RESISTANCE AND NEW R&D IN
VECTOR PEST CONTROL
DR. BILL DONAHUE
SIERRA RESEARCH LABORATORIES
The ability of a significant portion of a pest population
to survive a pesticide at rates that once killed most
individuals of that population.
A genetic change in response to selection.
A natural process controlled by genetics and expressed
in specific biochemical processes.
TYPES OF RESISTANCE
Metabolic – changes in detoxification (enzyme)
system within the arthropod.
Target Site Insensitivity - receptors
Reduced Penetration - arthropod cuticle or plant
Behavioral - avoidance
1914 – San Jose Scale (insect) insensitive to lime sulfur
1946 – Resistance documented in 11 species of arthropods
1947 – DDT resistance first reported
1962 – Silent Spring – Environmental awareness of pesticides
1948 – 1983 - # of arthropod species demonstrating resistance
doubles about every 6 years.
1988 – 504 species of arthropods are resistant to one or more
REASONS FOR RESISTANCE
High Intensity Cropping Systems – Agriculture
Food Production Animal Operations
Disease Vector Control Programs
Urban Pest Control Programs
Routine pest control relying primarily on chemical
control, often a single pesticide or class of pesticides.
TIME UNTIL DEVELOPMENT OF
Organophosphates – 14 years
Organochlorines (DDT) – 7 years
Carbamates – 5 years
Pyrethroids – 4 years
IGR‟s, Bacterial Insecticides, Avermectins
Formulations – Cockroach Gel Baits, Ear Tags
The Way It Was
DDT was hailed as “the
miracle insecticide” and
“almost perfect control
product for this pest”
Resistance was observed
after only 5 years of use.
1930‟s – 40‟s: DDT insecticide of choice
1952-1956 DDT resistance wide spread
1950‟s: Malathion insecticide of choice
1960-2000: Low incidence of bed bugs world wide
1990‟s: Pyrethroids insecticides of choice
Pessimist View of Resistance
Resistance is sure to develop and there is
nothing we can do about it!
Optimist View of Resistance
When you can’t change the direction of the
wind – adjust you sails!
Why Does Resistance Develop?
Resistance is quick to develop to compounds with high
effective kill, long residual and are highly selective at a
single biochemical target site.
Why? High Selection Pressure within the Population!
How Can We Slow Down Resistance?
Resistance is slow to develop with inefficient, short
residual compounds because selection pressure is low!
Select compounds that interfere with multiple
biochemical or physiological systems.
Mixtures like Botanical Insecticides, Synergists, IGR‟s
Refugia – A source of susceptible individuals (genetic)
within a population – Don‟t Kill „em All!
Integrated Pest Management – Ecology in Action!
INSECTICIDE RESISTANCE IN FLEAS
8 Species of fleas demonstrated resistance including cat fleas
Low Resistance Ratios (same for German Cockroaches)
High Strain Variability – Relatively Isolated Populations
Much Insecticide Resistance Ascribed to Cat Fleas may be
Variation in Flea Susceptibility.
The Modern Environmental Movement
NEW INSECT CONTROL STRATEGY
Reduce Reproductive Potential
Extend Generation Time
Early Season Treatment
Season Long Control
Breaking the Life Cycle
Target most Vulnerable Life Stage
Planned & Integrated Control Methods
Education, Knowledge & Surveillance
Least Toxic Approach – Chemical, Mechanical, Cultural Control
SO WHERE DO WE START?
Pesticides must be used judiciously in an
IPM program so as to preserve cost
effective pesticides and maintain
susceptible individuals in a pest population
INTEGRATED PEST MANAGEMENT
IPM – An ecology-based control system which
combines many techniques in an organized program
to keep pest populations below levels of economic
damage or nuisance.
Control techniques are selected and applied to
minimize risk to human health, beneficial and non-
target organisms, and the environment.
COMPONENTS OF AN IPM PROGRAM
Natural Control – Use or Enhance What‟s There, Biological
Control – Parasites, Predators and Pathogens
Cultural Control – Modify Existing Practices such as
Temperature, Watering, Fertilizing
Mechanical/Physical Control – Specialized Equipment or
Practices Such as Mowing and Tilling
Chemical Control – Many Choices – Least Toxic Approach!
ELEMENTS OF AN IPM PROGRAM
Knowledge – Pest Biology and Ecology
Integrated System of Strategies – A Plan With Depth
Surveillance and Monitoring – Visual, Traps, Data Recorders
Continuous Evaluation and Updates – Is the Plan Working?
Education – New Information, Update the Plan
Resistance Management - Bioassays
Discovering New Chemistries
From Concept to Reality
Chemical Synthesis and Basic Research
Laboratory Bioassays – Multiple Tiers
Field Testing – Multiple Geographical Sites
Toxicology Studies from Cells to the Environment
Product Chemistry, Packaging & Stability
Regulatory – EPA, States , Global/International
Marketing & Sales
Dose Response - Adult Fleas on filter paper, nylon
discs, spun glass wool, dog hair, carpet, sand/soil.
Evaluate technical materials or formulations
Topical Bioassays - Adult Fleas
Treated Media or Substrates - Larval Fleas
Artificial Membrane Feeding Systems - Eggs and
Adults - Systemic or Contact Effects
Screening New Chemistries
Test #1 1, 9, 13, 20 & 28 days
@ 1, 2, 4, 8 & 24 hours
Test #2 1, 7, 14, 28, 45, 59 & 91
Flea & Tick Screening
On Farm Surveillance
Bacteria, Viruses, Protozoa
Ticks in the Urban Environment
Wildlife, Pets - Activities, Wooded Environments
Disease Potential, Lyme Disease
Public Perception - Monitoring
Tick Habitats - Rural
RESEARCH AND NEW PRODUCTS
Repellents – People, Pets & Livestock, Environmental
Acaricides – New Compounds, Formulations, Traps
Habitat Modification, Mapping (GIS), Models
Field & Lab Research – Acarology, Epidemiology
Basic Physiology – “Tick Spit” - Vaccines
Nuisance Fly Control
House Flies, (Musca domestica); Stable Flies, (Stomoxys calcitrans);
Little House Fly, (Fannia canicularis).
Season – Late Spring through Late Fall
Pest Control Measures – Truck Mounted Sprayers (mist blowers)
Integrated Pest Management
Other Measures? Light traps,
Sticky Ribbons, Parasitic Wasps,
Manure Management, Vacuum,
Fly Counts from pans –
Visual or Volumetric
Where Do We Go From Here?
Identify Current Problems or Concerns
Determine the Magnitude of the Problem
Surveillance and Monitoring
Develop Long Term Strategies
Integrated Pest Management (IPM)
Evaluate New Products