Malaria & Zika

The X-Tube

 

An innovative way of culling mosquito populations
without polluting the environment

No insecticides or genetically modified insects are needed.

 

According to the World Health Organisation the mosquito is the deadliest animal on the planet with mosquito bites causing one million deaths per year from malaria alone.

 

Zika is now emerging as another life changing disease being spread by these insects.

X-Tubes can tackle both problems, working on Zika during the day and malaria at night. 

 

Patent application number GB1602604.9

 

 

 

 

Overview

X-Tubes are proposed for capturing flying insects and dosing them with ionising radiation.

A unique feature of the X-Tube is that it treats male and female mosquitoes in separate operations.

Females can be killed with a lethal radiation dose and males released after receiving a sterilising dose. A budget version is used simply for killing females and capturing males for sterilisation by other unit.

We are not offering a “plug and play” solution to flying vector problems. Field research will be required to develop a portfolio of strategies using both types of X-Tubes, to tackle a range of disease transmission problems.

X-Tubes form part of our long term vision, looking forward to a time when Latent Power Turbines are widely used for power generation and air conditioning in tropical regions.

 

 

 

Figure 1. The X-Tube is a new method for killing female mosquitoes and sterilising male mosquitoes without using chemicals or genetically modified insects.

 

This difference in the way that male and female mosquitoes are treated is intended to maximise the effectiveness of the X-Tube treatment.

 

Zika, malaria and many other tropical diseases are spread by female mosquitoes when they bite people to drink their blood.

Female mosquitoes can lay 100 - 200 eggs about every third day after mating only once. Typically, they lay as many as three sets before dying.

A unique feature of the X-Tube strategy is to locally sterilise males that subsequently mate with female mosquitoes. After mating the females still produce eggs but the eggs fail to develop into adult mosquitoes.

 

In contrast, male mosquitoes can mate several times during their lives, so sterilising them is more effective than killing them for population control.

 

This “Sterile Insect Technique” has been used for many years using sterile males bred in captivity. But the process is costly with only one species of mosquito being bred and released at a time. [https://en.wikipedia.org/wiki/Sterile_insect_technique ]

 

We bring two new features to solving mosquito spread diseases:

(i)          Wild mosquitoes are sterilised in the field. We only sterilise small batches at a time, but breeding fitness is optimised because the mosquitoes spend a minimum amount of time away from their natural habitat.

(ii)         The X-Tube can be used for sterilising different species of males, but is only effective for treating one species at a time.

Most of the time, the tubes will be busy killing females, with batches of males being sterilised in a separate operation approximately every seven days.

The ability to treat a range of species is important because daytime flying Aedes species spread Zika and the night time flying Anopheles genus spread malaria.

 

The X-Tube can work day and night tackling both problems. It requires an electricity supply and offers maximum benefits in urban areas where its broad spectrum approach, culling mosquitoes of all species will reduce the mosquito nuisance in general.

 

How the mosquito trap works

We exploit the fact that mosquitoes can only fly at speeds of up to 1.5 miles per hour. (2.4 km per hour,)

 

 

Figure 2. The mosquitoes are blown back into the radiation chamber if they try to escape. Inside the main body of the radiation chamber the air speed falls to gentle breeze levels.

 

This is how the X-Tube is used to sterilise male mosquitoes

Male mosquitoes are attracted to females of the same species by the characteristic sound the females’ beating wings make.

We will use the luring technique based on this discovery that has developed by the Australian researchers Johnson and Ritchie [1].

[ http://entomologytoday.org/2015/10/26/male-mosquitoes-lured-to-traps-by-sounds-of-female-wing-beats/ ] 

Small loudspeakers linked to MP3 players will be placed close to the X-Tubes. These will broadcast sounds that fool the males into thinking, “Wow girls!”

The X-Tubes will then treat the mosquitoes in three phases.

 

Phase 1 Induction

Insects are drawn in to the X-Tube.

 

 

Figure 3.   Induction.
Insects flow in, but only insect filtered air flows out.

 

Phase 2 Sterilization

This is done by bombarding the mosquitoes with x-rays. In order not to over-radiate the insects, the x-ray tube is only switched on when the radiation chamber is full to capacity.

 

Phase 3 Release back into the wild

Two options will be employed.

 

Option 1. Close vicinity release

The fan is operated in reverse so that the sterilised insects are blown back into the local environment.

 

 

Figure 4.  The male insects are gently blown back into the wild. Alternatively, they may be retained in a large holding cage where they are stored until the end of the days operations, when they are released in bulk.

  

Option 2. Release at a distance

 

 

Figure 5. We don’t want to repeatedly dose the same males because this would make them too sickly to mate. The X-Tube will come with a number of internal bags or cartridges that can be sealed and used for carrying sterilised males to delivery points beyond the insects’ normal flying range. These could be delivered by volunteers while going about their daily journies. In addition to maximising mosquito protection for the X-Tube owner, it would spread the protection benefits to the wider community. 

