Alex Kiener
Effects of Temperature on Flour Beetle Activity Level
Flour beetles are insects that are around 1/7 of an inch long in their adult phase. We used Red
Flour beetles which are reddish-brown and have a smooth-sided thorax (Grain and Flour Beetles). These
flour beetles are considered pest for their eating habits. They consume starch products and often
inhabit storage rooms and destroy crops. They are commonly used for laboratory research because they
do not require a lot of maintenance. The flour beetle is describes as hardy leading to the little elaborate
laboratory equipment for maintenance (Grain and Flour Beetles). Studies done have revealed that the
beetle prefers dry environments. Arthur found that beetles preferred the lowest relative humidity that
they tested which was 40% relative humidity (Arthur). In an experiment done to try and see the affects
of environmental factors on the beetles they found some evidence to suggest that there are some
factors that the beetles have preference over. Two of these factors include the depletion of the
nutrients in the area and then the accumulation of cast larval skins, dead imagoes, and similar debris.
This makes sense because the beetles will not want to live in a place with no food or a place that is
crowded with more than the carrying capacity of bodies (Ghent).
We did our experiment to determine what the optimum temperature for the flour beetles was
and to see whether the hot temperature or the cold temperature decreased the amount of activity they
had. Applications of this would include using this data to control starch product temperature. Because
beetles are considered pests, farmers would want to keep them out. By
controlling temperature and possibly humidity, they could create an
environment that is undesirable for the beetles making them less likely
to infest the stock.
We would like to believe that it the temperature has an effect
on flour beetle activity, cold temperature will have less activity. Our
null hypothesis for this experiment is that temperature has no affect on
flour beetle activity. To test these hypotheses, we chose 3
temperature; hot (44 degrees C), room temp (26 degrees C), and cold
(4 degrees C). If an effort to save time we could not test more, less
extreme temperature for any slightly less affects. We places 10 flour
beetles into 3 different Petri dishes. These were then placed in
Refrigerator, Incubator, and Room Temp respectively, that is one into
each of the environments. These were left in the environment
to acclimate for 13 minutes. Then were then removed and we
measured the beetle’s activity.
Activity was measured on a relative scale from 1-5, 1
being little to no activity and 5 being lots of activity and
movement. Each beetle was rated by each of me, Michael, and
Simon and then the average of our scores was given. That way,
ideally, we would come up with 10 ratings from each
Temperature. To deal with the possibility of death we decided
Alex Kiener
to ignore the dead beetles and just decrease the number of ratings from that environment. Also beetles
could get flipped on their backs and be unable to move. To deal with this we decided to flip those
beetles back over so we could rate their activity.
Here is our data table where you can see the activity of each beetle in each environment rated by us
then averages. As you can see there were four beetles that were dead and so were removed from the
experiment.
Flour Beetle Activity Vs Temperature
3
2.5
2
Room
Cold
1.5
Warm
1
0.5
0
Avg Activity
Alex Kiener
This is a graph of the means of each group and as you can see the room temperature has a lot higher
mean activity meaning that the beetles in the room temperature moved more than those at both the
cold and hot temperatures.
We used an ANOVA test to find whether the difference we see in our results is significant in the scope of
our experiment. After conducting the ANOVA we found that the p-value was .005. This means that there
is significant evidence to reject the null hypothesis. We now find that the 3 temperature do not have the
same activity level and that the room temperature is the highest one.
The room temperature is the optimum temperature for the four beetles and both cold temperatures
and warm temperature are unfavorable for the beetles. To be able to adapt this to farmers producing
grains, further studies would need to be done to show at what temperature does this effect begin to
take place, so that they can adapt it without exerting too much energy to keep it at these extreme
temperature
Sources:
Grain and Flour Beetles . Michigan. 24 June 2003. Michigan State University
Extension . 1 May 2009 <http://web1.msue.msu.edu/imp/mod02/
01500523.html>.
Ghent, Arthur W. "Studies of Behavior of the Tribolium Flour Beetles. I.
Contrasting Responses of T. castaneum and T. confusum to Fresh and
FH Arthur. “Toxicity of Diatomaceous Earth to Red Flour Beetles and Confused Flour Beetles
(Coleoptera: Tenebrionidae): Effects of Temperature and Relative Humidity”
Arthur, F. H. Residual studies with cyfluthrin wettable powdertoxicity toward red flour beetles
(Coleoptera: Tenebrionidae) exposed for short intervals on concrete. J. Econ. Entomol 91:309–319.1998.
Carlson, S. D. and H. J. Ball. Mode of action and insecticidal value of a diatomaceous earth as a grain
protectant. J. Econ.Entomol 55:964–970.1962.