Genetically controlled insect behviours are narrated

1. Genetics and insect
behaviour
KARTHIKEYAN, S (2015 800503)
Ph.D., Scholar,
Agricultural Entomology,
TNAU, Coimbatore.

2. BEHAVIOR
• Any action that an individual carries out in
response to any stimulus or to its environment,
especially an action that can be observed and
described (Hoy 2013)
• How an insect takes in and process an
information and acts
• CNS
• Steps: stimulus recognition, signal
transduction, integration, and
response or motor output

3. Prologue
• More complex than genetics of morphological and anatomical traits
• Careful control of environmental conditions
• possible influence of learning always must be considered
• It grown as a field of study in 1960s
• First demonstrations that behavior is genetically determined
• But was limited to
• Trait was heritable
• Determining whether dominance or recessive
• Single or multiple gene
Ehrman and Parsons (1973)
Rothenbuhler (1964)

4. Traditional Genetic Analyses of Behavior
1. Crossing
2. Selection
3. Fate maps
• embryonic origin of various tissues
• locate the anatomical site of abnormalities that affect behavior
Hotta and Benzer (1972)

5. Crossing experiments
• Mating individuals that differ in a particular kind of behavior
• Examining the behavior of their F1 and backcross progeny
• Easy only with regard to a single behavioral attribute
• If many genes, it is difficult to
• Determine the number of loci
• Their relationship to each other
• Their location on specific chromosomes

6. Hygienic behavior of Apis mellifera
Rothenbuhler (1964)

7. EAG - olfactory and behavioral responses
• Hygienic and nonhygienic bees to diseased brood
• Hygienic bees have a higher sensitivity to low concentrations of the
odor of diseased bee pupae
• Differences due to a lower stimulus threshold
• Not a direct result of age or experience of the bee
Masterman et al. (2001)

8. House-Entering Behavior in Aedes aegypti
• Domesticated Ae. aegypti commonly entered houses (D)
• Others rarely did so (either peridomestic P, or feral, F)
• Crossed to produce hybrid (DP, PD, DF, FD, PF, and FP) populations
• Different colored fluorescent powders and released
• 45% D
• 13.9 % DP and PD
• 9.8% P
• 5.7% DF and FD
• Only 1.5 and 0.6% of the PF and FP
• F 0.6% Trpis and Hausermann (1978)

9. Selection Experiments
• To determine the degree to which a given behavior is determined
genetically
• Individuals with a specific behavioral attribute are allowed to
reproduce and this process is repeated over succeeding generations
• Response of the population to selection can be analyzed to estimate
the heritability of the trait

10. Migratory Behavior in Oncopeltus fasciatus
• Bidirectional selection on wing length
• Individuals also were selected for flight time
• 13 generations
• Response to selection on wing length was rapid

11. Molecular-Genetic Analyses of Insect Behavior
• Enables to identify, clone, and sequence specific genes
• Periodicity of biological rhythms
• Mating behavior
• Locomotion
• Learning
• Clone gene P-element vector mutant D. melanogaster
• Cloned genes of Drosophila used as probes to identify genes from other
arthropods

12. The period+ Locus of Drosophila
• period+ locus (per+) is on the X chromosome
• Mutations of it influence
• Eclosion
• Locomotor activity
• Length of the interpulse interval of the courtship song

13. Bargiello et al. (1984)

14. Song-Cycle Behavior in Transgenic Drosophila
• The variation in interpulse intervals ranges from a period of 56 ms in
D. melanogaster and 35–40 ms in D. simulans
• The males of D. melanogaster with the
• perS mutation sing with 40-ms periods,
• perL males sing with 76-ms periods,
• and per0 males are arrhythmic
Wheeler et al. (1991)

15. Pheromones
• Pheromone biosynthesis appears to use one or a few enzymes that
convert the products of normal primary metabolism into compounds
that act as pheromones (Tillman et al. 1999)
• Pheromones arise from isoprenoid biosynthesis, or by the
transformation of amino acids or fatty acids
• Genes encoding the enzymes involved in transforming metabolites
into pheromones have been cloned and sequenced
Field et al. (2000)

16. Detection of pheromones
• Odorant Binding Proteins (OBP)
• Analysis indicates that the binding proteins of unrelated species
have low levels of amino-acid sequence similarity
Christophides et al. 2000

17. Social Behavior in Bees and Ants
• Apis mellifera whole genome has been sequenced
• Whole genome microarray analysis and quantitative RT - PCR
• Parallels between honey bees and humans in novelty-seeking behavior
• Although behavioral variation are similar
• Inherited them from a common ancestor?
Liang et al. (2012)

18. Fire ant - Solenopsis invicta
• Gp-9, encoding a pheromone-binding protein
• Some fire ant colonies have polygyne form
• Workers’ ability to recognize queens and regulate their numbers
• Polygyne and monogyne form apparently associated with an allele of
the Gp-9 gene
Krieger and Ross (2002)