Detecting changes in habitat-scale bee foraging in a tropical fragmented landscape using stable isotopes

As the body of research on the ecosystem service of pollination grows, our ability to tackle a range of agricultural, conservation, and land management issues is limited by our understanding of pollinator foraging patterns and requirements. In particular, better knowledge of which habitats bees utilize for foraging over their lifetime would inform a range of applied and theoretical questions. Traditional methods of studying foraging are either impractical for insects (e.g. radio tracking) or else are limited spatially or temporally (e.g. observations by researchers). Here we describe a method for using stable isotopes of carbon and nitrogen from bee tissues to gain an integrated signal of which habitats a bee has foraged in over its lifetime, using three species of social stingless bee (Apidae: Meliponini) in a fragmented tropical forest landscape in southern Costa Rica as a test case.     

Three years of banning neonicotinoid insecticides based on sub‐lethal effects: can we expect to see effects on bees?

The 2013 EU ban of three neonicotinoids used in seed coating of pollinator attractive crops was put in place because of concern about declining wild pollinator populations and numbers of honeybee colonies. It was also concluded that there is an urgent need for good field data to fill knowledge gaps. In the meantime such data have been generated. Based on recent literature we question the existence of recent pollinator declines and their possible link with the use of neonicotinoids. Because of temporal non‐coincidence we conclude that declines of wild pollinators and of honeybees are not likely caused by neonicotinoids. Even if bee decline does occur and if there is a causal relationship with the use of neonicotinoids, we argue that it is not possible on such short term to evaluate the effects of the 2013 ban. In order to supply future debate with realistic (field) data and to discourage extrapolating the effects of studies using overdoses that are not of environmental relevance, we propose – in addition to field studies performed by the chemical industry – to use the ‘semi‐field worst case’ treated artificial diet studies approach to free flying colonies in the field. This kind of study may provide realistic estimates for risk and be useful to study realistic interactions with non‐pesticide stressors. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Toxicity of diafenthiuron to honey bees in laboratory,semi‐field and field conditions

BACKGROUND: Cardamom, an important spice crop often attacked by many insect pests, is controlled mainly using synthetic insecticides. As honey bees play a vital role in pollination in cardamom, the impact of insecticides on honey bees needs to be explored to assess its safety. RESULTS: Risk assessment based on contact toxicity revealed diafenthiuron to be a non‐selective insecticide to bees with a low selectivity ratio (the ratio between the LD₅₀ for beneficial and pest species). A dose of diafenthiuron that killed 90% of cardamom borer, Conogethes punctiferalis Guenee, was found to kill 100% of Indian bees. Based on the hazard ratio (the ratio between the field‐recommended dose and the LD₅₀ for the beneficial), diafenthiuron was found to be slightly to moderately toxic to bees. Diafenthiuron, even at low concentrations of LC₁ (the concentration that killed 1% of bees), was found to affect the foraging and homing behaviour of Indian bees. Of bees fed with 30 µg mL^?1 of diafenthiuron, 40% were found missing on the third day after exposure. However, diafenthiuron did not affect bee visits to the cardamom fields. CONCLUSION: Diafenthiuron is more highly toxic to Apis cerana indica F. than to C. punctiferalis by contact, using selectivity ratio and probit substitution methods of risk assessment, but the hazard ratio revealed diafenthiuron to be a slightly to moderately toxic chemical. Diafenthiuron was found to affect the foraging and homing behaviour of bees at sublethal concentrations. Thus, sublethal effects are more relevant in risk assessment than lethal and acute effects. Copyright © 2010 Society of Chemical Industry     

