8.3 Structural Pest Control, Public Health, Seed Treatment & Fumigation

8.3 Structural Pest Control, Public Health, Seed Treatment & Fumigation

Quick Answer: The industrial, institutional, and structural, public health, seed treatment, and nonsoil fumigation classes (NDAC 60-03-01-05(8), (9), (5), and (12)) represent specialized, high-liability commercial certifications in North Dakota. German cockroaches are managed with crack-and-crevice baiting and Insect Growth Regulators (IGRs) like pyriproxyfen, while commensal rodents require tamper-resistant bait stations to prevent secondary poisoning of non-targets. Bed bugs are eradicated using heat (120°–135°F) and silica aerogel desiccant dust. Public health mosquito abatement focuses on larviciding with Bti and nocturnal ULV cold fogging against West Nile virus vector Culex tarsalis. All commercially treated seed requires an EPA-approved colorant dye. Stored-grain fumigation with phosphine gas ($PH_3$) demands a written Fumigation Management Plan (FMP), mandatory SCBA respirators whenever levels exceed 0.3 ppm or are unknown, bilingual warning placards, and aeration until phosphine drops below 0.3 ppm throughout the commodity.

Industrial, Institutional, and Structural Pest Control

Structural pest control encompasses residential structures, commercial facilities, food-handling establishments, warehouses, and grain elevators across North Dakota.

1. German Cockroach (Blattella germanica)

The German cockroach is the most economically significant indoor structural insect pest. Adults are 1/2 inch long, pale brown, with two dark parallel longitudinal stripes on the pronotum:

• Reproductive Dynamics: Females produce an egg case (ootheca) containing 30 to 40 eggs, which they carry attached to their abdomen until 1 to 2 days before hatching. Under warm indoor conditions, they complete a life cycle in 60 days, yielding 3 to 4 overlapping generations annually.
• Precision Baiting: Foggers and baseboard sprays repel roaches, dispersing colonies deeper into structural voids. Modern control utilizes non-volatile gel baits (fipronil, indoxacarb, dinotefuran) applied as pea-sized placements directly into cracks, crevices, plumbing chases, and electronic appliance housings.
• Insect Growth Regulators (IGRs): Synthetic juvenile hormone analogs (pyriproxyfen, hydroprene) prevent cockroach nymphs from completing their final molt into viable adults. Exposed nymphs develop into sterile, deformed adults with twisted, crinkled wings. While IGRs do not cause immediate mortality, they systematically eliminate reproductive capacity and prevent insecticide resistance.

2. Commensal Rodents & Secondary Poisoning Mitigation

North Dakota structures harbor three commensal rodent species: the Norway Rat (Rattus norvegicus), the Roof Rat (Rattus rattus), and the House Mouse (Mus musculus):

• Tamper-Resistant Bait Station Mandates: Under EPA and state regulations, rodenticides placed outdoors, above ground, or indoors in areas accessible to children, pets, or non-target wildlife must be secured inside EPA Tier 1 tamper-resistant bait stations. Stations must be anchored to the ground or wall, locked, and labeled with active ingredient warnings.
• Exclusion & Monitoring: Physical exclusion is the only permanent solution. Mice enter openings larger than 1/4 inch, while rats enter openings larger than 1/2 inch. Openings must be sealed with copper mesh, steel wool, or metal flashing.
• Secondary Poisoning Hazards: Second-Generation Anticoagulant Rodenticides (SGARs: brodifacoum, bromadiolone, difenacoum, difethialone) inhibit vitamin K epoxide reductase, blocking blood coagulation factors. Because SGARs bind tightly to liver tissue and have extended biological half-lives, non-target predators and scavengers (barn owls, hawks, eagles, foxes) that consume dying rodents experience fatal internal hemorrhaging. Applicators must prioritize mechanical snap trapping and first-generation or non-anticoagulant baits (cholecalciferol) in outdoor sensitive zones.

3. Bed Bugs (Cimex lectularius)

Bed bugs are nocturnal, dorsoventrally flattened blood-sucking ectoparasites that harbor in mattress tufts, box springs, headboards, and electrical wall plates:

• Thermal Remediation: Exposing infested structures to forced-air convective heat maintaining 120°F to 135°F for 2 to 4 hours achieves 100% mortality of all life stages, including heat-tolerant eggs, without chemical residues.
• Desiccant Dusts: Silica aerogel is an amorphous dust that physically adsorbs the protective waxy epicuticle layer of the bed bug exoskeleton, causing rapid death by dehydration. Because silica aerogel kills through physical desiccation rather than physiological nerve poisoning, bed bugs cannot develop chemical resistance.

Public Health Pest Control

Public health pest control protects human populations from vector-borne diseases under municipal abatement programs and county weed/mosquito control boards.

