Comparative pesticide exposure to Apis mellifera via honey bee-collected pollen in agricultural and non-agricultural areas of Northern Thailand

Abstract

Pollen is a known route of pesticide exposure in bees, and pollen diversity and quality are necessary for optimal honey bee development and longevity. Here, the nutritional richness of protein for bees based on pollen/plant diversity and the pesticide residues in pollen were studied. Honey bee colonies (Apis mellifera L.) were used to collect pollen at monthly intervals in four provinces (Chiang Mai, Lampang, Phayao and Phrae) of Northern Thailand. One agricultural and one non-agricultural site in four provinces were selected for a total of eight distinct sites. Bee-collected pollen was sorted by color and identified to family using light microscopy to estimate plant diversity at each location. Gramineae and Asteraceae were the most common pollen types collected by honey bees in eight locations in northern Thailand. The two sites in Chiang Mai province consistently showed ample plant diversity as six or more pollen types were recorded on dates of collection. In general, Phayao had the lowest pollen diversity in both agricultural and non-agricultural sites with only 1–3 pollen types collected in each area. Plantaginaceae was only found in March-April in the agricultural area of Phrae province. Moreover, we found eight different pesticides such as herbicides, fungicides, formamidines, organophosphates, pyrethroids and neonicotinoids at different levels in agricultural area but only four pesticides were detected in non-agricultural locations. Overall the detection of agricultural chemicals was low relative to other studies in Europe and North America. Therefore, many areas of Northern Thailand do offer a relatively clean environment in which to keep honey bees and produce honey.