Pierrick Aupinel

A Common Pesticide Decreases Foraging Success and Survival in Honey Bees

Bad News for Bees Neonicotinoid insecticides were introduced in the early 1990s and have become one of the most widely used crop pesticides in the world. These compounds act on the insect central nervous system, and they have been shown to be persistent in the environment and in plant tissues. Recently, there have been controversial connections made between neonicotinoids and pollinator deaths, but the mechanisms underlying these potential deaths have remained unknown. Whitehorn et al. (p. 351, published online 29 March) exposed developing colonies of bumble bees to low levels of the neonicotinoid imidacloprid and then released them to forage under natural conditions. Treated colonies displayed reduced colony growth and less reproductive success, and they produced significantly fewer queens to found subsequent generations. Henry et al. (p. 348, published online 29 March) documented the effects of low-dose, nonlethal intoxication of another widely used neonicotinoid, thiamethoxam, on wild foraging honey bees. Radio-frequency identification tags were used to determine navigation success of treated foragers, which suggested that their homing success was much reduced relative to untreated foragers. Honey bees cannot find their way home after exposure to sublethal doses of a widely used insecticide. Nonlethal exposure of honey bees to thiamethoxam (neonicotinoid systemic pesticide) causes high mortality due to homing failure at levels that could put a colony at risk of collapse. Simulated exposure events on free-ranging foragers labeled with a radio-frequency identification tag suggest that homing is impaired by thiamethoxam intoxication. These experiments offer new insights into the consequences of common neonicotinoid pesticides used worldwide.

Nutritive value of 15 single pollens and pollen mixes tested on larvae produced by bumblebee workers (Bombus terrestris, Hymenoptera: Apidae)

AbstractLaboratory trials were performed at 27 °C on micro-colonies comprised of three Bombus terrestris workers. They were fed with syrup and pollen paste ad libitum. The micro-colonies were terminated on the 14th day after egg-laying. Two bioassays tested the nutritive value of 6 pure pollens and 9 commercial pollen mixes on bumblebee larvae. Among 10 criteria tested, the most sensitive to the different pollens were the mean weight of larvae and the rate of discarded larvae. Differentiation between treatments was easier with single pollens that ranged from 14.4% to 24.9% crude protein for Helianthus and Castanea respectively, than with mixes that ranged from 12.9% to 17.6%. The best performance ranking was assigned to Castanea, Papaver and Rubus, which produced larvae weighing 110–150 mg, the lowest to Helianthus and Cistus which resulted in larvae of 20–50 mg. The largest larvae (240 mg) were produced with the mix at 96% Brassica and 15.9% protein and the smallest with the mix at the lowest protein content (12.9%) assembling Picris, Hedera, Amaranthus, Solanum, Helianthus and graminaceae.ZusammenfassungDer Nährwert von Pollen, der von Honigbienen gesammelt wurde, stellt einen Schlüsselfaktor für die kommerzielle Hummelzucht dar. Wir wollten eine einfache, schnelle und empfindliche Methode entwickeln, mit der man routinemäßig den Nährwert verschiedener Pollen vergleichen kann. Die Ziele unserer Studie waren: (i) Ein Vergleich der Empfindlichkeit der vorhandenen Kriterien zum Test der Nährwerte von Pollen bei der Produktion von Larven in weisellosen Mikro-Völkern mit Arbeiterinnen; (ii) Ein Test der Qualität von 6 Pollen, die zu verschiedenen Pflanzenfamilien gehören und von 9 kommerziellen Pollengemischen, die derzeit von Hummelzüchtern benützt werden.Für die Tests wurden Mikro-Völker mit drei Bombus terrestris Arbeiterinnen in kleinen Kästen (11 × 5 × 5 cm) benutzt, die bei 27 °C, 70 % RF und einem Dunkel-Licht-Rhythmus von D8 : L16 gehalten wurden. Pollen und Zuckerwasser wurden ad libitum angeboten. Der Pollen wurde als Paste in 1–2g-Bällchen angeboten. Neun Diäten mit kommerziellen Pollengemischen, die aus Honigbienenvölkern gesammelt wurden und 6 Diäten mit nur einer Pollensorte wurden den Mikro-Völkern gefüttert und die Versuche 10 bis 13 mal wiederholt. Die Hauptpollen in den Gemischen waren: Salix, textit-Picris, Brassica, Prunus, Quercus (Tab. I).Einzelpollen waren: Castanea, Actinidia, Cistus, Papaver, Helianthus und Rubus. Über folgende Kriterien wurde der Nährwert bestimmt: (i) Eiweißgehalt anhand der Stickstoff-Bestimmung, (ii) Anzahl und Größe der Larven (Gewicht der Larven pro Mikro-Volk, mittleres Gewicht der Larven), (iii) Verluste (Arbeiterinnenmortalität, ausgeräumte Larven, Oophagie und Zerstörung von Eizellen), (iv) Pollenaufnahme und Effektivität der Pollenverwendung (Pollenaufnahme durch Arbeiterinnen während der 5 Tage vor Eiablage, Pollenaufnahme während der 14 Tage nach Eiablage, Polleneffektivität, Eiweißeffektivität). Die Pollen- und Eiweißeffektivität wurden durch den Quotienten „Gewicht der produzierten lebenden Larve / Pollen- bzw. Eiweißaufnahme“ bestimmt.Zwei aus Einzelpollen gebildete Pasten wiesen den höchsten Stickstoffgehalt auf: Papaver (3,98 %) und Castanea (3,25 %). Pasten aus Cistus und Helianthus (2,31 % und 2,30 %) hatten den geringsten Gehalt, während Rubus (3,08 %) und Actinidia (2,91 %) dazwischen lagen. Der Stickstoffgehalt von gemischten Pasten reichte von 2,06 % für Mix B, bis 2,82 % für Mix G. (Tabs. II und III). Castanea, Papaver und Rubus produzierten die größten Larven (0,15 g, 0,12 g and 0,11 g), während Actinidia, Cistus und Helianthus die kleinsten hervorbrachte (0,09 g, 0,05 g bzw. 0,02). Die höchsten Larvenausräumraten wurden bei Fütterung mit Papaver (27 %) und Helianthus (22,4 %) beobachtet, die geringsten bei Fütterung mit Castanea (4,5 %) und Rubus (6 %). Darüber hinaus gab es bei 4 weiteren Kriterien Unterschiede (Tab. IV).Bezüglich einiger der 9 Mischungen traten nur bei drei Parametern Unterschiede auf: durchschnittliches Larvengewicht, Entfernen von Larven und Futterverbrauch durch die Arbeiterinnen. Obwohl keine klare Rangordnung bezüglich der Qualität der Mischungen aufgestellt werden konnte, scheint es, dass Mischungen mit hohem Anteil an Picris oder Quercus einen Effekt auf die Larven haben (Tab. V). Die wichtigsten Parameter in einem solchen Bruttest sind das durchschnittliche Larvengewicht und die Ausräumrate der Larven 14 Tage nach Eiablage. Einzelpollen sind leichter zu vergleichen als Mischungen. Pollen von Compositae ist von eindeutig schlechter Qualität. Es muss geprüft werden, ob Tests in Mikro-Völkern eine Vorhersage bezüglich des Nährwertes von Pollen in weiselrichtigen Völkern erlauben.

