CAREER: Phylogeny and Evolution of Armored Scale Insects (Hemiptera: Diaspididae) and Their Bacterial Endosymbionts

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

The abstract. Normark DEB 0447880 Armored scale insects are unusual organisms in many ways. The males fly, and look like ordinary insects, but the females are wingless, legless blobs. Armored scale insects have strange genetics, in which males start life with chromosomes from both parents, but lose their fathers' chromosomes and pass on only their mothers'. They have strange anatomy and nutrition, with no gut connecting mouth to anus. UMass grad student Matthew Gruwell recently discovered that armored scale insects are also associated with unusual bacteria -- unlike the Proteobacteria found in most sap-feeding insects, armored scale insects have Flavobacteria. The role of bacteria in the nutrition and genetics of their hosts are vibrant areas of current research, and this field may be illuminated by the connections betwen armored scale insects' unusual nutrition, genetics, and bacteria. But the simplified anatomy of armored scale insects, and consequent difficulty of identifying them, classifying them, and understanding their evolutionary relationships, has hindered progress. In this project, the principal investigator and his students will sequence DNA from four different genes of 250 species of armored scale insects, expanding upon an earlier study. They will also sequence DNA from bacteria associated with the scale insects, and investigate where in the scale insects tissues the bacteria occur. The DNA sequences will be used to infer evolutionary trees which will shed light on the evolution of the unusual characters of these insects and the nature of their co-evolution with bacteria, as well as providing a sounder basis for their classification. Armored scale insects are major pests of trees and shrubs in the US and in all but the coldest regions of the world, especially damaging fruit and nut crops and ornamentals. This project will lead to a better classification of these insects, which will help managers predict important biological features such as natural enemies. Ultimately these data will permit armored scale insects to be identified through "DNA barcoding." This will be especially useful in the case of armored scale insects, since currently only one life stage (adult females) is identifiable. The project directly supports education in that almost all of the funds go to support graduate and undergraduate students and their research. To foster direct undergraduate education and participation in the project, the principal investigator is teaching a new undergraduate course entitled "Molecular Biodiversity Lab," that will teach the basic principles of the field of molecular systematics, and the associated lab and computer skills.