In order to avoid multiple x-ray exposures for the close vicinity release of sterilised males, this release needs to be the last in the treatment series. Alternatively, all males would be released beyond the flying range of the mosquitoes.

The notes below are for early adaptors and explain how a single sterilising x-tube could be used. But it should be understood that for maximum effectiveness each house in an urban area should have its own X-Tube.

 

Figure 6. Altruism and self interest feed off each other because the X-Tube owner can extend their mosquito protection area by a factor of 9 by sharing sterilised male mosquitoes with the local community. [Area of large circle = px(3R)2 = 9x pxR2]

 

·        Zika-carrying mosquitoes stick close to home and have a flight range of about 0.25 miles.

·        Malaria carrying mosquitoes have a range of “just under a mile.”

 

Using the X-Tube to eliminate female mosquitoes

We humans give out a number of signals that female mosquitoes can pick up when they want to come and drink our blood.

The X-Tube exploits several of these signals to fool the females into thinking that dinner is ready.

(i)          They are attracted by dark clothing.
The grid at the front of the X-Tube is matt black to create a similar visual effect.

(ii)         They are attracted by body heat, especially the slightly higher body temperature of pregnant women. (37.8oC.)
The front grid can be heated to this temperature.

(iii)        The females just love the moist scented air created by the evaporation of human sweat.
A similar humid air zone can be created around the X-Tube by slowly dripping water onto the warm grid so that it evaporates. Salt can be added to the water, to create that extra enticing tang.

(iv)        Alternatively, the x-ray tube cooling system can be used to evaporate the water.

(v)         Female mosquitoes are very strongly attracted by the carbon dioxide (CO2) exhaled in human breath. Propane can be burned to generate combustion fumes that are CO2 rich.  Alternatively the X-Tube can be located outside a building, close to a stale air vent.

(vi)     Synthetic super-attractants are reported to be four times as attractive as human odurs, but these only fool females at distances of 30 meters. Other lures are required as the insects get closer [2].

 

Once the female mosquitoes have been enticed into the X-Tube they will be given the same three phase treatment offered to male mosquitoes but the radiation dose will be lethal.

 

Recycling dead insects to generate CO2

The X-Tube can be modified so that female insects are killed by red hot heat with the CO2 rich combustion fumes being fed back into the air.

 

A budget price X-Tube

This would dispense with the sterilising x-ray tube and kill off all off the insect by heat treatment alone.

 

Figure 7. This version of the X-Tube eliminates the need for an x-ray tube and the very high voltage power supply required to generate x-rays.

If the role of this Tube is simply to collect fertile male mosquitoes for sterilisation at another location then the heating element can be dispensed with and a lower power fan employed.

 

 

Figure 8. A budget X-Tube used solely for collecting fertile males can include a larger cartridge. The only critical air speed is the speed with which the air passes through the mosquito trap hole. The hole is fitted with a hinged flap that opens inwards when the air flows, but closes under gravity to seal the hole if the power supply fails.

Paradoxically a larger bladed fan running steadily at the minimum speed required to prevent mosquitoes escaping through the trap hole will require less power than using a parallel sided tube and a smaller fan. (We learned this trick while designing our Latent Power Turbines!)

Other important advantages of the design are that the larger cartridge combined with air travelling through the fan at a lower speed reduces the stress on the mosquitoes while they are in captivity.

The power could be supplied by a solar panel, with a rechargeable battery being used for night time work. [Mosquitoes love still air environments where the winds are too weak to power wind turbines.]

 

Applications for the budget price X-Tube

(i)          There will be an optimum for the number of more expensive sterilising X-Tubes required in a neighbourhood. If too many are deployed, male mosquitoes will be over-exposed to x-radiation. Budget X-Tubes designed to target female mosquitoes will be their ideal compliment.

(ii)         The tube can be fitted with a removable cartridge and used to attract male mosquitoes. The cartridge can then be taken to a central point for sterilisation, and then returned to the capture point for local release.
The role of these outlying supplies of wild male mosquitoes will become increasingly important late in the campaign when the supply of wild unsterilized males close to the central sterilising X-Tube has declined.

(iii)        During the final leg of a local eradication campaign, the release of sterilised mosquitoes can be extended to cover an area 25 times the area directly protected by the central X-Tube.

 

 

Figure 9. Budget X-Tubes can be deployed to increase the territory of sterilised males by a factor of 25 compared with the area of the close release zone. [Area of large circle = px(5R)2 = 25x pxR2]

·        For Zika control, 5R = 1.25 miles.

