9/4/2023 0 Comments Bumbled bee![]() ![]() ![]() crotchii populations continue to decline. Inbreeding is probably also becoming problematic, especially as B. Moreover, the toxicity to bumblebees from these types of pesticides lasts for several months, meaning the negative impacts can be observed over the long-term. crotchii, especially neonicotinoids, which are very commonly applied. Additionally, insecticides are problematic for the health of B. Another prominent issue for this bumblebee species is that of climate change as stated above, this species is a major climatic specialist compared to other bumblebees, so climate change and increasing aridity are significant threats to Crotch's bumblebee. Regions within the Crotch's bumblebee range have experienced urbanization and intensive agriculture, events that are thought to have contributed to the decline of the species. The Xerces Society (2019) reports a relative abundance decline of 98% over the last decade the group has also estimated an 80% decline in the relative persistence of the bumblebee in its range during this time. This bumblebee was once common in the Central Valley of California, but is now scarce in that area. Its current range area is estimated at 144,003 km 2. Observations since 2008 indicate a retraction from the northern portion of its range. ![]() The rationale provided was as follows: "This species has a modest range extent and within that, it is restricted to a very limited climatic range. In 2019, the species' global status was listed as imperiled. Conservation Ĭrotch's bumblebee is an endangered species that was last evaluated by IUCN in April 2014. Due to the wide range of host plants visited by Crotch's bumblebee, it is characterized as a dietary generalist. Due to the role of bumblebees as pollinators, monarch butterflies benefit from this situation. Milkweed is a favorite nectar source of Crotch's bumblebee. It also feeds on snapdragons, Clarkia, poppies, and wild buckwheats. Its food plants include milkweeds, dustymaidens, lupines, medics, phacelias, and sages. It is a nonmigratory species of bumblebee. Crotch's bumblebee nests underground, often in abandoned rodent dens. Ĭrotch's bumblebee inhabits grassland and scrub areas, requiring a hotter and drier environment than other bumblebee species, and can only tolerate a very narrow range of climatic conditions. The overwintering habitat of this bumblebee is not known, but it is believed that they have similar behaviors to other bumblebees in this respect, overwintering under leaf litter or soft soil. However, most observations of this species occur in southern California in coastal areas. Crotch's bumblebee is extant but uncommon in Baja California, Mexico, and into Nevada. This species lives primarily in California in the United States. Workers of this species are active from April to August and queen bees are active for only two months from March until May the peak of worker activity is between May and June, while queens reach maximum activity in April. crotchii males are generally present from May to September with their peak occurring in July. The front of the male abdomen has yellow, and the rest of their abdomen is predominantly black and reddish yellow. They display yellow hair on their faces, and a broad black stripe mid thorax. Their eyes are very large, occupying much of the face. Males have a slightly different appearance from queens and workers. Queens are 23-24mm long and workers are 14-18mm long. Queens and workers have a similar appearance, with the main difference being their body size. T3-5 are black or orange and T6 is black. T2 is usually yellow, sometimes black medially. The first metasomal tergum (T1) of the abdomen is all black or black in the middle portion. Queens and workers (females) have a black head and thorax, with yellow on the dorsal anterior thorax, and sometimes yellow on the scutellum. This species could be confused with Bombus californicus or Bombus occidentalis, as they have similar color patterns to Crotch's bumblebee. Description Ĭrotch's bumblebee is characterized as a short- or medium- tongue length species. It is classified as endangered due to the impacts of pesticides, climate change, and human development. Bombus crotchii var nigricaudus Frison, 1927īombus crotchii, commonly called Crotch's bumblebee, is a species of bumblebee named after the entomologist George Robert Crotch. ![]()
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