Entomology Lecture

Medical & Veterinary Entomology

The study of arthropods (insects, mites, ticks) that negatively impact human and/or animal health or well-being

How do arthropods negatively impact human and animal health?

1. Nuisance

2. Psychosis (phobias/fears; entomophobia/arachnophobia or delusions of parasitosis)

3. Food contamination (bug in soup as your about to eat it not the same as crop contamination; can also be bug left pathogen in your food

4. Envenomation (black widow, bees)

5. Allergic Reactions

6. Tissue Invasion (human bot fly larva in skin)

7. Biting (consumption of blood, tissues, feathers)

8. Pathogen Transmission (vector-borne disease; bug bring disease from affected person to an unaffected person)

2 diff allergic reactions

1. Anaphylaxis- severe immediate reaction like a bee sting

2. Delayed allergic reaction like dust mite allergy

Miasma Theory of Disease

Diseases are caused by bad smelling odors “bad air” coming from rotting organic matter

scientists by 1800 begun question theory and instead suggested microbes or germs were cause

Louis Pasteur and “Germ Theory”

Human illness is causd by microscopic “germs” that invade the human body

Elephantiasis

caused by filarial nematodes living in the lymphatic ducts of people

Patrick Manson

1877- associates mosquitoes and filarial nematodes

first to demonstrate a connection between mosquitoes and disease

conducted research using his filaria-infected gardener

Manson reported 3 important discoveries

1. Microfilaria (immature worms) in human hosts exhibit nocturnal periodicity (only present in host blood at night)

2. Mosquitoes acquire microfilaria when biting an infected human host at night

3. Microfilaria developed in the mosquito body through several life stages

Father of medical entomology

Patrick Manson

but didn’t get transmission cycle right, believed that mosquitoes release the nematodes into water when laying eggs and that ppl acquired nematodes by drinking water

Charles Laveran

1880- discovered pigmented granules in blood of patients suffering from Marsh Fever

determines that granules are protozoan parasite

but couldn’t find the parasite in marsh water, soil or air

Louis-Daniel Beauperthuy

1838- french physician suggets malaria was associated w mosquitoes

Josiah Nott

1848- american physician suggets mosquitoes were responsible for yellow fever disease

Carlos Finlay

1881 cuban physician proposes that “striped-legged mosquitoes” cause yellow fever

Albert King

1882-3- american physician assembled initial evidence for a mosquito-malaria theory

Cattle Fever

catle dying in large numbers from wasting disease made them anemic and really thin

cause found by theobald smith

Theobald Smith

1890- american pathologist proved that blood parasites cause a wasting disease of cattle and that these parasites are transmitted by ticks

Vertical Transmission

Ticks pass parasite directly to offspring

Complete Transmission Cycle

Ticks acquire parasite from infected cow pass parasite to offspring which then pass parasite to new cow during feeding

Infected cow → tick → tick offspring → new cow

Ronald Ross (1897-1898)

British military physician demonstrates full malaria transmission cycle; proves mosquitoe-malaria theory

Human malaria and “dappled wing" mosquitoes”

Ronald Ross found dappled wing mosquitoes can acquire malaria parasite from malaria-infected humans

failed to show full transmission cycle in humans

Bird malaria and “grey mosquitoes”

Ronald Ross found that grey mosquitoes can acquire and transmit bird malaria; showed full malaria transmission cycle in birds

Paul Louis Simond

1898- discovered fleas and plague

Walter Reed

1900- discovered mosquitoes and yellow fever

David Bruce

1903- discovered teste flies and sleeping sickness

Howard Ricketts

1906- discovered ticks and rocky mountain spotted fever

Frederick Percival Mackie

1907- discovered lice and epidemic relapsing fever

Carlos Chagas

1908- discovered kissing bugs and Chagas’ disease

Charles Nicolle

1909- discovered lice and epidemic typhus

Wilhelm Burgdorfer

1982- discovered ticks and lyme disease

Classification levels

Domain, Kingdom, Phylym, Class, Order, Family, Genus, Species

Rank

any level in the hierarchy

Taxon/taxa

any grouping created by classifaction

Why do we have binomial classification?

