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

Oriental fruit fly (OFF) Bactrocera dorsalis and peach fruit fly (PFF) Bactrocera zonata are the most notorious pests that invaded Sudan in 2005 and 2012, respectively, causing severe losses and hindering horticultural production and exports. Prior to 2012, OFF was the most abundant fly in guava orchards in Gezira State. Monitoring fruit flies to determine species composition, seasonality, and possibilities of competitive displacement was conducted in two guava (Psidium guajava) orchards in Gezira State; Fadasi and Gezirat Elfil, using food bait attractant and rearing flies from infested fruits..Longevity and survival percentages of developmental stages of the two species were also determined. Monitoring fly populations using Torula yeast and rearing of fruit flies from guava fruits revealed that OFF and PFF were the most prevalent species in guava ecosystem at both sites. At the Fadasi site, PFF was the predominant species representing (99.3%) of the guild of the trapped flies with an infestation level of 99.6%) flies/kg of guava fruits. At G. Elfil, OFF comprised 80.8% of the trapped flies with infestation level ca 53.6% while 19.2% of trapped flies were B. zonata with 46.4% infestation level. The high percentage of trapped OFF at G. Elfil might be attributed to multi-cropping system in the area. Developmental stages of PFF were 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 may have occurred as a result of the mono-cropping system, short developmental period, and high survival percentage of developmental stages of PFF on guava compared to that of OFF.