Entomology - Exam 3
introduction
- 360,000 phytophagous (herbivorous) insects
* ^^26% of species^^
degree of specialization
* monophagy: eat few things, very picky
* oligophagous: narrow range and food
* polyphagous: open feeders (still picky)
- insects originated 400mya
* fed on nonvascular plants
* first fed on pollen and pollen cones
* then reproductive parts of plant
* eventually would eat leaves and other parts
History of Interactions
- ^^angiosperms appear in Cretaceous, promoted radiation in plants/insects^^
* insects initially herbivorous to be antagonistic with plants
* ^^evolved to be mutualistic to help plants reproduce^^
* ^^bees, butterflies, beetles, flies^^ - insects promoted speciation in plants through pollinator-mediated reproductive isolation
- ^^phytophagy feeding strategies^^
* leaf chewing
* sap sucking
* eat cell sap and phloem
* seed predation
* gall induction
* mining (tunnels) and boring (holes)
^^theory of herbivory^^
- assumptions
* ==damage by insects is a major selective force==
* ==nutritional quality has a strong influence on abundance and damage caused== - varied herbivore rates
* nutritional quality
* some insects prefer stressed plants
* boring and sucking insects
* some prefer fast growing plants
* gall inducers and chewers
co-evolution
- reciprocal interactions (adaptions) between two different clades that are selective forces on each other
* they keep responding back and forth to each other
* Ehrlich & Raven - 1964
primary metabolites
- compounds that are needed for cells to be alive
- examples
* enzymes
* hormones
* carbs
* lipids
* proteins
* phosphorous
plant defense
- coevolutionary process from species interactions
- produce compounds not needed to survive
* secondary metabolites / allelochemicals
* chemicals involved in interspecific communication
* examples
* @@glucosinolates: mustard oils@@ - Brassicaceae
* irritates animal skin
* most potent antibiotic from plants
* Phyllotreta cruciferae - Flea Beetle
* @@alkaloids: nitrogenous-based comps@@ - Solanaceae
* nicotine - Nicotina
* solanine - Solanum tuberosum
* Manduca sexta - Tomato hornworm moth is specialist
* @@cardiac glycosides@@: Asclepidaceae & Apocynaceae
* milky latex of plants
* Euchaetias & Cycnia are specialist genera - some secondary compounds are highly toxic to insects
* nicotine
* sinigrin - mustard glucoside - @@other secondary metabolites influence fecundity and population growth of herbivore populations@@
* tannins & phenolics
* precipitate proteins
* turns to a solid and makes protein unusable
* Operophtera brumata - Winter moth larvae
* endopeptidase inhibitors
* reduce digestion of proteins
* cant breakdown
* juvabione
* juvenile hormone mimic, keeps insect as nymph
* reduces population size
* Pyrrhocoris apterus
* ecdysone-like compounds
* stimulates shedding of exoskeleton (molting)
* creates small adults with reduced fecundity
* Podocarpus & Polypodium - allocation of secondary compounds
* tend to be concentrated in structures at risk of being eaten (reproductive structures)
* examples
* THC - seeds of Cannibis
* pyrethrum - flowerheads from chrysanthemums
* requires trade off in biomass allocation from other structures
* Acyanogenic & cyanogenic morphs of Lotus corniculatus
* response to being eaten by slugs
* cyanogenic morph makes less seeds and has slower growth - @@responses of insects to plant defense@@
* @@evolved enzymes to metabolize toxic compounds@@
* microsomal mixed-function oxidases in some Lepidoptera
* break down pyrethrum w/ oxidases
* counterattack by chrysanthemums
* produces sesamin which inhibits mixed function oxidases
* @@ability to metabolically recognize toxins@@
* Dioclea megacarpa makes nonprotein amino acid
* Canavanine
* highly toxic to most herbivores bc its so similar to arginine
* Bruchid beetle - Caryedes brasiliensis
* can distinguish between two amino acids w. tRNA
* has lack of parasitoids as consequence
* @@temporal avoidance of toxins@@
* winter moth feeds on oaks by hatching early in spring
* avoids concentrated tannins
* im
* @@sequestering of toxin@@
* specialists of plants unaffected by toxin, hold it in fatty tissue
* monarchs feed on milkweed, parasitized by tachinid fly
- Insect Response
* Aposematic coloration
* bright coloration advertises prey on purpose
* insect is toxic, trains predator to leave it alone
* palatability spectrum
* Lygaeidae - Milkweed Bugs - @@Plant Counter Attack@@
* alternate defense methods