structure for naming & grouping organism

Keys

Used to identify unknown specimens based on criteria or characteristic

Creates a repeatable and reliable diagnosis for a taxon

Dichotomous keys requires

2 possible brances

Each split is a

couplet

Key couplets don’t _

imply relatedness, only sharing specific traits

Hemimetabolous

incomplete metamorphosis; immatures called nymphs and resemble adults

Holometabolous

complete metamorphosis; immatures called larvae and are distinctive from adults

Body segments of insects

Head, thorax, abdomen

Body segments of spiders

cephalothorax, abdomen

forward, middle, behind

pro, meso, meta

front, rear, upper, underside of insect

anterior, posterior, dorsal, ventral

Spiders

Araneae

Scropions

Scorpionida

Chelicerae

used to seize prey or defensively bite

Pedipalps

used for sensing, perceiving stimuli, and detecting/manipulating prey

Chilipoda; leg pairs per segment

Centipedes; 1

Diplopoda; leg pairs per segment

Millipedes; 2

Forcipules

poison claws

Toxins

a poison produced by an organism

Venoms

Toxin that’s injected by a bite/sting; a complex chemical blend that often cause pain

ex: bee, wasp, hornet, ant venom

Relative pain of sting venom

ant > wasps > bees

Social Bees

apidae; honey bees, bumblebees

identification: yellow/bellow aposematic (warning) coloration, pollen basket/cavity on side of legs, hairy body

Aposematic coloration

vibrant coloring to warn predators of danger/saying they’re toxic

Honeybees

Apis mellifera

fuzzy, domesticated- ppl collect their honey/wax

nests: comb

Bumblees

Bombus spp

fuzzy, black/yellow, larger than a honeybee, hundreds, not thousands, not domesticated

nests- pot-look not a comb

Bee sting

modified ovipositor w poison gland

ovi-egg

Sting autotomy

amputation of sting

each honeybee can only sting one time and dies after it stings

Alarm pheromone

chemical signal of danger, released by stining honey bee → more bees on the way if you’re near nest

Anaphylaxis

life threatening allergic reaction w rapid onset (within 30 min)

treatment: epinephrine (epi pen), benadryl (chewable) until you seek medical treatment

ppl who experience anaphylaxis shock attack after 1 sting are 60-70% likely to experience same reaction in future

Wasps

Family Vespidae

Not hairy, long legs, aposematic coloration like bees, thin waist, lacking nodes/bumps

predators of other small athropods or generalist scavengers

Do wasps have sting autonomy?

No sting autonomy, can sting you over and over again

Social Wasps

Yellowjacket wasps- vespula spp

Paper wasps- Polistes spp

Hornets- vespa spp

Nest characteristics of social wasps

Yellowjackets are in the ground

Paper wasps are in the air

Solitary Wasps

don’t live in colonies, rarely sting ppl

Thread-waisted Wasps & Mud Daubers- Sphecidae: thin waist, not likely to sting, eat spiders by paralyzing them

Velvet Ants- Mutillidae: very brightly colored- red/orange & black, really hairy

Spider Wasps- Pompilidae- blue wasps w/ orange wings, painful stings → paralyze large spiders

Ants

Family: Formicidae

Wingless (except reproductive ants), thin waist w/ 1-2 nodes/bumps

Nest characteristic of ants

Mount of dirts/ subterrian (in ground)

Monogynous Vs Polygynous

Monogynous species- have only one egg-producing queen

Polygnous species will tolerate multiple queens in same ant nest → results in very large colonies w many queens, produce many offspring

Fire ants

Solenopsis spp.

relly large colony, responsible for a lot of human stinging, live in grass, multiple stings/bites at once can kill young animals

