability of prey for immature stages of predators depends on the survivorship of them, developemental time and adult body weight. Indexing prey suitability for mature adults depends mainly on the reproductive capability, high fecundity and viability. If predators feed on diseased or paralyzed hosts, it may induce low body weight, low immunity and survivorship. This understanding helps in successful IPM bio-control
Presentation on preventive measures of weed control.pptxSudha Neupane
Weeds have been known since the ancient times. Weed are unwanted plant that grow along with the main crop in the field. Weed are considered as cumbersome for successful agriculture production. Due to crop-weed competition the crop yield losses are generally high in agriculture production. So, in order to minimize such losses farmers are practicing several weed management strategies which includes prevention, eradication, control (mechanical, cultural, biological and chemical method). The cultural methods are expensive and time consuming so, farmer have to move towards other alternative methods of weed control Varga et.al (2000). Furthermore, due to rising labor cost and non-availability of labor for manual weeding during the critical period of weed control has contributed to use of herbicides. Herbicides not only timely and effectively controls the weed but also offer a great scope for minimizing the cost of production Varga et.al (2000). Control methods are applied after the emergence of weed on the field while prevention methods of weed control are adopted before sowing the crops. Generally, there are two objectives: 1. To prevent the entry and establishment of weed species in an area.2. To prevent the spread of weed or to limit the weed build up in a field.
These objectives are referred as prevention. And any method that are applied before sowing the crop to prevent there entry , establishment and spreads comes under the prevention category. Focusing on second objective of preventive measures of weed control we can say that some cultural methods such as crop rotation or crop diversification, stale seed bed, tillage system, cover crops ( used as green manures or dead mulches),soil solarization, irrigation and drainage systems and crop residues managements can be included under preventive methods of weed control. In practice, weed management strategies should integrate indirect (preventive) methods with direct (cultural and curative) methods. The first category includes any method used before a crop is sown, while the second includes any methods applied during a crop growing cycle. Methods in both categories can influence either weed density (i.e., the number of individuals per unit area) and/or weed development (biomass production and soil cover). However, while indirect methods aim mainly to reduce the numbers of plants emerging in a crop, direct methods also aim to increase crop competitive ability against weeds.The success of prevention depends on awareness of the problem, species, effort, Co-operation, area.
•Most effective where adopted against a single species on a large area on a cooperative basis.
In conclusion we can say that farmers have several preventive methods in their arsenal that they can put together to build up a good weed management strategy. Preventive weed control is permanent weed control and usually require community action. it. For this process, a collective or joint effort and commitment is required.
FUNGICIDES COMPATIABILITY WITH AGRO-CHEMICALSsubhashB10
In this presentation you will come to learn (or) you will learn about the different types of fungicides and its application towards plants in the Sevier infestation of the plant diseases in an particular crop. and also you will come to learn about the different AGRO-CHEMICALS used for eradication of the particular plant diseases. and also you will come to know about the different FUNGICIDES mixtures & AGRO-CHEMICAL mixtures used for curing an particular plant disease or an diseases as a whole.
