Bourdon à tache rousse

Bombus affinis
Statut de l'espèce : En voie de disparition au Canada ; En voie de disparition à l'échelle mondiale (évaluation de l'UICN)
Action requise : Élevage de conservation et réintroduction

Rusty-patched Bumble Bee (Bombus affinis)

L'une des espèces de bourdons les plus communes du sud de l'Ontario jusque dans les années 1980, ce pollinisateur infatigable est aujourd'hui au bord de l'extinction dans toute son aire de répartition. Malgré des recensements approfondis de sites historiques à travers l'Ontario, le bourdon à tache rousse n'a pas été observé au Canada depuis 2009.

Characteristics

The rusty-patched bumble bee (Bombus affinis) is a medium to large fuzzy bee. The workers and males average around 11-17.5 mm in length, while queens are much larger at 21-22 mm. IAll individuals share distinctive entirely black heads (aside from males; they can possess some yellow hairs at the vertex of their heads), which helps separate them from many similar species. The main identifiers are in the workers and males: they display a rusty, reddish-brown to orange patch on the front portion of the second abdominal segment, and a black “thumb-tack” or T-shaped pattern on the thorax. Queens are noticeably larger and possess a different colour pattern than workers and males: lacking the distinctive rusty patch, their second abdominal segment is entirely yellow. Their thorax is predominantly yellow except for a small central bare patch.

Similar looking species

  • Brown-belted bumble bee (Bombus griseocollis)
  • Half-black bumble bee (Bombus vagans)

Habitat

The rusty-patched bumble bee is considered a habitat generalist, meaning that it can adapt to a wide range of environmental conditions. It forages from dozens of food plants, including milkweed, sunflowers, clovers and fruit blossoms. As recently as the early 1980s, it was seen quite commonly in the parks and ravines of the City of Toronto, as well as in urban gardens, wetlands and old fields and near forests. The last known location of rusty-patched bumble bees in Canada is in Ontario’s Pinery Provincial Park (last seen in 2009).

Aire de répartition

The rusty-patched bumble bee has a very large historical range along the east coast of the U.S. from southern Maine through Tennessee, with an extension west along the northern states through Minnesota. In Canada, it was found in southern Ontario and extreme southwestern Quebec. A study in southern Ontario in the early 1970s shows the rusty-patched bumble bee was then the fourth most common bumble bee species (out of 14)!

Currently, its range is reduced to fragmented patched across the Upper Midwest and eastern U.S.

Biology

Rusty-patched bumble bees live in eusocial colonies with a single queen and numerous female workers. In spring, a mated queen emerges from winter hibernation, finds an underground nest site (often an abandoned rodent burrow), and begins laying eggs. Eggs hatch after 5 days, and larvae develop through four stages before pupating. The entire egg to adult process takes roughly 5 weeks. The first brood consists entirely of female workers who take over foraging, brood care, and nest maintenance, allowing rapid colony growth. The queen continues to produce workers until mid to late summer, at which point she switches to producing males and new queens, which leave the colony to mate. After mating and building up their fat stores for the winter, new queens enter diapause and overwinter in protected underground locations, while all other colony members (the founding queen, workers, and males) die. 

Menaces

Les scientifiques n'ont pas encore identifié les raisons du déclin rapide d'un pollinisateur aussi répandu et commun. Au niveau local, l'utilisation de pesticides, la perte d'habitat et l'augmentation de la concurrence avec d'autres espèces comme l'abeille domestique européenne contribuent aux déclins. Les facteurs à l'échelle de l'aire de répartition peuvent inclure le changement climatique et les infections transmises par les abeilles d'élevage commercial.

Rétablissement

Actions de rétablissement recommandées

La stratégie de rétablissement de l'Ontario pour le bourdon à tache rousse prévoit un certain nombre de mesures de conservation, notamment la restauration de l'habitat, la poursuite des recherches de bourdons à tache rousse sauvages sur leurs sites historiques et, si des reines peuvent être localisées, l'établissement d'un programme l'élevage de conservation rentable.

Ce que nous faisons

Qu'est-ce que le projet de rétablissement des bourdons ?

Depuis les années 1990, les populations de bourdons sont en chute libre, ce qui représente une véritable catastrophe écologique. Quatre-vingt-dix pour cent de toutes les plantes à fleurs — y compris la plupart des fruits et légumes dans votre réfrigérateur — ont besoin de ces pollinisateurs pour se reproduire.

