This study assessed the effects of exposure to IGRs on the long-term development of the honeybee colony, viability of queens and sperm production in drones and integrated the data into a honeybee population model. Colonies treated with diflubenzuron resulted in a short-term reduction in the numbers of adult bees and brood. Colonies treated with fenoxycarb declined during the season earlier and started the season slower. The number of queens that successfully mated and laid eggs was affected in the fenoxycarb treatment group but there were no significant differences in the drone sperm counts between the colonies. An existing honeybee population model was modified to include exposure to IGRs. In the model, fenoxycarb reduced the winter size of the colony, with the greatest effects following a June or an August application. Assuming a 'larvae per nurse bee' ratio of 1.5 for brood rearing capability, the reduction in winter size of a colony following a fenoxycarb application was at its worst about 8%. However, even if only those bees reared within 2 weeks of the IGR being applied are subject to premature ageing, this might significantly reduce the size of over-wintering colonies, and increase the chance of the bee population dwindling and dying in late winter or early spring.
Systems have been developed to monitor the direct effects of insect growth regulator (IGR) pesticide exposure on honey bee development, but there has been little work on the longer-term impact of exposure on the colony. A honey bee population model provided the opportunity to investigate the effects of short-term mortality of brood and of sublethal changes in behaviour of the surviving adults on honey bee populations. The model showed that brood mortality alone has limited effect on colony size. There were two mechanisms that could have greater influence on productivity. Precocious foraging in affected adult bees, and hence early loss of brood-rearing (nurse) capabilities, had a much larger effect than expected. Increasing mortality rates by 30% to simulate sublethal effects on lifespan, rather than reduced brood-rearing capability, gave a significantly smaller effect. In order to simulate an effect with the 'shortened lifespan' mechanism as large as that with the 'premature ageing' mechanism, the mortality rate of affected adults had to be increased by 500%. A significant finding from the model is that application of IGRs in spring and early summer could have substantial effects on colony size and viability. Sublethal effects such as precocious foraging can have worse effects than massive brood mortality, as it severely reduces the ability to rear the next generation of nurse bees.
-Colonies infected with European foulbrood (EFB) were treated with the shook swarm method in combination with oxytetracycline (OTC) and compared with those treated with OTC alone, the usual treatment for EFB in England and Wales. Success rates and instances of recurrence in the following season were recorded in the seasons 2000 and 2001 respectively. Both treatments had similar success rates with respect to elimination of EFB in 2000. Shook swarm plus OTC treatment resulted in a lower level of EFB recurrence in the 2001 season than OTC treatment alone. Colonies treated with the shook swarm plus OTC method showed a recurrence rate of 4.8%, whereas those treated with OTC alone had a recurrence in 21.1% of cases. The differences were shown to be significant at the 10% level. These results suggest that the shook swarm plus OTC method could be a valid method for EFB treatment and control in the UK.European foulbrood / shook swarm / oxytetracycline / disease control / alternative method
-Kashmir bee virus (KBV) often persists in bees as a covert infection with no apparent symptoms. The virus can switch to become an overt lethal infection, especially in the presence of Varroa mites. Although the virus is distributed worldwide, it was thought to be absent from the UK. A real-time PCR assay was developed for specific detection of KBV. No cross-reaction was observed with other bee viruses. KBV was successfully amplified from different life stages of honey bees and from a wasp and bumble bee. Using the real-time PCR assay, a survey of hives was conducted in England and Wales to investigate the presence and geographical distribution of the virus. KBV was detected within three colonies at two locations. The virus titre in the positive samples was quantified and found to contain similar levels to other bees with covert KBV infection. We conclude that KBV is present in the UK and cannot now be considered an exotic disease. The discovery of KBV in the UK has major significance for import policies.
This study aimed to assess oxytetracycline (OTC) residue levels in honey up to 12 weeks after treatment of honeybee colonies with two methods of application (in liquid sucrose and in powdered icing sugar). Significantly greater mortality was seen in the all stages of brood development for the treated colonies when compared with the controls. Samples of honey were extracted up to 12 weeks after treatment and analysed by HPLC following metal chelation with a limit of quantitation of 0.05 mg/kg. These data showed that the current method of application of Terramycin in liquid form results in very high residue levels in honey with residues of 3.7 mg/kg eight weeks after application. Further work is required to determine whether the levels can be further reduced by changes in the method of application whilst ensuring efficacy and minimizing the effects on brood.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.