Golf Course Management

OCT 2014

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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88 GOLF COURSE MANAGEMENT 10.14 and they have exceptional residual activity. These shared properties are part and parcel of what makes them excellent insecticides, but these properties also contribute substantially to their potential as environmental contami - nants. The high water solubility of neonicoti- noids means they are easy to mix and apply as liquids and this undoubtedly lends to their systemicity, or their ability to be taken up by and moved throughout the plant via vascular tissue. High water solubility also means that irrigation or rainfall will allow the compounds to move with relative ease into the soil profle, where they can protect against damage from soil-inhabiting insects such as white grubs. Because most of the compounds in this class have a relatively long residual half-life, the ap - plication window tends to be much larger, al- lowing turfgrass managers, in particular, the opportunity to take advantage of a more fexi - ble application-timing window and the ability to target multiple pests with a single applica - vous system toxins over an extended period of time. Environmental monitoring data sug - gest that these compounds are present in soil, water and pollen and nectar of various plants throughout the season and across many envi - ronments. There are relatively few "neonicot- inoid-free" areas for pollinators to forage in human-dominated environments. The intricate communication system on which a bee hive relies for optimizing its col - lective foraging efforts involves subtle physi- cal and chemical cues. Bees returning from a successful foraging journey can communi - cate very precise navigational information to their hive mates, allowing them to fy to the exact location of a newly discovered source of nectar. Research conducted in France has demonstrated that sublethal exposure to neo - nicotinoids interferes with this crucial infor- mation network, putting the entire hive at risk because foragers given low doses of neonicoti - noid cannot fnd their way back to the hive (1). Imagine stopping at a gas station for direc - tions only to fnd the attendant stone drunk behind the counter. How reliable would his directions be? Understanding acute toxicity is important, but the hazard of chronic exposure could be equally devastating. Unfortunately, we know very little about this aspect of the neonicotinoid story. Products in the green industry Use of neonicotinoids in the green in- dustry is mainly represented by four active ingredients: imidaclorpid (Merit, Bayer; oth - ers), clothianidin (Aloft, Arysta LifeScience; Arena, Nufarm), thiamethoxam (Meridian, Syngenta) and dinotefuran (Zylam, PBI-Gor - don) (Table 1). Because these four compounds belong to the same class of insecticides, they have many shared properties. Aside from their direct mode of action as synaptic poisons at the molecular level, they are highly water-sol - uble, they are systemic via the xylem of plants, Insecticide (trade name/company) Insecticide class Toxicity † Mammal LD 50 (mg/kg) ‡ Bird LD 50 (mg/kg) ‡ Fish LC 50 (mg/liter) § Honey bee LD 50 (µg/bee) // Azadirachtin (Azatrol/PBI-Gordon; others) biorational >5,000 >225 440 >5.9 Beta-cyfluthrin (Tempo/Bayer) pyrethroid >77 >2,000 0.000068 0.001 Bifenthrin (Talstar/FMC) pyrethroid 54.5 1,800 0.00026 0.1 Carbaryl (Sevin/Bayer) carbamate 614 >2,000 2.6 0.14 Chlopyrifos (Dursban/Dow AgroSciences) organophos-phate 64 13.3 0.0013 0.059 Chlorantraniliprole (Acelepryn/Syngenta) anthranilic diamide >5,000 >2,250 >12 >4 Emamectin benzoate (TREE-äge/Arborjet) # avermectin 24 23 0.174 0.0035 Lambda-cyhalothrin (Scimitar/Syngenta) pyrethroid 56 >3,950 0.00021 0.038 Spinosad (Conserve/Dow AgroSciences) biorational >5,000 >2,250 2.69 0.024 Trichlorfon (Dylox/Bayer) organophosphate 212 >36.8 0.7 >0.4 † Toxicity only refers to active ingredient and does not take into account formulation. Data from IUPAC, material safety data sheets (MSDS), or U.S. EPA. ‡ LD 50 for mammals and birds represents acute oral toxicity. § LC 50 For fsh represents acute 96-hour toxicity. // LD 50 for honey bees may represent either acute contact or oral toxicity. # Ornamental insecticide not labeled for use in turf at the time of this writing. Table 2. Ecotoxicology of several common insecticides in several different animal species. LD 50 represents the amount of material (per unit body mass or individual) required to kill 50% of a test population. LC 50 represents the concentration of material in water required to kill 50% of the test population. Ecotoxicology of several common insecticides

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