·        For malaria control, 5R = 4.5 miles

This model assumes that the community can only afford one sterilising X-Tube and 25 budget tubes. Control will be quicker and more widespread if additional X-Tubes are available.

Multiple radiation exposures for the same male needs to be avoided because these just make the insect sickly and less sexually active. Male mosquitoes have a lifespan of up to 10 days. So the benefits of capturing, sterilizing and then releasing more than one batch every 10 days needs to be investigated before they can be claimed.

However it should be born in mind that X-Tubes can can capture a range of flying insects including different species of mosquitoes. The capture of male mosquitoes is species selective because each species requires a different frequency of sound wave to attract them.

This suggests that one method of using scarce equipment resources would be to spend 24 hours sequentially treating all species of fertile males at one location, and then move the equipment to a new location. The time lapse before returning to the same spot would need to be determined by field trials.

 

Our attrition strategy

Existing sterile insect techniques use a big bang approach, trying to take out the whole of a local population by overwhelming it with sterile males. In contrast our approach is long term and subtle.

X-Tubes work by attrition, gradually wearing down the size of the local mosquito population throughout the whole of the breeding season.  

Their effect is cumulative over the years as fewer mosquitos are alive to go into hibernation or lay winter hardy eggs.

Our broad spectrum approach uses different sound frequencies to attract different species of males using the same equipment. It can for example, tackle both daytime Zika vectors and night time malaria vectors. This flexibility will make X-Tubes very cost effective as a long term investment.

Globalization and global warming suggest that "new" diseases using flying insects as vectors are likely to become crises at short notice.

X-Tubes may be the tools we need to cope with these future threats.

 

The target market

In the early years X-Tubes are likely to be bought by businesses, public organisations and reasonably affluent middle class families.

However the long term vision of our sister company Latent Power Turbines Ltd is to generate electricity locally in developing countries to avoid the huge costs of installing a nation grid. As we explain on our Latent Power Turbine page, these turbines can be used in tropical regions for air conditioning, with free electricity being generated as a by-product. Hopefully this will help to extend the benefits of X-Tubes to poorer communities within the next twenty years.

 

Have we got the strategy right?

X-Tubes are a new weapon for fighting vector born diseases. As with all new weapons, strategies will probably have to change after lessons have been learned in the early campaigns.

For example, a "Converging resource" strategy may turn out to be the best. Using this strategy, fertile mosquitoes would be captured in an outer zone using budget X-Tubes, centrally sterilised, then used to saturate an inner zone so that the target species of mosquito is completely wiped out. The boundaries of the outer zone could then be expanded, more budget X-Tubes acquired and the size of the inner clean zone increased. This strategy would be financially attractive because additional X-Tubes would only be purchased or hired if the results to date were encouraging.

State of development

To date we have only got as far as filing a patent and our expertise is in engineering. We need the input of entomologists to refine our design and carry out the field research.

 

Interested in collaborating with us or investing in our X-Tube and Latent Power Turbine projects?

 

Please contact Bill Courtney by email to start a dialogue.

billcourtny AT lineone.net

  

Safety

The x-ray tube and very high voltage power supply required are similar to those used in old fashioned cathode ray tube TV sets and computer monitors.

X-radiation is potentially very dangerous but good design can be used to bring the risk under control.

For example, the TEL-X-Ometer is an x-ray machine that is used for school physics teaching. [Bill Courtney, the inventor of the X-Tube used one regularly during his years as an A level physics teacher.]

Here is an extract from the manufacturers' catalogue.

 http://www.telatomic.com/x-ray/

 

References

 

[1] Brian J. Johnson, Scott A. Ritchie. (2016) The Siren’s Song: Exploitation of Female Flight Tones to Passively Capture Male Aedes aegypti (Diptera: Culicidae). Journal of Medical Entomology 53, 245-248.  [http://entomologytoday.org/2015/10/26/male-mosquitoes-lured-to-traps-by-sounds-of-female-wing-beats/ ]

 

[2] Fredros O. Okumu et. al., (2010) Potential benefits, Limitations and Target Product-Profiles of Odour Baited Mosquito Traps for Malaria Control in Africa PLoS ONE, volume 5, issue 7, e``573

 

[3] Arnold S. Mmbando et.al,(2015) Effects of a new outdoor mosquito control device, the mosquito landing box, on densities and survival of the malaria vector, Anopheles, inside controlled semi-field settings, Malaria Journal, 14: 494

 

[4] Samson S. Kiware et. al., (2015) Predicting Scenarios for Successful Autodissemination of Pyriproxyfen by Malaria Vectors from their Resting Sites to Aquatic Habitats; Description and Simulation Analysis of a Field-Parameterizable Model, PLoS ONE,DOI: 10.1371/journal.pone.0131835