The role of deformed wing virus in the initial collapse of varroa infested honey bee colonies in the UK.

The mite Varroa destructor has been associated with the collapse of millions of Apis mellifera honey bee colonies world-wide. During the past decade, a large body of research has revealed various interactions between varroa, the honey bee and various viral pathogens. One pathogen in particular, deformed wing virus (DWV), has emerged as the key pathogen involved in colony collapse. As varroa has permanently changed the viral landscape in which honey bees exist, we present a large body of data on the effects of DWV during the initial phase of varroa infestation in the UK during 1998. This provides baseline data for further comparative studies. We carried out DWV transmission studies, and observed the effects of DWV on bee longevity. As the ELISA technique used in these studies had a detection limit of ~107 viral particles per bee, only high viral (overt) titres were detected. During the initial phase of varroa establishment, DWV was detected in 0.6 % of non-infested sealed brood, but in 89 % of sealed brood invaded by varroa. Once DWV was introduced into the bee’s haemolymph via mite feeding on either pupae or adults, an overt virus infection was rapidly produced in 3-4 days. In sealed brood the presence of varroa was fatal for 21 % of the brood, caused wing deformity in some emerging adults and significantly reduced longevity as an adult. However, adult bees that became infected after they had emerged, did not develop wing deformity nor show any reduced longevity, but acted as reservoirs of DWV infection

Honey bees repellent device: preliminary experimental research with the bees hearing sensitivity

Bees are insects that attack, to protect the hive, when they feel threatened. The main objective in this paper was to build an electronic device capable of repelling bees. Thus, a study of the hearing thresholds, of honey bees, has been developed to find out the frequencies range are most sensitive. This knowledge can be important to identify a frequency or a sound capable of repealing them. We also present an electronic circuit developed to build a repelling device able to reproduce a recorded sound or periodic sound. We report also a series of laboratory behaviour experiments, where honey bees (Apis mellifera spp.) had to make the choice between a box where a sound was being played or another box without sound. The experiments were conducted using the following sound frequencies: 100, 150, 200, 300, 400, 500 and 550 Hz; and also, with the sound of three natural predators: the drone, the swallow and the Asian wasp. The honey bees used in the experiments were previously conditioned to go to the box with sound that contained food in order to associate the sound to the presence of food.info:eu-repo/semantics/publishedVersio

Entomological and functional role of floral strips in an organic apple orchard: Hymenopteran parasitoids as a case study

Habitat manipulation techniques improve the availability of resources required by natural enemies to increase their effectiveness. This study focused on the effects of floral strips on Hymenopteran parasitoid presence. The experiments were conducted during spring 2007 in one organic low-input apple orchard located in south-eastern France. The density and the diversity of parasitic wasps collected from sown floral strips were higher than those from mown plants. The family of parasitic wasps of Braconidae was strongly dominant, followed by Mymaridae and Pteromalidae. By studying 26 flowering species, the greatest diversity and density of parasitic wasps were collected from Potentilla reptans, Achillea millefolium, Trifolium repens and Torilis arvensis. In terms of the early flowering plants, the most important results were observed in Euphorbia helioscopia, Senecio vulgaris and Veronica persica. To give an idea of the functional role of these plants, we studied the parasitic wasps of the diapausing larvae (cocoon) of codling moth Cydia pomonella. We recorded three emerged species: Ascogaster quadridentata, Pristomerus vulnerator and the hyperparasite Perilampus fulvicornis. However, none of these species have been observed on the 26 studied plants. Hence, this result may be suggesting that the studied plants do not have a functional role concerning these parasitoids. These studies may be advantageous for biological control programs in order to select flowering plant species attracting parasitic wasps specific to fruit pests

Effect of acute pesticide exposure on bee spatial working memory using an analogue of the radial-arm maze

Pesticides, including neonicotinoids, typically target pest insects by being neurotoxic. Inadvertent exposure to foraging insect pollinators is usually sub-lethal, but may affect cognition. One cognitive trait, spatial working memory, may be important in avoiding previously-visited flowers and other spatial tasks such as navigation. To test this, we investigated the effect of acute thiamethoxam exposure on spatial working memory in the bumblebee Bombus terrestris, using an adaptation of the radial-arm maze (RAM). We first demonstrated that bumblebees use spatial working memory to solve the RAM by showing that untreated bees performed significantly better than would be expected if choices were random or governed by stereotyped visitation rules. We then exposed bees to either a high sub-lethal positive control thiamethoxam dose (2.5ng-1 bee), or one of two low doses (0.377 or 0.091ng-1) based on estimated field-realistic exposure. The high dose caused bees to make more and earlier spatial memory errors and take longer to complete the task than unexposed bees. For the low doses, the negative effects were smaller but statistically significant, and dependent on bee size. The spatial working memory impairment shown here has the potential to harm bees exposed to thiamethoxam, through possible impacts on foraging efficiency or homing

Agricultural policies exacerbate honeybee pollination service supply-demand mismatches across Europe

Declines in insect pollinators across Europe have raised concerns about the supply of pollination services to agriculture. Simultaneously, EU agricultural and biofuel policies have encouraged substantial growth in the cultivated area of insect pollinated crops across the continent. Using data from 41 European countries, this study demonstrates that the recommended number of honeybees required to provide crop pollination across Europe has risen 4.9 times as fast as honeybee stocks between 2005 and 2010. Consequently, honeybee stocks were insufficient to supply >90% of demands in 22 countries studied. These findings raise concerns about the capacity of many countries to cope with major losses of wild pollinators and highlight numerous critical gaps in current understanding of pollination service supplies and demands, pointing to a pressing need for further research into this issue

Landscape context not patch size determines bumble-bee density on flower mixtures sown for agri-environment schemes

Bumble-bee declines across Europe have been linked to loss of habitat and forage availability due to agricultural intensification. These declines may have severe ecological and commercial consequences since bumble-bees pollinate a range of wildflowers and crops. In England, attempts are being made to reintroduce forage resources through agri-environment schemes, yet there are few data on how the area of forage, or the landscape context in which it is provided, affects their success. We investigated the effects of sown forage patches on bumble-bees across sites varying in landscape characteristics. Bumble-bee densities were higher on sown patches compared with control habitats but did not vary with patch size, i.e. total forager numbers were proportional to patch area. Importantly, the relative response to sown forage patches varied widely across a landscape gradient such that their impact in terms of attracting foraging bumble-bees was greatest where the proportion of arable land was highest