Standard methods for artificial rearing of Apis mellifera larvae

Summary Originally, a method to rear worker honey bee larvae in vitro was introduced into the field of bee biology to analyse honey bee physiology and caste development. Recently, it has become an increasingly important method in bee pathology and toxicology. The in vitro method of rearing larvae is complex and can be developed as an art by itself, especially if the aim is to obtain queens or worker bees which, for example, can be re-introduced into the colony as able members. However, a more pragmatic approach to in vitro rearing of larvae is also possible and justified if the aim is to focus on certain pathogens or compounds to be tested. It is up to the researcher(s) to decide on the appropriate experimental establishment and design. This paper will help with this decision and provide guidelines on how to adjust the method of in vitro rearing according to the specific needs of the scientific project.

Standard methods for toxicology research in Apis mellifera

Summary Modern agriculture often involves the use of pesticides to protect crops. These substances are harmful to target organisms (pests and pathogens). Nevertheless, they can also damage non-target animals, such as pollinators and entomophagous arthropods. It is obvious that the undesirable side effects of pesticides on the environment should be reduced to a minimum. Western honey bees (Apis mellifera) are very important organisms from an agricultural perspective and are vulnerable to pesticide-induced impacts. They contribute actively to the pollination of cultivated crops and wild vegetation, making food production possible. Of course, since Apis mellifera occupies the same ecological niche as many other species of pollinators, the loss of honey bees caused by environmental pollutants suggests that other insects may experience a similar outcome. Because pesticides can harm honey bees and other pollinators, it is important to register pesticides that are as selective as possible. In this manuscript, we describe a selection of methods used for studying pesticide toxicity/selectiveness towards Apis mellifera. These methods may be used in risk assessment schemes and in scientific research aimed to explain acute and chronic effects of any target compound on Apis mellifera.

Territorial biodiversity and consequences on physico-chemical characteristics of pollen collected by honey bee colonies

Pollen resources may become a constraint for the honey bee in cereal farming agrosystems and thus influence honey bee colony development. This survey intended to increase knowledge on bee ecology in order to understand how farming systems can provide bee forage throughout the year. We conducted a 1-year study to investigate the flower range exploited in an agrarian environment in western France, the physico-chemical composition of honey bee-collected pollen, the territorial biodiversity visited by the bee at different periods, and the relationships between these three datasets. Palynological analyses showed the importance of maize among crop pollens and that of weeds during the food shortage period. Pollen protein varied from 16% to 29% and lipids from 7% to 24%. The contribution of different habitats to pollen harvest, was from crops (62%), woods (32%), grasslands (4%), and gardens (1%).

