Yes
Can insects perform endothermy?
Odonata, Orthoptera, Hemiptera, Coleoptera, Lepidoptera, Diptera, and Hymenoptera
What insect groups employ endothermy?
Open Circulatory System
A circulatory system that allows the blood to flow out of the blood vessels and into various body cavities so that the cells are in direct contact with the blood.
Hemolymph
In invertebrates with an open circulatory system, the body fluid that bathes tissues.
Hemocoel
The primary body cavity of most invertebrates, containing circulatory fluid.
Dorsal Blood Vessel
This is the main pump of the insect ciruclatory system.
This runs from posterior end of the abdomen to under the brain.
Paired openings called ostia allow hemolymph to enter this structure.
No, circulation is regulated by muscle contractions and membranous sheets than direct the flow of blood.
There are also muscular pumps at the base of structures like the antennae, wings, and legs that help hemolymph move in.
Is insect circulation haphazard?
Transport nutrients, wastes, and hormones.
Hydrostatic pressure for molting, extending proboscis, etc.
Disease resistance.
Walling off parasites (encapsulating).
Clotting and repairing wounds.
Protect against freezing.
O2 and CO2 transport.
What are the functions of the circulatory system in insects?
Some groups allow glycerol to accumulate in the hemolymph to allow the supercooling of the liquid.
Another group promotes the hemolymph to freeze to dehydrate cells, thereby preventing the cell itself from freeing.
How does insect blood help protect against freezing?
Blood cells engulf viruses, bacteria, fungi, and protozoans that attack the body, in a process called phagocytosis.
How does the insect circulatory system help the insect resist disease?
Gas exchange occurs on the outer body surface (which must be moist).
How do Proturans and Collembolans perform gas exchange?
Water loss is fatal, and the surface area to volume ratio must be high in order to acquire sufficient amounts of oxygen.
Oxygen also diffuses much faster in air than in water, and other groups have higher oxygen demand due to flying.
Why don't all arthropods perform gas exchange like proturans and collembolans?
Spiracles, Trachaea, Trachioles, and the Cuticular Lining of Trachea
What are the insect solutions to the problems associated with gas exchange as performed by proturans and collembolans?
Spiracles
External respiratory openings in insects, with one pair per segment present.
These can be closed to minimize water loss, may have filter apparatus to keep dust out, and are extremely similar to stomata on plant leaves.
Tracheae
Chitin-lined air tubes that branch throughout body and open through holes that are often connected to collapsible air sacs.
Tracheoles
In insects, narrow tubes branching from trachea and making direct contact with cells to facilitate gas exchange.
- Minimizes Water Loss
- Efficient O2 Transport
What are the benefits of the spiracle, tracheae, tracheoles method of gas exchange?
- Contact with surface or frequent trips to surface.
- Bringing a bubble underwater.
- Closed tracheal system.
What are the methods of aquatic insect gas exchange?
The Rat Tailed Maggot
This insect has a respiratory siphon that it uses like a straw to collect air from the surface.
What is an example of an aquatic insect that gets air via contact with the surface?
- The bubble makes the insect very buoyant, so it must constantly swim down to avoid floating.
- The bubble is able to act like a physical gill, where oxygen flows into the bubble from the water and carbon dioxide flows out of the bubble into the water.
What are the costs and benefits of bringing a bubble underwater to perform gas exchange?
Plastron
A layer of air that covers the body of some insect types as they swim underwater.
The spiracles are open to this layer, and air is pulled in from it.
Closed Tracheal System
Found in many aquatic nymphs and endoparasites, this method of gas exchange involves oxygen diffusing across the body surface into the tracheae.
Essentially, the spiracles are closed by oxygen is allowed to diffuse over tracheal extensions.
Thoracic Pumping, Abdominal Pumping, Pump Reversal
What are some methods of respiratory system ventilation in terrestrial insects?
Thoracic Pumping
Changing the shape of the thorax pumps air in and out of spiracles.
Abdominal Pumping
Telescoping" of the abdomen to push air in out of the spiracles.
Pump Reversal
A process noted in resting flies wherein the direction of the heart's beating is reversed approximately once per minute, thereby forcing air in or out of the spiracles.
Both air sacs and individual tracheae can be compressed either laterally or dorsoventrally.
How are insects able to manage a 50% volume change during respiration?
Pumping water out of rectum (dragonfly nymphs).
Gill beating (mayfly, dobsonfly nymphs).
What are some strategies used by aquatic insects to ventilate their respiratory systems?
In some caterpillars, there are extensively branched tracheae that are briefly associated with blood cells that are charged with oxygen to distribute to body cells.
