Pests, Parasites, and Pathogens
by George Dzyndra
Integrated Pest Management (IPM)
Involves multiple tactics starting from the least intrusive
Overuse of pesticides has a negative impact on bees
Understand the biology of life cycle of pests
Controls – affect bee life:
Cultural controls – reduce stress
Suitable environment
Disrupt diseases that affect brood
Requeening/splits effect on brood populations
Physical deterrents to exclude pests
Biological controls:
Genetic stock
Nematodes that prey on pupating hive beetle larva
Fungal and microbial agents for bee health
Drone trapping
Heat treatments
There are no practical biological controls that have appeared
Purpose of IPM is to reduce pesticides with materials which are host specific to mites and have low toxicity to bees
Sources of Stress that Affect Honey bee Health
Parasites and pathogens (primarily mites and viruses)
Other pathogens: bacteria, fungi, and covert (asymptomatic) viruses
Overuse of pesticides breeds resistance and harms beneficial microbes
Poor nutrition – high floral diversity needed (vs. monocultures)
Agricultural pesticides and pollution
Pesticidal drift
Contaminants – highest level comes from beekeepers
Misuse of miticides and antibiotics
Poor brood patterns
Malnourished or sick queen
Inbred queen
Disease or mite infestations
Parasitic Mites
Impact:
Physically weaken bees and impair their immune systems
Mites vector viruses and other pathogens
Varroa mites spend most of their lives in comb cells feeding on fluids and protein reserves of adult bees and pupae
Life cycle of varroa:
Two phases:
Phoretic stage
mated females attach themselves to adult bees who carry them throughout the hive
Reproductive stage
a mature female mite (foundress) enters the brood cell before capping
once sealed she lays eggs – always a male first, and then between one and five females
foundress opens a wound on bee pupa – infecting it with viruses
offspring hatch and mature while feeding on wounded pupa
as the bees emerge, the foundress and mature females leave seeking new hosts, the male and immature females are left for bees to clean out of the cell
varroa prefer a drone cell because it is bigger and can harbor more daughters
mites seek out nurse bees that tend late stage brood
Management and options:
Hard chemicals – work on the nervous system (pyrethoids/organophosphates)
Commercial name: Apivar (contains amitraz) – tactile/contact pesticide
Downsides:
more readily absorbed by wax and leeches into honey
impairs the immune system of bees and shortens their lifespan
reduces queen fertility
weak doses increase the chance of mites surviving and becoming resistant
Upsides:
mites do not develop resistance easily
only chemical that penetrates brood cappings
Soft chemicals
Organic acids
formic acid (Mite Away Quick Strips):
highly effective with proper dosing
temperature range 50°F-95°F for five days
must volatize properly—too cool a temperature and it will not evaporate fast enough, too hot and it will evaporate too quickly causing brood and queen mortality
only soft chemical that treats brood
oxalic acid:
occurs naturally in plants
only treats phoretic mites
should not be used with honey supers present
applied two ways:
trickle method –via syringe of 3%-5% solution (35g/liter) of 1:1 sugar syrup
vaporization—2g or ½tsp in a vapor device three times, seven days apart
beta acids (HopGuard)
contact pesticide
must be repeated twice more after two weeks
Essential oils
thymol – via thyme plant (Apiguard, Thymol, Apilife Var)
must volatize in the hive
effectiveness is temperature dependent (65°F-85°F)
must apply second dose two weeks later
should not be used with honey supers present
WARNING: natural compounds can be just as dangerous to bees and beekeepers