Mosquito Vector Biology in North Dakota

Chemical & Biological Control Strategies

• Larviciding (Primary IPM Defense): Suppressing mosquito larvae confined to water bodies is vastly more cost-effective and environmentally sound than adulticiding:
  • Bacillus thuringiensis israelensis (Bti): Naturally occurring soil bacterium. When ingested by mosquito larvae, crystalline delta-endotoxins dissolve in the alkaline larval gut, destroying cellular permeability and causing death within 24 hours. Completely non-toxic to fish, bees, and mammals.
  • Methoprene: Insect growth regulator that prevents mosquito pupae from successfully transforming into flying adults.
  • Monomolecular Films & Surface Oils: Form an ultrathin layer across the water surface, altering surface tension and preventing mosquito larvae and pupae from attaching their breathing siphons, leading to physical suffocation.
• Adulticiding (Emergency Suppression): Deployed when mosquito trap counts exceed municipal action thresholds or when North Dakota Department of Health mosquito pool surveillance confirms active West Nile virus transmission:
  • Ultra-Low Volume (ULV) Cold Fogging: Atomizes concentrated synthetic pyrethroids (permethrin, sumithrin) or malathion into microscopic aerosol droplets with a Volume Median Diameter (VMD) of 10 to 30 microns. Droplets remain suspended in air currents, colliding directly with flying adult mosquitoes.
  • Nocturnal Application Mandate: ULV spraying is conducted strictly at night (between 9:00 PM and midnight) or early dawn. This matches the peak flight activity of Culex tarsalis, takes advantage of nighttime temperature inversions that trap aerosol droplets near the ground, and protects daytime foraging honey bees sheltered inside hives.

Seed Treatment: Commercial Seed Treatment Standards

Commercial seed treating facilities apply fungicides and systemic insecticides to agricultural seeds (wheat, barley, soybeans, field peas, canola) prior to planting to guard against soil-borne damping-off fungi (Pythium, Rhizoctonia, Fusarium) and early-season insect pests (wireworms, seedcorn maggots, flea beetles):

• Mandatory EPA Colorant Dye Requirement: Under strict federal and North Dakota regulations, all commercially treated seed must be formulated or mixed with an EPA-approved prominent visual colorant or dye (typically vivid red, magenta, bright blue, or green). The dye provides an unmistakable visual signal indicating the seed has been chemically treated, preventing treated seed from accidentally entering human food, livestock feed, or commercial oil crushing streams.
• Worker Safety & Inhalation Protection: Treating and augering seed generates pesticide-laden chemical dust. Handlers must wear chemical-resistant gloves, protective coveralls, and NIOSH-approved particulate respirators during treating, bagging, and equipment cleanout.
• Disposal of Surplus Treated Seed: Leftover treated seed is legally classified as chemical waste. It is illegal to burn treated seed, dump it in waterways, or mix it with commercial grain. Surplus seed must be planted at agronomic rates in designated setback fallow acreage or disposed of through an authorized hazardous waste collection program, such as NDDA Project Safe Send.

Nonsoil Fumigation: Commodity and Structural Grain Fumigation

Fumigation involves treating stored grain bins, concrete elevator silos, flat storage warehouses, railcars, and overseas containers with toxic, gaseous pesticides that disperse into the commodity mass.

Chemistry of Phosphine Gas ($PH_3$)

Phosphine is the most widely utilized stored-grain fumigant in North Dakota. It is generated on-site from solid formulations of aluminum phosphide ($AlP$) or magnesium phosphide ($Mg_3P_2$) pellets, tablets, or prepac strips reacting with moisture in ambient air:

$AlP + 3 H_2O \rightarrow Al(OH)_3 + PH_3 \uparrow$

Formulations incorporate ammonium carbamate, which simultaneously decomposes into carbon dioxide ($CO_2$) and ammonia ($NH_3$):

$NH_2COONH_4 \rightarrow 2 NH_3 + CO_2$

The ammonia and carbon dioxide reduce the flammability of phosphine gas and impart a pungent early-warning odor. Pure phosphine is colorless and odorless, but technical-grade phosphine has a characteristic carbide, decaying fish, or garlic-like odor.

Toxicity & Regulatory Safety Requirements

Phosphine is classified as EPA Toxicity Category I (DANGER / POISON with Skull and Crossbones). It is a non-selective cellular poison that blocks cytochrome c oxidase, shutting down cellular respiration:

• Mandatory Written Fumigation Management Plan (FMP): Prior to initiating any fumigation, the certified applicator must author a site-specific written FMP detailing commodity volume, calculated gas dosage, sealing procedures, gas monitoring schedules, notification of local emergency responders and fire departments, and emergency evacuation protocols.
• Respiratory Protection Mandate: A NIOSH-approved Self-Contained Breathing Apparatus (SCBA) operating in positive-pressure demand mode (or a positive-pressure supplied-air respirator) is MANDATORY whenever phosphine gas concentrations exceed the 0.3 ppm Permissible Exposure Limit (PEL), or whenever the gas concentration is UNKNOWN! Cartridge air-purifying respirators are strictly prohibited in unknown atmospheres and are limited to low concentrations (< 15 ppm) only when approved. The Immediately Dangerous to Life or Health (IDLH) threshold is 50 ppm.
• Two-Person Rule: At least two trained individuals must be present on site whenever fumigants are being applied, gas monitoring is conducted, or structures are aerated.
• Gas Detection Instrumentation: The human nose cannot detect low, hazardous phosphine levels. Applicators must use calibrated low-range photoionization detectors (PIDs) or direct-reading colorimetric gas detector tubes sensitive down to 0.05 ppm.
• Placarding Mandate: Bilingual warning placards (English and Spanish) displaying the Skull and Crossbones, date and time of fumigation, fumigant name, and applicator contact info must be posted on all access doors, hatches, and aeration fans.
• Aeration & Clearance Standard: Following the exposure period, the structure must be mechanically aerated until gas monitoring verifies that atmospheric phosphine levels are strictly BELOW 0.3 ppm throughout the entire commodity mass and working areas before placards can be removed and uncertified personnel may enter without SCBA.

Independent Preparation Notice

This study guide is an independent educational publication developed by OpenExamPrep. It is not affiliated with, sponsored by, endorsed by, or produced in partnership with the North Dakota Department of Agriculture, North Dakota State University Extension, or the EPA.