Non-target Effects: Reducing Risks

Risks for Different Groups of Non-target Organisms Source: Food and Agriculture Organization of the UN, 2003

Environmental Profile Carbaryl Malathion Diflubenzuron CAR OP BU (IGR) Human toxicity (WHO/EPA class) II (Moder.) III (Low) Unlikely to be toxic Fish toxicity Moderate Low Low Aquatic invertebrate toxicity Low Moderate High Mammalian toxicity Moderate Low Low Toxicity for birds and reptiles Low Moderate Low Toxicity for honey bee High High Low Toxicity for other non-target arthr. High Moderate Moderate

Half-Life in Soil Malathion: 1-25 D Carbaryl:7-28 D Diflubenzuron:3-4 D DDT:2-15 YR! Half-Life in Water Malathion: <7 D Carbaryl:10 D Diflubenzuron: 3 D DDT:28-56 D

HAZARD to NON-TARGETS Hazard = Toxicity X Exposure Toxicity: LD (LC) 50 – intrinsic characteristic of a chemical Exposure: Dose rate [and Persistence]

TOXICITY to MAMMALS Oral LD 50 of active ingredients for rats (in mg/kg): Malathion – 2,100 (1,000-10,000) Carbaryl – 450 ( ) Diflubenzuron – >4,640 Dermal LD 50 of active ingredients for rats (in mg/kg): Malathion – >4,000 Carbaryl – >2,000 (rabbit) Diflubenzuron – >10,000

Parameter Insecticides (active ingredient and trade name) MalathionFyfanonCarbarylSevinDiflubenzuronDimilin Oral Toxicity (LD 50 mg/kg) 2,100450>4,640 Relative Toxicity 2.2x10.3x1.0x Exposure (oz and [g a.i./ac]) 8 [227] 16 [100] 1 [7] Relative Exposure 32.4x14.3x1.0x Hazard (Rel. Tox. x Rel. Exp.) Hazard relative to Diflubenzuron ~70x~150x1x HAZARD to MAMMALS (rats)

Parameter Insecticides (active ingredient and trade name) MalathionFyfanonCarbarylSevinDiflubenzuronDimilin Oral Toxicity (LD 50 mg/kg) 1,485* [167**] >2,0003,763 Relative Toxicity 2.5x [22.5x] 1.9x1.0x Exposure (oz and [g a.i./ac]) 8 [227] 16 [100] 1 [7] Relative Exposure 32.4x14.3x1.0x Hazard (Rel. Tox. x Rel. Exp.) 81 [729] Hazard relative to Diflubenzuron ~80x [~700x] ~30x1x HAZARD to BIRDS * - mallard ducks ** - pheasants

HAZARD to GAME BIRDS Malathion: LD mg/kg Carbaryl:LD 50 2,000 mg/kg Diflubenzuron:LD 50 3,763 mg/kg Applied at recommended dose rates, the area of 1 square foot will receive: Malathion: 5.3 mg Carbaryl:2.3 mg Diflubenzuron:0.16 mg To pick up a 50% lethal dose, a 2 ¼ - lb bird should consume all vegetation on: Malathion: 32 square feet Carbaryl:900 square feet Diflubenzuron:½ acre

Parameter Insecticides (active ingredient and trade name) MalathionFyfanonCarbarylSevinDiflubenzuronDimilin Toxicity (LC 50 mg/L) Relative Toxicity 2,400x184.6x1.0x Exposure (oz and [g a.i./ac]) 8 [227] 16 [100] 1 [7] Relative Exposure 32.4x14.3x1.0x Hazard (Rel. Tox. x Rel. Exp.) 77,7602, Hazard relative to Diflubenzuron ~80,000x~2,600x1x HAZARD to FISH (brown, rainbow, and cutthroat trout)

Hazard = Toxicity X Exposure How to Reduce the Risks? RAATs!!! Observe buffers around water bodies Do not overdose Appropriate formulation Protect bees Use insecticides with lower toxicity

Is Dimilin Dangerous for Honey Bees?

Dimilin and Honey Bees Citrus pest control: (Schroeder et al., 1977) Six consecutive applications of Dimilin at 140 g a.i./acre each, approximately at a monthly intervals. No difference in brood numbers between treated and untreated hives. No detectable diflubenzuron residues in honey. Cotton pest control: (Robinson, 1979) Eight consecutive applications of Dimilin at 57 g. a.i./acre each, at one week intervals. No difference in treated/untreated brood ratio. No change in brood developmental rate. No detectable residues of diflubenzuron in wax, pollen or honey.

Dimilin and Honey Bees Conclusion: Repeated exposure of bee colonies to six to eight, consecutive Dimilin applications of 57 to 140 g a.i./acre presented no hazard to adult honey bees or to their brood. For comparison: In grasshopper control, a single Dimilin application at a rate of 7 g a.i./acre is used. This reduces the hazard by 64 to 120 times.

Excerpt from: Honey bee poisoning by chemicals: signs, contributing factors, current problems and prevention – Johansen, 1980 Extremely toxic to honey bees and should not be applied to blooming crops or weeds: Carbaryl (EC and ULV formulations) Malathion ULV To minimize hazard to bees, should be applied only during late evening: Malathion EC Relatively safe to bees and can be applied at any time: Diflubenzuron Insecticides and Bees

Which formulation is better? Worst Best WettableMicro-Oil-basedWater-based PowderEncapsulatedULVEC Source: Johansen, 1980