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1. Importance of Color in Insect
Control: Sweetpotato Weevil
Nirupa Gadi
Conrad High School
Conrad, MT 59425

2. Introduction
• Sweetpotatoes are the sixth most
important crop in the world
• They are nutritious, high in
carbohydrates, proteins, Vitamin A,
riboflavin, and calcium
• Leaves can also be used as a
vegetable
• Sweetpotatoes can also play a vital
Healthy Sweetpotatoes
role in future energy supply from
organic production

3. Problems
• The Sweetpotato Weevil (Cylas
formicarius) is one of the most
serious insects that causes damage
to the sweetpotato crop
• Even a small grub population can
cause severe damage to the roots of
a plant
Grub of the Sweetpotato Weevil
• Because of the high incidence, many
farmers are frustrated and are giving
up cultivation.
• Without proper and effective control,
they may cause complete loss of
sweetpotato production
Damaged Sweetpotatoes

4. Problems (cont’d)
• Control methods such as using
toxic pesticides are somewhat
effective but are not desirable to
the environment
• There is an urgent need for
development of an eco-friendly
control methods
• Pheromone traps are currently Standard Trap Currently Being Used
being used for monitoring, but no
effective control has been reached

5. Hypothesis
• While reading some literature, I realized the
importance of color to insects
• Each species of insect is attracted to a different
color
• What color trap would attract the highest number
of weevils?
• Color preference would help in mass trapping
these weevils from various fields

6. Materials
• Nine standard unitraps
• Colored tapes of brown, black, gray, yellow, red, white,
green, and blue to cover eight of the traps
• Stopwatch
• Datasheets
• Pencils and meter stick
• Pheromones
• Sweetpotato Weevils

7. Methods
• Tests were conducted at the Chemical Ecology
and Entomology Laboratory at the University of
Guam
• Experiments were run in a dimly lighted laboratory
with the standard unitrap of different colors
• Tested colors were
brown, black, gray, yellow, red, white, green, and
blue
• One standard trap was also added as the control

8. Methods (cont’d)
• Different colored traps were placed
one meter from the center and had
an equal distance apart
• Ten weevils were released in the
center of the trap circle and given
five minutes to go to a trap
• The number of adults attracted by
the different colored traps were
Color Choice Experiments Conducted in a
recorded for the duration of the time Laboratory

9. Methods (cont’d)
• Two sets of test were carried out in the laboratory
• One set was tested with a pheromone which is a
chemical that attracts insects
• The other was conducted without a pheromone
• Each set was repeated 70 times for validity

10. Analysis
• The total number of weevils that responded per
color were combined and set as a percentage that
was attracted to each trap color

11. Results
Percentage ( SE) of sweetpotato weevils attracted to traps (without pheromone
lures) of different colors.
Different letters indicate significant differences between treatments (one-way ANOVA)
45
A
40 20% increase
Percentage of weevils attracted
35
30
B
25 B
B
20
15 C
10 C
C C
C C
5
C
0
Green Standard Yellow Black Brown Gray Blue Red White

12. Results (cont’d)
Percentage ( SE) of sweetpotato weevils attracted to traps (with pheromone lures of
different colors.
Different letters indicate significant differences between treatments (one-way ANOVA)
70
A
60
Percentage of weevils attracted
42.5% increase
50
40
30
B
20
C
10
C C C C C C
0
Green Standard Yellow Black Brown Gray Blue Red White

13. Results (cont’d)
• Green colored traps were most attractive to the
weevil compared to the standard (a combination
of white, yellow, and green) traps
• Without pheromone, they drew 20% more than the
standard traps that were currently used
• With the pheromone, the green traps lured 42.5%
more weevils than the standard traps

14. Discussion
• The green colored traps attracted nearly 50%
more weevils than the currently used standard
trap
• My results are agreed with the results of
Frederiksen et al. (2008), Kelber et al.
(2003), Reddy and Raman (2011)
• They indicated the color importance for insects
• I recommend my results for the sweetpotato
weevil control

15. Conclusions
• My study showed that green colored
traps with a pheromone highly
attracted sweetpotato weevils
• If used by farmers, we can trap most
of the weevils by this “attract and kill”
method and save the sweetpotato
crops
• You can kill the weevils with these
traps by filling them halfway with
soap water
• When the weevils enter the
trap, they will drown Effective Green Colored Trap

16. References
• Kelber, A., A. Balkenius, and E.J. Warrant. 2003.
Color vision in diurnal and nocturnal hawkmoths.
Integrat. Comp. Biol. 43: 571-579.
• Fredericksen, R., W.T. Wcislo, and E.J. Warrant.
2008 Visual reliability and information rate in the
retina of a nocturnal bee. Curr. Biol. 18: 349-353.
• Reddy, G.V.P., and A. Raman. 2011. Visual cues
are relevant in behavioral control measures for
Cosmopolites sordidus (Coleoptera:
Curculionidae). J. Econ. Entomol. 104: 436-442.

17. Acknowledgements
• I would like to thank G.V.P. Reddy for providing lab
facilities and for guidance
• I acknowledge the help I received from the staff of
the Chemical Ecology Laboratory at the University
of Guam
• I would also like to thank Sigma Xi for giving me
the opportunity to present my results