Integrated Pest Management and Fumigation Safety Training

January 24 – 26, 2017 Kansas State University, Manhattan, Kansas

Phosphine Fumigation of Grain

Tom Phillips Professor of Entomology Kansas State University

What is a fumigant?

• A toxic chemical pesticide that is applied to the pest in the gas phase

• Fumigation represents a pest management “hammer”, intended to disinfest quickly, when needed

• Since acting as a gas, it leaves very little or no chemical residue

• Key uses: commodities, buildings, in transit, quarantine

• Very dangerous for people; applicators and bystanders must be protected!!!

Fumigation should give effective, immediate CONTROL

• Need to ACT if monitoring detects a problem

• Fumigation – Best for bulk-stored grain in silos, bunkers, sealed warehouses and tarped bag stacks

• Alternatives include controlled atmospheres, high temperature and cold temperature

Variables that Affect Fumigation Success

• Species of target pest: tolerance level • Insects’ most tolerant life stage:

egg, larva, pupa, adult • Gas concentration

–High better than low

• Exposure time – Long better than short

• Temperature –Warm better than cool

Dose-Mortality Results for Cool Eggs

0

20

40

60

80

100

0 20 40 60 80 100 120 140 160 180 200 220 240

% M

ort

alit

y

Dose-Concentration of Fumigant

% Egg Mortality at 60oF (= 16 oC)

Dose-Mortality Results for Warm Eggs

0

20

40

60

80

100

0 10 20 30 40 50 60 70 80 90 100

% M

ort

alit

y

Dose-Concentration of Fumigant

% Egg Mortality at 77oF (=25oC)

Common and Available Fumigants

•Methyl Bromide

•Phosphine

• Sulfuryl Fluoride

Phosphine: The Primary Fumigant for Grain

Metallic Phosphide Salts: Most Common

Magnesium Phosphide

Mg3P2 + 6H2O 3Mg(OH) 2 + 2PH3

Aluminum Phosphide

AlP + 3H2O Al(OH)3 + PH3

Phosphine: Cheap, Easy and Effective

• Gas is light-weight; penetrates well

• Tablets/pellets are very economical

• Effective for most pests

• Corrosive to electrical fixtures

• Some insects are resistant,….. and it’s spreading!

What is Insecticide Resistance?

• Resistance occurs when an insect has a genetically controlled trait that allows it to survive an exposure to a toxin that would normally kill others of the same species that lack that trait.

• Resistance is heritable. It can be selected quickly in a population with each fumigation. Once the proper genes are present each application of phosphine can lead to a resistant population!

Evolution of Resistance:

► One healthy insect is born with

a mutation (DNA mistake at

cell division) for resistance to a

specific pesticide

O=susceptible individual O=resistant individual http://en.wikipedia.org/wiki/Pesticide_resistance

Evolution of Resistance:

► One healthy insect is born with

a mutation (DNA mistake at

cell division) for resistance to a

specific pesticide

► Human selection: We apply

insecticide to insects with the

resistance gene(s); they live and

mate with others who may/may not

have the genes

O=susceptible individual O=resistant individual http://en.wikipedia.org/wiki/Pesticide_resistance

Evolution of Resistance:

► One healthy insect is born with

a mutation (DNA mistake at

cell division) for resistance to a

specific pesticide

► Human selection: We apply

insecticide to insects with the

resistance gene(s); they live and

mate with others who may/may not

have the genes

► Repeated use of the insecticide

selects for all resistant survivors

in the population!!!

O=susceptible individual O=resistant individual http://en.wikipedia.org/wiki/Pesticide_resistance

Determine number of insects that are phosphine

resistant or susceptible at a given location

• Need a dose that discriminates

between susceptible, which die and

survivors, which are resistant

• Test adults from a given population

• Test adults with the discriminating dose

of gas for 20 hour fumigation

• Assess mortality after 14 days, to allow

time for recovery or delayed mortality

Controlled Laboratory Fumigation Tests

Analyze Gas Concentration with Gas Chromatography

Red flour beetles from around

North America resistant to phosphine

Population State/Prov.1 City2 % Resistant

1 AL Uniontown* 31

2 Red Level 100

3 Ozark 98

4 AR Jonesboro* 20

5 CA Arbuckle 0

6 Davis 0

7 Goshen* 52

8 Princeton* 2

9 Williams 0

10 FL Walnut Hill* 88

11 GA Nashville 22

12 Tifton* 0

13 KS Abilene23 41

14 Hudson* 0

15 Junction City 0

16 Kansas City* 0

17 Manhattan 15

18 Minneapolis3 93

19 MO Excelsior Sprgs 0

20 OK Calumet* 0

21 TX Victoria 2

22 MB Winnipeg 0

23 QC St. Agathe 0

24 SK Saskatoon 0

25 AB Calgary 0

Found that some places had beetles more resistant than others: Two Bioassays

• Red Flour Beetle in Kansas: 30 ppm vs 180 ppm

0

10

20

30

40

50

60

70

80

90

100

Ab1 Ab2 McP MIT MIN RU WA

Surv

ivo

rsh

ip (

%)

Weak Assay

Strong Assay

Dose-Mortality plots for populations of Red Flour Beetle with Weak vs Strong Resistance Relative to the Susceptible Strain

Susceptible

Weak

Strong

Pop. No. State/Pro City2 % Res (n)

