Acute and massive bee mortality - Mass spectrometry as investigation tool

Bees play an essential role in the balance of our ecosystems. Bee mortality is a natural phenomenon in apiaries, with 5-10% of colonies dying each winter. However, since the mid-80s, cases of over-mortality of bee colonies have been observed worldwide. Since 1998, the phenomenon has been known as Colony Collapse Disorder (CCD). It is a complex phenomenon with multiple origins: biological causes, exposure to chemicals used in the environment, diet, beekeeping practices, etc. The diversity of these causes, which may occur in isolation or in combination, is likely to contribute to the weakening of colonies, or even cause acute mass bee mortality (AMBM). A bee colony is considered to be a victim of AMM when, suddenly and over a period of less than 15 days, adult bees are found dead or moribund in the form of a carpet in front of or in the hive (volume of bees affected greater than one liter), and/or when the colony suffers from depopulation (excluding swarming), i.e. the disappearance of a large proportion of adult bees, with the presence in the hive of a very small population of bees with brood, honey and pollen reserves.

In Normandy, the Departmental Directorates for the Protection of Populations (DDPP) centralize beekeepers' MMAA declarations and observations. The veterinarian must then direct the investigations if there is a suspicion of diseases classified as first category health hazards, such as: American foulbrood, nosema, the small hive beetle (Aethina tumida) and the parasitic mite Tropilaelaps clareae, or if there is a suspicion of MMAA linked to poisoning by chemical agents such as phytopharmaceutical products, biocides or veterinary medicines. Cases of decline or weakening are not currently taken into account in this system, as they are not of an acute nature. Among these potentially toxic products, research has focused mainly on pesticides such as organophosphates, organochlorines, pyrethroids and neonicotinamides. However, it would be interesting to monitor other insecticide families or other types of pesticide molecules, such as herbicides and fungicides, to which bees may be potentially exposed in their environment. In order to meet these needs, the aim of this article is therefore to determine rapidly, after the collection of dead bee samples, the presence of chemicals in a sufficiently broad spectrum, to help the authorities take the appropriate sanitary measures and to define the follow-up to be given, by investigating the origin of the contamination. To this end, several analyses are carried out in the laboratory.