Nathan E. Harms

Unraveling the biogeographic origins of the Eurasian watermilfoil (Myriophyllum spicatum) invasion in North America

PREMISE OF THE STUDY Using phylogeographic analyses to determine the geographic origins of biological invaders is important for identifying environmental adaptations and genetic composition in their native range as well as biocontrol agents among indigenous herbivores. Eurasian watermilfoil (Myriophyllum spicatum) and its hybrid with northern watermilfoil (M. sibiricum) are found throughout the contiguous United States and southern Canada, forming one of the most economically costly aquatic plant invasions in North America, yet the geographic origin of the invasion remains unknown. The objectives of our study included determining the geographic origin of Eurasian watermilfoil in North America as well as the maternal lineage of the hybrids. METHODS DNA sequence data from a cpDNA intron and the nrDNA ITS region were compiled for accessions from 110 populations of Eurasian watermilfoil and hybrids from North America and the native range (including Europe, Asia, and Africa). Datasets were analyzed using statistical parsimony and Bayesian phylogenetics to assess the geographic origin of the invasion. KEY RESULTS The two Eurasian watermilfoil cpDNA haplotypes in North America are also found from China and Korea, but not elsewhere in the native range. These haplotypes did not overlap and were limited in native geographic range. The ovule parent for hybrids can come from either parental lineage, and multiple haplotypes from both parental species were found. CONCLUSIONS The geographic origin of this prolific aquatic plant invasion of North America is in Asia. This provides critical information to better understand the invasion pathway and inform management into the future.

Insect herbivores of water stargrass (Heteranthera dubia) in the US

We examined insect herbivores associated with Heteranthera dubia from surveys conducted from 2006 to 2009. Plants were collected, invertebrates were removed, and signs of feeding damage were noted. Herbivores were quantified, and geographic regions were compared based on herbivore density, taxa richness, evenness, and diversity. The greatest density of herbivores occurred at Parker Pond, Washington, which was largely influenced by an abundance of aphids (Rhopalosiphum spp.). Density, richness, and evenness were not significantly different among regions. At least 23 potential insect herbivores were recorded from 15 sites in Texas, Washington, Minnesota, Wisconsin, Vermont, and New York. Of these, five taxa were collected from the order Lepidoptera, one from Coleoptera, six from Diptera, and at least 11 from Trichoptera. The majority of the herbivores were generalists; several had unknown diets. Damage observed to H. dubia included extensive tunneling in the stems of the plant and, in some cases, substantial chewing damage to the leaves.

Aquatic Larvae of Two Acentropines, Usingeriessa onyxalis (Hampson) and Oxyelophila callista (Forbes) (Lepidoptera: Crambidae)

Abstract. Pyraloid moths in the subfamily Acentropinae have developmental stages that are aquatic, they live and breathe underwater during all or part of their life cycle. We discovered and describe the previously unknown larvae of Usingeriessa onyxalis (Hampson) (Crambidae) reared on Hygrophila polysperma (Roxb.) T. Anderson (Acanthaceae) and Eleocharis sp. (Cyperaceae) in Texas.We also describe Oxyelophila callista (Forbes) feeding on at least five species of aquatic plants in Texas. Morphological and molecular characters were used to associate immatures with adults. These are the first accounts of the immature stages of U. onyxalis and the first detailed description of the immatures of O. callista, so we discuss the current classification and generic placement of these and associated species. Images and line drawings of the aquatic larvae, adults, and male and female genitalia of U. onyxalis are provided, as well as a table comparing the larval habit and morphology among genera. The current process of boiling larvae for preservation as voucher specimens and morphological study is discussed in light of current molecular techniques.

Herbivorous Insects Associated with Ludwigia peploides (Onagraceae) in the Southern United States

Abstract The wetland plant Ludwigia peploides (floating primrose-willow) often is problematic in the southern USA, as well as elsewhere in its introduced range. Surveys to identify potential herbivorous insects to use as biological controls have focused on South America, but implementing a management program with foreign insects in the USA is difficult and can take years of testing in quarantine. During 2006–2008, populations of floating primrose-willow were surveyed in the southern USA to determine presence and extent of native herbivorous insects. At least nine species were identified, represented mainly by weevils (Curculionidae) and leaf beetles (Chrysomelidae). Of these, two were undescribed species of weevils (Auleutes), and six species, including Tyloderma sphaerocarpae and Chaetocnema, have never been associated with floating primrose-willow.

Evidence-based economic analysis demonstrates that ecosystem service benefits of water hyacinth management greatly exceed research and control costs

Invasive species management can be a victim of its own success when decades of effective control cause memories of past harm to fade and raise questions of whether programs should continue. Economic analysis can be used to assess the efficiency of investing in invasive species control by comparing ecosystem service benefits to program costs, but only if appropriate data exist. We used a case study of water hyacinth (Eichhornia crassipes (Mart.) Solms), a nuisance floating aquatic plant, in Louisiana to demonstrate how comprehensive record-keeping supports economic analysis. Using long-term data sets, we developed empirical and spatio-temporal simulation models of intermediate complexity to project invasive species growth for control and no-control scenarios. For Louisiana, we estimated that peak plant cover would be 76% higher without the substantial growth rate suppression (84% reduction) that appeared due primarily to biological control agents. Our economic analysis revealed that combined biological and herbicide control programs, monitored over an unusually long time period (1975–2013), generated a benefit-cost ratio of about 34:1 derived from the relatively modest costs of

Surveys for biological control agents of Hydrilla verticillata and Myriophyllum spicatum in the Republic of Korea and the People’s Republic of China in 2014

124 million (

Rearing and Release of Megamelus scutellaris Berg (Hemiptera: Delphacidae) for Biological Control of Water hyacinth in 2015

2013) compared to the

The Influence of Fluctuating Temperature on Megamelus scutellaris Berg (Hemiptera: Delphacidae)

4.2 billion (

Viability of Hydrilla Fragments Exposed to Different Levels of Insect Herbivory

2013) in benefits to anglers, waterfowl hunters, boating-dependent businesses, and water treatment facilities over the 38-year analysis period. This work adds to the literature by: (1) providing evidence of the effectiveness of water hyacinth biological control; (2) demonstrating use of parsimonious spatio-temporal models to estimate benefits of invasive species control; and (3) incorporating activity substitution into economic benefit transfer to avoid overstating benefits. Our study suggests that robust and cost-effective economic analysis is enabled by good record keeping and generalizable models that can demonstrate management effectiveness and promote social efficiency of invasive species control.

Suitability of using introduced hydrellia spp. for management of monoecious hydrilla verticillata (L.f.) royle

PURPOSE: The purpose of this Technical Note (TN) is to summarize overseas work conducted in 2014 to locate insect biological control agents of dioecious and monoecious Hydrilla verticillata (L.f.) Royle (hydrilla) and Myriophyllum spicatum L. (Eurasian Water Milfoil) (EWM) in the Republic of Korea (RK) and the People’s Republic of China (PRC). This work includes surveys of hydrilla and EWM sites in the RK and the PRC, and represents ongoing efforts towards identifying previously collected and reared agents.