Biology Commons^™

Effect Of Mycorrhizal Colonization And Light Limitation On Growth And Reproduction Of Lima Bean (Phaseolus Lunatus L.), Daniel J. Ballhorn, Jess A. Millar

Biology Faculty Publications and Presentations

Plants can respond with sink stimulation of photosynthesis when colonized with fungal or bacterial root symbionts, compensating costs of carbohydrate allocation to the microbes. However, constraints may arise under light limitation when plants cannot extensively increase photosynthesis. We hypothesize that under such conditions the costs for maintaining the symbiosis outweigh the benefits, ultimately turning the mutualist microbes into parasites, resulting in reduced plant growth and reproduction.

Using lima bean (Phaseolus lunatus) as experimental plant, we applied two levels of light (full light, 75% shading) and microbial inoculation (sterile soil, mycorrhizal fungi) and quantified both vegetative and generative plant …

Distance And Sex Determine Host Plant Choice By Herbivorous Beetles, Daniel J. Ballhorn, Stefanie Kautz, Martin Heil

Biology Faculty Publications and Presentations

Background: Plants respond to herbivore damage with the release of volatile organic compounds (VOCs). This indirect defense can cause ecological costs when herbivores themselves use VOCs as cues to localize suitable host plants. Can VOCs reliably indicate food plant quality to herbivores?

Methodology: We determined the choice behavior of herbivorous beetles (Chrysomelidae: Gynandrobrotica guerreroensis and Cerotoma ruficornis) when facing lima bean plants (Fabaceae: Phaseolus lunatus) with different cyanogenic potential, which is an important constitutive direct defense. Expression of inducible indirect defenses was experimentally manipulated by jasmonic acid treatment at different concentrations. The long-distance responses of male and female beetles to …

Arthropod Abundance And Diversity In Street Trees Of South Texas, Usa, Alexis Racelis, Ann T. Vacek, Carol Goolsby, John Brush, John A. Goolsby

Biology Faculty Publications and Presentations

In urban areas, street trees provide a variety of ecological services, including biodiversity conservation. In this study we examined arthropod diversity on native and non-native street trees sampled during the fall of 2010 and spring of 2011 in McAllen, Texas, one of the most rapidly growing urban areas in the country. Eighty-eight street trees were sampled by removing arthropods from the lower canopy foliage using a hand held vacuum. Arthropods were collected into nylon bags, identified to order, and counted by morphospecies. Overall, street trees supported a significant and diverse population of arthropods: a total of 1,971 arthropods were collected, …

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 …

Opportunistic Pathogenic Bacteria Colonize Thorns Of Native Rio Grande Valley Plants, Felicia A. Charles, Sergio Cepeda, J. Andrew Mcdonald, Kristine L. Lowe

Biology Faculty Publications and Presentations

Thorns serve as mechanical defenses of plants against herbivory. However, plant thorns harbor microorganisms that are potentially pathogenic. These pathogens may be transferred to herbivores and other animals and provide an additional defense for the plants. Thorns from 5 plant species native to the Rio Grande Valley of South Texas were collected and used to isolate bacteria colonizing the thorn surface. Thorns, leaves and stems of plants were visualized using Scanning Electron Microscopy (SEM) to observe any bacteria on the plant surface. Isolated bacteria were tested for their ability to grow in aerobic versus anaerobic environments, to produce hemolysis, carbon …