**7. Environmental concerns**

Most data on the deposition, toxicity, and environmental fate of insecticides in western for‐ ests come from aerial applications to control tree defoliators, and therefore are of limited ap‐ plicability to bole sprays or tree injections used to protect trees from bark beetle attack. [49] studied the effects of lindane, chlorpyrifos and carbaryl on a California pine forest soil ar‐ thropod community by spraying normal levels of insecticide, and levels five times greater than would be operationally used to protect trees from bark beetle attack. The authors con‐ cluded carbaryl was least disruptive to the soil arthropod community [49]. Persistence and movement of 2.0% carbaryl within soils of wet and dry sites has been evaluated [50]. The highest concentrations of carbaryl were detected within the uppermost soil layers (upper 2.54 cm), with levels exceeding 20 ppm 90 d after application on most sites [50].

Carbaryl is relatively nontoxic to *Enoclerus lecontei* (Wolcott) [51] and *E*. *sphegeus* (F.) [52], and less toxic than either lindane or chlorpyrifos to *Temnochila chlorodia* (Mannerheim) [51], common predators of bark beetles in the western U.S. [32] measured the remedial efficacy of 0.25%, 0.5%, 1.0%, and 2.0% chlorpyrifos (Dursban®), fenitrothion (Sumithion®) and perme‐ thrin (Pounce®) on emerged and nonemerged predators and parasites of spruce beetle in Alaska. Two percent Pounce® had the least impact on emerged natural enemies while Durs‐ ban® and Sumithion® had the greatest impacts. In many cases, the lowest concentrations re‐ sulted in the highest mortality of emerged parasites and predators (74-94% mortality), but lowest mortality of nonemerged individuals. The authors attributed this to higher concen‐ trations resulting in prolong emergence [32]. Mortality of nonmerged parasites and preda‐ tors was <45% for all active ingredients and concentrations, except 2.0% chlorpyrifos [32].

Werner and Hilgert [53] monitored permethrin levels in a freshwater stream adjacent to Lutz spruce that were treated with 0.5% permethrin (Pounce®) to prevent spruce beetle at‐ tack. Treatments occurred within 5 m of the stream. Maximum residue levels ranged from 0.05 ± 0.01 ppb 5 h after treatment to 0.14 ± 0.03 ppb 8-11 h after treatment, declining to 0.02 ± 0.01 ppb after 14 h. Levels of permethrin in standing pools near the stream were 0.01 ± 0.01 ppb. Numbers of drifting aquatic invertebrates increased two-fold during treatment and four-fold 3 h after treatment and declined to background levels within 9 h. Trout fry, periph‐ yton and benthic invertebrates were unaffected [53].

Two studies have been published on the amount of drift resulting from carbaryl applica‐ tions to protect trees from bark beetle attack. In the early 1980s, [54] used spectrophotofluor‐ ometry to analyze ground deposition from the base of the ponderosa pine to 12 m from the bole in California. In a more recent study, [14] used high performance liquid chromatogra‐ phy (HPLC) to evaluate ground deposition occurring at four distances from the tree bole (7.6, 15.2, 22.9 and 38.1 m) during conventional spray applications for protecting individual lodgepole pine from mountain pine beetle attack, and Engelmann spruce from spruce beetle attack. Despite substantial differences in these methods (i.e., spectrophotofluorometry limits detection of finer particle sizes that are accounted for with HPLC), they yielded some similar results. For example, [14] reported application efficiencies of 80.9% to 87.2%, while [54] re‐ ported values of >80%. Furthermore, [14] found no significant difference in the amount of drift occurring between lodgepole pine and Engelmann spruce at any distance from the tree bole despite differences in application rate and pressure, while [54] reported drift was simi‐ lar between two methods applied at 276 kPa and 2930 kPa. However, [14] reported higher levels of ground deposition further away from the tree bole, which is expected given use of HPLC, a more sensitive method of detection.

appear effective from reducing levels of lodgepole pine mortality due to mountain pine bee‐ tle attack in Utah or ponderosa pine mortality due to western pine beetle attack in Califor‐