Predators are one of the most important aspects of biologial control of crop pests. The predators may be insects or mites or nematodes or any other living organisms. Like the parasitoids, predators also follow a typical prey selection strategy. It includes Prey Habitat Selection, Prey Finding, Prey Acceptance and Prey Suitability. Prey Habitat Selection can be obtained by different plant odors or prey odors (like- honeydew, prey frass etc) or herbivore induced plant volatiles (HIPV). The HIPV is the most of important and reliable one to select the prey species by the predators. Actually when a plant is attacked by the pest species, the defense system is activated and it includes production of de novo or phytoalexins or secondary plant metabolites of various odors which actually attract the predators. Like- the bean plants attacked by Tetranychid mites, are attracted by the predatory Phytoseiid mites. Besides plants attacked under pests, release Methyl Salicylate like molecules which also attracts predators like Chrysopa spp. After habitat finding, the predators forage for suitable prey and if initial inspection of the habitat leads to evidence of prey in the local area, the predator is likely to engage in Intensified Local Search (ILS). ILS includes frequent turning, sinous search paths and slower walking. Theere are a number of factors which influence the efficiency of ILS. These include- Host Plant Architecture, Surface Texture of Plants, Hunger Status of Predators, Visual Cues, Patch Quality and Prey Products. Like- Larvae of some ladybirds foage less frequently for aphids on highly branched varieties than on normal branched varieties of crops. Similarly waxy surfaces can reduce their foragig efficiency and some of the predators are entrapped and died within the trichomes. Native adults of Harmonia axyridis are more attracted to yellow colour as compared to green colour. They are also attracted to the surface treated with prey products like honeydew to search for the preys while there are lots of exceptions regarding this. After a prey has been contacted, the age and experience of the predator, size of the prey and prey's defensive actions can influence the success of attack. The acceptance of prey depends on certain features like- food habit of the prey, chemical composition of prey cuticle, warning colourations and gregarious nature of prey species. After the acceptance, the suitability of prey is important to determine. This depends on- whether it supports both developement and reproduction or only developement or unpalatable. Suitability of prey for immature stages of predators depends on the survivorship of them, developemental time and adult body weight. Indexing prey suitability for mature adults depends mainly on the reproductive capability, high fecundity and viability. If predators feed on diseased or paralyzed hosts, it may induce low body weight, low immunity and survivorship. This understanding helps in successful IPM bio-control
Presentation on preventive measures of weed control.pptxSudha Neupane
Weeds have been known since the ancient times. Weed are unwanted plant that grow along with the main crop in the field. Weed are considered as cumbersome for successful agriculture production. Due to crop-weed competition the crop yield losses are generally high in agriculture production. So, in order to minimize such losses farmers are practicing several weed management strategies which includes prevention, eradication, control (mechanical, cultural, biological and chemical method). The cultural methods are expensive and time consuming so, farmer have to move towards other alternative methods of weed control Varga et.al (2000). Furthermore, due to rising labor cost and non-availability of labor for manual weeding during the critical period of weed control has contributed to use of herbicides. Herbicides not only timely and effectively controls the weed but also offer a great scope for minimizing the cost of production Varga et.al (2000). Control methods are applied after the emergence of weed on the field while prevention methods of weed control are adopted before sowing the crops. Generally, there are two objectives: 1. To prevent the entry and establishment of weed species in an area.2. To prevent the spread of weed or to limit the weed build up in a field.
These objectives are referred as prevention. And any method that are applied before sowing the crop to prevent there entry , establishment and spreads comes under the prevention category. Focusing on second objective of preventive measures of weed control we can say that some cultural methods such as crop rotation or crop diversification, stale seed bed, tillage system, cover crops ( used as green manures or dead mulches),soil solarization, irrigation and drainage systems and crop residues managements can be included under preventive methods of weed control. In practice, weed management strategies should integrate indirect (preventive) methods with direct (cultural and curative) methods. The first category includes any method used before a crop is sown, while the second includes any methods applied during a crop growing cycle. Methods in both categories can influence either weed density (i.e., the number of individuals per unit area) and/or weed development (biomass production and soil cover). However, while indirect methods aim mainly to reduce the numbers of plants emerging in a crop, direct methods also aim to increase crop competitive ability against weeds.The success of prevention depends on awareness of the problem, species, effort, Co-operation, area.
•Most effective where adopted against a single species on a large area on a cooperative basis.
In conclusion we can say that farmers have several preventive methods in their arsenal that they can put together to build up a good weed management strategy. Preventive weed control is permanent weed control and usually require community action. it. For this process, a collective or joint effort and commitment is required.
Here I would like to inform you in host selection process by the parasitiods.I hope It would increase your understanding on the steps involved n the host selection process.............................
Here I would like to inform you in host selection process by the parasitiods.I hope It would increase your understanding on the steps involved n the host selection process.............................
