William A. Donahue, Jr., Ph.D. Sumiko De La Vega Sierra Research Laboratories, Modesto, CA Nebraska Urban Pest Management Conference February 12-13, 2013

 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.

 Metabolic – changes in detoxification (enzyme) system within the arthropod.  Target Site Insensitivity - receptors  Reduced Penetration - arthropod cuticle or plant surfaces (leaves)  Behavioral - avoidance

 High Intensity Cropping Systems – Agriculture  Food Production Animal Operations  Disease Vector Control Programs  Urban Pest Control Programs  Commodity Treatments  Routine pest control relying primarily on chemical control, often a single pesticide or class of pesticides.

 1930’s – 40’s: DDT insecticide of choice  DDT resistance wide spread  1950’s: Malathion insecticide of choice  : Low incidence of bed bugs world wide  1990’s: Pyrethroids insecticides of choice

 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!

 Resistance – The genetically acquired ability of an organism to survive a pesticide application at doses that once killed most individuals of the same species.  Baseline dose response  Field-collection and colony start-up  Diff. rates of reproduction, length of time until obtaining usable numbers

 Evaluate the insecticide susceptibility of specific populations of bed bugs  Compare dose response bioassays of selected populations  Establish discriminating dose bioassays

 “Harlan/Ft. Dix” – susceptible laboratory strain in colony since 1973, obtained 2008  “Earl” –pyrethroid-susceptible field strain, collected in Modesto, Stanislaus County, CA, 2007  “Cincinnati” –field strain, collected in Cincinnati, Hamilton County, OH, 2007, pyrethroid- resistant upon initial testing  “James” – pyrethroid-susceptible field strain collected in Modesto, Stanislaus County, CA, 2009  “Jersey” – moderately pyrethroid-resistant field strain collected in Jersey City, Hudson County, NJ, 2010  “Wolverine” –moderately pyrethroid-resistant field strain collected in Modesto, Stanislaus County, CA, 2010  “Stockton 2” – highly pyrethroid-resistant field strain collected in Stockton, San Joaquin County, CA, 2011 © Sierra Research Laboratories, 2012

© Sierra Research Laboratories, 2010  Formulated Permethrin LD evaluations – in 2008, 2010, and 2012  Permethrin technical – 0.05%  Deltamethrin technical – 0.05%  Imidacloprid technical – 0.05%  Propoxur technical – 0.5%

LD and LT Evaluations – Materials and Methods 1 mL test substance applied inside a wax outline of a 10 cm circle on a glass panel 10 bed bugs per replicate, mixed sex ratio, confined with a 100 x 15 mm Petri dish lid Mortality: 5, 15, 30, 45, 60 min, 2, 4, 6, and 24, 48, 72, 96, and 120 hr.

Initial Permethrin Dose Response Test, 2008 Harlan strain 100% mortality at 24 hours at all rates %, 0.005%, 0.05%, and 0.5% Cincinnati strain Maximum % mortality was 20.0% at the 0.5% rate (approximately 10x label rate!)

Permethrin Dose Response Test – Establishing Baselines For New Field Strains and Re-evaluating Existing Strains, 2010

Permethrin Lethal Time Tests Repeated Over a Span of Two Years Against “Earl” susceptible field strain

Permethrin Lethal Time Tests Repeated Over a Span of Four Years Against “Cincinnati” Resistant Field Strain

 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!

 Discriminating dose – important in evaluating a newly-collected field strain or assisting PMPs in selecting treatments  Full Dose Response – difficult to run on new populations  Genetic shifts in populations associated with resistance – need to re-evaluate colonies over time

© Sierra Research Laboratories, 2010