Hexapoda: the Megadiverse Orders

Question 1

clade known as Endopterygota

Answer 1

(“endo” = internal, “ptery” = wing)

Question 2

Development

Answer 2

Ametabolous, Hemimetabolous, Holometabolous

Question 3

Ametabolous insects

Answer 3

no true metamorphosis
Primitive wingless insects, Apterygota (bristletails, silverfish)

Question 4

Hemimetabolous insect

Answer 4

incomplete metamorphosis
e.g. Hemiptera (true bugs), Orthoptera (grasshoppers), Odonata (dragonflies)

Question 5

Holometabolous insects

Answer 5

complete metamorphosis
(mnemonic : “whole” metamorphosis)

Question 6

Coleoptera: Beetles

Answer 6

Contains more described species than any other insect order
400,000 named species
Nearly 40% of all insects are coleopatera

Question 7

Elytra Coleoptera

Answer 7

Protect wings
Cover spiracles (prevent dehydration)
Protect body from damage
Protect against infection

Question 8

Eating Coleoptera

Answer 8

Mandibulate (chewing) mouthparts
Phytophaga are a clade of phytophagous (plant-eating) beetles 150,000 spp
Powerful jaws = voracious predators
Tiger Beetles (carabids - Carabidae; Cincindelinae) are perhaps the most voracious terrestrial insect predators

Question 9

Halteres

Answer 9

Modified hind wings
Beat in time with forewings
As body turns/rotates in flight gyroscopic forces are exerted on halteres
Sensitive mechanosensors at base detect these forces
Allow fly to make adjustments & stabilize body rapidly in flight

Question 10

Diptera: suborder Nematocera

Answer 10

Mosquitoes, craneflies, midges & gnats
Slender flies long legs & elongated abdomens
Poor fliers, often nocturnal / crepuscular
Piercing mouthparts; many are blood feeders & important disease vectors
Long, thin antennae (Nematocera = ‘thread horns’) (flagellomeres); long maxillary palps also present
Often aquatic in larval stages

Question 11

Suborder Brachycera

Answer 11

Hoverflies, Houseflies, Blowflies, Dungflies, Beeflies, Horseflies, Soldierflies, etc
Excellent fliers, usually diurnal and sometimes very colourful. Often have sucking mouthparts; many nectar feeders (pollinators), but also many predators
Antennal segments reduced (Brachycera = ‘short horns’) and reduced maxillary palps
Larvae (Maggots) with internal mouthparts, often living within substrate / other organism

Question 12

Diptera: ecological roles

Answer 12

Parasitism / Disease Transmission
Predation / Biological Control
Waste Disposal / Nutrient Recycling
Nectar Feeding / Pollination

Question 13

Hymenoptera (Bees, Wasps & Ants)

Answer 13

Hymenoptera = “Married Wings”
Usually two pairs membranous wings
Reduced venation
Front wing larger
Wings connected together by series of hooks (Hamuli)

Question 14

Mouthparts Hymenoptera

Answer 14

Chewing Mouthparts - Ants & Wasps
Lapping Mouthparts - Bees

Question 15

Holometabolus Hymenoptera

Answer 15

Symphyta (Sawflies), Active plant-feeding larvae (caterpillar-like)
Apocrita (“Waisted Wasps”)
Helpless larvae, dependent on food provision by adults (maggot-like)

Question 16

Waisted wasps Apocrita

Answer 16

1st Abdominal segment (Propodeum)
2nd Abdominal segment (Petiole: “waist”)
Rest of Abdominal segments (Gaster)

Question 17

“Parasitica”

Answer 17

(Parasitoid & Gall Wasps)
Ovipositor for laying eggs in: Insects (parasitoids)
Plants (galls)

Question 18

Aculeata

Answer 18

(“Stinging Wasps”)
Ovipositor modified into a sting with venom gland

Question 19

Hymenoptera. Three key facets of their ecology:

Answer 19

Parasitism (hyper-diversity) & Biological Control (importance)
Co-evolution with Plants (hyper-diversity) & Pollination (importance)
Evolution of Social Complexity (dominance)