The human interest in the sense of smell dates back thousands of
years. The first information on this question is found in Egyptian
papyri. Sekhut Enanuch - the court physician of Pharaoh Sahure
(5th Dynasty 2500-2300 B.C.) was a specialist in diseases of the
nose, throat and ears. He was an otolaryngologist and dealt, among
others, with the sense of smell.
Evolution of plant animal interaction via receiver biasUASB and ICAR IIHR
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Bat is an important keystone member in the ecosystem, which is the only flying mammal. It plays a vital role in
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techniques used to study bats are surveyed.
Sound Strategies: the 65-million-year-old battle between Bats and InsectsJayantyadav94
An ancient battle rages high above our heads in the night sky as bats, the consummate nocturnal predators hunt their insect prey using ultrasonic sonar. One of the most important factors in the successful adaptive radiation of bats is their effective echolocation system. Echolocating bats emit ultrasonic pulses and listen for the presence, delay, and harmonic structure of the echoes reflected from the objects in the environment (Jones and Teeling, 2006). The frequency of the echolocation calls varies from 8 to 215 kHz depending on the bat species. The pulse repetition rate of the calls can vary from roughly 3 to approximately 200 pulses s−1 (Simmons et al., 1979). The echolocation sequence of hunting insectivorous bats involves three main phases: search, approach, and terminal (buzz) (Griffin et al., 1960). Many, if not most, cases of insect hearing probably originated as a means for detecting and avoiding predators such as sensitivity to ultrasound appears to have coevolved with echolocation signaling by insectivorous bats (Greenfield, 2016). In moths bat-detection was the principal purpose of hearing, as evidenced by comparable hearing physiology with best sensitivity in the bat echolocation range, 20–60 kHz, across moths in spite of diverse ear morphology (Nakano et al., 2015). Tympanic organs (ears) of moths are sufficiently sensitive to detect the echolocation cries of most bats before the bats can register their echo (Greenfield, 2014 and Goerlitz et al., 2010). In addition to hearing ultrasound, many moths belonging to sub-family Arctiinae are also capable of producing ultrasound in the form of short, repetitive clicks in response to tactile stimulation and the ultrasonic signals of echolocating bats when they detect the sonar signals of attacking bats (Corcoran et al., 2010). Anti-bat sounds function in acoustic aposematism, startle, Batesian mimicry, Mullerian mimicry and sonar jamming. Beetles, mantids, lacewings, crickets, mole crickets, katydids, and locusts can detect the sonar emissions of bats and exhibit various forms of anti-bat behavior. Researchers are beginning to use sophisticated high-speed infrared videography and high-frequency microphone arrays to study bat-insect interactions under natural conditions that will yield a multitude of exciting predator-prey interactions in the future.
Chemoreceptors
Chemoreceptors or organs of chemical sense consist of olfactory organs and organs of taste. Both these organs are stimulated only by chemical substances or odours in air (nostrils) and in solution (tongue).
The medium for dissolving substances for taste is water for aquatic animals and mucus for land animals.
The olfactory organs can respond to a low concentration of the dissolved substance, whereas organs of taste need a higher concentration of the dissolved substance for a response.
Olfactory Organs in Vertebrates:
Odours bind to and activate olfactory receptors located on the dendrites of sensory neurons in the nose. Olfactory organs (olfactory-receptors) are a pair of invaginations of the ectodermal cells of the skin forming olfactory sacs on the anterior end of head.
Their external openings are called nostrils or nares.
In most fishes the olfactory organs consist of a pair of pits lined with folds or ridges of sensory epithelium.
The cyclostomes have a single median olfactory organ. This is a blind pit in the lampreys, but in hagfishes it opens into the pharynx.
Dipnoans resemble higher vertebrates in possessing paired nasal passages that open by means of choanae into pharynx. The nasal passages, therefore, have both internal and external openings. The olfactory epithelium within canals appears in the form of folds.
Sensory systems consist of peripheral receptor cells and integrating neurons in the brain.