Apply dosages as manufacturer directs – not time to experiment on your own
Genetic mite resistance
Purpose: to create a suitable host-parasite relationship – never eradicate the mites (manage numbers)
Types:
Russian bees vigorously groom themselves
Varroa sensitive strains (VSA) like Minnesota hygienic bees remove infected pupae through uncapping and disrupting mite reproduction
Purdue Ankle Biters chew off mite legs
Redline Italians or mite maulers dismember the mites
Problems:
the genetic trait can be lost through crossing with non-resistant strains
queen supersedure
swarming
Other controls
Drone trapping
Good beekeeping practices:
sampling mite populations
need a three day period for accuracy
count average three mites per day in the spring
formula: 9 mites x 300 bees x 100% = 3% infection
tools:
alcohol wash
sugar shake
Tracheal Mites
Infest and breed in the tracheal tubes causing damage to the tracheal wall
Feed on hemolymphatic (blood) system
Young mites must disperse and find an adult bee host younger than three days
Result is short-lived bees
In the spring they host a single generation, in the summer they host multiple generations
Usually are associated with winter losses
Common symptoms:
K wing
Inability to fly/crawl
Dwindling and weak hives
Treatment:
Some lines of bees are bred for good resistance
Formic acid (Mite Away Quick Strips)
Oxalic acid does not remain in vapor form long enough to affect tracheal mites
Menthol
Pests
Small Hive Beetle (SHB)
Scavenger originating from sub-Saharan Africa
¼ inch, reddish brown color
Lay eggs in hive cracks and crevices
Feed on pollen, brood, and cannibalize their own dead
Introduce yeast when feeding on honey, giving it a foul smell
High levels of SHB will cause bees to abscond
Beetle larvae feed seven to ten days then exit the hive to pupate in the top four inches of surrounding soil
New adults locate hives by smell
Treatment:
Physical and chemical traps (use soapy water to break surface tension)
Tape cracks and seams in hive boxes
Use of parasitic nematodes
Treat soil with permethrin
Wax Moths
Seek weak/dwindling hives
Deposit eggs in crevices of hive
Hatch in a few days, burrowing through comb and consuming wax
Larvae feed for six to seven weeks and pupate by burrowing into wax and spinning a cocoon, emerging in six days
Produce two thousand eggs in their lifetime
Defense:
Queen right, strong hives
Plug crevices with tape
Freeze comb for at least forty-eight hours
Moth crystals (paradichlorobenzene) – Paramoth kills adults and larva but not their eggs
Ants
Can invade a hive
Use physical barriers: ant bait outside the hive, cinnamon inside (does not bother bees)
Skunks
Physical barriers
Raccoons
Secure hive
Bears
Electric fence
Other Pathogens
Sacbrood
Cause: common bee virus
Vector: nurse bees pass it on to the brood
Symptoms:
Larvae have small heads
Bodies curve up canoe shaped, and change in color from grey to brown
When pulled out of the cell, bodies appear as bags of liquid with one end a dark color
Larvae fail to pupate
Adults have high levels of the virus with no symptoms (except a possibly shortened lifespan)
Treatment:
Adult bees remove pupae
Requeening will clear it up
American Foulbrood (AFB)
Cause: Paenibacillus (bacteria) spores – highly contagious and resistant to extreme temperatures
Vector: airborne – spread through robbing behavior, equipment bought without knowledge of history
Symptoms:
Capped brood appear sunken and spotty with perforated cappings
Test:
Ropiness—insert a toothpick into a dead larva, stir the tissue and withdraw the toothpick. If it comes out as a ¾ inch string before snapping back, you probably have AFB
Call your apiary inspector if you suspect AFB
Treatment:
None
You must kill the spores with fire. That means burning your hive, bees and all.
