Bee Byte: Agapostemon texanus

Male Agapostemon texanus
Male Agapostemon texanus

 

Generalist. Widespread. Solitary.

 

 

Map made via Discoverlife
Map made via Discoverlife

 

 

Name: ‘The Green Sweat Bee’ (there are several)

Family: Halicitinae (with: other sweat bees, alkali bees)

States: Most likely all except Hawaii and Alaska

 

Agapostemon texanus belongs to one of North America’s most striking genera – all Agapostemon males and females have beautiful, metallic blue/green coloration. Males and females of Agapostemon species look very different (a phenomena called sexual dimorphism). Male abdomens are yellow-and-black/brown striped while female abdomens are consistently metallic and blue-green.

Abdomen of female Agapostemon texanus (public domain image, Lexi Roberts as part of ‘Insects Unlocked’)
Abdomen of female Agapostemon texanus (public domain image, Lexi Roberts as part of ‘Insects Unlocked’)

Of all the AgapostemonA. texanus is the most widespread, appearing from Costa Rica to Southern Canada. In the US, it is most common west of the Mississippi River. A. texanus has two generations a year, with mostly males active in the early fall and mostly females hibernating through the winter and active in spring and early summer (this split is due to a unique system called haplodiploidy).

Female A. texanus are strictly solitary, though females of closely-related species (like A. radiatus) have been found to make all their nests together in one area (called an aggregation) or potentially even use singular nests communally (A. nastus).

Agapostemon texanus (public domain image, Alejandro Santillana as part of ‘Insects Unlocked’)
male Agapostemon texanus (public domain image, Alejandro Santillana as part of ‘Insects Unlocked’)

A. texanus nest in the soil, creating long tunnels by digging. Females search for dark spots under pebbles or leaves to construct the entrance to the nests, making nests hard to spot by parasites. Females leave their nest open during the day as they forage on a variety of flowers (A. texanus are generalists) before closing the nest entrance in the late afternoon/early evening by pushing soil up from inside the main tunnel to close the door for the night. High security area!

Nests tunnels have been found up to 150 cms deep (nearly five feet!).

Sources and Further Reading (first is freely available and has a great drawing of an A. texanus nest!):

Roberts, R (1973). Bees of Northwestern America: Agapostemon (Hymenoptera: Halictidae). Technical Bulletin of the Agricultural Experiment Station at Oregon State University, 125: 1-23.

Eickwort, G (1981). Aspects of the Nesting Biology of Five Nearctic Species of Agapostemon (Hymenoptera: Halictidae). Journal of the Kansas Entomological Society, 54: 337-51.

Porter, C (1983). Ecological Notes on Lower Rio Grande Valley Augochloropsis and Agapostemon (Hymenoptera: Halictidae). The Florida Entomologist, 66: 344-53.

Waddington, K (1979). Flight patterns of Three Species of Sweat Bees (Halictidae) Foraging at Convolvulus arvensis. Journal of the Kansas Entomological Society, 52: 751-8.

Continue Reading

Bee Byte: Are All Bees Social?

BeeByteLogoThink quick: Bee!

For most of us, a highly social hive of buzzing honey bees come to mind. But this is actually only a tiny sliver of the social structural pie. Here are some (but not all) other types of organization:

Solitary: Most bees are solitary, where a single female makes her nest alone. Solitary bees lay their eggs in small cells on top of a bed of food – the egg later hatches and feeds itself. Adults typically emerge from their cells around the same time, forage, lay their eggs, and then die while larvae/pupae wait underground for the next appropriate ’emergence’ season. This means adult generations do not overlap.

Gregarious nesters: These bees often appear social, as many solitary females will nest individually, but nearby one another, in ‘aggregations’.

Communal nesters: This is when multiple solitary females all share one nest, but lay their own eggs in individual cells within that nest.

Facultatively social: These species can be solitary or social, depending on environmental cues. In one species, Ceratina australensis, two sisters will sometimes form a colony together instead of nesting alone, with one foraging and reproducing and the other acting solely as a guard.

Primitively eusocial: Here, there are reproducing ‘queens’ and nonreproducing (but not sterile) ‘workers’. Queens and workers generally look similar, and workers can sometimes replace queens.

Photo credit: Meghan Barrett Apis mellifera, the Honey Bee
Photo credit: Meghan Barrett
Apis mellifera, the Honey Bee

Advanced eusocial: The honey bee colony: reproducing queens, nonreproducing, functionally sterile workers. Workers and queens do not look similar. The workers care for the queen’s young, and there are overlapping generations of adults.

Additional sources:

Wikipedia has a great chart (bottom of page) showing the differences between terms used to describe sociality, including: Eusocial, Semisocial, Subsocial,and Quasisocial.

This paper discusses some theory on the evolution of eusociality.

This paper addresses how advanced eusociality may have arisen through other types of sociality.

Continue Reading

Bee Byte: Can you #WildID a Bee?

BeeByteLogoOn Twitter, nature-lovers will send scientists photos of an animal asking for a #WildID – or species identification. But can you #WildID a bee?

The answer: sometimes yes (but usually no).

