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Sources Of Variability In Agronomic Weed Seed Predation: Time, Space, Habitat, And Hyperpredation, Sonja K. Birthisel

Electronic Theses and Dissertations

Weed seed predation is an ecosystem service that benefits farmers by decreasing seedbank inputs, thereby reducing weed pressure in subsequent growing seasons. Seed predation can be considerable, but is highly variable. Sources of variability may include time, space, habitat, and trophic interactions such as hyperpredation. Two experiments were conducted to measure the impacts of these sources of variability on weed seed predation rates in Maine mixed vegetable agroecosystems.

Chapter One of this thesis describes a series of landscape-level field experiments conducted to quantify the effects of time, space, and habitat on seed predation rates. Seed assays, with and without vertebrate …

Life History Comparison Of Two Green Lacewing Species Chrysoperla Johnsoni And Chrysoperla Carnea (Neuroptera: Chrysopidae), Kaushalya G. Amarasekare, Peter W. Shearer

Agricultural and Environmental Sciences Faculty Research

We investigated the life histories of two green lacewing species, Chrysoperla johnsoni Henry, Wells, and Pupedis from western North America, and Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) from western Europe in the laboratory. There were both similarities and differences in their life history characteristics. C. johnsoni exhibited a significantly longer developmental time for egg, first instar, and pupal stage than C. carnea. C. carnea exhibited a significantly shorter egg to adult developmental time than C. johnsoni. Except for the pupal stage, the survival of all other life history stages was not species-specific. All C. carnea pupae were able to develop …

Laboratory Bioassays To Estimate The Lethal And Sublethal Effects Of Various Insecticides And Fungicides On Deraeocoris Brevis (Hemiptera: Miridae), K. G. Amarasekare, P. W. Shearer

Agricultural and Environmental Sciences Faculty Research

This laboratory bioassay focused on lethal and sublethal effects of five insecticides (chlorantraniliprole, cyantraniliprole, spinetoram, novaluron, and lambda-cyhalothrin) and two fungicide treatments (sulfur and a mixture of copper hydroxide and mancozeb) on the predatory mired bug, Deraeocoris brevis (Uhler) (Hemiptera: Miridae) using second instars and adult males and females. Formulated pesticides were tested using concentrations that were equivalent to the high label rate (1x) (high rate) and 1/10th of that amount (0.1x) (low rate) dissolved in 378.5 liters of water. Lambda-cyhalothrin was highly toxic to D. brevis nymphs and adults at both rates, whereas both rates of novaluron were highly …

Mitigating Predatory Ants Promotes Establishment Of Biological Control Of Arundo By Arundo Scale In The Cattle Fever Tick Quarantine Zone, A. Velez-Bonner, W. L. A. Osbrink, D. W. Thomas, Kenneth R. Summy, A. T. Showler, A. Perez De Leon, John A. Goolsby

Biology Faculty Publications and Presentations

Ant collection, identification, and control experiments were conducted to improve the establishment of the arundo scale, Rhizaspidiotus donacis, a biological control agent of Arundo donax, an invasive weed in the riparian habitats along the Rio Grande in Texas. Observational studies indicated R. donacis immatures are preyed upon by a variety of predator insects, especially ants. A survey of the principle ant species was made at sites along the Rio Grande with Arundo donax to help direct biological control strategies. We conclude that uses of ant baits can effectively control the common ant species found in these habitats and improve the …

A Phylogenetic Analysis Of Species Diversity, Specificity, And Distribution Of Mycodiplosis On Rust Fungi, Donald Jay Nelsen

LSU Master's Theses

There are more than 7800 species of Pucciniales (rust fungi) described. Aeciospores and urediniospores of rust fungi are a food source for the larval stage of members of the fly genus Mycodiplosis, hence these could be of interest as potential biological control agents. Currently, Mycodiplosis contains 49 described species based on adult male morphology. A survey of 1,350 rust-infected plants from 44 countries was recently conducted to assess the occurrence of Mycodiplosis fly larvae across a broad spectrum of Pucciniales. Larvae were found on 261 collections from 25 countries. Statistical analyses explored the distribution of larvae in relation to host …