This only occurs in the posterior spiracles, however.
Does the circulatory system in insects assist with oxygen distribution?
Bloodworms (chironomids) that live in polluted water use hemolymph to hold onto oxygen.
Horse botfly maggots (inside horse intestines and stomach) also use hemoglobin to hold onto oxygen, as it is scarce in this environment.
Some stoneflies and silverfish
Do insects use respiratory pigments, like hemoglobin?
Adult lays eggs on horse leg, where the horse will lick them off. Eggs develop inside the mouth, and are swallowed when they develop into maggots. The maggots live in the horse's digestive tract, pupate, and are excreted out. They then emerge as adults, a
What is the lifecycle of horse botflies?
Dermal Detection, Simple Eyes and Compound Eyes
What are the types of insect vision besides x-ray? (haha jk)
Dermal Detection
Light sensitive cells or receptors under the insect's cuticle that can detect the presence or absence of light, but not create a picture.
In some insects, like the peppered moth caterpillar, color can be detected via dermal detection.
(Even when blindfolded, the caterpillars are able to sense what color stick they are standing on, and modify their color to match it!)
Can dermal detection cells pick up more than just presence or absence of light?
Simple Eye
A single lens formed from transparent cuticle to concentrate light onto several light-sensitive cells underneath.
Dorsal Ocelli
Often found in a triangle of three on top of an insect's head, these simple eyes are sensitive to low light intensities.
These integrate light over a large visual field, and may assist in horizon detection for flight stabilization and polarized light dete
Stemmata (Lateral Ocelli)
Found in holometabolous insect larvae, each of these covers a different portion of the insect's visual field.
These are highly variable: some only detect light while others can create simple images.
Compound Eyes
Found in hemimetabolous nymphs and many pterygote adults, these eyes are composed of repeating ommatidia (each ommatidia resembles a single stemma).
- Corneal lens
- Conical Lens
- Pigment Cells
- Sensory Neuron w/ Visual Pigment
- Axon
What are the components of an ommatidia?
Corneal Lens
Transparent cuticle that caps an ommatidia.
Conical Lens
A cone-shaped lens under the corneal lens in an ommatidia.
Rhabdom
The special light-collecting area that converts light energy into nerve impulses, visual pigments present.
Found in the center of a sensory neuron.
These cells block interfering light, allowing only the concentrated light from the lens onto the sensory neuron.
They serve a similar function as the human sclera.
What is the function of pigment cells in the ommatidia?
Sensory Neuron
Consists of 8 tightly packed nerve cells with a central rhabdom (contains visual pigments)
No, each ommatidium only captures a tiny portion of the visual field, and the brain pieces these images into one whole image.
Do flies really see 100 tiny images with their compound eyes?
Blue, Green, and UV
What colors can insects see?
Butterflies and some Hymenoptera
What groups of insects can see red?
Blue and Yellow flowers, because those are colors they can see.
(These flowers also often have UV patterns to appeal to insects).
What color flowers do bees and wasps prefer, and why?
Pigment cells block interfering light, vision is less sensitive than it would be in low light, has a sharper image.
Seen in groups such as butterflies, bees, and dragonflies.
Describe diurnal vision characteristics in insects.
A transparent zone is present between the cone and rhabdom, allowing interfering light from other ommatidia to reach the sensory neuron. Pigments may be able to migrate, allowing for sharp images during the day and high-resolution vision during the day.
S
Describe nocturnal vision characteristics in insects.
Color, movement, and shape.
Resolution: can separate objects divided by one degree (we can only see 1/90th of a degree).
What can insects see with their compound eyes?
Stoneflies and icecrawlers can be active on snow or ice.
What insects are at the lower extreme of temperature tolerance?
Desert Ants die at around 120F (53.6C).
What insect is at the upper extreme of temperature tolerance?
They come out of their burrows at around 46.5C (exactly above their main predator's thermal max) to collect insects that have succumbed to the heat. They do a mad dash to collect as much as possible before retreating back to the burrows when temperatures
How do desert ants behaviorally avoid burning?
Maintain temperature within optimal temperature range for the organism.
What is the "goal" of thermoregulation?
Insects have little volume to generate heat, and high surface area from which to lose heat.
Why is thermoregulation important for insects?
Behavioral Thermoregulation
Behaviors that raise or lower the body's heat.
Ex: Basking, using wings to reflect light onto body.
They contract their flight muscles rapidly to generate heat in the thorax.
How do moths increase internal body temperature?
