On the eyes of male coffee berry borers as rudimentary organs.
The coffee berry borer, Hypothenemus hampei, is the most damaging insect pest of coffee worldwide. Like males in other species in the genus, male coffee berry borers have a lower number of facets in the compound eyes than females. The rudimentary eyes in male coffee berry borers could be an evolutionary response to their cryptic life habit, whereby they are born inside a coffee berry and never leave the berry. The main objective of the study was to determine if the differences in the number of facets translates into differences in visual acuity. We used low-temperature scanning electron microscopy to visualize and quantify the number of facets in the compound eyes. There was a significantly lower (p<0.0001) number of facets in males (19.1 ± 4.10) than in females (127.5 ± 3.88). To assess visual acuity, we conducted optomotor response experiments, which indicate that females respond to movement, while males did not respond under the conditions tested. The coffee berry borer is an example of an insect whereby disuse of an organ has led to a rudimentary compound eye. This is the first study that has experimentally tested responses to movement in bark beetles.
Sustainable Perennial Crops Laboratory, United States Department of Agriculture, Agricultural Research Service, Beltsville, Maryland, United States of America.
Fernando E
FE
Vega
Sustainable Perennial Crops Laboratory, United States Department of Agriculture, Agricultural Research Service, Beltsville, Maryland, United States of America.
Ann
A
Simpkins
Electron and Confocal Microscopy Unit, United States Department of Agriculture, Agricultural Research Service, Beltsville, Maryland, United States of America.
Gary
G
Bauchan
El Colegio de la Frontera Sur, Tapachula, Chiapas, México.
Francisco
F
Infante
Biometrical Consulting Service, United States Department of Agriculture, Agricultural Research Service, Beltsville, Maryland, United States of America.
Matthew
M
Kramer
School of Life Sciences, University of Sussex, Brighton, United Kingdom.
Michael F
MF
Land
D000818:Animals; D005075:Biological Evolution; D001517:Coleoptera / Q000502:physiology*; D054910:Compound Eye, Arthropod / Q000502:physiology*; D005260:Female; D008297:Male