Improved techniques for mass rearing of the cigarette beetle and the tobacco moth

MISSING IMAGE

Material Information

Title:
Improved techniques for mass rearing of the cigarette beetle and the tobacco moth
Physical Description:
Book
Language:
English
Creator:
Bare, C. O ( Clarence Owen ), b. 1889
Tenhet, Joseph N ( Joseph Nesbitt ), b. 1897
Brubaker, Ross W
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine (Washington, D.C )
Publication Date:

Record Information

Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030360857
oclc - 783206054
System ID:
AA00023156:00001

Full Text

S r !UBR RY

November 197 TAT PLANT BOARD ET-247


United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine



IMPROVED TECHNIQUES FOR MASS REARING OF THE
CIGARETTE BEETLE AND THE TOBACCO iQiOTH

By Clarence 0. Bare, Joseph N. Tenhet, and Ross W. Brubaker
Division of Truck Crop and Garden Insect Investigations l/


Techniques for the mass rearing of the cigarette beetle (Lasioderma
"serricorne (F.)), and of the tobacco moth (Ephestia elutella (Hbn.))
have been developed at the Richmond, Va., field laboratory of this Bureau.
Much of the early work of rearing the cigarette beetle was reported by
Livingstone et al. (2), but many modifications and improvements of these
methods were developed later.

The cigarette beetle is a most satisfactory insect for mass rearing.
It is easy to handle, stands crowding, and is not especially susceptible
to disease. Because of the ease with which it may be reared and handled,
it offers many advantages as a test insect.

The tobacco moth is not a very satisfactory insect for mass rearing.
It will not tolerate crowding, therefore only relatively few insects can
be reared in a container, and it is subject to a disease which is diffi-
cult to control.

Description of Rearing Room

For the most satisfactory results in rearing these insects it was
found necessary to have an insulated room in which constant temperature
and humidity could be maintained. A small room, about 8 by 10 by 10 feet
was found satisfactory. Such a room was insulated with wallboard made
from sugarcane fiber. The door opening into the room was also covered
with the Wallboard, and weather strips were installed around the edges of
the door. Shelves were built to accommodate the rearing containers. A
small table mounted on casters served as a convenient workbench (see
figure 1).

Temperature and Humidity Control

It was found that a uniform temperature of 80 F. was about the opti-
mum for these insects. A radiator connected to the regular hot-water
heating system of the building afforded some heat in winter, but a supple-
mentary source of heat was necessary to maintain a constant temperature.


.!/W. D. Reed, E. M. Livingstone, A. W. Morrill, Jr., J. P. Vinzant,
and Herschel Pollard developed many of the earlier methods used in rearing
these insects.






-2-


Such a source was Frovided by a small electric heater of the resistance
type, controlled by a thermostat. This heater was placed on the floor in
front of the humidifying apparatus, so that the fan of the humidifier
would help circulate the hot air.

The humidifying a-paratus in a metal cabinet consisted of & fan and
of a perforated copper tube from. which water trickled over a layer of
shredded'wood fiber lining the sides of the cabinet. The flow of water
and the runrin: of the fan were controlled by a humidistat. The fan
drew air through the moist fiber and blew it cut into the room, so that
constant relative humidity of 70 percent was maintained.

On a control panel above the electric heater and the humidifier
v.ere mounted the thermostat and the humiidistat, which automatically turned
the equi mtnt on or off (see figures 2 and 3).

A hygrothermograph placed in the room enabled a close check to be
made on the operation of the heating and humidifying equipment. With this
equipment, equable temperature and humidity could be maintained. Under
most conditions the temperature could be held at a constant figure of
plus cr minus 2 F., and the relative humidity at plus or minus 2 percent.

Rearing Methods

Containers.--The most satisfactory type of rearing container for
eith-r insect v.as found to be the 1-pint fruit j.r with a 2-piece screw
top. This glass jar was of a handy size and could be readily cleaned
and sterilized. V.hen in use, the top of the jar was covered with a
square of tightly woven cotton cloth, such as sheeting, and the metal
rim of the top was screwed down over the cloth, thiis container provided
a tirh.t closure while permitting some entry of air (see figure 4).