Most data on the deposition, toxicity, and environmental fate of insecticides in western for‐ ests come from aerial applications to control tree defoliators, and therefore are of limited ap‐ plicability to bole sprays or tree injections used to protect trees from bark beetle attack. [49] studied the effects of lindane, chlorpyrifos and carbaryl on a California pine forest soil ar‐ thropod community by spraying normal levels of insecticide, and levels five times greater than would be operationally used to protect trees from bark beetle attack. The authors con‐ cluded carbaryl was least disruptive to the soil arthropod community [49]. Persistence and movement of 2.0% carbaryl within soils of wet and dry sites has been evaluated [50]. The highest concentrations of carbaryl were detected within the uppermost soil layers (upper

Carbaryl is relatively nontoxic to *Enoclerus lecontei* (Wolcott) [51] and *E*. *sphegeus* (F.) [52], and less toxic than either lindane or chlorpyrifos to *Temnochila chlorodia* (Mannerheim) [51], common predators of bark beetles in the western U.S. [32] measured the remedial efficacy of 0.25%, 0.5%, 1.0%, and 2.0% chlorpyrifos (Dursban®), fenitrothion (Sumithion®) and perme‐ thrin (Pounce®) on emerged and nonemerged predators and parasites of spruce beetle in Alaska. Two percent Pounce® had the least impact on emerged natural enemies while Durs‐ ban® and Sumithion® had the greatest impacts. In many cases, the lowest concentrations re‐ sulted in the highest mortality of emerged parasites and predators (74-94% mortality), but lowest mortality of nonemerged individuals. The authors attributed this to higher concen‐ trations resulting in prolong emergence [32]. Mortality of nonmerged parasites and preda‐ tors was <45% for all active ingredients and concentrations, except 2.0% chlorpyrifos [32].

Werner and Hilgert [53] monitored permethrin levels in a freshwater stream adjacent to Lutz spruce that were treated with 0.5% permethrin (Pounce®) to prevent spruce beetle at‐ tack. Treatments occurred within 5 m of the stream. Maximum residue levels ranged from 0.05 ± 0.01 ppb 5 h after treatment to 0.14 ± 0.03 ppb 8-11 h after treatment, declining to 0.02 ± 0.01 ppb after 14 h. Levels of permethrin in standing pools near the stream were 0.01 ± 0.01 ppb. Numbers of drifting aquatic invertebrates increased two-fold during treatment and four-fold 3 h after treatment and declined to background levels within 9 h. Trout fry, periph‐

Two studies have been published on the amount of drift resulting from carbaryl applica‐ tions to protect trees from bark beetle attack. In the early 1980s, [54] used spectrophotofluor‐ ometry to analyze ground deposition from the base of the ponderosa pine to 12 m from the bole in California. In a more recent study, [14] used high performance liquid chromatogra‐ phy (HPLC) to evaluate ground deposition occurring at four distances from the tree bole (7.6, 15.2, 22.9 and 38.1 m) during conventional spray applications for protecting individual

2.54 cm), with levels exceeding 20 ppm 90 d after application on most sites [50].

nia. Thus, registration is not being pursued at this time.

484 Insecticides - Development of Safer and More Effective Technologies

yton and benthic invertebrates were unaffected [53].

**7. Environmental concerns**

**Figure 6.** Average drift following experimental applications of carbaryl to protect trees from bark beetle attack, Uinta-Wasatch-Cache National Forest, Utah, U.S. Data obtained from Fettig et al. (2008). Wind speed was correlated with drift up to 22.9 m from the tree bole, and direction largely influenced the direction of prevailing drift. For example, while deposition is detected at 38.1 m on the leeward side of treated trees (maximum wind speeds averaged 3.5 km/h), drift is undetectable less than half that distance on the windward side. Less drift is expected in dense forest stands due to reduced wind speeds and interception by foliage. Studies show no-spray buffers will ensure that adja‐ cent aquatic and terrestrial environments are protected from negative impacts.

