Insects Lecture 1


 

Takeaways from this lecture: Insect diversity, the insect orders, basic insect morphology

Taxonomy

DOMAIN: Eukaryotes

KINDGDOM: Animals

PHYLA: Arthropods

  • No backbone

  • Exoskeleton

  • Segmented body

  • Paired, jointed appendages

  • Chitinous cuticle

  • Bilaterally symmetrical

SUBPHYLUM (superfamily/class): Hexapods

  • Body with 3 distinct regions

  • One pair (sometimes no) antennae

  • One pair of mandibles

  • One pair of maxillae

  • A hypopharynx

  • A labium

  • Three pairs of legs

  • Gonopore

 

Age and Diversity

Hexapods are old

  • hexapods came before plants, then insects developed

  • Insects and plants are a relationship that has existed for a very long time (411 million years ago). This is why there’s so much insect diversity and why essentially every plant has an insect pest that will eat it

We’ve described a million species, but there’s likely millions more out there. (There’s only 250,000 plant species for reference)

  • Taxonomy is important for identifying what it is (or what it isn’t) so you know how to manage them

 

Common Morphology

Insects are defined by a common body plan:

  • having 6 legs in 3 paired sets (though some have developed no legs). always attached to thorax

    • adapted for specific purposes: clasping, digging, jumping, swimming, etc.

  • having 1 or 2 sets of wings (again, not in all. Primitive orders don’t have wings. wingless is called apterous). always attached to thorax.

    • higher orders usually have one set of smaller hind wings (like bees)

  • having body segments. a head, thorax, and abdomen. these sections can vary in length and shape between species but will always have the same generic construction.

  • one pair of antennae, always attached to the head

Beyond this there’s all sorts of features. The terms for describing these features are VERY particular. They’re obscure and imprecise in that they feel like they overlap to anyone not studying insects for a living

  • Mouths are made of 5 parts, but they can be arranged and sized in many ways. specialised for chewing, sucking, etc

 

Orders

-              about 30 orders, some are more diverse than others

-              Classified by shared morphology and development (i.e. we lump together all the things that look the same and assume they’re evolutionarily related)

 

Subclass

Order

Details

Example

Apterygota

Archaeognatha

Primitive order

Jumping bristle tails

Apterygota

Thysanura

Primitive order

silverfish

Pterygota

Ephemeroptera

no mouths? swim in water and eat larvae

mayflies

Pterygota

Plecoptera

Aquatic juvenile stage, carnivores

dragonfly, dasmelfly

Pterygota

Mantodea

mostly terrestrial

mantids

Pterygota

Blattodea



Pterygota

Dermaptera


Cockroaches, termites

Pterygota


not often a pest


Pterygota

Mantophasmatodea

rarely we see


Pterygota

Gryloblattodea

must be -14C, lost their wings

Rockcrawlers, iceworms, icebugs

Pterygota

Orthoptera


crickets

Pterygota

Embioptera

of little concern

webspinners

Pterygota

Phasmatodea

not an issue here, but are elsewhere


Pterygota

Zoraptera

only 30 species found

angel insects

Pterygota

Phthiraptera

parasitic lice, biting and sucking. in mammals, transmit disease (like typhoid)


Pterygota

Psocodea


book lice, barklice, parasitic lice

Pterygota

Thysanoptera

big issue in greenhouse

thrips

Pterygota

Megaloptera

harmless

alderflies, dobsonflies, fishflies

Pterygota

Neuroptera

eat aphids, carnivores

lacewings, dobonflies, snakeflies, ant lions

Pterygota

Strepsiptera

parasitic to bees

twisted wing parasites

Pterygota

Mecoptera


scorpionflies and maybe fleas (!?)

Pterygota

Trichoptera


caddisflies

Pterygota

Siphenoptera

issue in animals not plants

fleas (maybe should be merged into mecoptera)

 

The following five orders are important to crop management:

!Pterygota

Hemiptera

True bugs, the rest are insects. pest on plants and animals.


!Pterygota

Lepidoptera


caterpillars, moths, butterflies

!Pterygota

Diptera

many eat plants

Flies, mosquitos, horse flies

Pterygota!

Hymenoptera


ants, bees, wasps, sawflies

Pterygota!

Coleoptera

many are plant pests, some as adults, some as juveniles

Beetles

 

Insects: Taxonomy (Diversity and Morphology)

February 4th – PLSC260 – Dr. Sean Prager

Part 2/2

 

Hemiptera used to be called homoptera so if you run into that term in literature don’t be confused

 

Naming Insects

Because there’s so many insects, good taxonomy is especially important. Subdivisions are sometimes added such as suborder, tribe, subfamily, and subgenus.

  • Differentiating between similar species where only one is a pest

They tend to have two names: the scientific name and the common name.

  • Scientific names will: follow specific rules, reflect evolutionary history (to a degree), be grouped by similarity, Latin/Greek based, universal. Sometimes these names can give clues to its morphology if your know what the Latin/Greek roots mean.

  • Common names: don’t exist for more species, differ between countries/regions/languages, more often refer to groups rather than species. There are sometimes official common names given by entomological groups, then they refer to one specific species or group

Rules

  • In common names, if it correctly refers to the taxon use a space (e.g. honey bee, stink bug, leafooted bug). If the name doesn’t, don’t use a space (e.g. wireworm, dragonfly, ladybug)

  • First letter of the genus is capitalised

  • Species in all lowercase

  • Italics for both genus and species

  • Include the name of the author that described the species after the name

  • Overall example: Lygus hesperus (Knight, 1917)