Until the causes of these declines can be reversed, conservation breeding and reintroduction is the only way to safeguard at-risk bumble bees. Today, WPC is the only organization in Canada rebuilding wild bumble bee populations through captive breeding. Thanks to recent breakthroughs, we’ve figured out how to dramatically increase the number of queens we produce. Once they’re released into the wild, they can establish their own colonies, producing hundreds of pollinators to sustain the ecosystems around them. While our work currently focuses on the yellow-banded bumble bee, we hope that the knowledge we glean from rearing and releasing this closely-related species will be transferable to the rusty-patched bumble bee, if and when captive rearing and translocations are a viable option.

But

Nous travaillons à prévenir la disparition des espèces d'abeilles indigènes en établissant des populations autosuffisantes au Canada, en étudiant les différentes espèces d'abeilles pour mieux comprendre les menaces auxquelles elles font face, et en créant des opportunités de participation communautaire.

Objectifs

En 2023, nous prévoyons :

  • 60 colonies de bourdons établies dans le laboratoire de conservation
  • Produit 300 reines élevées en captivité pour l'hivernage
  • 17 sites dans le sud et le centre de l'Ontario surveillés pour le déclin des populations de bourdons

Découvrez comment Conservation de la faune au Canada aide à sauver les pollinisateurs indigènes, y compris les bourdons, et comment vous pouvez faire une différence.

Visitez la page du projet

What you can do

Plant native wildflowers that bloom throughout April-October. Leave small patches of your yard unmowed with bare soil, brush piles, leaf litter, and long grass – bumble bees need underground nesting habitat. Avoid pesticide use. Report any bumble bee sightings to BumbleBeeWatch.org, a community science platform that directly informs conservation actions. Even small urban and suburban gardens contribute to bumble bee survival.

FAQs

A: Absolutely not. Captive breeding without massive habitat restoration would simply create a species dependent on perpetual human management. True recovery requires restoring native prairie, reducing pesticide use in agricultural landscapes, protecting overwintering habitat, and addressing pathogen pressures. Breeding programs buy time and maintain genetic diversity, but reintroduction to restored habitat is where genuine recovery occurs.

A: Their ability to generate heat and fly in cool conditions is actually a strength:, it allows them to forage in weather when other pollinators are inactive. However, this requires enormous energy expenditure. When food becomes scarce, stressed colonies can’t maintain the energy needed for this thermoregulation. Pesticides and parasites also impair their metabolic efficiency, making temperature regulation more costly and weakening their ability to survive poor conditions.

A: Buzz pollination is a specialized technique where the bee grasps a flower’s pollen-producing structures in its jaws and vibrates its wing muscles at a specific frequency, causing the flower to literally shake loose pollen that would otherwise remain trapped in the flower’s anthers. Bumble bees, including the rusty-patched bumble bee, use this to access plants like tomatoes, peppers, potatoes, raspberries, and cranberries – some of which are impossible to pollinate without this behaviour. This makes them irreplaceable for certain crops, and is why there is a commercial bumble bee sector.

A: Bumble bees and honeybees are complementary pollinators with different foraging capabilities. Bumble bees can forage in cooler temperatures and lower light conditions than honeybees. They’re more effective pollinators of many native wildflowers, and they’re essential pollinators of major crops including tomatoes, blueberries, almonds, and cucumbers. Approximately 90% of flowering plants depend on animal pollinators, the loss of bumble bees threatens entire ecosystems, regardless of honeybee abundance. Honey bees are an agricultural species not native to North America and so are not in need of conservation action.

A: Commercial bumble bees (most commonly the common eastern bumble bee (Bombus impatiens)) used in greenhouse pollination can escape or become feral, spreading diseases and parasites to wild populations. Mismanagement of commercial bumble bees can also lead to their introduction outside of their native range.

A: Insects have complex life cycles, specific temperature and humidity requirements, sensitivity to disturbance, and ecological specialization that make rearing difficult – especially so for eusocial insects like bumble bees. Unlike vertebrates, you can’t simply provide food and shelter, bumble bees need precise environmental conditions, specific pollen types, proper mating opportunities, and colony dynamics.