Fettig et al. [14] reported mean deposition values from 0.04 ± 0.02 mg carbaryl/m2 at 38.1 m to 13.30 ± 2.54 mg carbaryl/m2 at 7.6 m. Overall, distance from the tree bole significantly af‐ fected the amount of deposition. Deposition was greatest 7.6 m from the tree bole and de‐ clined quickly thereafter. Approximately 97% of total spray deposition occurred within 15.2 m of the tree bole (Fig. 6). To evaluate the potential risk to aquatic environments, the authors converted mean deposition to mean concentration assuming a water depth of 0.3 m selected to represent the average size of lotic systems, primarily small mountain streams, adjacent to many recreational sites where bole sprays are often applied [14]. No adjustments were made for the degradation of carbaryl by hydrolysis, which is rapid in streams or for dilution by natural flow. Comparisons were made with published toxicology data available for select aquatic organisms. No-spray buffers of 7.6 m are sufficient to protect freshwater fish, am‐ phibians, crustaceans, bivalves and most aquatic insects. In laboratory studies, carbaryl was found to be highly toxic to stoneflies (Plecoptera) and mayflies (Ephemeroptera), which are widely distributed and important food sources for freshwater fishes, but negative impacts in field populations are often short-lived and undetectable several hours after contamination [55]. No-spray buffers >22.9 m appear sufficient to protect the most sensitive aquatic insects such as stoneflies.

technical assistance in the U.S. can be obtained from Forest Health Protection (USDA Forest Service) entomologists (www.fs.fed.us/foresthealth/), state forest entomologists, and county extension agents (www.csrees.usda.gov/Extension/). We encourage use of these resources

Advances in Insecticide Tools and Tactics for Protecting Conifers from Bark Beetle Attack in the Western United States

http://dx.doi.org/10.5772/54178

487

We thank Stanislav Trdan (University of Ljubljana) and Romana Vukelic and Danijela Duric (InTech) for their invitation to contribute and guidance during the publishing process. Nu‐ merous colleagues from Arborjet Inc., BASF, Bayer ES, Bureau of Land Management (U.S.), FMC Corp., Fruit Grower's Supply Co., Mauget Inc., Nevada Division of Forestry, Sierra Pa‐ cific Industries, Southern Ute Reservation, Syngenta Crop Protection, Texas A&M Forest Service, Univar USA Inc., University of Arizona, University of California, University of Georgia, and USDA Forest Service have contributed to the success of much of the research

This publication concerns pesticides. It does not contain recommendations for their use, nor does it imply that the uses discussed here have been registered. All uses of pesticides in the United States must be registered by appropriate State and/or Federal agencies. CAUTION: Pesticides can be injurious to humans, domestic animals, desirable plants, and fish or other wildlife—if they are not handled or applied properly. Follow recommended practices for the

and A. Steven Munson3

[1] Fettig CJ, Klepzig KD, Billings RF, Munson AS, Nebeker TE, Negrón JF, Nowak JT. The Effectiveness of Vegetation Management Practices for Prevention and Control of Bark Beetle Outbreaks in Coniferous Forests of the Western and Southern United

discussed in this chapter. We are thankful for their support and helpful insights.

disposal of surplus pesticides and their containers.

\*Address all correspondence to: cfettig@fs.fed.us

2 Forest Health, Texas A&M Forest Service, Lufkin, USA

, Donald M. Grosman2

3 Forest Health Protection, USDA Forest Service, Ogden, UT, USA

States. Forest Ecology and Management 2007; 238 24-53.

1 Pacific Southwest Research Station, USDA Forest Service, Davis, CA, USA

before applying any insecticides to protect trees from bark beetle attack.

**Acknowledgements**

**Author details**

**References**

Christopher J. Fettig1

An advantage of tree injections is that they can be used on environmentally-sensitive sites as these treatments represent an essentially closed system and therefore little or no contamina‐ tion occurs outside of the tree. However, following injection residues move within the tree and are frequently detected in the foliage [e.g., 44,56-57], which could pose a risk to decom‐ posers and other soil fauna when needles senesce. This has been shown for imidacloprid in maple [57], but injections of emamectin benzoate in pines appear of little risk. For example, [56] reported emamectin benzoate was not detected in the roots or the surrounding soil, but was present at 0.011–0.025 µg/g in freshly fallen pine needles. However, levels gradually de‐ clined to below detectable thresholds after 2 months [56].
