Martian landscapes… or ants?

Not strictly entomological…  but still worth a look!

GigaPan is a US company that creates interactive gigapixel images. This technology was developed through a collaboration of Carnegie Mellon, NASA and Google. It was developed for NASA’s rovers to capture high definition panoramas of Mars.

Thankfully Jay Longson a graduate of UC Santa Cruz realised that the technology would be better employed in entomological pursuits..

See here: http://gigapan.com/gigapans/22723/snapshots

And here: http://nanogigapan.blogspot.co.nz/

 

 

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Ever considered a career change?

Most entomologists will be familiar with the idea of polyethism – the idea an ant will conduct different roles inside the colony at different times in its life.  This behaviour is not novel, but has recently been demonstrated on an unparalleled scale.

Danielle Mersch and her colleagues tagged every single worker in six colonies of Camponotus fellah and monitored each ant’s position within the colony twice per second using a computer. Over 41 days the researchers collected over 2.4 billion readings and 9.4 million interactions between the workers.

Even within the very limited nest spaces available researchers found there was strict spatial structuring within the nest – nurses and foragers rarely mixed. This has two probable benefits. First, pathogen transfer to nurses tending to brood and the Queen would be limited. Secondly, it allows for more efficient transfer of information to other foragers.

If possible, this kind of technique would best interesting to use in natural environments to monitor behaviour at a colony level.

Video of the heat maps generated showing worker location can be found here: https://www.youtube.com/watch?v=UbRRS-eDL0o

The article was published in April in Science.

Conducting behaviour

A study recently published in Proceedings of the Royal Society B suggests that honey bees may communicate using the electric fields that build up on their wings when they fly . The authors showed that electric fields change the position of the bees’ antennae. This in turn affects the sensory Johnstone’s organ the base of the antennae, which sends signals to the brain. Tests were conducted that showed honey bees learned a carbohydrate rich reward was present when they detected a specific electric field. This is another, fascinating way in which honey bees may be able to communicate with each other… or aid in communication such as the waggle dance. 

 

Interestingly, another study, recently published in Science, suggests that bumblebees can distinguish between the electric fields of flowers recently visited and those which are unvisited and have untapped reservoirs of nectar. In lab experimentation bees were able to distinguish between artificial flowers with two potential electric fields: one gave a sweet reward and the other gave a bitter reward. If bumblebees are able to do this in nature it would mean more efficient foraging behaviour.

 

 

 

 

 

 

Caterpillar Bodyguards

The interaction of parasitoid wasps with their hosts are often fascinatingly macabre. The interaction between the wasp Glyptapanteles sp.and its host, Thyrinteina leucocerae is no exception.

 

Adult female wasps oviposit directly into caterpillars of the moth. These parasitised caterpillars continue to develop along with up to 80 parasitoid larvae inside them. When the caterpillar reaches the 4th or 5th instar the parasitoid larvae tunnel out of the host to pupate. The larvae spin cocoons close to the caterpillar.

 

This is where things become interesting. The host then undergoes a series of behavioural changes. It ceases to feed and remains stationary near the cocoons. However, if the cocoons are approached by a potential disturbing agent, the caterpillar violently swings its head, apparently attempting to dislodge the disturbing agent.

 

Grosman et al compared the behaviour of parasitised and unparasitised caterpillars and the relative survival of wasps. They found that unparasitised individuals ignored wasp cocoons, as well as potential threats to the cocoons. They also found that removing parasitised caterpillars doubled the death rates of the wasps.

 

The authors dissected caterpillars from which parasitoids had egressed and found 1-2 active parasitoid larvae that had remained in the host. They hypothesise that the remaining larvae are responsible for the changes in host behaviour and that they represent the cost of host manipulation – some offspring are sacrificed for the survival of their kin.

 

The full paper can be found here: http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002276Image