Food.--Both the cigarette beetle and the tobacco moth will breed
readily in many seeds and in cereal products, as well as in tobacco. The
most satisfactory food tested was found to be a mixture of 5 pounds of
corn meal and 6 ounces of dry yeast, either bakers' or brewers'. Both
insects thrive on this mixture and it has proved satisfactory for about
10 years. One advantage of this food over tobacco is that larvae may be
easily sifted from it and adults can be removed much more readily than
fro, tobacco.

It was founa desirable to fill the jars about one-third full of the
meal-yeast mixture, and then to tamp it down firmly in the jar. The
ci-arette beetle could crawl about readily over the packed surface and
seemed to :.refer a firm material in which to oviposit.

-tcrilizaticn of food.--The eggs and newly hatched larvae of both
the c. rette beetle an'.1 the tobacco moth tze ul.most microscopic. It
would be difficult to determine whether food was already infested by
these or other insects. To insure pure cultures of the desired insects
some method of'sterilization was necessary. heating the jars containing
the corn meal and yeast in an electric oven at a te-rperature of 140 F.






-3-


for 4 hours proved satisfactory.

Obtaining eggs.--The eggs of the cigarette beetle are glued to the
surface on which they are depos.itod. They cannot be easily sifted from
corn meal because of the adherence of particles of the meal and because
of their fragility. The beetle likes to oviposit in tiny cracks and
crevices, and a tobacco stem (midrib of a leaf) is a preferred place. An
easy method of obtaining cigarette beetle egrs is to split open short sec-
tions of tobacco stems, clamp the halves together with a paper clip, and
introduce the sections into a cage of beetles. Many eggs will be deposi-
ted between the halves of the split stem and by separating the halves the
eggs are readily accessible. The stems should be sufficiently mist so
that they are not brittle (see figure 5).

The eggs of the tobacco moth have a tough integument and most of
them are deposited loosely, not glued to any surface. Eggs can be ob-
tained in quantity by confining large numbers of tobacco moths in a bell
jar resting on a disk of fine-mesh wire gauze stretched over a wooden
frame 1/2 of an inch thick. The moths readily oviposit upon the wire
gauze, and most of the eggs drop through onto a piece of paper placed
beneath to receive them. Large quantities of moth scales and appendages
also pass through the gauze, but they can easily be removed by screening
the material again onto a paper towel and rolling it from side to since.
The scales that pass through even a fine sieve adhere to the rough sur-
face of the towel, whereas the eggs do not.

Handling adults.--The cigarette beetle is a very small insect, only
2 to 3 mm. long, and can be handled most easily by a suction device. By
means of an aspirator, or a device such as is shown in figure 6, indivi-
dual beetles may be counted or mass collections quickly made. This de-
vice was operated by rubber tubing connected to the intake of an air
compressor. However, in using a suction device care must be exercised
not to use too much suction force, lest the insects strike the receiving
jar hard enough to injure them. In the procedure described in this paper
the suction was regulated by means of an adjustable pinchcock on the air
line.

The tobacco moth is fragile and also very active. To handle this
insect without injury, an anesthetic was found very helpful. Three or
four drops of ether placed on the cloth top cf the container soon
quieted the moths. Caution should be exercised not to use too much
ether, nor to leave the moths exposed to the fumes longer than necessary.
However, with experience on the part of the operator, moths may be anes-
thetized, removed from the jar, and transferred to another container with
little apparent injury and no loss.

Starting insect cultures.--Since cigarette beetle eggs cannot be
readily handled, the most satisfactory method o-f obtaining mass cultures
of this insect was found to be the introduction of adult beetles into
each jar. Approximately 1 cc. (about 300) of active, newly matured
beetles were placed in a jar. These beetles deposited their eggs in the
corn meal and died. After approximately 2 weeks, the dead beetles were






-4-
removed from the jar by means of the suction device previously described.

Cultures of the tobacco moth were started by placing in each jar
from 200 to 250 eggs, lifting them on the tip of a knife blade or small
spatula and scattering them on top of the corn meal-yeast mixture.

The label and date were placed on the cloth top of each jar by
means of a rubber stamp.

