COLONIZATION OF A NEW FRUIT CROP BY ANASTREPHA-FRATERCULUS (DIPTERA, TEPHRITIDAE) IN BRAZIL - A DEMOGRAPHIC-ANALYSIS

Following the introduction of apples in Brazil in the early 1970s, Ana strepha fraterculus (Wiedemann) has become a major pest.We present a s tudy on the insect's life cycle in guavas !primary hosts) and the main apple cultivars grown in Brazil ('Gala', 'Fuji', and 'Golden Deliciou s') with particular emphasis on demographic parameters and the role pl ayed by larval physiological abilities in host range expansion by this polyphagous and aggressive species. Host type had strong effects on i mmature stages, mainly on larval development and survivorship, and the following suitability rank was observed: guava > Golden Delicious > G ala > Fuji. High mortality was observed during the immature stages, wi th only 8% egg-to-adult survivorship in apple and 24% in guava Adult p arameters were measured for guava and Gala cohorts. Guava produced adu lts with significantly higher survivorship and reproductive rates, whi ch is probably associated with higher preadult survivorship. In spite of the high mortality observed in immature stages, females showed a hi gh reproductive output, yielding positive values of intrinsic rates of increase (0.056 in guava and 0.031 in Gala apples). The status of app les as A. fraterculus hosts is discussed.