Health status of honey bee colonies (Apis mellifera) and disease-related risk factors for colony losses in Austria

Abstract

Austrian beekeepers frequently suffered severe colony losses during the last decade similar to trends all over Europe. This first surveillance study aimed to describe the health status of Austrian bee colonies and to analyze the reasons for losses for both the summer and winter season in Austria. In this study 189 apiaries all over Austria were selected using a stratified random sampling approach and inspected three times between July 2015 and spring 2016 by trained bee inspectors. The inspectors made interviews with the beekeepers about their beekeeping practice and the history of the involved colonies. They inspected a total of 1596 colonies for symptoms of nine bee pests and diseases (four of them notifiable diseases) and took bee samples for varroa mite infestation analysis. The most frequently detected diseases were three brood diseases: Varroosis, Chalkbrood and Sacbrood. The notifiable bee pests Aethina tumida and Tropilaelaps spp. were not detected. During the study period 10.8% of the 1596 observed colonies died. Winter proved to be the most critical season, in which 75% of the reported colony losses happened. Risks for suffering summer losses increased significantly, when colonies were weak in July, had queen problems or a high varroa mite infestation level on bees in July. Risks for suffering winter losses increased significantly, when the colonies had a high varroa mite infestation level on bees in September, were weak in September, had a queen older than one year or the beekeeper had few years of beekeeping experience. However, the effect of a high varroa mite infestation level in September had by far the greatest potential to raise the winter losses compared to the other significant factors.

A citizen science supported study on seasonal diversity and monoflorality of pollen collected by honey bees in Austria

“…This meant that the apiary locations were not selected for special landscape traits as in previous studies, but comprised a real situation at often year-long established apiaries. We obtained samples from all nine Austrian federal provinces, with a majority coming from Eastern Austria, which also reflects the distribution of beekeeping intensity in Austria 40 . As retention is important in citizen science investigations 41 , we tried to keep motivation high, by providing detailed palynological results of their sampling location to the citizen scientists.…”

Detection of amitraz resistance and reduced treatment efficacy in the Varroa Mite, Varroa destructor, within commercial beekeeping operations

“…The parasitic mite, Varroa destructor (hereto referred to as Varroa), is the most critical cause of honey bee colony loses in commercial beekeeping operations [22][23][24][25]. Since its arrival in the late 1980s, the detrimental impact of Varroa has amplified in commercial beekeeping operations in the USA [26].…”

Summer weather conditions influence winter survival of honey bees (Apis mellifera) in the northeastern United States

“…Thus, factors which undermine the ability of the bees to collect and store adequate amounts of food during the summer and fall, or to thermoregulate effectively during the winter, or reduce the lifespan of winter bees, can contribute to colony mortality. These factors include: beekeeper management practices that affect parasite and pathogen loads, particularly control of Varroa mites 11 – 13 ; forage quality and pesticide exposure due to the surrounding land use 14 ; and weather factors which influence the availability of forage, the thermoregulatory ability of the bees in the winter, and the amount of time before bees are able to initiate brood rearing in the spring 15 . Modeling and predicting honey bee winter survival requires consideration of all of these factors.…”