After a generation of insects had completed development, the glass
4ar was emptied and the jar and top were scrubbed with a brush in hot
soapy water. The used cloth covers were discarded.

Life History

Cia&rette beetle.--Under controlled conditions of 80F. and 70 per-
cent reut-ve humidity, the entire life cycle of the cigarette beetle
-e .uires about 50 days. The length of the incubation period is about
7 days, the larval period about 30 days, the prepupal period about 5 days,
and the pupal period about 8 days. There is usually a preoviposition
period of 2 or 3 days. The adult feeds very little, if any, and, accord-
inp. to Runner (4), usually lives for 3 weeks or more.

Tobacco moth.--Under similar controlled conditions, the tobacco moth
also has a life cycle of approximately 50 days. The incubation period
lasts about 5 days, the larval period about 35 days, and the pupal stage
about 10 days. This moth may mate and begin egg layin- within 24 hours
after emergence, according to Reed and Living stone (3).

Parasites, Predators, and Diseases

In the rearing room the most annoying enemies of the ci, .otte
beetle and the tobacco moth were certain mites, includinr- the straw itch
mite (Pediculoides ventricosus Ulewp.). A mite of Seiulus sp, and another
mite, tentatively identified by H. E. Eu ing as Monieziella ant'.ta BFink.,
have also given considerable trouble, according.to Bare (1). '7te most
satisfactory methods of control have been as follows Immi'Jate elimina-
tion of any infested jars; quick removal and cleaning ot, :,J .rs aft'-r
e-,"rr.eice of adult beetles or moths; use of ti-ht, closely woven cloth
over jbrs; and wiping off the shelves with a solution of 2-percent
chlordane in oil.

A'hymenopterous parasite, Aplastomorpha calandrae tow., and a
pteromalid, Lariophagus distinguendus (FoertC.), were parasitic on the
cigarette beetle in the laboratory, and sometimes a braci id, Microbracon
hebotor (Say), attacked larvae of the tobacco moth. lovwover, infestLtil n
by these parasites could be prevented by reasonable care and attention.

One of the* worst problems encountered was an unidentified disease,
apparently bacterial, which attacked the larvae of the tobacco moth.
Once or twice this disease threatened to wipe out an entire stock of the
tobacco moth. The only procedures that seemed of any value in combating






-5-


it were immediate discarding of infested jars, careful sterilization of
all glassware, and reducing the number of tobacco moth larvae in each jar
Crowding in the rearing jars seemed to favor the spread of the disease.

Literature Cited

(1) Bare, C. 0.
1942. Some natural enemies of stored tobacco insects, with
biological notes. Jour. Econ. Ent. 35: 185-189.

(2) Livingstone, E. M., Reed, W. D., and Morrill, A. W., Jr.
1936. Rearing the cigarette beetle for experimental use. U. S.
Bur. Ent. and Plant Quar. ET-84, 7 pp., illus.

(3) Reed, W. D., and Livingstone, E. M.
1937. Biology of the tobacco moth and its control in closed
storage. U. S. Dept. Agr. Cir. 422, 39 pp., illus.

(4) Runner, G. A.
1919. The tobacco beetle: an important pest in tobacco products.
U. S. Dept. Agr. Bul. 737, 77 pp., illus.







-6-





-7-


Figure 2.-Humidifier and control panel, with thermostat
and humidistat. Note electric heater on floor in front
of humidifier.





-8-


it-K N .'-:. -. ""- "-ah


..., ^

s ~f~Ju-^,


Figure 3.--Interior of humidifier showing water pipe above
wood-fiber lining of cabinet. The fan is for circulation
of the moist air.


W'E


~Ki #~$(





-9-


Figure 4.--Rearing jar for the cigarette beetle and the tobacco moth.




10-


.6_\J


'-T T I| I I I I i I.. I .1_1 1
[INCHES" 1

Figure 5.--Section of split tobacco stem showing eggs of
the cigarette beetle adhering to interior surface.






-11-


.A,
I'-""-
i, "


Figure 6.-Suction device being used to collect adult cigarette beetles.




UNIVERSITY OF FLORIDA

IIllll ll3 1262 09240 9571111iii
3 262 09240 9571