title: Genetic variation amongst biotypes of Dactylopius tomentosus.
abstract: The tomentose cochineal scale insect, Dactylopius tomentosus (Lamarck) (Hemiptera: Dactylopiidae), is an important biological control agent against invasive species of Cylindropuntia (Caryophyllales: Cactaceae). Recent studies have demonstrated that this scale is composed of host-affiliated biotypes with differential host specificity and fitness on particular host species. We investigated genetic variation and phylogenetic relationships among D. tomentosus biotypes and provenances to examine the possibility that genetic diversity may be related to their host-use pattern, and whether their phylogenetic relationships would give insights into taxonomic relatedness of their host plants. Nucleotide sequence comparison was accomplished using sequences of the mitochondrial cytochrome c oxidase I (COI) gene. Sequences of individuals from the same host plant within a region were identical and characterized by a unique haplotype. Individuals belonging to the same biotype but from different regions had similar haplotypes. However, haplotypes were not shared between different biotypes. Phylogenetic analysis grouped the monophyletic D. tomentosus into 3 well-resolved clades of biotypes. The phylogenetic relationships and clustering of biotypes corresponded with known taxonomic relatedness of their hosts. Two biotypes, Fulgida and Mamillata, tested positive for Wolbachia (α-Proteobacteria), a common endosymbiont of insects. The Wolbachia sequences were serendipitously detected by using insect-specific COI DNA barcoding primers and are most similar to Wolbachia Supergroup F strains. This study is the first molecular characterization of cochineal biotypes that, together with Wolbachia sequences, contribute to the better identification of the biotypes of cochineal insects and to the biological control of cacti using host-specific biotypes of the scale.
authors.affiliation: School of Science and Health, University of Western Sydney (Hawkesbury Campus).
authors.forename: Catherine W
authors.initials: CW
authors.lastname: Mathenge
authors.affiliation: Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797, Penrith, NSW 2751, Australia.
authors.forename: Markus
authors.initials: M
authors.lastname: Riegler
authors.affiliation: School of Science and Health, University of Western Sydney (Hawkesbury Campus).
authors.forename: G Andrew C
authors.initials: GA
authors.lastname: Beattie
authors.affiliation: School of Science and Health, University of Western Sydney (Hawkesbury Campus).
authors.forename: Robert N
authors.initials: RN
authors.lastname: Spooner-Hart
authors.affiliation: School of Science and Health, University of Western Sydney (Hawkesbury Campus).
authors.forename: Paul
authors.initials: P
authors.lastname: Holford
mesh_terms: D000818:Animals; D061046:Biological Control Agents; D029421:Cactaceae / Q000145:classification / Q000469:parasitology*; D004269:DNA, Bacterial / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics; D050259:Genes, Mitochondrial; D014644:Genetic Variation; D006430:Hemiptera / Q000235:genetics* / Q000382:microbiology*; D006790:Host-Parasite Interactions; D010802:Phylogeny; D020577:Wolbachia / Q000235:genetics
chemical_list: D061046:Biological Control Agents; D004269:DNA, Bacterial; D003576:Electron Transport Complex IV
keywords: Cylindropuntia spp; Dactylopiidae; Hemiptera; Wolbachia spp; biotypes; tomentose cochineal scale