Red imported fire ant

Solenopsis invicta

from south america, bites first then stings

Argentine ant

Linepithema humile

during summer come in house looking for water

house pests

polygynous

Harvester ants

Pogonomyrmex spp

large body, harvest seeds

in souther ca

black & red- painful sting

one ant group that’s homogynous

Class Arachnida

Scorpions & Spiders

Scorpions

not insects but are athropods, have exoskeleton

are predators of other arthropods or small animals, deliver venom through sting on barb at the tip of their tail

20 species lethal to humans

smaller they are stronger the venom

fluorescent under uv light

Bark scorpions

Centruroides spp.

found in desert in southwest

arizona

venom is neurotoxic- affects nerves causes vomitting/nausea

Antivenom

medication made from antibodies

venom is neurotoxic

Spiders

predators of other athropods, deliver venom through bite

Widow Spiders

Latrodectus spp

Males are smaller than female- enlarged pedipalps for sperm transfer

Western black widow vs Brown widow

Black: latrodectus hesperus, native to riv, egg case is round and smooth

Brown: latrodectus geometricus, recent invader in socal, egg case is spiky

Widow venom is

neurotoxic, affects nerves causing vomitting and nausea

Brown recluse

Loxosceles reclusa

3 pairs of eyes

violin shape on cephlothroax

in mid-southwest not CA

hid out in protected places (abandoned places)

Recluse venom is

cytotoxic- results in necrotic wound near bite-p[en wounds, leaves ulcers near bites

Hymenoptera Diagnostic Features

Bees, wasps, ants

Holometabolous development

2 pairs of membranous wings

chewing nouthparts

thin waists, and ants have thin waists w nodes

Blattodea Diagnostic Features

cockroaches

Hemimetabolous development

pronouced Pronotum, long antennae, overlapping wings, chewing mouthparts, 10 segmented abdomen

Blister beetles in family

Meloidae

Paederus beetles in family

Staphylindae

Skin/Hide bettles in family

Dermestidae

Beaver parasite beetles species name

Platypsullus Castonis

Coleoptera Diagnostic Features

Beetles

holometabolous development

2-5 segments per tarsi

Elytra are hardened forewings; membranous hindwing

chewing mouthparts

Lepidoptera Diagnostic Features

butterflies

holometabolous development

2 pairs of membranous wings

wings/bodys have scales

siphoning mouthparts, coiled proboscis

Cockroaches

order blattodea

most aren’t associated w human activity, 1% are pests

have semi-hardened and often darkened forewing that’s not used in flight but instead to protect hind wings

Cockroach life cycle

Hemimetabolous/incomplete metamorphosis

immatures looks like adults (nymphs) so they all live in same area

life cycle/reproduction: 2-3 months, cockroach females have multiple batches of eggs

What is an ootheca?

egg case- female cockroaches will carry them around, specific to this species, carries 10-20 eggs

Nocturnal periodicity

active at night; cockroaches active at night

Domestic species of cockroaches indicator of

poor sanitation, cockroaches are scavengers & live off anything

German cockroach

Blattella germanica

small cockroach with two vertical black stripes on pronotum (head)

domestic species; dependent on humans; found in kitches, pantries, bathrooms

highest reproductive potential (30-40 eggs per case) & develop really rapidly → outcompete other cockroaches in same space

Brown Banded Cockroach

Supella longipalpa
domestic species; dependent on humans

small cockroach, brown with light colored horizational bands on body

no racing stripes, dark bands on wings

nymphs have 2 circles/bands on thorax

instead of carrying ootheca they glue to ceilings or drawers

can survive in dryer areas

American cockroach

Periplaneta americana

Peridomestic (semi-domestic)

large (longest) cockroach, reddish brown w yellow margins on pronotum

take advantage of human dwelling/not dependent tho

associated with sewer systems

Oriental cockroach

Blatta orientalis

Peridomestic species

large (2nd largest of 4 we learned) cockroach, dark brown to black body color

non functional wings, females completely wingless

associated w gardens.outside → higher moisture areas

another name for waterbug