European Foulbrood (EFB)
Cause: Melissococcus (bacteria) – not as serious as AFB
This pathogen exists in the honey bee in latent form
Outbreaks occur mostly in winter when colony contains older bees
Vector: nurse bees accidentally contaminate brood food with bacteria
Symptoms:
Larvae die before being capped
Most obvious sign: spotty brood pattern
Most critical when you have brood buildup—larvae appear twisted, curled, or melted down and develop rubbery scale. Does not rope out as with AFB
Does not form long-lasting, resistant spores
Treatment:
oxytetracycline antibiotic
intervention by breaking brood cycle (case queen)
requeen with new genetic stock resistant to EFB
Chalkbrood
Cause: Ascophaera apis (fungus) infects larva
Symptoms:
mimics white, grey, green, black found in cells
Larvae have a chalky look (mycelium) and can be noticed on the landing board
Treatment:
No known medication
Most common in the spring
Environmental treatment
well vented, elevated hive
nest area kept from excess moisture
use VHS strains of honey bee
Sterilize tools
Stonebrood
Cause: Aspergillus fungi (soil dwelling microbe)
Fairly rare
Symptoms:
Mummified larvae coated with yellow, green, and black spores become hardened/difficult to crush
Spores cause respiratory problems in mammals
Treatment:
Good nutrition and overall colony health
Reduce physical stress
Combs from infected colonies should be destroyed with fire
Bald Brood
Cause: wax moths
Treatment: see: wax Moths
Viral Diseases
Exist at low levels
Twenty different types with no symptoms
Black Queen Virus (BQCV):
Cause: virus associated with high level of nosema spores
Symptoms: only affects developing queens
Vector: drones and worker bees, via food glands
Treatment: antibiotics will not kill the virus but eliminates other pathogens that follow, allows immune system to better cope with nosema and other pathogens
Manage environmental stressors such as poor nutrition and high mite levels
Viruses in General:
Some replicate in specific organs and tissues
Some passed to larvae via brood food
Others vectored by parasites that weaken the bee and impair immune response while transmitting the pathogens and impact colony health
Diagnosis is difficult/costly
Reduce virus populations by keeping mite populations low
Deformed Wing Virus (DWV):
Cause: DWV is transmitted between bees via varroa mite
Symptoms: adult bees emerge from pupation with wrinkled, malformed wings
Other deformities
rounded/shortened abdomen, mostly noticed during summer
crawling on the ground or in front of the hive entrance
can’t fly – either are expelled from the colony or put to limited job functions
infected bees have shortened lifespans and learning disabilities
Treatment: Reduce virus populations by keeping mite populations low
Paralysis Virus:
Cause: group of viruses that cause paralysis of honey bees, including SPU (slow paralysis virus), ABPU (acute bee paralysis virus), IAPU (Israeli acute paralysis virus), CBPU (chronic bee paralysis virus), each affecting different tissues
Symptoms:
walking around, unable to fly
shiver their wings
may have a dark, greasy, hairless appearance
all exhibit progressive paralysis that leads to death
Usually expelled from the hive
Can infect other insects/bees
All common to honey bee populations
Treatment: Reduce virus populations by keeping mite populations low
Nosema:
Cause: Microsporidia (microscopic fungi)
two species:
Nosema apis (European strain)
Nosema ceranae – occurs in summer/fall, difficult to detect
Nosema is common in honey bee populations and may not effect honey bee health
Vector: mites, poor nutrition, and other pathogens when the colony becomes stressed
Symptoms:
invades immune system, impairs foraging and reduces brood care
these microbes parasitize the bees mid gut region by bee consuming spores and sharing infected food or through hive cleaning
bees can’t digest food, so waste accumulates
most obvious sign is poop everywhere
also contributes to K wing and impairs adult bees’ ability to make brood food
severe infestation results in high winter mortality
Treatment:
Fumagillin
antibiotic (strains become resistant)
best way is to ensure good nutrition (probiotics) and access to cleansing flights
essential oil mixer
Honey B Health
Hive Alive during summer dearth
these help flush the digestive system and rid bees of excess spores
woodwork and combs can be sterilized through freezing
Parasitic Mite Symptom (PMS):
Cause: high level of mites plus high load of one or more viruses
Symptoms:
poor queen nutrition and hive can’t support substantial brood levels
may exhibit deformed wing
spotty brood
other diseases – chalkbrood, sacbrood, or EFB
Starvation
Honey bees run out or lack energy to forage and raise brood
May fall prey to robbing and nuisance pests
Solution: feed bees and make sure honey frames are placed above the cluster
Conclusion:
Honey bee decline in numbers and species (diversity) is a mystery we can’t afford.