Locusts and polymorphism Flashcards
What is the most significant factor that causes a locust to become gregarious?
Touching the insects hind leg that contains many mechanoreceptors
What conditions cause the locusts to come into contact with each other?
Significant rainfall followed by a drought causing the vegetation to become patchy, the patches have to be relatively close together
Why is the hind leg (femora) more sensitive to touch?
It is not consistently self stimulated during normal behaviour
How long does it take for a solitarious locust to become gregarious when there’s crowding?
4 hours
What morph consumes toxic alkaloid plants?
The gregarious morph
Why is it more advantageous for the gregarious morph to consume toxic plants?
Because predators are more likely to associate their black and yellow colours with toxins compared to the green solitarious locust
What hormone is involved in causing gregarious behaviour?
Serotonin
How much more serotonin does a gregarious locust have?
3x more
What happens if a locusts serotonin receptors are blocked?
They fail to gregarize
Where in the locust is serotonin found?
The CNS of the thoracic ganglion
What causes offspring to be either solitarious or gregarious?
The foam put over the eggs from the mother
Are the genetic instructions for producing the two phases in the same genome?
Yes
What other factors besides direct contact triggers the behavioural phase change?
The sight and smell of other locusts
What causes the black patterning on the locust?
The smell of other locusts is sufficient
What causes the yellow background colour?
It requires direct contact with other locusts
How are gregarious locusts able to survive in a crowded group?
They are more resistant to pathogen infection than solitarious individuals, which helps reduce disease spread
Why do locusts migrate?
To keep moving in order to find new resources and avoid being attacked by cannibalistic conspecifics
Who found that gregarious behaviour is evoked by touching their back legs?
Simpson et al. (2000)
Who found that vegetation had to be clumped?
Collett et al. (1998)
Who found gregarious locusts eat toxins and solitarious don’t?
Simpson et al. (2004)
Who found that egg foam conditions cause the phase state of the locust?
Hamouda et al. (2009)
