Comparative analysis of development and survival of two Natal fruit fly Ceratitis rosa Karsch (Diptera, Tephritidae) populations from Kenya and South Africa

Comparative analysis of development and survivorship of two geographically divergent populations of the Natal fruit fly Ceratitis rosa Karsch designated as C. rosa R1 and C. rosa R2 from Kenya and South Africa were studied at seven constant temperatures (10, 15, 20, 25, 30, 33, 35 degrees C). Temperature range for development and survival of both populations was 15-35 degrees C. The developmental duration was found to significantly decrease with increasing temperature for C. rosa R1 and C. rosa R2 from both countries. Survivorship of all the immature stages of C. rosa R1 and C. rosa R2 from Kenya was highest over the range of 20-30 degrees C (87-95%) and lowest at 15 and 35 degrees C (61-76%). Survivorship of larvae of C. rosa R1 and C. rosa R2 from South Africa was lowest at 35 degrees C (22%) and 33 degrees C (0.33%), respectively. Results from temperature summation models showed that C. rosa R2 (egg, larva and pupa) from both countries were better adapted to low temperatures than R1, based on lower developmental threshold. Minimum larval temperature threshold for Kenyan populations were 11.27 degrees C and 6.34 degrees C (R1 and R2, respectively) compared to 8.99 degrees C and 7.74 degrees C (R1 and R2, respectively) for the South African populations. Total degree-day (DD) accumulation for the Kenyan populations were estimated at 302.75 (C. rosa R1) and 413.53 (C. rosa R2) compared to 287.35 (C. rosa R1) and 344.3 (C. rosa R2) for the South African populations. These results demonstrate that C. rosa R1 and C. rosa R2 from both countries were physiologically distinct in their response to different temperature regimes and support the existence of two genetically distinct populations of C. rosa. It also suggests the need for taxonomic revision of C. rosa, however, additional information on morphological characterization of C. rosa R1 and C. rosa R2 is needed.