Impulses are transmitted from receptors by sensory fibres to the central nervous system where they are interpreted as sensations or messages, which are sent to effector organs through efferent or motor nerve fibres, for responding in an appropriate manner.
A vertebrate has receptors or sense organs for touch, smell, taste, sight, and hearing, which are stimulated by the environment. These sense organs are termed external receptors or exteroceptors.
There are other sense organs found in the body, which detect temperature, pain, hunger, thirst, fatigue, and muscle position. They are spoken of as internal receptors or interoceptors.
Besides these two, third is proprioceptors, which are stretch receptors found in the muscles, joints, tendons, connective tissue and skeletons. All receptors are closely associated with the nervous system and respond to external or internal stimuli.
List of Common Senses:
1. Touch.- It includes contact, pressure, heat and cold, etc.
2. Taste. -Receive stimulus by chemicals in solution.
3. Smell.- Receive volatile chemicals and gases in air.
4. Hearing.- Receive sound vibrations.
5. Sight. -Receive light waves.
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Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
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Insect Antennal Morphology-The Evolution of Diverse Solutions to Odorant Perception.pptx
1. ICAR- Indian Agricultural Research Institute
Pusa Campus, New Delhi- 110012
By-
Sourav Chakrabarty
Division of Entomology
ICAR-IARI, New Delhi
Email id- tublu0002@gmail.com
Contact- +91 7001801455
Insect Antennal Morphology: The Evolution of
Diverse Solutions to Odorant Perception
2. INTRODUCTION TO INSECT
ANTENNAE
First appendicular organs of adult
insects.
Innervated from Deutocerebral lobes
of insect brain.
3 major parts of an insect antenna-
Scape
Pedicel
Flagella
Involved in olfactory perception, hearing, communication, seizing
the preys, gasping female during copulation etc.
3. OBJECTIVES
To know about mechanisms of Olfactory
perceptions in different insects.
To know about Odor specific Signal or
Cue detection using different antennal
sensilla.
To determine costs and benefits of
antennal morphology towards odor
perception, odorant-receptor interactions and
computational modeling.
To know about evidences in selection of
antennal morphology and its evolutionary
significance.
4. DIVERSITY OF INSECT ANTENNAE
Fig:- From Simple Filiform to Complex Lamellate; from Easy Setaceous to
Modified Bipectinate- Insect Antennae are diverse.
5. Fig:- Antennae of male and female insects with well-developed olfactory sense: (a)
honey bee (Apis mellifera L.); (b) flesh fly (genus Sarcophaga); (c) cariion beetle
(genus Necrophorus); (d) scarabid beetle (genus Rhopaea); (e) saturniid moth (genus
Antheraea); (f) hawk-moth (sphingidae, genus Pergesa) (g) butterfly (genus Vanessa).
INSECT ANTENNAE ARE THE STOREHOUSE
OF OLFACTORY SENSILLA
6. GENERAL CONCEPT OF OLFACTORY
COMMUNICATION
Most olfactory sensilla are found in the flagellum, with their greatest
densities towards distal ends.
Antennal morphology is likely to “optimize” rather than “maximize”
odorant-receptor interactions.
7. More than one receptor could expand the range of activating ligands for the neuron,
allowing it to respond to ligands detected by either receptor (an ‘or’ gate) (Top panel).
Alternatively, neuronal activation to specific ligands could require activation of both
receptors (an ‘and’ gate), only firing in the presence of both ligands (Bottom panel). In
principle, an ‘and’ gate would impart high selectivity, whereas an ‘or’ gate would
expand the odor response space of the neuron.
OLFACTORY PERCEPTION BY
Drosophila – A Case Study
8. SIGNALS, CUES & ODOR DETECTION
An Odor is a “Signal” if it influences the behavior of the other
organisms and which is evolved or co-evolved specifically because of
that effect.
An Odor can be considered as a “Cue” if an incidental source of
information that may influence the behavior of the receiver, despite not
having evolved under selection for that end.