* produce gum that pushes off egg
* exploding fruits to disperse seed
* indehiscent fruits for ovipositors that lay on exposed seeds
* seed surface swells to detach eggs
* seeds too thin for larvae to mature in
* seeds to small for larvae to mature in - evolution of plant defense compounds
* plant apparency hypothesis
* Feeny - 1971
* described extreme endpoints
* @@apparent plants@@
* late successional habitat plants
* %%have quantitative defenses that are metabolically expensive%%
* %%have dosage effect%%
* regulate population compounds
* @@unapparent plants@@
* early successional plants
* wont be around long, short lived
* %%have qualitative defenses that are metabolically inexpensive%%
* %%have large toxic effect%%
* %%rapid irritant or lethal effect%%
* secondary compounds are highly toxic and function to kill
* R-selected plants select for R-type insects
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pollination
why is it important
- part of sexual reproduction
function of flowers
- to attract pollinators
* color petals
* scent
* rewards
* nectar, pollen, & oviposition sites - floral organs
* sepals: outer whorl (collectively calyx)
* petals: second whorl (collectively corolla)
* stamens: third whorl
* ovary: inner whorl (collectively carpel)
Coevolution
- coevolution: reciprocal adaptations between interacting species that increases their codependence
* plants and insects evolve around each other to keep getting pollinated - Darwin’s Classic Example
* orchids adapt to benefit pollinators with a long proboscis
* Angraecum sesquipedale
* nectar spur up to 30cm long, Darwin predicted something must match
Pollination Syndromes
- %%Beetles: Cantharophily%%
* flowers open at night
* white color, strong fruit smell
* petals are food reward, no nectar
* flowers form a chamber to house beetles
* Magnolias - %%Flies: Myophily%%
* flowers open during day and near ground
* looking for place to lay eggs
* rotting, decaying flesh smell
* green to maroon color
* Symplocarpus foetida (Skunk Cabbage) - %%Butterflies: Psychophily%%
* flowers open during day
* bright colors
* corolla throat is narrow
* match proboscis
* corolla spur to restrict visitors
* Phlox drummondii (Woodland Phlox) - %%Moths: Phalaenophily%%
* flowers open in twilight hours
* Crepuscular
* white in color
* lots of nectar
* moths hover so they need more carbohydrates
* long corolla tube matches proboscis
* exterted anthers and stigmas
* pollen is sticky
* Datura (Jimson weed)
* Oenothera missouriensis (Missouri evening primrose) - %%Bees: Melittophily%%
* Enclose anthers and stigmas to only let in strong bees
* must push open to get to reproductive organs and nectar
* bright colored flowers w/ nectar guides
* spots or lines
* flowers reflect UV light and look like target
* not much nectar, sweet smell
Decline in Pollinators
- Honeybees
* 1/3 of every bite of food is dependent on pollinators
* Colony Collapse Disorder
* most likely from widespread use of pesticides and fungicides
* fungicides mainly kill larvae
* spread of viral pathogens
* parasitic mites in hives
* bees get confused while out in the field and never return to the hive
Bee Adaptations to Plants
* yellow green
* blue
* UV as a distinct color
* Iris pseudocornus- Electrostatic charge
*
*
* opposite charges makes the pollen jump from flower to bee
* bees are able to sense charge difference
*
* lets bumblebees forage when its too cool for honeybees
* makes bumblebees important pollinators in colder climates
* allows more pollen to stick to bees
* NOT IN WASPS just bees
* hairs on tarsus used to comb pollen off body onto back legs
* strong spirally ridged hairs
* scoop shaped hairs on tarsal segments to pick up oils
* rasp their legs across flowers]
* Centris bees (not in Missouri)
* concavity on tibia that carries pollen
* used for feeding to larvae (mixed with spit and nectar)
* only in Apis and Bombus
* similar to pollen baskets
* dense mass of branched hairs pollen is pressed into on body
* articulation between tibia and tarsus to compress pollen before moving to basket
* row of stiff hairs off tibia articulation of worker bees, similar to pollen packer
* row of hairs use to get pollen off body
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insect sociality
- ==solitary insects==
* do not live in pairs or more
* usually have one offspring to the one mother - ==subsociality in insects==
* ==aggregations==
* nonreproductive, gregarious interactions
