Arthropods Flashcards
Coleoptera, Diptera, hemiptera, lepidoptera, and hymenoptera are the…
Most diverse orders of insects.
What is the main key feature of the phylum Arthropods?
Hard exoskeleton with jointed legs.
Where is most insect diversity found geographically?
In tropical areas.
Insects are commonly keystone species, how so?
They disproportionatly play a role in their environments via pollination, herbivory, nutrient recycling, being a food source, etc.
What are some evolutionary reasons for insect success?
Small size, exoskeleton, highly organized sensory and neuromotor systems, short generation time, flight, metamorphosis, etc.
What is the paranotal theory of wings?
That they derived from rigid non-movable lobe-like expansions of the thoracic terga (dorsal region).
What is the pleural theory of wings?
They derived from articulated lateral extensions from pleuron (abdominal region).
What’s the difference between direct and indirect flight?
Direct has muscles directly attached to wings - slower and more control - indirect has asynchronous muscles attached to thorax cuticle that allows for faster wing beating - less control.
What is metamorphosis?
Process of distinct development and growth from juvenile into an adult.
What are the three kinds of metamorphosis?
Ametaboly - no metamorphosis, hemimetaboly - incomplete, and holometaboly - complete.
Key features of Collembola?
Ametabolous, present antennae, entognathous (mouthparts within folds of head), and have a forked jumping organ on abdomen (furcula).
Key features of Protura?
Ametabolous, entognathous, lack eyes andd antennae, found in soils, moss, and leaf litter.
Key features of Diptera?
Homometabolous, one pair of wings.
Insects are all divided into three parts, what are they?
Head, thorax, and abdomen.
The cuticle is secreted from the ___, and is made up of ___ layers.
Secreted from the epidermis and made up of 3 layers, the epicuticle, exocuticle, and endocuticle.
How many segments does the head typically have?
Six.
Entognathous vs. Ectognathous.
Internal mouthparts (ento) and external mouthparts (exo).
Three types of mouthparts.
Mandibulate, sectorial, and mouth hooks.
Scape, pedisel, and flagellum are parts of what?
Antenna.
What are the three parts of the thorax?
Prothorax, mesothorax, and metathorax.
How many legs are attached to the thorax?
6, three pairs - forelegs, mid legs, and hind legs (can be modified).
The abdomen can have how many segments?
A varied amount - 6+.
What is an ovipositor?
A tube-like organ for laying eggs. - Consists of a maximum of three pairs of appendages.
What is cerci?
Sensory organs that can be modified (rarely) for defense and predation.
How do insects undergo respiration?
Their body cavity (hemocoel) filled with hemolymph allows for gas exchange via tracheas system - with spiracles or gills.
What are the three main parts of the gut?
Foregut - for breaking down food, midgut - for absorbtion, and hindgut - for excretion.
What are the two midgut areas?
Ventricles and caeca.
What kind of muscles do insects have?
Striated muscles with sarcomeres that can be synchronous or insynchronous.
What are the key features of the class Orthoptera?
Enlarged hind legs for jumping (tegmina), hemimetabolous, herbivores.
What are the key features of Coleoptera?
Holometabolous, forewings modified as elytra, herbivores, predators, and scavengers.
When does size increase in insects?
When they moult.
What is the juvenile stage of hemimetabolous insects?
Nymphs, they lack wings and grow them when they’re adults.
What are the juvenile stage of holometabolous insects?
Larvae and pupae.
What is the pupal stage of a holometabolous insect?
The final juvenile stage where they transition into an adult - via chrysalis, etc. This is called eclosion.
What is diapause?
The process where insects pause development in the winter to conserve energy for better environmental conditions.
What is the imago stage of insects?
The adult stage/the stage of sexual maturity.
What is pupation and eclosion?
Pupation is the moult into the pupal stage and eclosion is the transition from pupae to adult.
What is voltinism?
The number of generations per year: univoltine (1 py), bivoltine (2 py), multivoltine (many py), and semivoltine (1> py).
Plecoptera, ephemeroptera, trichoptera, megaloptera, and odonata have what in common?
All have almost exclusively aquatic juvenile stages.
What is the difference between lentic and lotic water?
Lentic water is still with slow oxygen diffusion, whilee lotic is flowing water with increased oxygen diffusion.
What is behavioural ventilation?
SOme insects can move their gills to increase gas exchange in closed tracheal systems.
In feeding insects can be autocthonous or allochthonous, what do these mean?
Autochthonous means that insects eat via the stream, e.g. algae. Allochthonous means that insects eat via the surrounding vegetation, such as tree leaves.
What are the key features of Odonata?
Dragonflies, etc, large compound eyes, heimetabolous, nymphs have a mask (extensive labium),hindwings wider than forewings.
What are the key features of megaloptera?
Holometabolous, larvae have spine-looking gills, huge wings.
WHat are the key features of Plecoptera?
Stoneflies, hemimetabolous, with two filamentous cerci.
