Ellen C. Lake

Release and distribution of Lilioceris cheni (Coleoptera: Chrysomelidae), a biological control agent of air potato (Dioscorea bulbifera: Dioscoreaceae), in Florida

ABSTRACT From 2012 to 2015, 429,668 Lilioceris cheni Gressit and Kimoto (Coleoptera: Chrysomelidae) were released in Florida for biological control of air potato Dioscorea bulbifera L. (Dioscoreaceae). In the fall of 2015, a state-wide survey was conducted at 113 randomly selected air potato infestations in order to determine the spatial distribution of L. cheni. Damage due to L. cheni was found at 86% of locations and was low in the Florida panhandle where air potato was relatively uncommon and fewer beetles had been released, and in far south Florida, despite high numbers of beetle releases. On average, beetles travelled 9.5 km from the nearest release site to survey sites from the date of release to the time of the survey, with a maximum distance of nearly 67 km. The rate of spread was estimated at 8.2 km/year under the assumption that beetles present at survey sites migrated or were moved from the nearest release site. Air potato vines produced fewer aerial tubers, the vegetative propagule of air potato, as foliar damage due to L. cheni increased. The results suggest that future research efforts should focus on determining the biotic and abiotic factors that may be limiting establishment in some areas of Florida.

Variable Seed Viability of Mile-a-Minute Weed (Devil's Tearthumb, Persicaria perfoliata)

Abstract Mile-a-minute weed or devils tearthumb (Polygonum perfoliatum, syn.  =  Persicaria perfoliata) is an invasive annual vine in the Mid-Atlantic and Northeastern United States that reproduces solely through seeds. Our study aimed to identify how mile-a-minute seed viability is affected by time of year and the maturity of the fruit surrounding the achene. Full-sized immature (green) and mature (blue) fruits were collected from five field sites every 2 wk over a 3 mo period, and seed viability was assessed using a triphenyl tetrazolium chloride (TZ) assay. At the onset of seed production in mid-August, 35% of seeds from immature fruits were viable. This percentage increased steadily, peaking at 84% in late September before declining at some sites around the time of the first frost. In contrast nearly all seeds with mature fruits (96%) were viable at all collection dates. Thus land managers who apply physical or chemical control methods for mile-a-minute weed should do so before the onset of any seed production and not simply before fruit maturation. If it is necessary to apply control methods after fruit set, it should be done as early in the season as possible. Nomenclature: Mile-a-minute weed; devils tearthumb; Persicaria perfoliata (L.) H. Gross; Polygonum perfoliatum L., POPE10. Management Implications: This study highlights two important implications for managing the invasive vine mile-a-minute weed (devils tearthumb) using either chemical or physical control methods. First, mile-a-minute seeds surrounded by immature fruits were shown to be viable to some extent throughout the entire season of seed production. Therefore, physical and chemical controls should be applied before any full-sized immature (green) fruits are produced and not just before mature (blue) fruits are present. Second, the viability of seeds in green fruits increased throughout the season, peaking before the first frost. This indicates that if it is necessary to apply physical or chemical control methods during the fruiting period, these methods should be applied as early in the season as possible, when immature fruits are less likely to contain viable seeds.

Comparative Evaluation of Development and Reproductive Capacity of Two Biotypes of Lilioceris cheni (Coleoptera: Chrysomelidae), Biological Control Agents of Air Potato (Dioscorea Bulbifera) in Florida

Abstract A Chinese biotype of Lilioceris cheni Gressitt and Kimoto (Coleoptera: Chrysomelidae) is being mass reared and released in Florida for biological control of the invasive air potato vine, Dioscorea bulbifera L. (Dioscoreales). Another biotype from Nepal is under investigation for determining whether its release would benefit the ongoing biological control program. We compared temperature-dependent development, fecundity, life table parameters, and consumption of the two biotypes in the laboratory. Both biotypes completed development at 20–30 °C, although survival of Chinese beetles was higher at 20 °C and 27.5 °C, and survival of Nepalese beetles was higher at 30 °C. In addition, Nepalese beetles developed at a faster rate at 20 °C, and consumed air potato foliage at a higher rate at 25 °C. The most important difference between the biotypes, with regard to biological control purposes, was the shorter generation time of Nepalese beetles, which resulted in a higher intrinsic rate of population increase, despite much higher fecundity of Chinese beetles. The higher intrinsic rate of increase of the Nepalese beetles may allow a more rapid population increase in the field, and thus, greater damage to air potato plants. However, differences in other life history traits, such as overwintering ability, diapause, and cold tolerance, will also influence field performance.

