Evidence of competitive displacement of Bactrocera dorsalis (Hendel) by Bactrocera zonata (Saunders) (Tephritidae: Diptera) in guava Psidium guajava ecosystem in Sudan.

Abstract Oriental fruit fly (OFF) Bactrocera dorsalis and (Peach fruit fly) (PFF) B. zonata are the most notorious pests that invaded Sudan in 2005 and 2012 respectively, causing severe losses and hindered horticultural production and exportation. Monitoring fruit flies to determine species composition, seasonality and occurrence of competitive displacement was conducted in two guava orchards in Gezira State; Fadasi and Gezirat Elfil, using food bait attractant and rearing flies from infested fruits procedure (Infestation level). The role of longevity and survival percentages of developmental stages in displacement of species was determined. Monitoring population of fruit flies using Torula yeast and rearing of fruit flies form guava Psidium guajava fruits revealed that OFF and PFF were the most prevalent species in guava ecosystem at both sites. At Fadasi site PFF was the dominant species representing (99.3%) of the guild of the trapped flies with (99.6%) (Flies/Kg of guava fruits) as infestation level. At G. Elfil, (OFF) represented (80.8%) of the trapped flies with infestation level ca 53.6% (Flies/Kg of guava fruits). Longevity of developmental stages of (PFF) was shorter than that of (OFF) by 9.2 days, while its survival percentage was higher than that of OFF for all developmental stages. Competitive displacement of OFF by PFF in guava orchards at Fadasi site has already occurred and could be attributed to the mono cropping system, short period and high survival percentage of developmental stages of PFF compared to that of OFF.