What are the key features of Ephemeroptera?
Mayflies, two adult winged stages, three cerci, nymph has abdominal gills, hemimetabolous.
What are the key features of trichoptera?
Hairy wings, larvae build cases/shelters and have a hook at the end of abdomen, holometabolous.
Alternating tripod gait is used by how many legged insects?
6 legged.
Insects sense mechanical stimuli via…
Mechanlreceptors (tactile, sound, and position) in the form of setae covered in sensilla.
What is the main organ that detects sound stimuli?
Tympanum - ‘eardrum’-like organ that’s located on the thorax, abdomen, or legs.
How do insects most commonly produce sound?
Stridulation, “scraper rubbed against a file”. Also tymbals - clicks from elastic cuticle - produced by cicadas.
How do insects sense thermal/temperature stimuli?
Receptors at the end of the antenna or legs- has two different reception neurons - one fot hot and the other for cold.
Insects are ectothermic, what does this mean?
They can’t internally regulate their body temperature and instead must rely on external temperature.
How do insects detect chemical stimuli?
Chemosensors (which are sensilla with 1 or more pores) on antennae, feet, ovipositors, mouth, etc.
What are the two kinds of receptors for chemical stimuli?
Gustatory receptors (for taste) and olfactory receptors (for smell).
What are semiochemicals?
Chemical signals produced by organisms that influence other organisms behaviour, e.g. pheromones and allelochemicals.
What are pheromones, and some examples?
Chemical signals from animals that trigger behaviour in the same species. Sex, aggregation, orientation, trail-making, alarm, etc.
What are allochemicals and the three kinds?
Kairomones: predator attraction - disadvantages producer and benefits receiver. Allomones: benefit producer, neutral/disadvantage reciever. Synomones: benefit both, e.g. pollination.
How do insects detect visual stimuli?
Detect light through ocelli, Compound eyes made of individual units (ommatidia).
What is phytophagy and the different kinds?
Herbivory. Monophage: feed on unique plants. Oligophage: feed on few taxa. Polyphage: feed on many taxa.
What are the types of plant defenses?
Physical (constitutive) and chemical (constitutive or induced).
Indirect induced defence?
Induced chemical defence induced by herbivory.
Systemic acquired resistance?
Plant defence response to another plants phytophagy/pathogen production.
Different forms of herbivory (ways of eating - not what)?
Leaf chewing, leaf mining (lives inside leaf epidermis), plant borers (target fruits, etc), sap suckers, seed predation, and gall formers (make little huts (domatia) on leafs).
Parasitoids vs. Parasites?
Parasitoids eventually kill the host, parasites don’t.
What are generalist predators?
Predators that hunt a wide range of prey - most common form of predation. (parasitoids are typically specialists).
What are idiobionts and koinobionts?
Idiobionts are parasitoids that kill or paralyze their host , while koinobionts are parasitoids that lay eggs into the host.
Ectoparasitoids vs. Endoparasitoids?
Ectoparasitoids are juveniles that develop on the outside of the host, e.g. fleas. Endoparasitoids are juveniles that develop inside the host.
What are the three main strategies for prey location? Cost-benefit trade off?
Ambush prey: wait till prey arrives (high time-low energy). Random active foraging: search till prey/prey cues are found (high energy-less time). Non-random directional foraging: use of prey cues w/ developed sensory structures usually. Attraction of prey.
What are kairomones and synomones?
Kairomones are chemicals produced by prey, synomones are produced by plants (e.g. during herbivory). These can help predators locate prey.
What are aposematic colours in insects?
Using colour to advetise toxicity - or to act as as if they are toxic.
What are the two kinds of mimicry?
Batesian and mullerian. Batesian - mimic copies a toxic model but can still be eaten. Mullerian is mimic copies a toxic model and is toxic. Mimicry can be more than just appearance - e.g. smell, behaviour, etc.
What’s a cryptic insect?
Insects that resemble their background - camoflague into it.
What are some examples of behavioural insect defences?
Escape, Thanatosis - play dead, Autonomy - sacrifice a limb for escape.
What are some morphological defences?
Spines, heavy scleretation cases, fluffy/wooly.
What are some chemical defences? What are endogenous and exogenous chemicals?
Class #1 chemicals- toxic/poisonous, and class #2 chemicals - taste bad. Advertise with aposematic colours. Endogenous = produced by insect - exogenous - stored in hemolymph/tissues.
What’s an example of an immune defence against parasitoids? Counter?
Encapsulation: immune response - encapsulation of the foreign body (parasitoids egg) to prevent growth. Counter - some parasitoids have anti-immune proteins to inject with the egg.
What are the key features of Phasmatodea?
Stick insects - hemimetabolous, parthenogenetic.
Key features of hemiptera?
True bugs, e.g. cicadas, hemimetabolous, mouthparts without palps.
Key features of arachnids?
Two part body plan (prosoma and opisthosoma), book lungs, open circulatory system, ametabolous.
