Aphid Responses to Colors in Artificial Rearings 1
By
Research Station,
JEAN JACQUES
Canada Department
IKTRODUCTION
:,[y interest in aphid responses to colors dates back to
1963 when the rearing of aphids on synthetic diets was
progressing with difficulty at St. Jean. The solution to
the problem of rearing aphids and, in general, of several
homoptcrous vectors of plant diseases has been attempted
with more or less success by several people over the past
forty years (Carter 1927, 1928), (Hamilton 1930, 1935),
(PIetsch 1937), and my former colleague Maltais (1952).
Mittler and Dadd (1962) had just published their pioneer
paper on the artificial feeding of Myzus persieae (Sulzer). However, no definite method or diet was apparently
satisfactory
for our pea aphids, Aeyrthosiphon
pisum
(Harris).
It was a frustrating period in spite of deep
meditations and "imaginccring," and hard hopes. I welcome the opportunity to talk to you during this symposium about the evolution of my ideas and laboratory
methods which, over the past two years, have made possible the first study of color responses of winged and
apterous aphids in vitro. The classical works of V. Moericke (1952) demonstrated that in nature winged aphids
were attracted to yellow surfaces. Aphid flight was also
investigated by J. S. Kennedy and his associates and reviewed by Kennedy and Stroyan (1959).
ECOLOGICAL ASPECTS
OF APHID
MICROENVIRONMENT
Aphids spend most of their lives in close contact with
foliage. Except during moulting and short periods of
flight, in the case of alatae, they feed to sustain their
rapid rate of growth and reproduction, which is of absolute necessity to counterbalance effectively the ravages of
numerous parasites and predators. They live in an atmosphere of relatively high humidity where oxygen and
carbon dioxide may not only attain concentrations higher
than those of the surrounding air but may show also
variations from day to night. Such an atmosphere might
also have a specific odor. Whenever possible, an aphid
will start a colony under a leaf or between leaves or in
the whorl of a plant. For example, I could mention the
corn leaf aphid, RhopalosiPhum maidis (Fitch), found on
corn and various grasses, the green peach aphid, M. persieae, found on potatoes, and the currant aphid, CrYPlomyzlts ribis (L.). I am not including such species as the
poplar leaf-petiole gall aphid, Pemphigus populieaulis
Fitch, or the sugar-beet root aphid, Pemphigus belae
Doane, that live in galls or on roots. When leaving direct sunlight, an aphid enters into a habitat of subdued
light filtered by chlorophyl. The human eye sees this
transmitted light as greenish yellow, a fact which can be
demonstrated by bringing a green leaf close to the eyeball
while facing a source of light. If the feeding activity of
aphids causes the formation of anthocyanins in the plant
tissues, the environmental light at the aphid level may
shift from yellow to orange, to red, to reddish purple, and
Presented as part of a symposium on "Insect Responses to
Light and Color," at the annual meeting of the Entomological So·
ciety of America, New Orleans, Louisiana November 30, 1965.
The author expresses his gratitude to the Rockefeller Foundation
for granting funds to the Entomological Society of America and
thereby permitting his participation in this symposium.
1
378
CARTIER
of Agriculture,
St. Jean, Quebec
to purple. The physical characteristics
environment are therefore apparently
LET THE APHID
of the aphid micronumerous.
DECIDE
\Ve must bear in mind that transferring
an aphid
nymph or adult from a natural host plant to a rearing
cage made of glass, plastic, or other material, and hoping
for instantaneous colonization is asking indeed for a
"rapid evolution" by the aphid. The design of elaborate
mechanical devices to feed aphids by pressure (van Hoof
1958 and Maltais, unpublished) had the disadvantage that
aphids were sometimes more attracted to the shiny metallic surfaces and were not "clever" enough to locate, behind a steel grid, membranes that sometimes exploded
under a pressure of 10-15 atmospheres. Not so long ago
(Kennedy and Stroyan 1959, p. 142) pressure was considered the logical step in this problem.
