Phylogeny and Genetic Diversity of Flea Beetles (Aphthona sp.) Introduced to North America as Biological Control Agents for Leafy Spurge

Abstract

A molecular pbylogeny is presented for tbe five main species oí Aphthona ñea beetles that were introduced to North America in conjunction with the leafy spurge {Euphorbia esula L.) biological control program. The mitochondrial genome was examined using polymerase chain reaction-restriction fragment length polymorphism (RFLP) of a 9,000-bp segment and nucleotide sequencing of a 575-bp piece of coxl-cox2. A neighbor-joining tree of the RFLP data, along with neighbor-joining and maximum parsimony trees of the sequence alignments, all had the same major branching pattern. Each of the recognized species was a well defined clade. Three within species subbranches had very limited mitochondrial DNA diversity. One was a Wolbachia-iniected lineage of A. nigriscutis most likely generated by a Wolbachia sweep where the spreading Wolbachia infection brought along the infected mitochondrial haplotype. Two of three subclades of A. lacertosa also had very little genetic diversity. One of these subclades also displayed a divergence from the other two that was analogous to the divergence observed between some of the other species pairs, suggesting it may be a cryptic species. Its distribution was restricted to Canada. Tbe other genetically depauperate A. lacertosa line was the only lineage recovered in the United States. The geographically restricted nature of some of the genetic lines could be exploited to possibly improve biological control in some habitats through redistribution to other locations. It is not obvious that either Wolbachia infection or a narrow genetic base has had any detrimental effect on biological control.

Two in one: cryptic species discovered in biological control agent populations using molecular data and crossbreeding experiments

“…A possible cryptic species of the flea beetle, Aphthona lacertosa Rosenheim [Coleoptera: Chrysomelidae], a biological control agent for leafy spurge, Euphorbia esula L. [Euphorbiaceae], was identified using genetic techniques after its release in North America (Roehrdanz et al. ). The leafy spurge flea beetle is the only example of a cryptic species of weed biological control agent that was discovered after release besides E. catarinensis .…”

“…[Asteraceae], having a variety of different host plants in the indigenous range, were all regarded as a single species but were divided into three possible cryptic species using genetic analyses (Gaskin et al 2011 (Roehrdanz et al 2011). The leafy spurge flea beetle is the only example of a cryptic species of weed biological control agent that was discovered after release besides E. catarinensis.…”

Diversity of Wolbachia infections in Sri Lankan mosquitoes with a new record of Wolbachia Supergroup B infecting Aedes aegypti vector populations

“…At present, Wolbachia plays an important role in many of the insect vector control programs due to its biosafety and environmentally friendly nature. Its application is enormous and promising for agricultural pests such as fruit flies; flea beetle, Aphthona spp., to control leafy spurge 1 ; house fly, Musca domestica , and stable fly, Stomoxys calcitran s 2 . In addition, this approach has been practiced for medically important vector control programs including Aedes vectors 3 – 5 ; and paratransgenesis of Wolbachia is being considered for use in mosquitoes to reduce the spread of malaria 6 and in tsetse fly to reduce the spread of sleeping sickness 7 .…”