Chronic exposure to neonicotinoids reduces honey bee health near corn crops.

Experiments linking neonicotinoids and declining bee health have been criticized for not simulating realistic exposure. Here we quantified the duration and magnitude of neonicotinoid exposure in Canada's corn-growing regions and used these data to design realistic experiments to investigate the effect of such insecticides on honey bees. Colonies near corn were naturally exposed to neonicotinoids for up to 4 months-the majority of the honey bee's active season. Realistic experiments showed that neonicotinoids increased worker mortality and were associated with declines in social immunity and increased queenlessness over time. We also discovered that the acute toxicity of neonicotinoids to honey bees doubles in the presence of a commonly encountered fungicide. Our work demonstrates that field-realistic exposure to neonicotinoids can reduce honey bee health in corn-growing regions.

Managing selenium-contaminated agricultural drainage water by the integrated on-farm drainage management system: role of selenium volatilization.

The Integrated on-Farm Drainage Management (IFDM) system was designed to dispose of selenium (Se)-contaminated agricultural irrigation drainage water through the sequential reuse of saline drainage water to grow crops having different salt tolerance. This study quantified the extent of biological volatilization in Se removal from the IFDM system located in the western San Joaquin Valley, California. Selenium volatilization from selected treatment areas, including pickleweed (Salicornia bigelovii Torr.), saltgrass (Distichlis spicata L.), bare soil, and the solar evaporator, was monitored biweekly using an open-flow sampling chamber system during the pickleweed growing season from February to September 1997, and monthly from September 1997 to January 1998. Biological volatilization from the pickleweed section removed 62.0 +/- 3.6 mg Se m(-2) y(-1) to the atmosphere, which was 5.5-fold greater than the Se accumulated in pickleweed tissues (i.e., phytoextraction). The total Se removed by volatilization from the bare soil, saltgrass, and the solar evaporator was 16.7 +/- 1.1, 4.8 +/- 0.3, and 4.3 +/- 0.9mg Se m(-2) y(-1), respectively. Selenium removal by volatilization accounted for 6.5% of the annual total Se input (957.7mg Sem(-2) y(-1)) in the pickleweed field, and about 1% of the total Se input (432.7 mg Se m(-2) y(-1)) in the solar evaporator. We concluded that Se volatilization under naturally occurring field conditions represented a relatively minor, but environmentally important pathway of Se removal from the IFDM system.

In vitro acaricidal effect of plant extract of neem seed oil (Azadirachta indica) on egg, immature, and adult stages of Hyalomma anatolicum excavatum (Ixodoidea: Ixodidae).

Effects of the plant extract of neem seed (Azadirachta indica) on eggs, immature, and adult stages of Hyalomma anatolicum excavatum was studied at concentrations of 1.6, 3.2, 6.4, and 12.8%. The extract was found to have a significant effect on the hatching rate of eggs. It significantly increased the hatching rate during the first 7 days post-treatment (DPT) giving incompletely developed and dead larvae; however, it cause hatching failure at DPT 15. Neem Azal F induced a significant increased in mortality rates of newly hatched larvae, unfed larvae, and unfed adults reaching 100% on 15th, 3rd, and 15th DPT, respectively. The mortality rates increased with the extract concentrations. Although, it had no significant effect on the moulting rates of fed nymphs, it caused malformation or deformities in 4% of adults moulted. It was concluded that the concentration of Neem Azal F which may be used for commercial control of this tick species were 1.6 and 3.2%.