Heat and Conventional Insecticides

1
Heat and ConventionalInsecticides

• Frank H. Arthur
• USDA-ARS-GMPRC
• Manhattan KS 66502

2
Spot, Crack Crevice Treatments

• Organophosphate and pyrethroid insecticides are
  used as spot or crack crevice treatments
• Specific language on the label defining a spot
  (often 2 ft2 or less)
• Specific directions for crack crevice
  applications

3
General Surface Treatments

• Spray volume and area are specified
• 1 gal of formulated spray per 1,000 ft2
• Different label language and application
  directions
• Limited number compared to crack crevice

4
Insecticides

• Malathion OP, not being reregistered
• Cyfluthrin EC WP (Tempo) pyrethroid
• Hydroprene (Gentrol) insect growth regulator

5
Residual degradationor inactivation

• OPs degrade as temperature increases
• Summer degradation is a serious problem with
  grain protectants
• Residues drop below levels that will control
  insects
• Example degradation at controlled temperatures

6
Degradation of chlorpyrifos-methyl on wheat
(values in ppm)
7
Pyrethroids

• More heat-stable compared to OPs
• Degrade primarily by UV light
• Example wheat treated with chlorpyrifos-methyl
  and deltamethrin
• Wheat stored in a metal shed from Oct-July in
  south GA
• Mean monthly temp was 14-31 C during the study

8
Degradation of chlorpyrifos-methyl (CM) and
deltamethrin (D) on wheat stored for 10 months
(values in ppm)
9
Heat treatments and insecticides

• Insecticide would probably degrade rapidly at
  45-55 C
• Pyrethroids a more practical choice

10
Cyfluthrin WP

• Gives better residual control on porous surfaces
  than cyfluthrin EC
• Common treatment in food warehouses and other
  indoor structures
• Will extreme temperatures associated with heat
  treatments affect residual efficacy?