The future of the Mediterranean fruit fly Ceratitis capitata invasion of California: A predictive framework Original Research Article

The objective of this paper is to predict the state-wide invasion patterns and eventual distribution and abundance of the Mediterranean fruit fly Ceratitis capitata in California if current eradication efforts fail. The predictions are based on four assumptions: (1) the medfly is established in the state; (2) existing eradication technologies are inadequate; (3) no new and effective eradication technology will be developed in the near future; and (4) the population will not become extinct due to natural causes. Based on climatic, agricultural and demographic information and historical capture patterns, the invasion is predicted to progress in five stages, the first two of which are already completed: Phase I-Introduction and establishment (in Los Angeles Basin and Bay Area); Phase II-Range expansion within LA Basin and Bay Area; Phase III-Escape from LA Basin/Bay Area and spread along Pacific coast; Phase IV-Colonization of the interior; and Phase V-Invasion completion. The highest medfly populations will probably occur along the south coast region of Los Angeles and San Diego as well as in the southern San Joaquin Valley; high population densities will also likely exist along the central coast region (Santa Barbara to Santa Cruz), in the Bay Area and in the Sacramento Valley. Low populations will exist along the north coast and populations will be rare or absent in Sierra Nevadas and in the northeastern and southeastern interior regions. Generalizations and implications for invasion biology are discussed.