9. UNDERSTANDING SIGNALS vs CUES
Sex Pheromones of moths are
evolved to attract members of the
opposite sex. It is a “SIGNAL”!!
Release of CO2 by human beings
don’t evolve as signal to feeding
mosquitoes, but rather mosquitoes
use CO2 as a “CUE” for locating
victims !!
10. Both sexes release 25
types of different volatile
organic compounds.
These aid in mating,
defense and aggregation.
The organic compounds
are received by the
terminal flagellar segment,
containing 3 types of
olfactory sensilla viz. type
C, type D and type E.
SIGNAL PERCEPTION BY TEMPERATE
BED BUG- A Case Study
11. RHINO STOMACH BOT FLY USES ITS COMPLEX
ANTENNAL SENSILLA TO LOCATE HOST
Rhino Stomach Bot Fly (Gyrostigma
rhinocerontis) has significantly larger antennae with
more sensilla and sensory pits than any other
Oestridae species, which could be an adaptation to
locate their rare and endangered hosts.
12. COSTS AND BENEFITS OF ANTENNAL
MORPHOLOGY TOWARDS ODOR PERCEPTION
COST
BENEFIT
13. OLFACTORY SENSILLA INCREASES WITH
THE INCREASE IN FLAGELLA LENGTH
Odorant-receptor interactions are
enhanced primarily by larger
antennae as it can support larger
number of sensilla.
Usually males have longer
antennae and more sensilla than
those of females.
Pectinate (Lepidoptera) or
Lamellate (Coleoptera) type of
antennae can support more sensilla
as the surface area is increased. The number of sensilla qualitatively increase
with flagella length across insects
14. ANTENNAL COMPLEXITY &
VOLATILITY OF PHEROMONES
Beetles with more elaborate antennae use pheromones of low volatility.
Beetles with relatively simpler antennae use more volatile pheromones.
Fig:- Top 3 species (with simple antennae & pheromones more volatile) and
Bottom 3 species (with elaborate antennae & less volatile pheromones)
15. IDENTITY DETERMINATION THROUGH
ANTENNAL SENSILLA- A Case Study
Workers of Oecophylla smaragdina, brush their antennae across non-
nestmate workers aggressively .
The level of aggression towards non-nestmates is positively correlated
with antennal sensilla of workers.
Large number of sensilla are required for the workers to identify correctly
whether conspecifics are from same or different nests.
16. VARIATIONS IN ODOR PERCEPTION WITH
RESPECT TO ANTENNAL LENGTH IN COCKROACH
Directionality in odor perception is
lost when maximum removal of antennal
segments are done.
This arises though loss of total
antennal length across two antennae
rather than antennal symmetry.
17. EFFECT OF ANTENNAL ABLATION IN MATING
OF DIAMOND BACK MOTH- A Case Study
25% ablation= Not impaired.
50% ablation= Imapaired.
If one antenna removed= Directionality is lost
18. ODORANT-RECEPTOR INTERACTIONS &
COMPUTATIONAL MODELLING
Fig:-Predicted concentration (red is high) around the surface of the antennae of nano-
particles (pheromone molecules) in the (a) parallel and (b) ringed arrangement of antennal
scales, and of micro-particles in the (c) parallel and (d) ringed arrangement of antennal
scales. Sensilla number increases with the angle of the scales across genera (indicated by
different colors) of heliozelid moths
19. EVIDENCE OF SELECTION ON
ANTENNAL MORPHOLOGY
Mate Location & Sexual Selection.
Anticipatory Investment in Antennal
Morphology
Social Environment
Searching for Food
Searching for Hosts
Background Noise & Abiotic Modifiers
20. MATE LOCATION AND SEXUAL
SELECTION
Male insects generally have elaborate, feathery antennae whereas their
conspecific females have simple, filiform antennae.
Males with more “highly developed” organs of sense would be better
equipped to find the signaling female and thus be at competitive
advantage over other males.
Females also want “high quality” males who can encounter their
extremely low concentrations of pheromones.
