الملخص الإنجليزي
Fruit flies are important pests of fruit and vegetable crops. They cause significant
economic losses to farmers. The objectives of this study were to characterize the fruit
fly species present in Oman, their geographical distribution, host plants, and
parasitoids, and to evaluate the effect of plant extracts and entomopathogenic fungi
against Bactrocera dorsalis and B. zonata. Fruit samples were collected from different
locations across Oman during 2019 and 2020. Fruit flies that emerged from fruits were
then identified using morphological and molecular characterization methods. Results
showed that there were eight fruit fly species in Oman. The polyphagous Bactrocera
dorsalis and Bactrocera zonata were collected from fruits of different trees, while
Dacus ciliatus was collected from cucurbit fruits. Carpomyia vesuviana and
Carpomyia incompleta were collected from fruits of Ziziphus species. Dacus persicus
was collected from the wild plant, Calotropis procera (Sodom's apple). Bactrocera
oleae was collected from fruits of the wild olive (Olea europea) in Al-Jabal Al
Akhdhar Wilayat. Capparimyia savastani was collected from flower buds of wild
Capparis cartilaginea (relative of caper). The most widely distributed fruit flies were
B. zonata and D. ciliatus, however, there were variation in the presence and abundance
of B. zonata and B. dorsalis in different locations. In Musandam and Al Batinah North
only B. zonata was present and this species was more dominant in Al Mudaibi (Al
Rowdah), Al Awabi (Al Alia), Yanqul (Al Buwairdeh) and Al Jabal Al Akhdar (Seeq).
B. dorsalis was found to be more dominant in Salalah (Al Baleed, AdDahareez), Al
Kamil & Al Wafi (Saiq), Qurayat (Hail Al Ghaf) and Samail (Wadi Samail). Molecular
fingerprinting allowed the correct identification of Dacus persicus, as specimens from
Oman were previously known in error as D. longistylus, a closely related species found
in Africa. Braconid parasitoids collected from sampled fruits included Fopius arisanus
from Ziziphus spp., Psyttalia concolor from cucurbits and Ziziphus spp., and
Diachasmimorpha longicaudata from Indian almond. Numerically, these parasitic
wasps were mainly associated with B. zonata, C. vesuviana and C. incompleta on
Ziziphus fruits. Different local plant extracts and commercial substances of plant origin
were tested as oviposition deterrents against B. zonata and B. dorsalis. Two different
methods were used to determine the deterrent effect of the extracts, the first one using
fresh fruits and counting the resulting puparia numbers, and the second using mango
domes and counting the egg numbers in each dome. Neem, linalool, and extracts of
frankincense resin, juniper, and fresh garlic showed good oviposition deterrence
effects under laboratory conditions. Neem showed significant deterrent effect at a
concentration of 0.003%. Fresh garlic and linalool caused reduction in puparia
numbers reaching 80.7% and 86.2%, while frankincense at 100% and 50%
concentrations, and juniper caused reduction in eggs numbers reaching 61.1%, 31.0%
and 59.1% respectively. The effects of entomopathogenic fungi were tested against
adults and larvae of B. zonata under laboratory conditions. Among the
entomopathogenic fungi used, Beauveria bassiana fungal spores in the Botanigard
formulation was effective on adults, causing 97.5% mortality due to direct application
to both adults and caging container, and 88% mortality due to indirect application (on
cage walls only). The same material was also effective on the larvae, causing 28%
mortality. The T Stanes Verticillium lecanii formulation caused 20% and 6.67%
mortality on larvae and puparia respectively.
