Vergara - 1976 - Physiological and morphological adaptability of ri

356 criixinrs Aim RICE
sider how this problem was met while still using constant temperature equipment.
Working in lain/an, the Japanese entomologist Koidsunii (1934. 1937, 1942)
undertook to investigate the possibilities that the tropical fruit flies D. dorsalis
and D. cucirrbitae could become established in Japan by evaluating fruit fly
responses to simulated climates of mainland southern Japan. For this simulation.
Koidsumi used alternating temperatures rather than constant temperature
conditions. concluding that such alternations xvould more closely approximate
the diurnal fluctuations that occur in nature. He. like Bodenheimer (vide supra),
studied not only development. but also reproduction and suntival. He evaluated
not only the full tolerance range of responses to temperature, but also alternating
temperature patterns corresponding to conditions on the Japanese mainland
(Koidstimi 1939, 1942). His results suggested to him that the two species could
successfully establish in southern Japan in any month of the year except Decembcr.
January. or February He further concluded that winter climates were
severe enough that any previously‘ established infestation ivould be eliminated.
These predictions have clearly stood the test of time; although much commercial
traffic and travel has occurred between the Ryukgxu Islands and Taiwan.
xvhere the pests occur naturally‘, and mainland Japan, neither species has ever
gained a permanent foothold there.
BIOCLIMATIC GROWTH CHAMBERS
Given thc general finding that insects respond in a quantitatively different mailner
to fluctuating conditions compared with constant conditions. and considering
the need for bioclimatic purposes of rather precisely measured responses of
insects to realistic climatic factors. a number of researchers have tried to resolve
the matter by construction of laboratory equipment capable of simulating climatic
patterns as they occur in nature. One of the first to attempt something on
this order was Stone (1939), who, in an examination of the climatic responses of
the Mexican fruit tly. flimstrepha Iudens (Loev-r"). invented a cam-activated
temperature controller to be attached to the usual laboratory incubator so that
actual temperature cycles as recorded in the field could be reproduced.
Probably the most ambitious attempt to develop and use laboratory equipment
to provide actual climatic patterns under controlled and repeatable conditions
fcr use in insect ecological studies was that described in Flitters and
Messenger (1953). Seven large bioclimatic chambers were constructed in Hawaii
to provide climatic conditions recorded for various localities in mainland United
States so that responses of certain insect pests not yet present on the continent
could be measured. From this. the potentials for invasion. establishment. and
spread of such foreign pests could be estimated. The chambers were large. wall;-
iii. plant grrovath chambers. with floor area measuring 2 in >< 2 m. the interiors
of which were air-conditioned and illuminated so that actual diurnal cyjcles of
temperature and relative humidity and natural photoperiods could be provided.
The cam-actuated control instruments were designed to follow and reproduce