Improving Pollination of Early Strawberry Crops

ABSTRACT

Our work on strawberry pollination started in 1996 because die top cultivar grown in France is ‘Gariguette’ and growers get good prices widi this cultivar very early in the season (March-April) as the quality of the product is well recognized. Crop management aimed at earliness (early covering, covering with a layer of non-woven fabric or under greenhouse polyethylene film, heating, etc.) induces the plant to flower under conditions unfavorable for pollination such as short days with low irradiation levels and temperatures around 8-10°C which hinder pollen formation. Such conditions often lead later on to problems in strawberry development and shape (large areas with unfertilized ovules, furrows, etc.). This is especially true for primary flowers, which should provide the largest strawberries. A preliminary study was first conducted to assess whether pollination was, indeed, a limiting factor for strawberry production in early crops and whether female reproductive structures also have played a role as well. When this work was completed and pollination was demonstrated as the main limiting factor for strawberry development from the first batch of flowers, the authors studied the different pollen vectors and quantified their action to determine their incidence in terms of production under “limiting” early cropping conditions.     

Short-Term Response of Two Beneficial Invertebrate Groups to Wildfire in an Arid Grassland System,United States

Rangeland invertebrates contribute greatly to biodiversity and provide important services including pollination, pest control, and nutrient cycling. As wildfire frequency increases across these areas of the United States, it is imperative to understand how these disturbances affect beneficial invertebrate communities. We examined bee (Hymenoptera), spider (Araneae), and vegetative communities 1 yr before and 1 yr after a large wildfire swept across an intact grassland in eastern Oregon. Several sites were left unburned after the fire, and a before-after-control-impact study design was used to assess changes within the communities. Fire had no effect on bee or spider abundance, or spider diversity or richness; however, fire significantly increased native bee diversity and richness. In addition, composition of both native bee and spider communities differed significantly between burned and unburned areas 1 yr after the fire. Sheet web spiders (Linyphiidae) and several bee species (primarily large, generalist species) were associated with burned sites. Invasive annual grass and biological soil crust cover decreased significantly in burned sites, but maximum vegetation height and litter cover did not differ significantly among treatments. Forb abundance increased in burned sites; however, species richness of forbs in burned and unburned sites did not differ significantly 1 yr after the fire. Several forbs were indicative of burned areas including non-native species, such as Douglas’ knotweed (Polygonum douglasii) and Russian thistle (Salsola tragus), and native species such as Canadian horseweed (Conyza canadensis), hoary tansyaster (Machaeranthera canescens), and tall willowherb (Epilobium brachycarpum). This study demonstrates that both invertebrate and plant communities show strong short-term responses to wildfire, and our results can be used to inform management of rare habitat and biodiversity in rangelands impacted by wildfire in arid grasslands.     

The relevance of sublethal effects in honey bee testing for pesticide risk assessment

The option of an evaluation and assessment of possible sublethal effects of pesticides on bees has been a subject of discussion by scientists and regulatory authorities. Effects considered included learning behaviour and orientation capacity. This discussion was enhanced by the French bee issue and allegations against systemic insecticides that were linked to the hypothesis that sublethal intoxication might even have led to reported colony losses. This paper considers whether and, if so, how sublethal effects should be incorporated into risk assessment, by addressing a number of questions: What is meant by a sublethal effect? Which sublethal effects should be measured, when and how? How are sublethal effects to be included in risk assessments? The authors conclude that sublethal studies may be helpful as an optional test to address particular, compound‐specific concerns, as a lower‐tier alternative to semi‐field or field testing, if the effects are shown to be ecologically relevant. However, available higher‐tier data (semi‐field, field tests) should make any additional sublethal testing unnecessary, and higher‐tier data should always override data of lower‐tier trials on sublethal effects. © Crown copyright 2007. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.     

