1. Presentation by Trevor Caughlin 4/6/04 Introduction to Entomology
Aquatic Bugs
Presentation by Trevor Caughlin
4/6/04
Introduction to Entomology

2. 8.5% of Heteroptera are fully aquatic
Classification
Insecta
Order Hemiptera
Suborder Heteroptera
8.5% of Heteroptera are fully aquatic
Families in Heteroptera that are completely aquatic in all phases of life cycle: Nepidae
Belostomatidae
Corixidae
Pleidae
Naucoridae
Notonectidae

3. Common adaptations: limbs
Picture courtesy of amnh.oef
Natatorial legs
Covered with fine hairs
Function like paddles
More pronounced in swimming forms
Second and third sets of legs
Raptorial legs
Nearly all are predatory, use these limbs to capture prey
First set of limbs

4. Stridulation Most Aquatic Hemipterans use stridulation
Body parts make noises for communication
Used for territory demonstrations, attracting mates, sex discrimination, signaling when female should oviposit
spacing, territoriality, and food defense. In various species, experimental playbacks of signals have demonstrated functions of attraction of females by males, induction of oviposition, sex discrimination, mate-guarding, enhancement of female foraging, nonterritorial individual spacing, and intra- and interspecific territoriality. In giant water bugs, ripple signals occur in the contexts of male courtship and aggressive displays and may be involved in induction of oviposition. Ripple signal playbacks have demonstrated that males which signal longer obtain more copulations than males which signal more briefly. Ripple signals could have evolved through ritualization from virtually any body motions. For example, in belostomatids, male ripple signals may have evolved from the aeration motions of males incubating eggs on their backs.

5. Common adaptations: mouthparts
Belong to Hemiptera, so have long sucking beaks
Mandibles, maxillae form four piercing stylets inside beak (labium)
Pierce prey, inject toxins, then suck out the fluids
Most have nasty bites (toebiter)
Toe-biter feeding on a minnow

6. Aeropneustic respiration
Aeropneustic: rely upon oxygen in the air
May use modified cerci as siphons
                          
Water scorpion with siphon for breathing
Periodic contact breathers: carry an air supply underwater
Capture bubble in underwing chamber
Dense coverings of unwettable hairs hold bubble to insect’s body

7. Hydropneustic respiration
Absorb oxygen from the water
Physical gill
Bubble under the wingsheath can absorb oxygen release carbon dioxide from water (osmosis)
Bubble called a plastron
Cutaneous respiration
Absorb air directly through a thin cuticle
Rare

8. Ecology of Aquatic Hemiptera
Common in shallow, heavily vegetated water (lentic)
Well-adapted to ephemeral ponds (wings allow for migration when pond dries up)
Some live in heavily polluted areas (such as a German lake with a pH of below 3)
Regulate populations of fish, tadpoles, mosquito larvae
Provide food for fish

9. Economic importance Important predators of mosquito larvae
Pests in fish hatcheries
Giant water bug used as food in Thailand
Water boatman eggs used as food in Mexico
Mangdana

10. Family Nepidae Water scorpions Poor swimmers
Ambush predators: cling to vegetation, wait for prey
Long, non-retractable breathing siphon
15-45 mm long

11. Family Pleidae Pygmy backswimmers Less than 3 mm long
Found in aquatic vegetation
Rarely swim

12. Family Naucoridae Creeping water bugs 6-15 mm long
Similar to giant water bugs
Live in well-aerated water
Often hydropneustic

13. Family Notonectidae Backswimmers 5-16 mm Swim upside down Toxic bite
Have hemoglobin which helps maintain buoyancy

14. Family Corixidae Water boatmen 3-11 mm Largest group in North America
Plastrons efficiency increased by rowing motion in legs
Important fish prey
Only group with species that can feed on algae and detritus

15. Family Belastomatidae
Giant water bugs
Other names: toebiters, electric light bugs, fish killers
20-65 mm
In some species males carry eggs on back and aerate them
Subsocial