Zoology Lecture 11+12 (BIO-2040)

Myriapods

• terrestrial Species, no wax on the cuticle

• all segments similar to uniramous

• tagmata: head and trunk

Appendaged of Myriapods

Pair 1: Antenna

Pair 2: Lost

Pairs 3-5:mandibles and maxillae

Remaining Pairs: all walking legs

Millipedes

• round (tubular) worms with diplosegments

Diplosegments

segments fused in pairs with two pairs of legs per segment

Centipedes

• elongated, flattened worms, knows to control pests like roaches, moths, flies and termites

Hexapoda

• six legs

• hugely diverse (about 1 million species)

• Tagmata: head, thorax, and abdomen

• 4 Adaptions

Avoidence of desiccation in Hexapoda

important to control hea

• waxy water resistant cuticle that reduces water loss

• ecretion of highly concentrated uric acid after reabsorbtion of water by the malpighian tubules, located at the end of the gut

High Mobility in Hexapoda

provides an advantage for dispersal (reproduction), feeding, and escape from predators.

Primitive Wings

Cannot be folded

Advanced wings

folded and pleated, in some cases also modified to other functions

Mouth parts in Hexapoda

allows for high feeding specialization, maximizing the use of different niches and reducing competition.

• labrum

• labium

• mandibles

• maxillae

Small size in Hexapoda

favours the exploitation of many habitats within the same area (inside or outside plants, animals, leaves roots, etc.)

tagmata in Hexapoda

• one pair of antennae

• compound eyes and ocelli

Thorax in Hexapoda

3 segments

• prothorax

• mesothorax

• metathorax

Wings in Hexapoda

only associated with the mesothorax and metathorax

Abdomen in Hexapoda

• digestive and excretory systems

• up to 11 segments plus terminal genitallia (for reproduction)

• legs are lost, but the abdomen holds more of the body system

No metamorphosis

Ametabolus

• incests emerge from eggs looking like small, immature adults

• Adults are wingless

• ex. Silverfish

Incomplete Metamorphosis

Hemimetobolus

• go through distant stages: egg to nymph to adult

• very young lack wings

• adults have fully formed wings

• ex. dragonfly, cricket, grasshopper

Complete Metamorphosis

Holometobolous

• 4 stages → egg, larva, pupa, adult

• ex. Butterflies

Hexopoda relevance to people

insect-transmitted diseases, only 3% are harmful

• malaria 

• bubonic plaque

• small pox

Pollution - benifits from insects

bees and other insects pollinate flowers of many trees, so are essential for many crops

Dispersal of seeds - benifits from insects

also essential; done by dung beetles, wasps, ants etc.

Medicine - benifits from insects

fly larvae (maggots) were using IN THE PAST to prevent gangrene

Biological Control - benifits from insects

recycle nutrients and control other insect and plant pests

Causes of decline in insects

Agriculture → 47%

Climate Change → 5%

Aquatic Habitat → 6%

Deforestation → 9%

Urbanization → 11%

Ecological Traits → 12%

Other Factors → 10%

Diptera Common Species

• biting and houseflies

• simuliidea (blackfly)

• Culicidea (mosquito)

• Muscidae (housefly)

Lifecycle of Diptera

egg, several larval stages, pupa, reproductive adult.

Blackflies

• lay eggs in still water

• larvae absorb oxygen from water

• go through 4-8 larval stages

• spin cacoons in spring

larval stages of a blackly

instars

Mosquitoes

• lay eggs in moving water

• breath through siphon, 4 larval stages complete in water

• last stage is free-swimming pupa

• change to get oxygen through trumpets on head

Blackfly and Mosquito shared traits

• feed on sugar, usually in the form of nectar

• males eat only sugar

• Females need blood to feed larvae

Bacillus thuringensis israelensis

• little risk to human health

• harms the larval stages

• selective and environmentally benign

Methoprene

• Little toxicity to mammals and birds

• harms the larval stages

• Somewhat toxic to shrimp, crab, and fish

• releases slowly over several weeks

Pyrethrum

• short residual life

• Little toxicity mammals

• toxic to fish

Chorpyrifos

• used to control mosquitos

• toxic to crusteans, fish and bees

• not recommended to use

easiest way to treat diptera

by adding something to the water containing the larva so they take it in

dermaptera

• european earwig

• leathery forewing

• omnivorous

• nocturnal and thigmotatic

• 2 cerci

• taste bad

white earring

earwig that just shedded their skin

Biocontrol of Dermaptera

They have been tested as biocontrol agents of aphids in apple trees. Known to consume codling moth eggs

Coleoptera

• scarlet red or leaf lily beetles

• eat flowers from liliaceae family

• protect themselves with poop

• chemicals for them are poisonous to bees

• attractent to parasitoids

Japanese Beetle

• no good control

• spend a lot of time underground

• nematodes can kill all stages of soil-dwelling insects

Hemlock woolly adelgid

• invasive insect

• kills hemlock trees by eating its nutrients and water

• can be found at the base of needles

lifecycle of Hemlock woolly adelgid

• all female, reproduce via parthogenesis

• population grows fast

Lariobius niginus beetle and silver flies

• consume Hemlock woolly adelgid

• began releasing them in NS in fall

Mud dauber wasps

• dont sting people

• roll up mod

• hide larva in it