The problem with rearing aphids off plants is to incorporate in the rearing methods enough stimuli to obtain
aphid responses similar to those operative in the natural
host plant selection. As Baerends (1959, p. 222) stated:
"Very often when an insect reacts to an object, only a
few of all physical properties the animal is able to perceive actually contribute to releasing the response. Properties that are of importance in evoking one special reaction are often of negligible value for another response."
So, the problem has many similarities with behavioral
components involved in plant resistance to feeding. Beck
(1965) recently proposed a classification of stimuli influencing different feeding behavior responses such as
orientation, biting or piercing and maintenance of feeding.
After all, aphids are expected to orient themselves in
cages, pierce a membrane, and maintain their feeding.
This phenomenon is exactly what I had in mind when I
designed a very simple and inexpensive test chamber to
find out whether pea aphids had color preferences and to
what extent certain wavelengths could favor the colonization of artificial feeding cells (Auclair and Cartier 1963
and Cartier and Auclair 1964). To provide aphids with
light of low intensity and an atmosphere of high humidity
was relatively easy. The odors of plants and the oxygen
and carbon dioxide content of their environment have not
been thought of as a primary necessity, although I still
think that these factors should be investigated. I believe
that we should not impose our views on insects any more
than on people. Let the aphid decide whether complete
light or a fraction of it is better for it. In more precise
terms, allow light to attract the aphid during its orientation response to a surface which might also be an arrestant stimulus or a repellent. The events that take place
during and after piercing of membranes may also be
governed partly by light.
LIGHT
AND COLORS
Before discussing in detail the responses of aphids to
colors, I wish first to comment on the nature of light and
colors, and on the determination of quality and quantity
of energy produced by various filtering substances like
colored glass, plastics, colored rubber membranes, and
anilin solutions. As the moderator of this symposium remillllt:d, light is but a fraction of the spectrum of radiant
energy. Selective elimination or absorption of certain
spectral radiation present in white light leaves a residue
which imparts a sensation of color to the eye (Brode
1955). This phenomenon is observed color. A yellow
surface or solution of dye appears yellow because of the
elimination of blue radiation, though it may still be composed of green, yellow, orange, and red. Spectral color
is light of a specified narrow band of wavelengths such as
the yellow light emitted from a spectrophotometer when
the wavelength selector is set at 5800 Angstroms.
A
tungsten filament has a continuous spectrum, a mercury
arc has a line spectrum.
20.0
15.0
10.0
5.0
In the laboratory, one can test color responses of insects
by c.-..::posingthem to spectral bands coming out of a projector cquipped with prisms, or use various light sources
and filters to produce colors. Filtering light is a process
involving wavelength and intensities of energy. Usually,
lamp manufacturers
provide upon request spectral data
with calibration in microwatts per 10 millimicrons per
lumen, or comparable units that permit the calculation
with precision of the actual level of energy in ergs per
nn" per sec. or in microwatts per cm'.
COLOR PREFERENCE
AND GROWTH
WHITE
BLACK
YELLOW
ORANGE
REO
FIG. I.-Growth
responses of two aphid species reared
under environmental light of various colors. White and
black stand for checks under complete light and in darkness.
RESPONSES
The original preference chamber equipped with rubber
filters (Cartier and Auclair 1964, 1965) was not designed
to solve Ilroblems of equal irradiances. In my first experimcnts on color responses, the aphids were attracted or
repelled by colors and also fed through the colored membranes. At that time, anyone who could rear aphids off
plants for 10--15 days, albeit with toy balloons, was proud
of such results. Better techniques for the measurement of
wavelength and light intensity will soon be published.
Spectrophotometric
analysis of these rubber membranes
have revealed the following facts: the pigments produced
vivid color effects with very definite spectral characteristics; the light intensity was from 20 to 30 footcandles;
their transmittance was 1-2%.
and the potato aphid, Macrosiphll1n
when free to choose, have shown
a preference for yellow and/or orange light over blue,
green, and rcd light. Nymphs, apterous and winged
adults, showed similar patterns of responses. With newer
types of chambers that allow the changing of light filters
from outside, the aphids that had settled on a particular
color were leaving their feeding site, migrating within
the chamber, and settling again on yellow and/or orange,
according to whether orange was changed to green, or
yellow to blue or red. These simple experiments have
negated the ideas of Moericke (1952) that aphids settle
during a phase of particular sensitivity to yellow and,
once settled, this stimulus would no longer be significant.
