Download slides (large)

Plecoptera, Blattodea
& Isoptera
(EE, pp. 84-104)
Phylogeny of
Hexapoda
(from p. 52)
Plecoptera,
Blattodea
& Isoptera
Division III: Neoptera
Primitively wingless insects
Winged insects
Subdivision: Exopterygota (Hemimetabola)
•
•
•
•
young stages are called “nymphs”
nymphs typically eat the same food as the adult stage
wings develop outside of the body (exopterygota)
metamorphosis is simple (hemimetabolous)
Subdivision: Endopterygota (Holometabola)
•
•
•
young stages are called “larvae” (singular = larva)
wings develop internally (endopterygota)
metamorphosis is complete (holometabolous)
The transition from hemi- to holometabolous
transition from larva to adult
takes place during a pupal stage
Plecoptera
stoneflies
•
•
•
•
plectos – pleated; pteron – wing
body 3 – 48 mm
wingspan up to 100 mm
incomplete metamorphosis
– hemimetabolous (egg, nymph, adult)
• worldwide but mainly cool temperate
• 15 families; 2000 spp. (0.2 %)
•
•
•
•
•
•
aquatic nymphs (naiads)
cold, fast flowing streams with stone or gravel
some have gills
mostly herbivorous (some omnivorous or predatory)
1 – 4 years before becoming adults
important in aquatic food chains
•
•
•
•
•
•
weak fliers, usually remain near water
adults rest with wings against body
weakly developed mouthparts; little or no feeding
males and females call each other via vibration
eggs laid in the water
important in aquatic food chains
• Sensitive to pollution
• Require high oxygen content
• Presence may indicate high water quality
Blattodea
cockroaches
•
•
•
•
•
•
blatta – cockroach
body 3 – 100 mm
incomplete metamorphosis
worldwide distribution
6 families
4000 spp. (0.4 %)
•
•
•
•
•
flattened, broadly oval and leathery-bodied
tegmina – front wings toughened
covers membranous hind wings
many are fast running
eggs often laid in a toughened case
•
•
•
•
most are scavengers or omnivores
some cannibalism or predation
some eat wood
cockroaches can’t digest cellulose
- symbiotic protozoans do it for them
• at each molt, juveniles must reingest protozoans
chemicals
- female pheromones
- male dorsal abdominal glands
auditory
- stridulation
- hissing
ootheca
Oviparous – young hatch from eggs
outside of female
Ovoviviparous – young hatch from
eggs inside female body
Viviparous – young receive nutrients
from female while inside of her
•
•
•
•
a few species are pests
live closely with humans
can transport bacteria and viruses
cockroach allergens and asthma
Control:
•
•
•
•
cleanliness
insecticides
resistance can develop
best approach is integrated pest management (IPM)
- hymenopteran parasitoids
- fungal pathogens
Isoptera
termites
•
•
•
•
•
•
•
•
isos – equal
pteron – wing
only reproductives have wings
body 3 – 20 mm
queens can be up to 100 mm
incomplete metamorphosis
hemimetabolous
worldwide but not more than 50 degrees N or S
7 families; 2500 spp. (0.25 %)
Caste – morphologically or behaviorally specialized individuals
queen – 1
male reproductive – few
worker:soldier – 50:1
•
•
•
•
•
soft-bodied
social insect with castes
mainly tropical and subtropical
destructive to wood and plant material
workers seldom forage or are exposed
– mostly in nests or runways
25
600,000 US homes per year
$1.5 Billion in damages
caste determination = genetics + environment
Burj Khalifa building
(Dubai, United Arab Emirates)
• temperature regulation
• air circulation
• feed on wood
– symbiotic protozoans to digest cellulose (like cockroaches
– fungus gardens
• nitrogen fixing gut bacteria
• trophallaxis – exchange of food between colony members
– pass on symbionts to young and newly molted
Soldier types
hitting
biting
spraying
exploding abdomen
Ecosystem benefits
• nutrient cycling
– decomposition of wood
• aerate soil
• food items for many species