Biologic, morphologic, and genetic aspects of Hypothenemus obscurus and Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae)

Abstract

There are two species of the genus Hypothenemus of economical importance in Colombia: H. hampei and H. obscurus. The first is the most destructive insect pest of coffee worldwide, while the latter attacks several crops including macadamia nut and coffee. This research was carried out in order to compare, biologically, morphologically and genetically, these two species to establish differences which explain the adaptation of coffee berry borer to coffee plants. The insects were reared on macadamia and coffee artificial diets. The morphology was studied through observations under light microscope, and Scanning Electron Microscopy (SEM). The genetic comparisons were made using cytogenetics, C-Banding of chromosomes, AFLP molecular fingerprints and parthenogenesis bioassays. H. obscurus life cycle (egg to adult) was estimated in 28.5±. 1.3 days, while H. hampei was 26.8±. 1.0 on macadamia and coffee diets respectively. Both species could develop on the alternative diet; however, their reproductive capacity was significantly reduced. The morphological comparisons showed specific characteristics for each species, and allowed to explain their feeding habits. The cytogenetic analysis showed facultative heterochromatization which offered identical functional haplo-diploid patterns in both species. We also reported similar kariotypes and chromosome number for both species. There was no evidence of parthenogenesis in these two species and each one showed distinguishable DNA fragments in their fingerprints. This basic information will allow advancing in the comparison of the transcriptomes of these two species in order to elucidate the genetic basis that supports the monophagous habits of coffee berry borer.