Peter Rosenkranz

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The ectoparasitic honey bee mite Varroa destructor was originally confined to the Eastern honey bee Apis cerana. After a shift to the new host Apis mellifera during the first half of the last century, the parasite dispersed world wide and is currently considered the major threat for apiculture. The damage caused by Varroosis is thought to be a crucial(More)
The Western honey bee, Apis mellifera, is the most important animal pollinator in agriculture worldwide providing more than 90% of the commercial pollination services. Due to the development in agriculture the demands for honey bee pollination are steadily increasing stressing the pollination capacity of the global managed honey bee population. Hence, the(More)
Africanized honey bees (AHBs) of Brazil and Mexico have proven to be tolerant to Varroa destructor mites. In contrast, European honey bees (EHBs: Apis mellifera carnica) at the same tropical study site are highly intolerant to these ectoparasites. A lower attractiveness of Varroa-tolerant AHB larvae has been hypothesised to be an important trait in reducing(More)
The honey bee parasite Varroa destructor Anderson & Trueman can disperse and invade honey bee colonies by attaching to "drifting" and "robbing" honey bees that move into nonnatal colonies. We quantified the weekly invasion rates and the subsequent mite population growth from the end of July to November 2011 in 28 honey bee colonies kept in two apiaries that(More)
In Europe and North America honey bees cannot be kept without chemical treatments against Varroa destructor. Nevertheless, in Brazil an isolated population of Italian honey bees has been kept on an island since 1984 without treatment against this mite. The infestation rates in these colonies have decreased over the years. We looked for possible(More)
Varroa destructor is a highly virulent ectoparasitic mite of the honey bee Apis mellifera and a major cause of colony losses for global apiculture. Typically, chemical treatment is essential to control the parasite population in the honey bee colony. Nevertheless a few honey bee populations survive mite infestation without any treatment. We used one such(More)
Very little data exists concerning the number of reproductive cycles performed by individual Varroa mites. To understand the population dynamics of the Varroa mite it is necessary to know the number of fertile female offspring each Varroa female produces during her lifetime. The lifetime reproduction capacity of the mite consists of the mean number of(More)
The reproductive cycle of the parasitic mite Varroa destructor is closely linked to the development of the honey bee host larvae. Using a within colony approach we introduced phoretic Varroa females into brood cells of different age in order to analyze the capacity of certain stages of the honey bee larva to either activate or interrupt the reproduction of(More)
Pathogens and parasites may facilitate their transmission by manipulating host behavior. Honeybee pathogens and pests need to be transferred from one colony to another if they are to maintain themselves in a host population. Inter-colony transmission occurs typically through honeybee workers not returning to their home colony but entering a foreign colony(More)
Varroa reproduction is closely synchronized to the development of its host. In this study we present a new bioassay for field and laboratory tests to evaluate host factors triggering Varroa oogenesis. Female mites deprived of feeding activated oogenesis when perceiving larval volatiles. In laboratory assays the living L5-larva and pentane extracts of the(More)