Risk assessment to honey bees: a scheme developed in France for non-sprayed systemic compounds

BACKGROUND: Directive 91/414/EEC envisages that the systemic properties of active substances, if any, are taken into account in evaluating the risk posed to the environment by plant protection products. Among others, honey bees may be exposed to substances via this route, which may pose problems when substances with high toxicity are ingested through pollen or nectar. The guidance documents in support of the risk assessment to bees within the framework of Directive 91/414/EEC do not provide detailed technical guidance on how to proceed in a risk assessment for substances with systemic properties. RESULTS: A stepwise approach aiming specifically to assess the risk posed by non-sprayed systemic substances to bees is therefore proposed. This approach first identifies substances with systemic properties, which should be quantified in plant material as pollen and nectar. Exposure estimates calculated for different categories of bees (e.g. foraging bees), based on expected concentrations of the product in pollen or nectar, may be compared with several toxicity endpoints for acute or chronic effects on adults and/or larvae with a toxicity/exposure ratio, which is a measurement of potential risks. CONCLUSION: Such a ratio is proposed to be used as a trigger for any further refined assessment that would focus on the measurement of effects at the colony level.     

Wind tunnel studies on spray deposition on leaves of tree species used for windbreaks and exposure of honey bees

A wind tunnel study was conducted to determine pesticide deposition on commonly used windbreak tree species used as spray drift barriers and associated exposure of honey bees. Although it has been known that windbreaks are effective in reducing chemical drift from agricultural applications, there is still an enormous information and data gap on details of the dependence of the mechanism on the biological materials of the barriers and on standardization of relevant assessment methods. Beneficial arthropods like honey bees are adversely affected by airborne drift of pesticides. A study was initiated by first establishing a wind tunnel to create a controlled environment for capture efficiency work. Suitable spray parameters were determined after a preliminary study to construct and develop a wind tunnel protocol. A tracer dye solution was sprayed onto the windbreak samples and honey bees located in the wind tunnel at various simulated wind speeds. Analysis of data from this work has shown that needle-like foliage of windbreak trees captures two to four times more spray than broad-leaves. In addition, it was determined that, at lower wind speeds, flying bees tend to capture slightly more spray than bees at rest.     

阿维菌素及其混配制剂对蜜蜂的安全性评价

为明确阿维菌素及其混剂对蜜蜂的毒性,采用摄入法和接触法测定了阿维菌素及其5种混配制剂对意大利成年工蜂的毒性。结果表明:摄入法测定,10%阿维菌素·哒螨灵微乳剂、15%阿·丁硫微乳剂、1.8%阿维菌素水乳剂、1.7%吡虫啉·阿维菌素微乳剂、30.3%炔螨特·阿维菌素水乳剂、5%阿维菌素·高效氯氰菊酯泡滕片剂,对蜜蜂LC50分别为3.20×10-1、9.00×10-2、4.91、1.79、16.7、11.9mg·L-1。10%阿维菌素·哒螨灵微乳剂、15%阿丁硫微乳剂对蜜蜂摄入毒性为剧毒,其余为高毒;接触法测定,这6种药剂LD50分别为0.0157、0.0439、0.0378、0.0390、0.576、0.0683g·蜂-1,对蜜蜂的接触毒性均为高毒。     

西方蜜蜂群势变化与蜜源植物泌蜜的关系研究(英文)

[目的]研究西方蜜蜂群势变化与蜜源植物泌蜜的关系。[方法]结合当地每年主要蜜源植物和辅助蜜源植物的泌蜜特点从2012年1月~12月选出6群西方蜜蜂进行周年卵虫量、封盖子量、成蜂量和总的群势量的测定,并据此分别绘出不同的周年变化曲线图和总的蜂群群势变化曲线图。[结果]全年蜂群繁殖达3个高峰。5月15日蜂群群势达到全年第1个高峰,正是采集石榴蜜源的理想蜂群。7月15日达全年第2个高峰,10月15日达全年第3个高峰,正是为采集野藿香蜜源发展的强群。[结论]防治大蜂螨应在两个主要蜜源流蜜后期处于断子时用两种以上杀螨剂杀灭,防治小蜂螨应适时用升华硫配合杀螨剂施治。这为蜜蜂优质高产和产品质量安全提供了理论依据。