Changes in latitude: overwintering survival of two Lilioceris cheni (Coleoptera: Chrysomelidae) biotypes in Florida

ABSTRACT Lilioceris cheni is a successful biological control agent on the invasive yam, Dioscorea bulbifera in many areas in Florida, Georgia, Alabama and Louisiana. Two biotypes are available for release and come from significantly different centres of origin. The Nepalese biotype was collected at higher altitude and latitude sites, whereas the Chinese biotype was collected at slightly lower latitude and lower altitude. We hypothesised that Nepalese beetles would survive winter better in north Florida and that Chinese beetles would overwinter better in subtropical south Florida. We established sites in Homestead, Fort Pierce, Gainesville and Tallahassee, Florida to gauge the overwintering survival of each biotype. Beetles that overwintered in each site for one to three seasons were collected and followed to assess their reproductive capacity. In the final year of the experiment, we extracted fat bodies to determine effects of biotype and site. Nepalese beetles overwintered significantly better overall. Beetles survived better in the first study year (2013–2014). Both biotypes reproduced very well after surviving winter and beetles in Fort Pierce survived better than beetles in other regions and maintained a higher fat body. Nepalese beetles may have a wider ecological envelope – a decided advantage for a large region such as peninsular Florida. We suggest that current release programmes incorporate Nepalese beetles into their protocol to increase overwinter survival and establishment.

The complete chloroplast genome of the invasive fern Lygodium microphyllum (Cav.) R. Br.

Abstract The Old World climbing fern, Lygodium microphyllum, is a rapidly spreading environmental weed in Florida, United States. We reconstructed the complete chloroplast genome of L. microphyllum from Illumina whole-genome shotgun sequencing, and investigate the phylogenetic placement of this species within the Leptosporangiate ferns. The chloroplast genome is 158,891 bp and contains 87 protein-coding genes, four rRNA genes, and 27 tRNA genes. Thirty-three genes contained internal stop codons, a common feature in Leptosporangiate fern genomes. The L. microphyllum genome has been deposited in GenBank under accession number MG761729.

Teaching Complex Ecological Concepts Through a Demonstration Garden: Biodiversity, Invasive Species, and Conservation in Practice

Abstract Biodiversity encompasses the variety within and between species in an environment. Native communities host a diverse array of species and interactions among members. Invasions by non-native species reduce biodiversity and a communitys ability to support diverse assemblages, and are among the largest drivers of modern species extinctions. The Keep It Native Demonstration (KIND) Garden demonstrates the differences between invaded and intact plant communities. Utilizing this resource, we developed an inquiry-based activity for grades 5–7 that focused on observational data. Student groups recorded the number of animal and plant species in multiple habitat types. We then compiled data from the separate groups and averaged the number of species observed in each habitat type. The results were graphed to enable students to visualize the differences in species diversity among habitats. This exercise illustrated differences in species richness and diversity between invaded and native plant dominated areas, and allowed students to begin initial data interpretation. We provide methods for this activity, strategies for implementing the activity on other sites, and adaptations to accommodate different grade levels and the associated Next Generation Science Standards.

Another New Lygodium-Boring Species of the Musotimine Genus Siamusotima (Lepidoptera: Crambidae) from China

Abstract. Siamusotima disrupta Solis, n. sp., is a stem-boring musotimine from China. It was discovered in the stems of several Lygodium Sw. species (Lygodiaceae) during exploration for biological control agents of Lygodium microphyllum (Cav.) R. Br., the Old World climbing fern. This is the second report of a stem-boring pyraloid larva with a unique, cup-like modification of the anal segment. The larval morphology of S. disrupta is compared with that of the previously described S. aranea Solis and Yen. Observations on life history are presented; the adult has not been captured in the wild.

Optimal Foraging by Birds: Experiments for Secondary & Postsecondary Students

Abstract Optimal foraging theory attempts to explain the foraging patterns observed in animals, including their choice of particular food items and foraging locations. We describe three experiments designed to test hypotheses about food choice and foraging habitat preference using bird feeders. These experiments can be used alone or in combination and can also provide a foundation for students to develop extensions incorporating the basic methodology. We see these experiments as most applicable in secondary and postsecondary education, but they could be adapted for a variety of educational environments and for students with a variety of backgrounds.