- Thorax hairs (insulate)
- Countercurrent Heat Exchange
- Heartbeat Suppression (bumblebees)
How are insects able to warm up their thorax without losing heat to the abdomen?
Counter Current Heat Exchange
warm and cold blood flow in opposite directions in two adjacent blood vessels
A narrow constriction (petiole) between the thorax forces blood flowing into the thorax and blood flowing into the abdomen to pass very close by. When this happens, the cool blood is warmed on the way into the thorax and the warm blood is cooled on the wa
How is countercurrent heat exchange employed in moths and hymenoptera?
Bees extrude nectar on their tongue during flight.
Bumblebees can stagger the blood flow through the petiole, thereby pushing warm blood into the abdomen (where it can dissipate) and cool blood is pumped into the thorax to cool the flight muscles.
What are some methods for insects to cool down?
The queen bee collects nectar during the day and stores it in a honeypot, which she sticks her tongue in all night while she moves her flight muscles and dumps heat into her abdomen. The ventral side of her abdomen is specialized for heat transfer, and sh
How do overwintering queens warm up their brood?
Humans thermoregulate to remain at a constant temperature, where insects can lower their body temperature to air temperature and selectively heat certain parts of the body.
How do human and insect thermoregulation differ?
4.6 BYA
How long ago was the solar system formed?
3.5 BYA
When did the first prokaryotes arise?
0.6 BYA
When did the first animal fossils arise?
200-300 Thousand Years Ago
When were the first human fossils found?
Collembola, Devonian Period
What were the first terrestrial arthropods/when did they arise?
Archaeognatha (from mid-Devonian)
What is the oldest insect fossil?
No. It is believed that there were numerous invasions of lands by many arthropods (and water bears, and velvet worms).
Is it generally assumed that one group colonized land and all terrestrial life stemmed from this?
Complex, similar wing venation and modifications to the thorax.
What are two evidences for a single evolutionary evolution of wings?
Phasmatodea
In what group were wings lost, subsequently regained, and sometimes has been lost again?
Paranotal Hypothesis
Wings from Legs
Wings from Gills
What are the three hypotheses on the origin of insect flight?
Paranotal Hypothesis
Suggests that the insect's wings developed from paranotal lobes on the body that where originally to slow the fall of insects that eventually lead to gliding, then flight.
Assumes de novo evolution of lobes, muscles, nerves, and articulation.
What are the problems with the paranotal hypothesis?
Some modern silverfish have thoracic lobes that can control descent when falling.
Broad thoracic lobes on nymph of extinct palaeodictyoptera.
Winglets found on thorax of fossil palaeodictyoptera, ephemeroptera, and protoroptera indicate a possible third w
What are the evidences for the paranotal hypothesis?
Order Paleodictyoptera
Extinct order of insects that once spanned 50% of existing insect species at the time. Resemble dragonflies. Terrestrial nymphs and adults, herbivores with sucking mouthparts.
Wings from Legs Hypothesis
Wings may have evolved from exties/endites.
Exite/Endite
Small appendages present point out from the insects body or inward toward the body.
Found in archaeognatha.
Legs are ventral, wings are dorsal.
What are some problems associated with the wings from legs hypothesis?
Wings from Gills Hypothesis
Suggests that gill-bearing nymphs had errors when molting into adults and were left with gill-like structures on thorax that could have become wing buds.
What good does it do to have wing buds (selection-wise) (surface skimming)?
If wings evolved with aquatic nymphs, all those descendants would likely be aquatic, but the majority of winged insects are terrestrial. Moving into the water as an immature appea
What are problems associated with the wings from gills hypothesis?
Order Protodonata
Griffinflies
Extinct
This insect was massive due to the increased oxygen concentration in the air during the late Carboniferous-Permian
Massive Volcanic Activity or Asteroid Impact
What are the two main theories behind the massive Permian extinction?
Amber
Resinous secretion from plants that hardens into a clear preservative that doesn't break down over time.
Most deposits of this material have washed onshore from the Baltic Sea.
Leaf cutter ants take leaves, clean them, tear them apart, then feed them to a fungus that provides nutritious fruiting bodies for the ants.
Ambrosia beetles tend to fungus for food resources.
Ants tend aphids/mealybugs to get access to honeydew.
What are some examples of insect agriculture?
Aggregation or Attraction
What strategies can male and females insects use to find one another?
Aggregation
Adult insects group over landmarks, emergence sites, feeding/oviposition sites, or simply clump into an aerial swarm.
Butterfly hilltopping, mayfly water emergence, midge swarms.
What are some examples of insect mating aggregations?