21. ANTICIPATORY INVESTMENT IN
ANTENNAL MORPHOLOGY
Insect antennae are invested with several qualities according to
their surrounding environment.
Solitarious locusts of Locusta migratoria have more olfactory
sensilla on their antennae than gregarious adults.
Gregarious phenotypes can get the senses by the touch with other
locusts.
SOLITARIOUS GREGARIOUS
More olf. sensilla Less olf. sensilla
22. SOCIAL ENVIRONMENT
Major workers of Oecophylla
smaragdina having more no. of antennal
sensilla (right beside).
Foraging workers of Tetragonula
carbonaria have well developed olfactory
sensilla (exact below).
Guards of Tetragonisca angustula have
larger surfac area in their antennae (below).
23. SERACHING FOR FOOD
According to Chapman, insects with a generalist diet require a
greater number of sensilla than species with a more specialized diet.
The chemoreceptor sensilla in polyphagus species will definitely
be greater than mono or oligophagus species.
(A & C):- Antennal Olfactory Sensilla of
Dendroctonus rhizophagus
(B & D):- Antennal Olfactory Sensilla of
Dendroctonus valens
The average number of long basiconic
sensilla is qualitatively greater in strongly
polyphagus D. valens than in oligophagus
D. rhizophagus
24. SERACHING FOR HOST/ PREY
According to Chapman, Host generalized parasitoids or predators are
predicted to have greater numbers of sensilla than specialist ones.
However, exceptions are there. Like- Sensilla density in host specialist
Microplitis croceipes is greater than generalist Cotesia marginiventris.
25. BACKGROUND NOISE & ABIOTIC
MODIFIERS
Not much information has been found whether the intensity of
background olfactory noise (produced by plants or other insects) acts as a
selection pressure on antennal morphology.
Abiotic factors like- Humidity, Temperature and Air Pollution can
reduce the life span of the odor. Like- Fewer males of Ostrinia nubilalis
take flight in response to female sex pheromones in trials with higher
levels of humidity.
However, humidity doesn’t affect the response of Ips grandicollis to
synthetic aggregation pheromone.
26. CONCLUSION
The antennal morphology definitely influences Odorant-receptor
interactions.
We know a great deal about chemistry and transmission of odors,
and the neurobiology of odorant perception but we know relatively
little about how insects optimize their perception of odors and cues.
There is a rich seam of potential research questions that address
how size and structure of insect antennae have been shaped by
natural and sexual selection.
In particular, fluid dynamic modeling coupled with phylogenetic
comparative analyses offer exciting opportunities to understand
precisely how micro-morphological features of antennae can
influence odorant-receptor interactions.
27. REFERENCES
Bassett, M. A., Baumgartner, J. B., Hallett, M. L., Hassan, Y and Symonds,
M.R. (2011). Effects of humidity on the response of the bark beetle Ips
grandicollis (Eichhoff) (Coleoptera: Curculionidae: Scolytinae) to synthetic
aggregation pheromone. Aust. J Entomol. 2011; 50: 48-51.
Camerini, G., Groppali, R., Rama, F., Maini, S. (2015). Semiochemicals of
Ostrinia nubilalis: diel response to sex pheromone and phenylacetaldehyde in
open field. Bull Insectol. 2015; 68: 45-50.
Chapman RF. Chemoreception: the significance of receptor numbers. Adv
Insect Physiol. 1982;16:247–356.
López, M. F., Armendáriz-Toledano, F., Sámano, J. E., Shibayama-Salas,
M., Zúñiga, G. (2014). Comparative study of the antennae of Dendroctonus
rhizophagus and Dendroctonus valens (Curculionidae: Scolytinae): sensilla
types, distribution and club Shape. Ann Entomol Soc Am. 2014;107:1130–43.
Missbach, C., Dweck, H. K., Vogel, H., Vilcinskas, A., Stensmyr, M. C.,
Hansson, B. S., et al. (2014). Evolution of insect olfactory receptors. eLife.
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And many more…….
