The document discusses desiccation resistance mechanisms in desert locusts and desert beetles, highlighting adaptations such as waterproofing, nutrient absorption strategies, and behavioral changes under extreme conditions. It details the physiological processes involved in water retention and loss, particularly focusing on the locust's midgut and the beetle's fog-basking behavior. Understanding these mechanisms could have implications for population control and species invasions.

1. Desiccation Resistance
Mechanisms in the Desert Locust
and Desert Beetle
April Irums and Alexa Mogle

2. What is Desiccation?
● It is a process in which an organism experiences
extreme loss of water and appears to be drying
out or is dried out completely.
- Desert Locust
- Desert Beetle
http://www.pd4pic.com/cartoon-bugs-bug-insect-beetle-insects-scarab.html

3. Desiccation Resistance
Mechanisms of the Schistocerca
gregaria
Water, Nutrient, and Behavioural Adaptations
http://blogs.bu.edu/bioaerial2012/2012/09/25/the-locust-swarm

4. Schistocerca gregaria
The desert Locust
(Showler, 1996)
Recession
area
Invasion area

5. Epidermal Water Loss
Cuticular hydrocarbons
(CHCs)
• Waterproofing of
the epidermis
• Research suggests
chemical functions
(Chung and Carroll, 2015)

6. Nutrient Uptake
Concurrent Flows Water Movements and Nutrient Absorption in the Locust Midgut
(Dow, 1987)
Counter-current system
• Used during extreme nutrient deprivation
• Maximizes nutrient absorption
• Use of amaranth dye
http://blogs.bu.edu/bioaerial2012/2012/09/25/the-locust-swarm

7. Nutrient Uptake
An Experiment
Abbreviations
Cr: crop
AC: anterior caeca
PC: posterior caeca
AM: anterior midgut
MM: middle midgut
PM: posterior midgut
Il: Ileum
Re: rectum
(Dow, 1987)
Figure 1: Observed dye density of fluid from alimentary tracts of fed
and starved Schistocerca gregaria.
Starved locusts
Fed locusts

8. Nutrient Uptake
An Experiment
Movement of ions, water and
nutrients within the alimentary
canal of the locust
a) Fed Locusts
• Caeca supplied with
nutrient rich fluid
• Solid and excess fluid
move along midgut
b) Starved Locusts
• Fluid from Malpighian
tubules moves anterior
• Digest nutrients into
caeca
• Re-absorption
(Dow, 1987)

9. Behavioural Changes
Life Phases
Solitarius
• Solitary
• During times of low
nutrients, following drought
• Slow moving
• No Flight capabilities
Gregarious
• Swarms
• Follow influx of rain and
nutrients
• Fast moving
• Flight("Locust handbook: 2. Desert Locust-Schistocerca
gregaria: Life cycle", 2016)

10. Tenebrionid Beetles
The Desert Beetle
-Arid Climate
-Annual rainfall of ~ 1.4
cm
-Several different
species of desert beetle
http://www.in-the-desert.com/insects.html

11. Components of Water Loss
(Ahearn, 1970)
-Major components of
water loss include faecal
production,
transpiration
(evaporation) , and the
release of Quinone
droplets

12. Avenues of Water Loss
Thorax
Figure 1: Areas of water loss in tenebrionid beetles.
Abdominal Region
Anus
(Ahearn, 1970)

13. Dehydration and Rehydration
Experiment
Figure 2: The effects of dehydration and hydration
on the % of original weight of Physadesmia
globosa.
Allowed to Rehydrate
-Rapid weight loss in
the absence of water
(dehydration).
-Increase in weight in
the presence of water
(rehydration).
(Naidu, 2001)

14. Dehydration and Rehydration
Experiment
Figure 3: Lipid content showed a strong
negative correlation.
Figure 4: Haemolymph volume
declined.
(Naidu, 2001)

15. Desiccation Resistance
1. Spiracles remain Closed
1. Discontinuous Gas Exchange
1. Fog-Basking Behaviour
(Zachariassen, 1996)

16. Desiccation Resistance Mechanisms of
Tenebrionid Beetles
Fog Basking behaviour

17. Significance
Understanding desiccation resistance mechanisms:
• Strategies for population control
• Modulate species invasions
• Fog-basking design in Tenebrionid beetles
https://www.gettyimages.ca/search?q=l9t

18. Thanks For Listening!