Attraction
A process wherein one sex produces species specific signals to attract the other sex.
Cicada males screaming, orthopteran chirping, and moth pheromone blends.
What are some examples of insect mate attraction?
When calling is risky (or energetically expensive), males will do it. When calling is safe and finding the partner is the risky part (and calling is less energetically expensive), females do it.
What is Dussourd's hypothesis for why some species males attract females and some species females attract males?
Species identity, sex, quality (vigor), and ability to contribute resources.
What are insects "saying" when they do courtship rituals.
Males are limited by the number of offspring they can create.
What limits male reproductive success (think about how much sperm they produce!)?
Female reproductive success is limited by resource availability.
What limits female reproductive success?
Males are trying to get as many mates as possible, where females are trying to get the best mate. The limiting resource for males is females, so they females get to be choosy.
Why are females able to be picky?
Spotted Cucumber Beetle
Females of this species select males based on the rate and consistency with which males stroke her with his antennae. She can selectively close off her bursa, so only males who meet her requirements are allowed to mate.
Combat, Female Mimicry, Sperm Displacement, and Parental Care
What are some male strategies to maximize reproductive success?
Male Combat, Stalk-eyed flies
A process where male insects fight over access to females. (Give an example)
Female Mimicry, Rove Beetles (small males pretend to be females to get past large males who guard females)
A strategy where male insects pretend to be a female either to trick another male to avoid fighting or trick a female to get access.
Sperm Displacement
A strategy where male copulatory organs can remove rivals' sperm.
Male Parental Care
Giant Water Bug wings are glued together with the eggs until they hatch on his back. What reproductive success strategy is the male employing?
Mate Selection, Maternal Care
What are some female strategies to maximize reproductive success?
Mate Selection
Females will select males who offer her a nuptial gift, increasing her reproductive success by offering her nutrients and other resources to care for her young.
Maternal Care
A success strategy whereby females look after her eggs/young.
Parthenogenesis
Asexual reproduction in which females produce offspring from unfertilized eggs, offspring are only female.
Reproduction is rapid, and by creating only females, every member of the population can increase the population.
What are the perks of parthenogenesis?
Genetic variety provided by sexual reproduction with males allows populations to respond to future changes in the environment by introducing genetic variability.
Why isn't parthenogenesis the only methods aphids use to reproduce?
Pupa Guarding
Male insects wait near female pupa and mate with them while they are still soft-bodied and can't do anything about it.
Herbivory, Insect-eating plants, pollenation, sheltering/protection
What are some types of insect plant interactions?
Phytophagus
Feeding on plants.
Leaf chewing, plant-sucking, leaf-mining, boring, and galling.
What are some modes of feeding in insects?
Top-down forces like predators, parasites, parasitoids, and pathogens.
Bottom-up forces (plant defenses).
What prevents insects from destroying all plant matter?
Trichomes, Toxins, Sap (Resins), Bribing Predatory Ants, Attracting Insects Predators with Volatiles, and Increasing Defensive Compound Production when Fed On.
What are some defenses exhibited by plants?
Trichomes
Tiny, spikelike projections on some leaves for protection from insects.
Can be glandular or non-glandular.
Strychnine
Alkaloid neurotoxin created by a plant that causes vomiting, convulsions, and possibly death in humans.
((Strychnos nux-vomica))
Canavanine
A non-protein amino acid that mimics arginine.
When introduced into an organism's body, translation mechanisms confuse canavanine for arginine, making protein products fold incorrectly, which is often deadly.
The plant emits white latex when injured.
What is milkweed named for?
The liquids are held in canals under high pressure, so when the plant is injured the resin/latex is released.
The liquids may be toxic or it may simply get the insect stuck.
How do resin/latex canals protect plants from herbivory?
Acacia trees produce huge thorns that give ants a place to live, provide food for ant larvae on the tip of their leaves, and make sugar water for the adult ants in return for the ants protection against other plants and herbivores.
What is the relationship between acacia trees and predatory ants?
When damaged, some plants release volatile compounds that signals insect predators and parasites to come attack the insect. These compounds may also deter insects from laying eggs on the plant.
How do plants use volatile compounds to defend against herbivores?
Selective feeding, galling, enzymes to nullify toxins, behavioral circumvention, and salivary enzymes.
How do insects manage to feed on leaves despite all the plant defenses?
Selective Feeding
Insects feed on a particular part of the plant or on a specific species of plant. Insects may even move around on a single plant to find areas with minimal defenses.
Galling
An insect injects a plant with chemicals that cause the plant to create a structure, a safe area for the insect to live with little intervention from the plant's defenses.
