Detections of the neonicotinoid insecticide imidacloprid in surface waters of three agricultural regions of California, USA, 2010-2011.

Seventy-five surface water samples were collected from three agricultural regions of California and analyzed for the neonicotinoid insecticide imidacloprid. Samples were collected during California's relatively dry-weather irrigation seasons in 2010 and 2011. Imidacloprid was detected in 67 samples (89%); concentrations exceeded the United States Environmental Protection Agency's chronic invertebrate Aquatic Life Benchmark of 1.05 µg/L in 14 samples (19%). Concentrations were also frequently greater than similar toxicity guidelines developed for use in Europe and Canada. The results indicate that imidacloprid commonly moves offsite and contaminates surface waters at concentrations that could harm aquatic organisms following use under irrigated agriculture conditions in California.

Passage of fiproles and imidacloprid from urban pest control uses through wastewater treatment plants in northern California, USA.

Urban pest control insecticides-specifically fipronil and its 4 major degradates (fipronil sulfone, sulfide, desulfinyl, and amide), as well as imidacloprid-were monitored during drought conditions in 8 San Francisco Bay (San Francisco, CA, USA) wastewater treatment plants (WWTPs). In influent and effluent, ubiquitous detections were obtained in units of ng/L for fipronil (13-88 ng/L), fipronil sulfone (1-28 ng/L), fipronil sulfide (1-5 ng/L), and imidacloprid (58-306 ng/L). Partitioning was also investigated; in influent, 100% of imidacloprid and 62 ± 9% of total fiproles (fipronil and degradates) were present in the dissolved state, with the balance being bound to filter-removable particulates. Targeted insecticides persisted during wastewater treatment, regardless of treatment technology utilized (imidacloprid: 93 ± 17%; total fiproles: 65 ± 11% remaining), with partitioning into sludge (3.7-151.1 µg/kg dry wt as fipronil) accounting for minor losses of total fiproles entering WWTPs. The load of total fiproles was fairly consistent across the facilities but fiprole speciation varied. This first regional study on fiprole and imidacloprid occurrences in raw and treated California sewage revealed ubiquity and marked persistence to conventional treatment of both phenylpyrazole and neonicotinoid compounds. Flea and tick control agents for pets are identified as potential sources of pesticides in sewage meriting further investigation and inclusion in chemical-specific risk assessments. Environ Toxicol Chem 2017;36:1473-1482. © 2016 SETAC.

The efficacy of Advantix® to prevent transmission of Ehrlichia canis to dogs by Rhipicephalus sanguineus ticks.

The capacity of a topical combination of imidacloprid and permethrin (Advantix(®)) to prevent transmission of Ehrlichia canis was studied in two groups of six dogs. One group served as controls, whereas the other group was treated. All dogs were exposed to E. canis-infected Rhipicephalus sanguineus ticks on Days 7, 14, 21 and Day 28 post acaricidal treatment. The adult R. sanguineus ticks were released into the individual kennels of the dogs to simulate natural tick exposure. In situ tick counts were conducted on Day 9, 16 and 23 and any remaining ticks were counted and removed on Day 30. The efficacy of the acaricidal treatment against R. sanguineus ranged between 96.1% and 98.9% at 48 h post-application and lasted up to 4 weeks. Four out of six control dogs became infected with E. canis, as demonstrated by the presence of specific E. canis antibodies and the detection by PCR of E. canis DNA in blood samples. These dogs became thrombocytopenic and displayed fever and were consecutively rescue-treated by doxycycline. None of the six treated dogs became infected with E. canis, as confirmed by the lack of specific antibodies and absence of E. canis DNA in blood samples. Advantix(®) prevented transmission of E. canis and provided protection against monocytic ehrlichiosis for 4 weeks post acaricidal treatment.

Field evaluation of reduced insecticide spray programs for managing plum curculio, Conotrachelus nenuphar (Coleoptera: Curculionidae), in Alabama peaches.

BACKGROUND: Plum curculio (PC), Conotrachelus nenuphar (Herbst.), is an important pest of peaches in the southeastern United States. Commercially acceptable control of this insect is typically achieved by weekly or biweekly application of broad-spectrum conventional insecticides, resulting in 6-12 sprays per season. Experiments were conducted in a peach orchard in Alabama during 2007-2009 to compare the conventional calendar-based insecticide spray program involving weekly applications of phosmet with three different reduced spray programs using three targeted (well-timed) insecticide sprays (TIS) of phosmet, permethrin or thiamethoxam applied in an alternated fashion. RESULTS: All three TIS programs significantly reduced PC damage at harvest compared with the untreated control in two of the three years (2008 and 2009). Fruit damage due to stink bugs, which are emerging pests of peaches in the region, was also significantly reduced in the TIS programs in both years. In a separate trial in which one of the TIS programs (three targeted sprays of phosmet) was evaluated in a larger peach block in 2009, percentage fruit damage due to PC increased from < 1% in June to ~4% in late July. CONCLUSION: All the TIS programs evaluated provided effective control of PC and represent potential alternatives to the conventional weekly spray program in peaches with concomitant reduction in insecticide usage and associated costs. However, an additional spray may be necessary for effective control of PC and stink bugs in late-season peach varieties.

[New drinking water reference values for monocyclic nitro compounds]. / Neue Trinkwasser-Leitwerte für monocyclische Nitroverbindungen.

Nitro compounds are important industrial chemicals with a broad range of applications. During their commercial production or practical use and through leaching from military waste sites they may be released into the environment and thus lead to a contamination of drinking water resources. In the last 15-20 years, the wider public first became aware of nitro compounds as contaminants in groundwater and drinking water resources that originated from manufacturing and processing of secondary explosives during World War II. In 1980, the former Bundesgesundheitsamt (BGA; Federal Health Office) had based its first risk assessment of monocyclic nitro compounds in drinking water on the known carcinogenicity of some aromatic amines in the working environment. On this basis, the BGA recommended for metabolites of aromatic nitro compounds a guide value of 0.1 mug/l for the sum of aromatic amines. From the beginning to the middle of the 1990s, the BGA established a more specific health-related assessment for the individual compounds, but not on the basis of tolerable or acceptable body doses but of dimensionless risk assessment scores ranking their combined toxic and carcinogenic potential on a scale from 1 to 100. In this contribution, we derived new health-based drinking water guide values for 19 nitro(aromatic) compounds and nitramines, including hexogen, octogen, and tetryl as well as the O-nitro compound PETN. All compounds under consideration have been detected within the last 15 years in Germany at contaminated sites close to or directly in groundwater resources for drinking water. For toxicological evaluation and derivation of guideline values for the nitro compounds of interest, the tolerable daily intake (TDI) approach was used for chemicals exhibiting a threshold for toxic effects. This was done by using established tolerable body doses for humans based on an identified NOAEL/LOAEL for the most sensitive toxic endpoint. In the case of non-threshold chemical substances, suitable estimates of excess lifetime cancer risk have been applied.