In accordance with the catenary process suggested by
Kennedy (1965), host selection would be the result of the
insect's making the previous response in the chain of
stimuli. I do not mean to say that Kennedy considered
the chain irreversible. However, in the case of aphids, it
is clear that the sequences can be reversed by the mere
action of the color of the light.
The
EFFECTS OF VARIOUS WAVELENGTHS ON
A. PISUM
ANO M. EUPHORBIAE
~
WEIGHT (MG.) OF APHIDS SUR\'IVING
c:::J
TOTAL
pea aphid
cupllorbiae (Thomas),
One of the most interesting aspects of this work is that
aphids are not only attracted by certain wavelengths, but
that rearing them under 24-hour environmental light of
those particular
wavelengths
has produced the best
growth responses. It was also found that blue, green, and
red radiations (Fig. 1) produced results about as poor as
those obtained in total darkness.
Compared with full
white light, orange radiations increased growth of A.
piSllm by 60%, and of M. euphorbiae by 2250/0. Orange
radiations were found also to favor better growth in
comparison with white light of high and low intensities,
or with darkness (Cartier 1965).
I am now completing, at my laboratory, work on a
gradient of color and energy. For that research I use
several solutions of anilin of sharp-cut characteristics to
filter the spectrum from 510 to 620 millimicrons by steps
of 10 millimicrons at 80% transmittance.
So far, the results obtained indicate that aphids are wavelength sensitive, and do not show certain responses because of the
radiant energy available. Under identical experimental
conditions, two aphid species responded very differently to
colors: a red clone of the potato aphid preferred higher
levels of energy in the green bands with a peak of response at 530 mu and another one at 550 mu; a green
clone of pea aphids preferred lower levels of energy in the
orange band at 590 mu. A black aphid, Aphis labac
Scopoli, also is being tested. This species, with its dark
pigments, could be absorbing radiant energy over a
broader spectrum than a green or a red species. In fact,
preliminary results indicate a growth response over a
broader band of the visible spectrum. Its color preferences are like those of the potato aphid.
CONCLUSION
Aphids have been referred to jokingly as "little stupid
bags of sap." Such a statement is probably a mark of
ignorance, since we have come to realize that they are
particularly well equipped to cope with their environment.
The extent to which aphids could discriminate between
various dietary components was not known with precision
until recently. I have data (Cartier, unpublished) indicating that A. pislItn and M. euPhorbiae have responded
differentially and positively in preference and in rearing
tests to food gradients with increments of 5% sucrose,
0.43% amino acids, and 0.3 of a unit of pH. The spectral
sensitivity of these two aphid species is much more exacting than I ever suspected. For example, under conditions
of nearly equal energy, M. euPhorbiae grew four times
heavier under a light filter that transmitted 800/0 of
379
encrgy at 520 mu than under a similar filter transmitting
800/0 at 510 mu.
The rearing of aphids on synthetic diets will now allow
for more critical evaluations than in the past. Moreover,
watcr-pan traps could be improved by running color preference tcsts in nature. It might be found that some species are more attracted either to yellow-green, yellow, or
orange. Anilin solutions, standardized with a spectrophotometer and poured to a depth of 1 cm in pan traps
should be a good technique. The possibilities of laser or
coherent light to either repel or attract aphids at great
distances in full daylight should be investigated. If physicists are contemplating communications between satellites
with coherent light, why should we not be anxious to
know what effects a beam of laser light of an appropriate
wavelength could have on aphids and other insects? The
emitter could be mounted on a radome rapid scanner or
reRected by a rotating mirror somewhat like an airport
beacon. One could determine the rate of scanning necessary to keep /lying insects on a continuous homing response. I think this might and should be realized soon,
first in the laboratory with aphids in artificial rearings,
or in aphid Right chambers.
REFERENCES CITED
Auclair, J. L., and J. J. Cartier.
