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Don’t bee home late

The other day I noticed a large bee enter the door of my train carriage. Later, I saw it depart at a station 10 miles further down the line. Is it likely the bee could find its way home, without using the train? If not, could it integrate into a new hive or colony, or would it face resistance and attack?

• Yes, there is a good chance the bee will find its way back home. Its large size suggests it was a queen or worker bumblebee – one of the Bombus species. Bees employ special orientation flights to memorise near and distant landmarks relative to the nest. As well as these cues, they also use the Sun’s position as a landmark, making use of an inbuilt clock to compensate for the Sun’s movement across the sky.

My colleague Mark O’Neill released tagged worker Bombus terrestris and Bombus pratorum bees at staged points from their nests and all returned safely, the farthest from 6 kilometres away. The bees were taken to their starting points by car, in the expectation that their usual navigational aids would be compromised, much as one might expect from a train journey. However, it is likely that their internal clock, compensating for the movement of the Sun, enabled them to use solar positioning to fly back to a distance from the nest at which their visual cues would come back into play.

The ability to find a nest from a long distance away is vital to bees because nest sites and food may not be found in the same habitat. The very large females of the solitary, non-social bee genera Anthophora and Proxylocopa, whose nesting biology I studied at one site in the Negev desert, always flew straight out from the nest entrance and over the horizon formed by the shoulder of a hill about half a kilometre away. From the top of this hill, I was unable to see any suitable flowering vegetation in the next valley. I calculated that the minimum foraging distance from the nest site was 4 kilometres, requiring a minimum round trip of 8 kilometres.

It is also known that workers of the much smaller honeybee Apis mellifera can forage up to 13 kilometres from the hive, even in wooded country, and females of some large neotropical bees are thought to have foraging ranges of up to 30 kilometres.

If the train-travelling bee was a queen Bombus, it might have been able to insinuate itself into an established colony of the same species by lying low in the nest to give it time to absorb the colony odour and avoid aggressive responses from resident bees. An egg-bound queen with aggressive tendencies might kill the resident queen and assume control of the colony. But an exhausted and disoriented bee entering a strange colony may well be killed by the workers. All of these behaviours have been reported for bumblebees.

A female Anthophora unable to find its nest might excavate a new nest if suitable sites were close by. However, as far as I know, no one has tried to see if such displaced solitary species will set up nest at a new site.

Chris O’Toole

Bee Systematics and Biology Unit, Oxford University Museum of Natural History, Oxford, UK

Call me for dinner

I placed my mobile phone in my microwave oven, closed the door and then called it from a landline. I expected the oven to shield it from the incoming microwaves, but to my surprise the phone rang. Does this mean the oven is tuned or that it is leaking?

• The principles of the answer lie in part in Inside Science No. 158 (New ÐÓ°ÉÔ­´´, 15 February) and in part in the question itself.

Mobile phones and microwave ovens are designed to operate efficiently within a narrow band of radio frequencies. The microwave oven is tuned to 2450 megahertz, which is 650 MHz higher than the highest band which a European dual-band mobile phone can use and 550MHz higher than an American phone. You might say that the oven and the phone are not on the same channel. The oven is designed to keep in all the energy it produces, in order to cook food. It does this well, thanks in part to regulations limiting leakage of the 2450 MHz microwave energy that it uses. But at other frequencies – say the 900 MHz, 1800 MHz or 1900 MHz used by mobile phones, but for which the oven shielding is not designed – it might well leak energy in or out, which would permit a mobile phone to work from inside the oven.

Michael Brady, Asker, Norway

• A friend of mine placed a mobile phone in the microwave and turned the oven on. This is not advisable. Because I am an electronic engineer, my friend then asked me if the phone could be repaired. It could not.

By e-mail, no name supplied

• I have made some interesting observations about microwave ovens.

In Alberta it is legal to drive with a microwave detector in the car. This, the manufacturers of the detectors tell us, is for our own safety, because the instruments alert us to the shower of microwave radiation which is emitted by emergency vehicles speeding to save property and lives.

Perhaps of more interest to many owners of these delicate scientific instruments is that they can detect the radiation emitted by police vehicles intent on reducing the bank balances of speeding citizens. Out of concern for my safety, I carry one of these machines in my 260 horsepower automobile, and guess what? Every time I pass a supermarket which uses microwave ovens, the microwave detector goes off – about 200 metres away, in fact.

Jamil Azad

Calgary, Alberta, Canada

• The answer lies in the sensitivity and different tuning of your microwave detector and the shielding of the ovens. The ovens will leak some radiation across the spectrum – which you can pick up – but not normally enough high-energy microwaves to make the ovens dangerous – Ed

This week’s question

Coast to coast

If the oceans on Earth receded and eventually disappeared, there would be no coastline left. Likewise, if the seas kept rising, the total global coastline would reach zero as the waters lapped over Mount Everest. At some height in between there must be a maximum total coastline on the planet. Does anyone know where this would be in relation to today’s sea level, and are we anywhere near such ideal conditions for a beach holiday?

Ben Cadoret

Sheffield, UK