* cooperative foraging: feed together with silk or pheromones
* sleep aggregations: Ammophila wasps
* hibernation:
* migratory aggregations: monarchs
* share nest entrance: solitary bees
* aposematic phytophagus insects aggregate as a color warning
* milkweed bugs
* ==parental care==
* rare in insects
* ==some tend young (egg and early instars)==
* Blattodea
* Orthoptera
* Hemiptera
* Dermoptera
* care w/o nest
* some Passalid beetles have all life stages living together
* adults chew wood for larvae to feed
* treehoppers delegate parental care to ant by producing honeydew for ants to eat
* care w/ nest
* dung and carrion (Nicrophorus) beetles
* aculeate hymenoptera - muddobbers
* linear or radial multicelled
* nests made from soil, mud, sand
* tunnels seal with leaves, resin, mud, oils
* Spider wasp - Pompilidae
* nest with larvae at various ages that feed on spider
* communal nesting
* daughters nest in natal nest - ==eusocial insects==
* ==3 defining features==
* overlapping generations in same colony
* reproductive division of labor with caste system
* cooperative brood care
* common features
* make nest or containment structure
* exhibit trophallaxis
* exchange of substances
* basis for maintaining social roles in colonies
* ==only found in Blattodea (Termitoidea) and Hymenoptera==
* Termitoidea
* evolved sociality once (2000 species)
* ==ancestral groups need symbionts to digest cellulose==
* makes an enzyme that can break down cellulose
* ==after each molt they need to be re-infected with symbionts through anal-feeding (anal trophallaxis)==
* derived groups have evolved to not need symbionts
* differ from Hymentopera:
* undergo complete metamophosis
* nymphs are workers
* colony is bisexual
* all individuals are diploid
* share ancestor with cockroaches
* most are sterile and never see the outside environmet
* ==ancestral termites:==
* reproductive adults
* some become alates (winged) and leave and make new colonies
* worker nymphs
* males: majors, large
* females: minors-small, majors-soldiers
* ==derived termites: nasutitermes==
* females: workers
* males: soldiers that lack mandibles (nasutes)
* both can squirt toxic liquid onto other things to blind them
* reproduction
* new colonies
* formed from reproductive king and queen
* winged reproductives leave after environmental cue
* after dispersal flight they lose wings, make a nest, form copularium
* young fed by trophallaxis
* ==caste determination for reproductives==
* reproductives
* juveniles hormone
* hi juvenile hormone: given to colony by fecal trophallaxis, keeps them from becoming reproductives
* nests
* random shapes in soil, elaborate tunnels to regulate temp and humidity
* %%Hymenoptera%%
* evolved sociality 11 times (11000 species)
* %%characteristics of hymenopteran societies%%:
* colonies mainly females, males only for mating
* castes are only reproductives and workers
* caste determined by queen dominance, nutrition, or temp
* colonies from single female, multiple females, or swarming
* %%social wasps%%
* ancestral wasps (paper wasps: Polistes)
* small colony
* several queens (polygynous)
* %%dominant queen by aggression from high juvenile hormone%%
* workers are sterile
* %%nest is open, hangs by pedicel, and its smeared with ant resistant goop%%
* derived (yellow jackets: Vespula)
* large colony
* %%one large queen (monogynous)%%
* nest is enclosed w/ multiple layers, entrance guarded by workers
* %%ants%%
* ancestral species (9000 spp)
* small colonies
* little morphological difference in queen and workers
* eggs laid in open nests
* larvae produce naked pupae
* derived species
* large colonies, up to 20mil
* small workers, large workers have long mandibles
* larvae fed saliva from queen
* larvae from silk cacoon
* queens can live up to 20 years, workers 5-6 years
* %%widest range of diet in all social insects%%
* carnivores, scavengers, honeydew collectors
* Atta grow fungus in gardens
* adults feed larvae w/ fluids from integument
* nests are not elaborate
* gravel mounds in harvester ants
* leafcutter ants in hollow acacia trees
* %%social bees%%
* evolved 8 independent times (1000 species)
* ancestral species
* little morph difference between queens and workers
* casts kept by queen dominance
* herbivores - eat pollen and nectar
* brood cells used to store food
* primitive eusocial tropical bees
* stingless bees - Trigona & Melipona
* 200 species
* colonies formed by swarming
* domesticated for honey production
