Ecological genetics of Melaleuca quinquenervia (Myrtaceae): Population variation in Florida and its influence on performance of the biological control agent Oxyops vitiosa (Coleoptera: Curculionidae)

Melaleuca quinquenervia (Cav.) Blake (Myrtaceae) was imported into Florida from Australia over a century ago as a landscape plant. A favorable climate and periodic wildfires helped M. quinquenervia thrive; it now occupies about 200,000 hectares in southern Florida. A biological control (i.e., biocontrol) program against M. quinquenervia has been initiated, but not all biocontrol releases are successful. Some scientists have argued that poor biocontrol agent success may relate to genetic differences among populations of invasive weeds. I tested this premise by determining (1) the number and origins of M. quinquenervia introductions into Florida, (2) whether multiple introduction events resulted in the partitioning of Florida's M. quinquenervia populations into discrete biotypes, and (3) whether Oxyops vitiosa, an Australia snout beetle imported to control this weed, might discriminate among putative M. quinquenervia biotypes. Careful scrutiny of early horticultural catalogs and USDA plant introduction records suggested at least six distinct introduction events. Allozyme analyses indicated that the pattern of these introductions, and the subsequent redistribution of progeny, has resulted in geographic structuring of the populations in southern Florida. For example, trees on Florida's Gulf Coast had a greater effective number of alleles and exhibited greater heterozygosity than trees on the Atlantic Coast. Essential oil yields from M. quinquenervia leaves followed a similar trend; Gulf Coast trees yielded nearly twice as much oil as Atlantic Coast trees when both were grown in a common garden. These differences were partially explained by the predominance of a chemical phenotype (chemotype) very rich in the sesquiterpene (E)-nerolidol in M. quinquenervia trees from the Gulf Coast, but rich in a mixture of the monoterpene 1,8-cineole and the sesquiterpene viridiflorol in trees from the Atlantic Coast. Performance of O. vitiosa differed dramatically in laboratory studies depending on the chemotype of the foliage they were fed. Larval survivorship was four-fold greater on the (E)-nerolidol chemotype. Growth was also greater, with adult O. vitiosa gaining nearly 50% more biomass on the (E)-nerolidol plants than on the second chemotype. The results of this study thus confirmed the premise that plant genotype can affect the population dynamics of insects released as weed biocontrols. ^

Altered Landscape or Arms Race? Making Sense of Military Spending in South America

In 2009, South American military spending reached a total of $51.8 billion, a fifty percent increased from 2000 expenditures. The five-year moving average of arms transfers to South America was 150 percent higher from 2005 to 2009 than figures for 2000 to 2004.[1] These figures and others have led some observers to conclude that Latin America is engaged in an arms race. Other reasons, however, account for Latin America’s large military expenditure. Among them: Several countries have undertaken long-prolonged modernization efforts, recently made possible by six years of consistent regional growth.[2] A generational shift is at hand. Armed Forces are beginning to shed the stigma and association with past dictatorial regimes.[3] Countries are pursuing specific individual strategies, rather than reacting to purchases made by neighbors. For example, Brazil wants to attain greater control of its Amazon rainforests and offshore territories, Colombia’s spending demonstrates a response to internal threats, and Chile is continuing a modernization process begun in the 1990s.[4] Concerns remain, however: Venezuela continues to demonstrate poor democratic governance and a lack of transparency; neighbor-state relations between Colombia and Venezuela, Peru and Chile, and Bolivia and Paraguay, must all continue to be monitored; and Brazil’s military purchases, although legitimate, will likely result in a large accumulation of equipment.[5] These concerns can be best addressed by strengthening and garnering greater participation in transparent procurement mechanism.[6] The United States can do its part by supporting Latin American efforts to embrace the transparency process. _________________ [1] Bromley, Mark, “An Arms Race in Our Hemisphere? Discussing the Trends and Implications of Military Expenditures in South America,” Brookings Institution Conference, Washington, D.C., June 3rd, 2010, Transcript Pgs. 12,13, and 16 [2] Robledo, Marcos, “The Rearmament Debate: A Chilean Perspective,” Power Point presentation, slide 18, 2010 Western Hemisphere Security Colloquium, Miami, Florida, May 25th-26th, 2010 [3] Yopo, Boris, “¿Carrera Armamentista en la Regiόn?” La Tercera, November 2nd, 2009, http://www.latercera.com/contenido/895_197084_9.shtml, accessed October 8th, 2010 [4] Walser, Ray, “An Arms Race in Our Hemisphere? Discussing the Trends and Implications of Military Expenditures in South America,” Brookings Institution Conference, Washington, D.C., June 3rd, 2010, Transcript Pgs. 49,50,53 and 54 [5] Ibid., Guevara, Iñigo, Pg. 22 [6] Ibid., Bromley, Mark, Pgs. 18 and 19