1 AL Uniontown 89 (90)

2 CA Parlier (1) * 97 (30)

3 CA Parlier (2) 72(90)

4 Williams* 53 (30)

5 Colusa 3 (60)

6 Princeton 71 (31)

7 Biggs 7 (150)

8 FL Belle Glade 87 (90)

9 KS Manhattan (1) 66 (59)

10 Manhattan (2) 77 (150)

11 Manhattan (3) 75 (60)

12 Manhattan (4) 71 (90)

13 Manhattan (5) 78(90)

14 Manhattan (6) 51(50)

15 Manhattan (7) 66(90)

16 Manhattan (8) 48(40)

17 Abilene (1) 93 (30)

18 Abilene (2) 90 (20)

19 Minneapolis 93 (60)

20 Clifton 80 (90)

21 Junction City (1) 57 (30)

22 Junction City (2) 50 (40)

23 Garden City 74 (39)

24 Wamego 54(149)

25 TX Victoria 67 (60)

26 Burleson 87 (90)

27 AB Lethbridge 4 (90)

28 Stirling 14 (90)

29 Bow Island 38(50)

30 SK Carnduff 0 (90)

31 Coronach 19 (90)

32 Weyburn 68(50)

33 Indian Head 62(100)

34 MB Starbuck 0(90)

Lesser Grain Borer

In North America

Kansas pops 9 through 24

Nearly all pops surveyed had some

level of resistance = 94% !!!

Dose-response plots for six populations of Lesser Grain Borers

Susceptible

Weak Resistance

Strong Resistance

Collections for Rusty Grain Beetle, Cryptolestes ferrugineus

Carnduff

Killarney

Sarnia

Prescott

Nova Scotia Junction City

Alabama

Weslaco

Rusty Grain Beetle–%Resistance with FAO Test

• Nova Scotia-lab 67%

• Ontario-Prescott 15%

• Ontario-Sarnia 0%

• Manitoba-Killarney-a 91%

• Manitoba-Killarney-b 55%

• Saskat.-Carnduff 86%

• Alabama-Coop. 65%

• KS-Junction City 92%

• TX-Weslaco 95%

Cigarette Beetle

Cigarette Beetle Collection Sites

KY GA

GA

NC

VA1

VA2

PH3 Discriminating Dose Results:

Cigarette Beetle from Six U.S. Warehouses

0

13.3

23.3

93.3 98.9 98.9 98.9

0

20

40

60

80

100

LAB GA FL KY NC VA1 VA2

Populations

% Resistance at 50 ppm Discriminating Dose

• Fumigate jars with all life stages—egg, larvae, pupae, adults--like real world!

• Normal dose = 200 ppm PH3 for 4 days

• Dose for resistant beetles = 600 ppm PH3 for 6 days

• Count all survivors at the end of the fumigation, and then count daily for 42 days – new adults may have been surviving eggs or larvae

Can we control resistant beetles with more phosphine

held for longer times???

Low Phosphine High Phosphine

Pop Air Control 200 ppm/4 d 600 ppm/6 d

GA 31.7 (4.8) A 0.0 (0.0) B 0.0 (0.0) B

FL 54.2 (13.8) A 0.2 (0.2) B 0.0 (0.0) B

KY 136.0 (60.0) A 103.5 (25.8) AB 12.5 (3.4) B

NC 162.2 (16.0) A 83.7 (11.4) B 6.5 (2.7) C

VA-1 112.0 (50.1) A 105.2 (25.3) A 7.2 (1.8) B

VA-2 41.8 (15.9) A 28.2 (6.0) AB 4.8 (1.8) B

CORESTA Challenge Results For Cigarette Beetle Populations

Try a simple “knock-down” test

Tablets placed in canister w/50ml water; get 6000 ppm

Dilute with air in knockdown chamber, to be approx. 3000 ppm

Count no. knocked down after given time period, such as 15 min

Can resistance be “easily” determined?

KSU Modified Test: Exactly 3000 ppm in glass tube; record time to Knock Down

Phosphine Resistance Management

• What do we do if we think we have a resistance problem?

• Should we expect that future use of phosphine for grain bins will simply not work—that we will lose phosphine?

• Should we have some plan in place to prepare?

• Have other countries faced this same problem?

Managing Phosphine Resistance

• First:….Is there is a problem controlling insects?

• If resistance is suspected, stop using phosphine!

• Use a totally different fumigant or good grain protectant! – ***New mode of action; must kill all PH3-resistant pests!

• PH3 can be resumed only when problem is managed.

• Practice good stored grain IPM: prevention, sanitation, monitoring, targeted action.

ProFume®

• Gas called Sulfuryl Fluoride (same as Vikane® for termites)

• Registered for stored grain, flour mills, nuts, dried fruits, etc.

• Non-corrosive

• Alternative for PH3 Resistance: totally different mode of action!

Alternatives to Current Fumigants

• Residual chemicals sprayed on grain

• Extreme Temperatures: Heat and Cold

–Below freezing or Near 100 F

• Controlled or modified atmospheric gases

–Reduce Oxygen, or increase CO2

Modified Atmosphere with Cocoon: Low Oxygen and High CO2

Thank You Very Much! Any questions?

• Feel free to contact me with any questions or comments:

– Tom Phillips

– E-mail: twp1@ksu.edu – Phone: 785-532-4720

• Thanks for attending!!!

This presentation was made possible by a grant from The Technical and Operational Performance Support (TOPS) Program. The TOPS Micro Grants Program is made possible by the generous support and contribution of the American people through the U.S. Agency for International Development (USAID). The contents of the materials produced through the Micro Grants do not necessarily reflect the views of TOPS, USAID, or the U.S. Government.