ECOBEE: a tool for long-term honey bee colony monitoring at the landscape scale in West European intensive agroecosystems

Summary In Central Western France, as in many other areas, traditional apiculture has been replaced by more intensive practices to compensate for colony losses and current decreasing honey yields. One neglected aspect concerns the choice by professional beekeepers of apiary sites in intensive agrosystems, with regard to landscape features, a choice which appears to be largely empirical. ECOBEE is a colony monitoring scheme specifically intended to provide beekeepers and researchers with basic ecological data on honeybees in intensive agrosystems, as well as colony population dynamics. ECOBEE was launched in 2008 as a long-term ecological project with three specific aims: 1. to monitor seasonal and inter-annual population dynamic parameters of honeybee colonies in a heterogeneous farming system; 2. to provide relevant and robust datasets to test specific hypotheses about bees such as the influence of landscape planning, agricultural inputs or human pressure; and 3. to offer opportunities for assessing the effectiveness of agro-environmental schemes or the effects of changes in agricultural policies on honey bee wellbeing. Here we present an overview of ECOBEE, the type of datasets collected over the first four years of monitoring, and their possible application and use. We found that colony dynamics were largely influenced by the phenology of the main mass-flowering crops foraged by bees, namely oilseed rape and sunflowers. Furthermore, we detected a sharp food shortage period in late spring between the flowering of oilseed rape and sunflowers, possibly temporarily constraining colony sustainability. We further discuss the research perspectives offered by ECOBEE, especially with regard to spatial ecotoxicology.

Pesticide risk assessment in free-ranging bees is weather and landscape dependent

The risk assessment of plant protection products on pollinators is currently based on the evaluation of lethal doses through repeatable lethal toxicity laboratory trials. Recent advances in honeybee toxicology have, however, raised interest on assessing sublethal effects in free-ranging individuals. Here, we show that the sublethal effects of a neonicotinoid pesticide are modified in magnitude by environmental interactions specific to the landscape and time of exposure events. Field sublethal assessment is therefore context dependent and should be addressed in a temporally and spatially explicit way, especially regarding weather and landscape physiognomy. We further develop an analytical Effective Dose (ED) framework to help disentangle context-induced from treatment-induced effects and thus to alleviate uncertainty in field studies. Although the ED framework involves trials at concentrations above the expected field exposure levels, it allows to explicitly delineating the climatic and landscape contexts that should be targeted for in-depth higher tier risk assessment.

Effect of photoperiodic regimes on the oviposition of artificially overwintered Bombus terrestris L. queens and the production of sexuals

SUMMARYBombus terrestris queens which had been overwintered in artificial conditions were transferred to small wooden boxes in a climate room at 28°C and 65% RH; the bees were supplied with food and subjected to one of four photoperiodic regimes (L24: DO; L8: D16; L16: D8; LO: D24. The photoperiodic regimes were applied until the queens had produced 10–15. workers, after which colonies were transferred from the small initiation boxes to larger ones to allow nests to increase in colony size. The proportion of queens in each treatment which founded colonies ranged from 42% to 61 %, but no significant difference was detected between photoperiodic regimes. Delays to oviposition were significantly shorter in the L8: D16 regime compared with constant dark and constant light: 33.4 ± 4.9 days, 47.3 ± 4.8 days and 58.9 ± 6.7 days respectively. In the L16: D8 regime the delay (42.4 ± 5.6 days) was not significantly different from that in the L8: D16 regime. The period from the start of brooding attitude to oviposit...

Internet resources for agent-based modelling

The use of agent-based models (ABMs) is steadily increasing in all the disciplines including environmental chemistry and toxicology. This growth is mainly driven by their ability to address problems that conventional modelling techniques cannot, such as the change of scale or the emergence of unanticipated phenomena resulting from interactions between their constitutive goal-directed agents. After a brief introduction on the basic principles of agent-based modelling and the presentation of selected case studies, the main software resources available on the Internet are presented. An attempt is made to estimate the complexity of these tools versus their potentialities and flexibility.

Validation of a method using queenless Bombus terrestris micro-colonies for testing the nutritive value of commercial pollen mixes by comparison with queenright colonies.

Abstract The nutritive value of pollen blends purchased by bumble bee producers from beekeepers is a key factor of successful mass rearing. We have already devised a method for quality ranking of pollen diets. It was a 1-mo bioassay using queenless micro-colonies of three callow workers (Bombus terrestris L.; Apidae: Bombinae). In the current study, we tested three pollen diets through the micro-colony method and compared the results to the development of queenright colonies supplied with the same diets. The three diets were “A,” a spring blend with a protein rate of 15.7% and a dominance of Corylus avellana L.(46%) and Buxus sempervivens L. (35%); “B,” a summer assemblage with a lower crude protein content (14.4%), with a dominance of Helianthus annuus L.(37%), Zea mays L. (35%), and Poaceae (21%); and “C,” a 50/50 mixture by weight of A and B, with a crude protein content of 15.8%. In micro-colonies, the more sensitive parameter for diet ranking was the mean weight of a larva, whereas in queenright colonies, the discrimination between treatments was enabled by considering the body size of new queens (weight and length of the radial cell) and the slope of the sigmoidal curve of the pollen consumption at the inflection point reflecting brood growth. Both testing methods assigned the lower rank to diet B compared with diet A. Despite the closeness of the three diets in terms of nitrogen content, we concluded that micro-colonies were a good estimate of colony development when nutritive value of pollen was tested.