* %%primitively eusocial bees%%
* bumblebees (Bombus) 200 species, temperate and tropical spp
* overwintering queens make new colony in rodent burrows
* larvae spin cocoon
* workers- adults are all female and small, forage and tend larvae
* males (drones) only produced in fall
* %%advanced eusocial bees%%
* honeybees (Apis)
* 6-9 species
* nest openly in trees/caves
* nest guarded, lined with propolis
* %%caste system kept by queen mandibular pheromone%%
* new colonies
* formed by swarming
* new queens are fed royal jelly made by nurse bees
* %%queens%%
* larvae fed royal jelly
* high amounts of hexose sugars
* high juvenile hormone
* high amounts of mandibular secretion from workers
* workers
* larvae fed worker jelly
* low in hexose sugar and juvenile hormone
* beebread: pollen and honey
* %%honeybee biology%%
* communication
* use polarized light to orient themselves off the sun
* %%communicate direction and distance using circle or figure eight dances%%
* foraging
* pollen collected in pollen baskets (corbiculae) and honey crop
* nest regulation
* keep nest at 30 degrees
* workers will fan nest w wings if it’s too hot
* evolution of socialization in Hymenoptera
* WD Hamilton (1964) - kin selection on the haplodiploidy form of reproduction
* kin selection is altruistic traits/behaviors that favors another individual
* daughters held raise sisters rather than their offspring
* socialization
* ==1/3 biomass in Amazon is termites and ants==
* allows division of labor and more efficiency
* ==inquilines - opportunistic organisms associated w colonies==
* beetles, mites, and roaches might help defend
* some are scavengers, predators, and parasites
* ==evolutionary trends==
* increased division of labor by castes, behavior, and morph
* increased population size
* daily provisioning
* production of nest, open to enclosed
* complex trophallaxis interactions w/ proctodeal and salivary substances
* colonies have identity odor, restricts activity to own colony
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^^insect defense^^
- insectivores: organisms that eat insects, usually specialized to eat them
- insects have evolved wide range of defense mechs to avoid predation
- defense strategies
* ^^hiding - crypsis^^
* ^^camouflage^^
* resembles background of inedible object
* uniform/patterned coloration: match background
* Pentatomidae (shield bugs)
* bizarre shape: disrupt body outline
* Membracidae
* countershading: light above, dark below on body
* cicadas
* ^^masquerade or mimesis^^
* looks like object in nature, not another organism
* often look like
* twigs, leaves, bird poop, flowers, etc
* ^^secondary lines of defense^^
* fake dead: thanatosis or reflex mobility
* weevils
* startle displays
* flash of color or spots to startle predator
* bright flashes of color, eye spots
* moths, grasshoppers
* ^^mechanical^^
* horns & spines
* dung beetles
* flattened dorsal/ventrally (biting lice) or laterally (fleas)
* retreats or shelters (caddisflies)
* artificial shields (Chyrsomelid & reduvidae)
* waxes & powders in predators mouth
* detaching body structures
* ^^chemical^^
* secrete allomones
* positive effect on producer, negative on receiver
* typically aposematically colored as a warning
* brightly colored
* chemical defense compounds derived from plants
* ^^classifications^^
* @@class 1:@@
* irritate, poison, hurt
* more specific to vertebrates
* cyanides and alkaloids
* aposematic
* @@class 2:@@
* anti-feedant, odor or taste inhibitors
* volatile compounds
* aromatic ketones, aldehydes, acids, and terpenes
* ^^defense organs^^
* evaginating storage gland to compound
* urticating (stinging) hairs
* venom stingers
* osmeteria (pouch w/ toxins)
* acoustical
* luna moths use curling tails to sense
* moths using echoing and frequencies
* ^^mimicry^^
* resemble other ANIMAL that’s recognized by natural enemies
* ^^3 components^^
* model
* mimic
* selective agent
* ^^batesian mimicry^^
* henry bates - 1933
* mimics aposematic org but is palatable to predator
* must be less abundant than the model
* frequency dependent selection
* examples
* bee flies - mimcs bee
* Syrphid fly - mimics bee
* ^^mullerian mimicry^^
* fritz muller
* mimic aposematic model but is also unpalatable
* both taste bad, both have advantage
* examples
* paperwasps - mimcs bees
* monarch and viceroy and queen
* monarch is model
* viceroy is mullerian, queen is batesian
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