Location:
2016 Annual Report
Objectives
Objective 1: Develop biological control agents against the pathogenic landscape created by Arundo donax, and measure impact on invasive ticks.
Subobjective 1A. Investigate the biology and host range of the arundo leafminer under quarantine conditions as a candidate biological control agent for release in the CFT PQZ.
Subobjective 1B. Determine if biological control agents mitigate negative impact of Arundo donax on operations by the Cattle Fever Tick Eradication Program by increasing visibility within the PQZ.
Subobjective 1C. Investigate other benefits of biological control intervention, including decreased habitat suitable for CFT larvae, and use these measurements to predict effects of climate change.
Objective 2: Innovate technologies to mitigate the negative impact of ecological interactions between invasive species.
Subobjective 2A. Investigate role of ants and ground-dwelling predator beetles on the survival of CFT and biological control agents in the PQZ affected by A. donax.
Objective 3: Develop biological control against livestock pests.
Subobjective 3A. Conduct foreign exploration in the native ranges of CFT to search for tick-specific biological control agents.
Objective 4: Assess the effects of global climate change on effectiveness of livestock pest control in south Texas and northern Mexico.
Subobjective 4A. Investigate the potential for climate change to alter the viability of CFT larvae in the PQZ.
Approach
Develop biological control agents against giant reed including testing of the leaf-feeding arundo leafminer, for release in the PQZ; determine if the leafminer, and two other agents that have already been released, can mitigate negative impact of giant reed on operations by the CFT Eradication Program by increasing visibility within the PQZ and investigate other benefits, including reduction of habitat suitable for CFT larvae; investigate the role of ants and ground-dwelling predator beetles on the survival of CFT in the PQZ in areas with and without giant reed; conduct foreign exploration in the native ranges of CFT to search for tick-specific parasitic insects and nematodes, and evaluate their potential as biological control agents to directly target CFT; assess the effects of global climate change on livestock pest control in south Texas by conducting field ecological studies in CFT infested pastures at the CFTRL; conduct field studies to investigate the effects of increased summer rainfall to determine its impact on exotic African range grasses and giant reed and their effect on CFT survival.
Progress Report
Objective 1: Develop biological control agents against the pathogenic landscape created by Arundo donax, and measure impact on invasive ticks. U.S. Fish and Wildlife has concurred with USDA on the release of the arundo leafminer in TX and CA. Release of this leaf defoliating agent is expected in the fall of 2016. The leafminer has the potential to increase with-in stand visibility which is important for APHIS mounted inspectors and allows for more sunlight to penetrate the canopy which stimulates revegetation of native plant competitors. The arundo scale has been established and is dispersing at 48 locations on the Rio Grande in Texas and Mexico. The arundo wasp continues to have the greatest impact on above ground biomass of A. donax. Water use studies have documented a decrease in evapotranspiration (ET) by A. donax which correlates with high populations and damage by the arundo wasp. This decrease in ET conserves water (6000 acre ft./year) for agricultural users and makes the riverside habitat less favorable for survival of cattle fever ticks (CFT) which invade the PQZ from Mexico. An IPM method which combines surge release of the arundo wasp with mechanical topping of the canes at 3 feet has been developed by ARS which meets immediate needs for visibility of the international border and causes long-term suppression of A. donax. The IPM method is being implemented by the U.S. Border Patrol along the 558 river miles between Del Rio and Brownsville, TX.
Objective 2: Innovative technologies to mitigate the negative impact of ecological interactions between invasive species, field studies at multiple locations in the PQZ showed that there were significantly fewer predatory, tick feeding beetles and ants in stands of A. donax as compared to paired locations with native vegetation. This shows that one of the key changes that happen in the pathogenic landscape after exotic weed invasion is suppression of beneficial predator insects. These valuable tick predators are expected to recolonize the PQZ after control of the invasive weeds which include A. donax.
Objective 3: Develop biological control against livestock pests, methods were developed to survey for potential biological control agents of cattle fever ticks (CFT). Collaborators in the native ranges of CFTs in Europe (Greece, Bulgaria and Turkey) and Asia (Philippines) are conducting field work using untreated, CFT infested cattle to attract and capture potential specialist parasitoids or predators. New initiatives are being developed to continue host exposures in India and China. Specialist tick biological control agents from the native range of CFT could control this invasive tick on wildlife host such as Indian nilgai antelope and white-tailed deer. Control of ticks on the wildlife host would greatly help control CFT on livestock that share the same rangeland habitats.
Objective 4: Assess the effects of global climate change on effectiveness of livestock pest control in south Texas and northern Mexico, this research is planned for FY 2017-18 after field test plots at the Cattle Fever Tick Research Laboratory are ready for field experimentation.
Accomplishments
1. Development of Integrated Pest Management technology. ARS researchers in Edinburg, Texas, developed integrated pest management technology to meet the needs of stakeholders on the Rio Grande. The method of this technology integrates mechanized topping of Arundo cane at 3 feet followed by an inundative release of biological control agents, thus providing immediate visibility of the international border for law enforcement agencies and long-term suppression of Arundo cane, which leads to re-emergence of desirable native vegetation. This Integrated Pest Management technology has been transferred to vegetation managers at the U.S. Border Patrol (DHS) and is being implemented widely on the Texas – Mexico international border.
2. Water conservation on the Rio Grande from biocontrol agents of Arundo cane. The arundo wasp biological control agent appears to be reducing the ability of Arundo cane to uptake and transpire water which results in water conservation and reduction of favorable habitat for cattle fever ticks. Populations of the wasp at the study site in Eagle Pass, TX were 75% greater during the spring of 2015 than 2014 which correlated with a long-term decrease in water use. Galling (deformed plant tissue) on Arundo cane stems induced by the arundo wasp appears to be restricting water uptake, which was predicted from earlier laboratory studies. These changes in water use are likely happening all along the Rio Grande which leads to increased water conservation and reduction of the pathogenic landscape which favors survival of cattle favor ticks.
3. Native origin of invasive cattle fever ticks. Extensive field collections and genetic analysis of Rhipicephalus microplus, southern cattle fever ticks show that invasive Texas/Mexico populations match closely with populations in the Philippines and Cambodia. These studies open new areas foreign exploration in South Asia that have not been surveyed for biological control agents of this important livestock pest. Discovery of biological control agents could have a significant impact on cattle fever ticks on wild hosts such as white-tailed deer and nilgai antelope that cannot be effectively treated with acaricides.
Review Publications
Goolsby, J., Moran, P.J., Racelis, A.E., Summy, K.R., Martinez-Jimenez, M., Lacewell, R.D., Perez De Leon, A.A., Kirk, A.A. 2015. Impact of the biological control agent, Tetramesa romana (Hymenoptera: Eurytomidae) on Arundo donax (Poaceae: Arundinoideae) along the Rio Grande River in Texas. Biocontrol Science and Technology. 26(1):47-60.
Thomas, D.B. 2015. Chaseleodes, a new subgenus of Eleodes (Coleoptera: Tenebrionidae) from the central plateau of Mexico. The Coleopterists Bulletin. 14:122-126.
Triplehorn, C.A., Thomas, D.B. 2015. A revision of Eleodes subgenus Litheleodes (Coleoptera:Tenebrionidae). The Coleopterists Bulletin. 14:11-21.
Goolsby, J., Dennis, M., Schuster, G., Amalin, D., M, C., Racelis, A., Perez De Leon, A.A. 2016. Rationale for classical biological control of cattle fever ticks and proposed methods for field collection of natural enemies. Subtropical Agriculture and Environments. 66:7-15.
