Go to National Library of New Zealand Te Puna Mātauranga o Aotearoa
Volume 77, 1948-49
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Summary and Conclusions.

In an investigation into the reactions of mosquitoes to the aircraft environment, it was found that:

(1)

When exposed to reduced air pressures corresponding to those prevailing at altitudes of about 10,000 feet to about 30,000 feet male and female Aëdes notoscriptus are sluggish in their movements and very rarely make voluntary flights.
(2)

When exposed to reduced air pressures corresponding to those prevailing at altitudes of about 30,000 feet to 40,000 feet these mosquitoes do not fly even in response to contact stimuli; they seldom move about voluntarily, but will move a few steps in response to contact stimuli, and still show a sluggish righting response when knocked off their balance.
(3)

When exposed to temperatures of 10° C. to 12° C. male and female Aëdes notoscriptus show some degree of sluggishness in their movements; fewer voluntary flights are made as the temperature falls, although brief flights are made in response to contact stimuli at temperatures ranging down to 8° C.
(4)

Aëdes notoscriptus will not fly even in response to contact stimuli, when exposed to temperatures below 8° C.; members of this species become inert and appear as though dead if exposed to temperatures below 3° C., and if maintained at 3° C. to 8° C. for long periods.
(5)

The life-span of Aëdes notoscriptus is not significantly shortened by exposure to vibration sufficiently intense to prevent the insects from resting, for periods of up to twenty-four hours and under various conditions of reduced air pressure and temperature.
(6)

Exposure to the aircraft environment does not shorten the life-span of Aëdes notoscriptus in any significant measure, provided that the mosquitoes concerned are able to feed at normal intervals.
(7)

Under laboratory conditions, male Aëdes notoscriptus survived for an average of four days after being deprived of food; this survival period did not vary on exposure to actual and simulated conditions of the aircraft environ-

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ment; the average survival period of females under similar conditions was a little longer than that of the males.
(8)

As male Culex pipiens pallens brought from Japan by air survived afterwards for an average of six weeks at New Zealand winter temperatures, and by analogy with known cases of mosquito introductions in other lands, it is likely that exotic mosquitoes could become established at least in the warmer parts of this country once introduced from abroad by air.
(9)

Aëdes notoscriptus and Culex pipiens pallens travelling in aircraft fly about in agitated fashion when the motors are first fully opened out and for some five minutes afterwards; similar activity is shown during landing and until a few minutes after the aircraft becomes stationary.
(10)

On being restored to normal conditions of air pressure and temperature Aëdes notoscriptus rapidly recovers from the state of inactivity induced by exposure to reduced air pressures and temperatures.

It is concluded that:

(1)

The most favourable time for carrying out insecticidal spraying on board aircraft is immediately before turning into the wind for the take-off run.
(2)

A pyrethrum-base insecticide should be sprayed from an automatic system controlled from the instrument panel in the cockpit.
(3)

Routine spraying with pyrethrum-base aerosols should be supplemented with residual D.D.T. treatment of all enclosed spaces of aircraft.
(4)

In the last analysis the safeguarding of New Zealand from insect introductions depends in large measure on the adequacy of insect-control measures taken at overseas airports used by planes flying to this country.
(5)

Until all international airports are obliged to be maintained under strict insect control, and until all aircraft flying to the Dominion are equipped with fully effective apparatus for insecticidal spraying, an adequately equipped mosquito-control organisation must be maintained at all New Zealand airports handling overseas traffic; the numbers of such airports should be kept at an absolute minimum in order that the efforts of this organisation may be concentrated within as small an area as possible.
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