Survival rate of honeybee (Apis mellifera) workers after exposure to sublethal concentrations of imidacloprid

Imidacloprid is a commonly used systemic insecticide which can induce several sublethal effects. Previous research has not shown any increased mortality in bees that were fed with sublethal doses. However, there is very little research conducted with the focus on survival rate of honeybees in the field. The aim of this study is to assess the influence of imidacloprid on the survival rate of honeybees under field conditions. Honeybees from different colonies were administered a single dose of imidacloprid of 0, 0.07, 0.7, 7 or 70 ng per bee. From each concentration one group was kept in the laboratory to assess lethal effects and one group was returned to the hive to assess possible sublethal effects. The surviving bees were counted regularly during 4 weeks. Analysis has shown no difference in survival rate between treatments in the laboratory. There is a difference between the 70 ng treatment and the control group in the field (

Care for bees: for many reasons and in many ways

Pollinating insects are in decline, probably worldwide. This may imply a pollination crisis, for (food) crops as well as wild plants. Eventually this decline might result in great economic losses, a human food crisis and loss of natural biodiversity. Although the world population of honeybee colonies still increases (despite decreases in many countries) it is urgently needed to take care for bees and other pollinators. Possible drivers for the decline of insect pollinators in general are (1) habitat loss and intensive land use, (2) globalization and introductions of foreign species, (3) pollution including pesticides, and (4) climate change. For honeybees in particular: (5) worldwide presence of the invasive parasitic mite Varroa destructor (as a consequence of [2]), (6) introduction and spread of other (new) parasites, (7) loss of the honeybee’s genetic diversity, and (8) detrimental beekeeping practices. Simultaneously the beekeeping sector in many countries is vanishing for demographical reasons and a lack of incentives for beekeeping. The Dutch beekeeping almost fully depends on hobbyists, which results in little professional education and the absence of a professional extension service. Nevertheless the beekeeping standard has to improve to help the beekeeping sector to cope with the upcoming challenges and to safeguard the need for pollination in professional agricultur

The Metaphysics of Mental Representation

The representational theory of mind (RTM) explains the phenomenon of intentionality in terms of the existence and nature of mental representations. Despite the typical characterisation of mental representations in terms of their semantics, RTM is best understood as a metaphysical – more specifically formal ontological – theory whose primary defining feature is stipulating the existence of a class of mental particulars called representations. In this regard it is false, since mental representations do not exist. My argument is primarily methodological. Using an extended analysis of mereology and its variants as paradigmatic examples of a formal ontological theory, I argue for a 'synthetic’ approach to ontology which seeks to form a sound descriptive characterisation of the relevant phenomena from empirical data, to which philosophical analysis is applied to produce a rigorous theory. The value and necessity of this method is proved by example in our discussion of mereology which is shown to be defensible given certain assumptions, in particular perdurantism, but still inadequate as an account of parthood without considerable supplementation. We also see that there are viable alternatives which adopt a more synthetic approach and do not require the same assumptions. Having effectively demonstrated the value of a synthetic approach in ontology I critically examine the methodology employed by RTM and find it severely lacking. In the guise of ‘commonsense psychology’ RTM cavalierly imposes a theoretical framework without regard to empirical data, and this results in a severe distortion of the phenomenon of intentionality it purports to explain. RTM is methodologically unsound, and so its commitment to the existence of mental representations is utterly undermined. Furthermore the most attractive aspect of RTM – its semantics – can be separated from any commitment to mental representations existing. Even RTM’s strongest advocates lack motivation to believe that mental representations exist

Neonicotinoids impact bumblebee colony fitness in the field; a reanalysis of the UK’s Food & Environment Research Agency 2012 experiment

The causes of bee declines remain hotly debated, particularly the contribution of neonicotinoid insecticides. In 2013 the UK’s Food & Environment Research Agency made public a study of the impacts of exposure of bumblebee colonies to neonicotinoids. The study concluded that there was no clear relationship between colony performance and pesticide exposure, and the study was subsequently cited by the UK government in a policy paper in support of their vote against a proposed moratorium on some uses of neonicotinoids. Here I present a simple re-analysis of this data set. It demonstrates that these data in fact do show a strong negative relationship between both colony growth and queen production and the levels of neonicotinoids in the food stores collected by the bees. Indeed, this is the first study describing substantial negative impacts of neonicotinoids on colony performance of any bee species with free-flying bees in a field realistic situation where pesticide exposure is provided only as part of normal farming practices. It strongly suggests that wild bumblebee colonies in farmland can be expected to be adversely affected by exposure to neonicotinoids

Deksel van de zwarte doos van Darwin op een kiertje.

Al sinds 1983, toen de Varroamijt in de Nederlandse bijenvolken aan zijn opmars begon, hebben wij als imkers ons best gedaan om de mijten te bestrijden. Wetend dat anders de volken in twee jaar zouden bezwijken. Dat heeft geholpen, en inmiddels lukt het om de jaarlijkse sterfte in de winter redelijk laag te houden (zie artikeltje van Bram Cornelissen). Alleen, bestrijden heeft ook nadelen. Het belangrijkste nadeel is dat door de bestrijding de bijen en de mijten zich niet aan elkaar kunnen aanpassen: de mijten kunnen niet milder worden, en de bijen niet weerbaarder. Jammer. Om die reden zijn wij, maar ook sommige imkers zelf, begonnen met het ‘niet-bestrijden’ van de Varroamijten. Zoals u weet werkt bijen@wur daar al meer dan tien jaar aan. Afgelopen maand zijn twee wetenschappelijke artikelen verschenen over dit werk: het eerste beschrijft en onderbouwt de methode die wij toepassen, het tweede beschrijft een elegante proef van de universiteit Gent waarbij de erfelijke veranderingen (op gen niveau) die ten grondslag liggen aan een van de resistentie-eigenschappen, het niet reproduceren van mijten in het broed, zijn blootgelegd. Beide artikelen zal ik hier introduceren. Allebei zijn het ‘open access’ artikelen, dus iedereen kan ze downloaden en lezen

Wie beslist, de natuur, de imker of beide? : selectie bij bijen

Selecteren is hetzelfde als kiezen. Sinds bijen worden gehouden hebben imkers gekozen welke volken ze aanhouden en welke niet. Er werd altijd al gekozen en daarmee de volgende generatie koninginnen, darrenmoeders en darren bepaald. Elke imker had zijn eigen wisselende voorkeuren voor eigenschappen en ras. Toch had de natuur ook inbreng: zwermen vertrokken en zwermen kwamen