Hommels

Neonicotinoïden veroorzaken bijensterfte op de lange termijn

Voor het eerst is de afname van Engelse wilde bijen gekoppeld aan het gebruik van controversiële neonicotinoïden. Dat zijn pesticiden waarmee boeren hun koolzaadolieplantages beschermen tegen ongedierte. Aan het zaadje van een koolzaadplant voegt de boer neonicotinoïden toe. Als de plant is opgegroeid en opgebloeid, zijn deze stoffen over de volledige koolzaad verspreid, dus ook in de bloemen. Hierdoor krijgen de beestjes die van de nectar snoepen de pesticiden binnen.

Decline of bumble bees in northeastern North America

Concerns about the rapid and severe declines of many bumble bee (Bombus spp.) species in Europe, and more recently North America, have spurred research into the extent and possible causes for these losses. Drawing conclusions has been difficult due to a lack of long-term data, especially for specific regions that may have different factors at play than the global trend. In this study, 150 years of Bombus records in the state of New Hampshire from the University of New Hampshire Insect Collection were examined.

Evidence for decline in eastern North American bumblebees

Bumblebees (Bombus spp.) have been declining rapidly in many temperate regions of the Old World. Despite their ecological and economic importance as pollinators, North American bumblebees have not been extensively surveyed and their conservation status is largely unknown. In this study, two approaches were used to determine whether bumblebees in that region were in decline spatially and temporally.

Bumble Bee Queens Slower to Start Colonies After Minimal Neonic Exposure

Spring is an important period for bumble bees, as that’s when new colonies get their start. When a solitary bumble bee queen emerges from hibernation, she initiates a nest and then does the foraging work herself, until her first offspring hatch, develop into workers, and relieve her from all duties but egg laying. Thus, should any harm befall the queen in this early period, it can have ripple effects on the health of the developing colony.

Drastic decline of New Hampshire’s bumble bee population over the last 150 years

In the first long-term study of New Hampshire’s bumble bee population, researchers with the New Hampshire Agricultural Experiment Station at the University of New Hampshire have found three of the state’s most important bumble bee species have experienced drastic declines and range constriction over the last 150 years, with a fourth bee also in significant decline.

Synergistic mortality between clothianidin and propiconazole in three bee species

We explore synergistic mortality between a neonicotinoid (clothianidin) and an ergosterol-biosynthesis-inhibitor fungicide (propiconazole) in three bee species (A. mellifera, Bombus terrestris, Osmia bicornis) following oral exposure in the laboratory. We developed a new approach based on the binomial proportion test to analyze synergistic interactions. We estimated uptake of clothianidin per foraging bout in honey bees foraging on seed-coated rapeseed fields.

The fungicide chlorothalonil may be implicated in bumblebee decline

Several species of bumblebees have recently experienced range contractions and possible extinctions. While threats to bees are numerous, few analyses have attempted to understand the relative importance of multiple stressors. Such analyses are critical for prioritizing conservation strategies. Here, we describe a landscape analysis of factors predicted to cause bumblebee declines in the USA.

The Resilience of the Bee Hive

A recent assessment of higher tier studies on the toxicity and risks of neonics in honeybees by Solomon and Stephenson reported a colony-level NOAEC of 25 μg/kg (ppb) for imidacloprid and clothianidin. The toxicity of these insecticides to honeybees is however known to be reinforced with chronic exposure, and extrapolation of time-to lethal-effect toxicity plots compiled from published studies indicate that an imidacloprid level of 0.25 ppb, i.e. one-hundredth of the reported colony NOAEC, would kill a large proportion of bees nearing the end of their life.

Paul Kirkland: How the plight of the butterfly may hit Scotland’s wild flowers

Much attention has been given to the plight of bees because of their importance as pollinators of major crops. But there is growing evidence that butterflies and moths – many of which have suffered dramatic declines in recent years – play an important role as specialist pollinators of some of our favourite wild flowers. A Swedish study recorded pollen on the bodies of three-quarters of butterfly species examined with some individuals carrying up to 350 grains.

Insect decline: the biodiversity of the entire world is at stake

Bees and butterflies are experiencing widespread population decline, creating public concern in recent years. Data collected in Germany suggest that it’s not just bees and butterflies at risk: insect populations overall have plummeted by more than 75 percent since 1989. Scientists have known about the population decline for several years. However, they didn’t know how many species were declining, and they didn’t expect it to be happening so fast.