Behavioral Circumvention
The act of cutting plant canals that would excrete latex before feeding on the leaf downstream of the flow, thereby avoiding the latex.
Enzymes in the caterpillar's saliva prevent the plant from producing an inductive response to feeding, so the caterpillar slobbers all over the feeding site while eating to avoid nicotine poisoning.
How do notodontid caterpillars avoid nicotine poisoning when eating from tobacco plants?
Pairwise Coevolution
Reciprocal evolutionary change in interacting species. This has occurred between Heliconius (butterfly) and passiflora (passionflowers).
Yellow spots on leave to mimic eggs (prevents actual oviposition), produce young leaves (caterpillar target) irregularly, highly variable leaf shape (deter recognition by butterfly), extrafloral nectaries attract ants to kill caterpillar, and finally thei
What defenses do passiflora flowers have against Heliconius insects?
Saliva prevents cyanide release during feeding, some males may sequester the cyanide to use as a nuptial gift to females to protect eggs.
What are Heliconius butterflies response to the defenses of passiflora?
1. Plants evolve a novel defense.
2. Reduced herbivory.
3. Adaptive radiation (plants).
4. Herbivore counterplay.
5. Adaptive radiation (insects).
...
Explain Erlich and Raven's hypothesis on coevolution of phytophagous insects and prey plants.
Pollination
The transfer of pollen from male reproductive structures to female reproductive structures in plants.
Wind (common), water (rare), animals (87.5% of all plants).
What methods do plants employ to disperse pollen?
Nectar
A bribe for insects created by plants that contain sugar, water, amino acids, lipids, antioxidants, vitamins, steroids, and mineral (maybe alkaloids and other secondary compounds that are used to exclude certain organisms from eating them).
Pollen
Composed of protein, sharch, free sugars, and fat; the male fertilization structure.
Nectar and Pollen
What are two things plants bribe insects with?
Plants get outcrossed (avoid inbreeding).
Insect gets food.
What do plants gain from insect pollination? Insects?
Yucca Moth
A moth that has a close relationship to the yucca plant. It is the only insect in the world who can pollinate the yucca flower, and the ovary of the flower is the only place where the yucca moth's larvae can develop.
The mother moth takes a ball of pollen
If the yucca larvae eat too many of the fertilized ovules, the yucca plant will abort the flower, thus killing the larvae.
How does the yucca plant prevent the yucca moth from overexploiting it?
Sexual Mimicry
Where plants take advantage of the sex drive of certain insects as a way of pollination. When pollinators try to mate with the flower, it gets pollen on itself, therefore pollinating the flower. The flower benefits while the pollinator doesn't (cheating t
Nectar Robbing
Insects bypass the reproductive parts of the flower, chew a hole at the base, and steal nectar.
The flowers bloom before the females emerge, and the scent profile
How do plants trick male insects into trying to mate with them?
Insect Trapping
Some plants can capture insects either permanently or temporarily and force them to pollinate the plant.
They lay the eggs after another moth has already pollinated the plant and seeds developing so the plant can't abort the flower.
How do some yucca moths cheat the yucca plant?
Pros: Don't have to waste energy on bright petals or nice smells, no need to feed pollinators.
Cons: Wind-dependent, must make huge quantities of pollen.
What are the pros and cons of wind pollination?
Pros: Only need small amounts of pollen, pollen is transferred precisely.
Cons: Pollinators needed, need to bribe/trick pollinators. Need to have pretty petals and smells to attract pollinators.
What are the pros and cons of insect pollination?
Reduced search time, more efficient extraction of pollen/nectar.
What are the benefits of generalist species like bees specializing in certain flower species per pollen collection trip?
Colony Collapse Disorder
A mysterious disease that causes adult bees to disappear from their hives without a trace. It may be caused by: parasites, fungus, viruses, bacteria, pesticides, poor nutrition, or stress.
Varroa Mite
External parasite of the honey bee, feed on blood, damage tissue and shorten life (transmit viruses).
Tracheal Mite
Internal parasite of the respiratory system of adult honey bees, can be resisted with grooming.
Zombie Flies, Small Hive Beetle, and Nosema Fungal Parasites
What are three notable non-mite bee parasites/pathogens?
Asian Giant Hornet
Small colonies of this insect attack small arthropods, but once the colony grows to a certain size, eusocial insects are targeted. One scout finds a eusocial colony and releases a pheromone that signals its own colony to come attack.
These insects are nat
Neonicotinoids, Pyrethroids
What pesticides are particularly deadly to bees?