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. ^

The new Jamaican migration : implications for theory and practice

While analysis of the effect which education and migration have on development is neither clear cut, nor obvious, regimes such as those of Jamaica have traditionally placed great emphasis on development through education at all levels. The process of human resource development and the accumulation of human capital is intended to unlock the door to modernization. Nevertheless, our findings indicate a considerable loss of professional and skilled personnel -- the same group that embody a disproportionate amount of educational expenditure relative to the population. Insofar as planning is concerned this migration represents a negative factor. The developing country of Jamaica is unintentionally supplying the developed world with an "annual gift" of human capital which its economy cannot afford. The major issue becomes: to what extent can any government "protect" its investments by restricting movements of capital and people. The general assumption of this paper is that the question of human rights cannot be ignored especially in democracies (which Jamaica decidedly is), where movement is seen as an ingrained human right. During the 1970s and 1980s, Jamaica and the Caribbean as a whole has lost much through intellectual capital migrations. Yet brains may also die in their own environment, if deprived the ability to create their own criteria and goals. Forcing people to stay with their money and know-how may only serve to produce and economic environment overgrown with weeds of lethargy, indolence and mediocrity.