Genetic variability and global distribution of the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae)
Abstract
The coffee berry borer, Hypothenemus hampei, is the most destructive insect pest of coffee throughout the world, and is seriously impacting the social and economic stability of many developing countries. This research was designed to provide a better understanding of the genetics of H. hampei. AFLP technique, which is used to genetically fingerprint organisms, was used to detect DNA polymorphisms in 101 samples collected from 17 countries in Africa, Asia, and North and South America. Six selective primer combinations were chosen based upon preliminary studies to examine 73 samples from 12 countries. These primers revealed a total of only 2.8 ± 3.6 percent polymorphism within countries, but 22.4% polymorphism across all primer combinations. The greatest variation was observed among samples from East Africa, consistent with this pest's presumed center of origin. The two most informative selective primer combinations were then used to DNA fingerprint all 101 samples. Only 26 fingerprints were discovered. An analysis of molecular variance (AMOVA) supported evidence that H. hampei reproduces as matrilineal lines, suggesting also that its genetic capacity to overcome control measures would be limited. The data were suggestive of an invasion of a West African source population into both Asia and America. The distribution of these fingerprints and their genetic relatedness, as determined by Neighbor-Joining analysis, suggested that there were two introductions of H. hampei into Brazil, which later dispersed throughout the Americas. A third introduction into the Americas was evident in Peru and Colombia. Estimation of the genetic variability of H. hampei and the distribution pattern of 66 Colombian samples revealed that this pest invaded Colombia from multiple Latin American introductions. A close association between samples from Colombia and Costa Rica suggested Colombia as the main source of the last invasion of H. hampei in the Americas. A dominant site-specific molecular marker from an isolated Colombian population was designed. The use of this genetic marker in addressing questions on the biology of this insect, the genetic variability of two bethylid parasitoids, and the discovery of the probacterium Wolbachia in H. hampei as a possible sex determination distorter are also discussed.
Degree
Ph.D.
Advisors
Stuart, Purdue University.
Subject Area
Entomology|Genetics
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