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

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

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

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.

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

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

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

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

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

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

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

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

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

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

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