 

Often bees of the same genera will look very similar (for example these two different species of male Agapostemon):

Agapostemon splendens (public domain image, Lexi Roberts as part of 'Insects Unlocked')
Agapostemon splendens (public domain image, Lexi Roberts as part of ‘Insects Unlocked’)
Agapostemon angelicus (public domain image, Lexi Roberts as part of 'Insects Unlocked')
Agapostemon angelicus (public domain image, Lexi Roberts as part of Insects Unlocked’)

 

 

 

 

 

 

 

And sometimes, two bees of the same species will look very different (like the abdominal coloration of these two female Augochloropsis metallica):

Augochloropsis metallica (public domain image, Lexi Roberts as part of 'Insects Unlocked')
Augochloropsis metallica (public domain image, Lexi Roberts as part of ‘Insects Unlocked’)
Augochloropsis metallica (public domain image, Lexi Roberts as part of 'Insects Unlocked')
Augochloropsis metallica (public domain image, Lexi Roberts as part of ‘Insects Unlocked’)

 

 

 

 

 

 

 

This makes telling a bee’s species from a photo very difficult; sometimes the features an entomologist must look at to ID a species are hidden under hairs, or even involve dissecting the bee.

However, sometimes a photo with location data can tell us everything we need to know to #WildID – some species have very distinctive features (especially when we know where the photo was taken, and thus what species are in that range). For example the triangle of black on the thorax of Bombus franklini (featured here), combined with information about the bee’s range, can be used to ID B. franklini with relative certainty. Sometimes even the time or flower a bee was spotted on can help #IDthatBee – if it is an early dawn forager, or a pollen-specialist that only visits a specific species.

Don’t be afraid to #WildID your next bee photo – even if the experts can’t get the species, often the next best thing (genera) can be ascertained with a glance. Check out Bees in Your Backyard to try your hand at IDing to genera, yourself!

Continue Reading

Bee Byte: Bombus franklini

BeeByteLogo

 

Endangered. Social. Narrow Range.

 

Map made via DiscoverLife; modified to most closely resemble Williams, Thorp, Richardson, and Colla (2014)
Map made via DiscoverLife; modified to most closely resemble Williams, Thorp, Richardson, and Colla (2014)Status: Critically Endangered, last recorded by Robbin Thorp in 2006

Status: Critically Endangered, last recorded in 2006 by Dr. Robbin Thorp

Name: Franklin Bumble bee

Family: Apidae (with: honey bees, carpenter bees)

States: Oregon and California

B. franklini has experienced a sharp decline since 1998, and has not been spotted in the wild for over a decade, earning itself a spot on the critically endangered species list and a spot as the Bee Bytes mascot. It also has one of the most narrow distributions for a bumble bee in the world.

The yellow half of the thorax (closer to the head) with an inverse U shape in black can be used to differentiate it from the similar looking B. occidentalis. 

Photo credited to Dr. Robbin Thorp
Photo credited to Dr. Robbin Thorp

Like other bumble bees, B. franklini are social; they live in colonies with a queen, who reproduces, and her daughters, who gather nectar and pollen. The colony does not overwinter.

B. franklini are generalists, meaning they can use a variety of flowers for food; like all bumble bees, they are buzz pollinators, vibrating at a high frequency to dislodge pollen from the flowers’ anthers.

A potential cause of B. franklini decline is the fungal pathogen Nosema bombi, which has been found with increasing prevalence on museum specimen from declining populations. It is possible exotic strains were introduced from Europe, due to the American agricultural industry’s use of bumble bees reared in Europe to pollinate crops.

These bees are ground-nesters, thought to live in abandoned rodent burrows in grassy meadows. A paucity of research on B. franklini means little is known about the species, making conservation efforts more difficult.

More resources on the species and its decline:

NPR: The Bumblebee Hunter

ICUN Redlist Entry

Test of the invasive pathogen hypothesis of bumble bee decline in North America

Evidence for decline in eastern North American bumblebees (Hymenoptera: Apidae), with special focus on Bombus affinis Cresson

Bumblebees of North America: An Identification Guide by Paul Williams, Robbin Thorp, Leif Richardson, Sheila Colla (2014; Princeton University Press).

 

Continue Reading

Introducing “Bee Bytes”!

BeeByteLogo
Welcome to Bee Bytes, a #scicomm project to introduce bees to the public!

What is Bee Bytes?

Bee Bytes will be a weekly to biweekly series on my blog, where I write “bite-sized” posts about an invasive or native bee species in the United States, describing its distribution, taxonomic relationship, and a few fun facts in brief! Each post will be 256 words or less – the number of unique characters you can represent with just one ‘byte’ (and exactly as long as this post). The end will have extra resources, in case you want to look for more about your favorite bees.

I don’t get it, why bytes?

A byte is used to encode a single text-character in a computer; my ‘bee bytes’ will be used to encode a single bee in your memory!

Where can I find these bytes?

For now, get your Bee Bytes fix here on my blog; in the future, I’m hoping to make a ‘trading card style’ website where you can search the deck for your favorite bees. That can be an after-quals project.

How long will you be doing Bee Bytes?

With 4000+ species in the United States, I can write for the next 77 years or so before I cover every species we’ve got! By that time, we’ll have so much new information I might even have to start over!

4000 species? Aren’t you byte-ing off more than you can chew?

Listen, bugger – you can buzz right off with that negativity.

Sorry.

Why?

Check out this link for the impetus behind ‘Bee Bytes’.

Continue Reading