Biology subjects

Odemer, R.

Publications and source records attributed to Odemer, R..

3 recordsLinked to original sources

bioRxiv2018

Effects of radiofrequency electromagnetic radiation (RF-EMF) on honey bee queen development and mating success

Mobile phones can be found almost everywhere across the globe, upholding a direct point-to-point connection between the device and the broadcast tower. The emission of radiofrequency electromagnetic radiation (RF-EMF) puts the surrounding environment inevitably into contact with this pollutant. We have therefore exposed honey bee queen larvae to the radiation of a common mobile phone device (GSM) during all stages of their pre-adult development including pupation. After 14 days of exposure, hatching of adult queens was assessed and mating success after further 11 days, respectively. Moreover, full colonies were established of five of the untreated and four of the treated queens to contrast population dynamics. We found that mobile phone radiation had significantly reduced the hatching ratio but not the mating success. If treated queens were successfully mated, colony development was not adversely affected. We provide evidence that RF-EMF only acts detrimental within the sensitivity of pupal development, once succeeded this point, no further impairment has manifested in adulthood. Our results are discussed against the background of long-lasting consequences for colony performance and the possible implication on periodic colony losses.\n\nHIGHLIGHTSO_LIChronic RF-EMF exposure significantly reduced hatching of honey bee queens\nC_LIO_LIMortalities occurred during pupation, not at the larval stages\nC_LIO_LIMating success was not adversely affected by the irradiation\nC_LIO_LIAfter the exposure, surviving queens were able to establish intact colonies\nC_LI\n\nGRAPHICAL ABSTRACT\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=117 SRC=\"FIGDIR/small/434142_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (27K):\norg.highwire.dtl.DTLVardef@920c50org.highwire.dtl.DTLVardef@668289org.highwire.dtl.DTLVardef@42b0corg.highwire.dtl.DTLVardef@1a6355a_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

bioRxiv2018

Honey bee workers reared in a neonicotinoid contaminated in-hive environment

With the currently updated risk assessment of three neonicotinoid pesticides, the European Food Safety Authority has confirmed that different applications of these substances represent a risk to wild and managed bees and their use was therefore severely restricted. However, to close further gaps in knowledge, this experiment covers exposure of honey bee worker brood reared in a neonicotinoid contaminated in-hive environment with focus on the individual. In a worst case scenario, mini-hives were fed chronically with a sublethal concentration of clothianidin (15 {micro}g/kg), which is highly toxic to bees already in small amounts. Freshly hatched workers from these colonies were subsequently marked and introduced into non-contaminated colonies, where their lifespan and behavior was monitored. Nineteen days after exposure, clothianidin treated bees had no reduced lifespan or showed any signs of behavioral impairment when compared to the control, demonstrating that social buffering is not a simple substitution of dead bees by rearing more brood. Our results suggest that the social environment plays a crucial role for the individual in terms of \"superorganism resilience\". These findings are discussed in context with the current use of lower tier test systems in risk assessment and contrary results obtained from laboratory experiments.\n\nHIGHLIGHTSO_LISublethal clothianidin treatment did not affect lifespan nor behavior of workers.\nC_LIO_LIEffects on individual bees reared within a mini-hive are translatable to full-sized colonies.\nC_LIO_LI\"Superorganism resilience\" is not a simple substitution of dead bees by rearing more brood.\nC_LIO_LILaboratory testing in the risk assessment of plant protection products bears severe weaknesses.\nC_LI

pharmacology and toxicology↗

bioRxiv2018

Chronic exposure to a neonicotinoid pesticide and a synthetic pyrethroid in full-sized honey bee colonies

In the last decade, the use of neonicotinoid insecticides increased significantly in the agricultural landscape and meanwhile considered a risk to honey bees. Besides the exposure to pesticides, colonies are treated frequently with various acaricides that beekeepers are forced to use against the parasitic mite Varroa destructor. Here we have analyzed the impact of a chronic exposure to sublethal concentrations of the common neonicotinoid thiacloprid (T) and the widely used acaricide {tau}-fluvalinate (synthetic pyrethroid, F) - applied alone or in combination - to honey bee colonies under field conditions. The population dynamics of bees and brood were assessed in all colonies according to the Liebefeld method. Four groups (T, F, F+T, control) with 8-9 colonies each were analyzed in two independent replications, each lasting from spring/summer until spring of the consecutive year. In late autumn, all colonies were treated with oxalic acid against Varroosis. We could not find a negative impact of the chronic neonicotinoid exposure on the population dynamics or overwintering success of the colonies, irrespective of whether applied alone or in combination with {tau}-fluvalinate. This is in contrast to some results obtained from individually treated bees under laboratory conditions and confirms again an effective buffering capacity of the honey bee colony as a superorganism. Yet, the underlying mechanisms for this social resilience remain to be fully understood.

zoology↗