Bees are ecologically important, as the world’s major pollinators. Out of the 100 crop species that provide 90% of food worldwide, 71 are estimated to be pollinated by bees [Food and Agriculture Organization of the United Nations (FAO), Global honey bee colony disorders and other threats to insect pollination, 2011]. Bees, specifically honeybees, have been used in experimental models for ecotoxicology studies. Other types of bees – bumblebees, solitary bees and stingless bees – are also important ecologically. New technologies now enable field and semi-field ecotoxicology studies of all types of bees and the assessment of new endpoints.
The gold standard in bee studies is the field study, which monitors bees in their normal environment. Field studies, however, are notoriously complex and expensive. Semi-field studies, where bees are kept outside in cages, mimic the natural environment while better controlling the test product. Having reliable, meaningful and sensitive semi-field and cage studies reduces the need for higher-tier field studies. The combination of bee studies with toxicology assessments can generate a robust and powerful ecotox data set.
New nest systems allow enhanced data collection
Bees can be monitored without disturbance using new nest systems which employ techniques more commonly used in engineering and electronics manufacturing. Innovations include electronic counters, image recognition software, sensors, pollen traps and dead bee traps.
For example, bumble bee movements in and out of the nests can be counted, timed and logged with the whole season’s data recorded on a memory card, or automatically transmitted by mobile phone technology. Queens can be distinguished from workers and drones; the movement of identified individuals can be tracked; and pollen loads can be photographed and the weight calculated. All of these functions can be carried out with minimal disturbance and without the need for field technicians to visit the site. Other bespoke features can be built in to the equipment as required.
New approaches to providing nests for solitary bees such as mason bees and leafcutter bees allow easy access to nest cavities during the active period. This enables the lifespan of every individual in the nest to be studied from egg to adult and the impacts both subtle and gross, of products to be recorded and assessed. The data is abundant and verifiable. The nest components are designed to fit in a commercial x-ray machine so that long-term viability can be assessed without opening cocoons. Once again there is the option of building in automatic recording systems.
More sophisticated endpoints
These advances in technology have expanded endpoint measurements. Historically, data collection and endpoints from bee studies have been quite crude. Bee mortality – measured by counting the number of dead bees – is the main endpoint of interest in most studies. By using technology, more sophisticated and robust data can be gathered more reliably, enabling the assessment of subtle endpoints and sublethal effects on bee pollinations.
The assessment of subtle changes in bee response to exposure is important to assess the whole agricultural process. This is especially important as many crops (and pollinators) are exposed to multiple chemicals at different times in their growth cycle.
Bees under pressure
Worldwide bee populations are under threat from parasites and pesticides. Governments and regulators are looking at bee protection measures, although uncertainties across the globe are causing some concern for their advancement.
The European Food Safety Authority (EFSA) has proposed extensive changes to European legislation. These are being critically analyzed by industry, laboratories, advisory bodies, academia, and bee organizations. How Brexit will impact this situation in the UK is unclear. The MUST-B group of the EFSA assesses the impact of a variety of stressors, including pesticides, on bee populations. Their recent report Specifications for field data collection contributing to honey bee model corroboration and verification will help inform risk assessment models for bees.
In the USA, Donald Trump’s announcement that he will take the USA out of the Paris Climate Accord confirms his hardline attitude to environmental issues and may indicate a further rolling back of ecotoxicology programs by the Environmental Protection Agency (EPA).
For more information about bee studies, you can read the Development in Life Sciences article ‘Innovations in ecotoxicology: it really is the bee’s knees’ by Matt Allan from Atlantic Pollination.