1963. Pea aphid:
Rearing on a chemically defined diet. Science 142:
1068-9.
Baerends, G. P. 1959. Ethological studies of insect behavior. Ann. Rev. Entomol. 4: 207-29.
Beck, S. D. 1965. Resistance of plants to insects. Ann.
Rev. Entomol. 10: 207-32.
Brode, W. R. 1955. Color and chemical constitution.
Amer. Scientist 43 (2) : 259--84.
Carter, W. 1927. A technique for use with homopterous vectors of plant disease, with special reference to
the sugar-beet leafhopper, Eutettix tenellus (Baker).
J. Agr. Res. 37: 449.
1928. An improvement ill the technique for feeding
homopterous insects. Phytopathology 18: 246.
Cartier, J. J. 1965. Action des radiations orangees sur
Ie puceron du pois, Acyrtlzosipltoll Pismn (Harr.) et
sur Ie puce ron de la pomme de terre, M acrosiphum
ellphorbiae (Thos.) en elevage sur dicte synthetique.
Phytoprotection 46(2) : 65-73.
Cartier, J. J., and J. L. Auclair.
1964. Pea aphid behaviour: color preference on a chemical diet. Canad.
EntomoI. 96: 1240-3.
1965. Effets des couleurs sur Ie comportement de diverses races du puceron du pois, Acyrtltosiphon
pisum (Harris), en elevage sur un regime nutritif de
composition chimique connue. Proc. XII Int. Congr.
Ent. London (1964).
Hamilton, M. A. 1930. Notes on the culturing of insects for virus work. Ann. AppI. BioI. 17: 487-92.
1935. Further experiments on the artificial feeding of
MY:l1Is persicae (Sulz.). Ann. AppI. BioI. 22: 243-58.
Hoof, H. A. van. 1958. Onderzoekingen over de bio10gische overdracht
van een non-persistent
virus.
Med. no. 161. Van Putten & Oortmeiier, Alkmaar,
Holland. 96 pp.
Kennedy, J. S. 1965. Mechanisms of host plant selection. Ann. Appl. BioI. 56: 317-22.
Kennedy, J. S., and H. L. G. Stroyan.
1959. Biology
of aphids. Ann. Rev. EntomoI. 4: 139-60.
Maltais, J. B. 1952. A simple apparatus for feeding
aphids aseptically on chemically defined diets. Canad.
EntomoI. 84(9) : 291-4.
Mittler, T. E., and R. H. Dadd.
1962. Artificial feeding and rearing of the aphid My:;us persicae (Sulzer), on a completely defined synthetic diet. Nature
195: 404.
Moericke, V. 1952. Farben als Landereize fUr gefliigelte Blattlaiise (Aphidoidea). Zeitsch. Naturf. 7(5) :
304-9.
PIetsch, D. J. 1937. Improved device for artificial
feeding of aphids. J. F-con. Entomol. 30: 211.
BOOK REVIEWS
INSECTPESTS, by George S. Fichter, illustrated by Nicholas Strekalovsky.
August 1966. Golden Press Inc.,
New York. Paperback $1.00, library edition $3.95.
The newest of the Golden Nature Guides is entitled
Insect Pests and covers some 350 of the more common
pest species of insects and related arthropods. The book
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are an introduction to the types of insect pests and various methods of control. The section on chemical control
is understandably general, with considerable emphasis on
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Specific control data on material, dosage, and time of
application are avoided in most cases, with the reader encouraged to seek this information from local extension
agencies, such as his county agent, after identification of
the pest is reasonably definite.
The author, George S. Fichter (an E.S.A. member),
received his entomological training at North Carolina
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writing and editing popular works of natural history.
Special mention should be given to the illustrations by
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JOHN J. FAVINGER,State Entomologist
Indiana Department of Natural Resources
Indianapolis
BIOLOGICALTECHNIQUES, by Jens W. Knudson.
1966.
Harper & Row, Publishers. New York. XI + 525 p.
Illus. $12.00.
This useful book attempts to give a variety of techniques for collecting, preserving, and illustrating all phyla
of plants and animals. It is designed as a textbook for
380
(Continued on page 383)