English abstract
Fruit flies from the family Tephritidae (true fruit flies) are important insect pests on
fruit trees and cucurbits in Oman. World-wide, there are different control methods for
the management of fruit flies including cultural, biological and chemical control
methods. In Oman, there is high emphasis on chemical control methods. However,
there are no effective yet economically feasible alternatives to the current dependence
on chemical control in Oman. The present study was done to develop an effective lure
system for female fruit flies based on ammonia releasing compounds and to improve
the efficiency of currently used male lures. Experiments were conducted in a mango
farm in Qurayyat Wilayat (Muscat Governorate) from April to October 2021, and were
divided into male and female lure experiments. In female lure experiments, traps
containing different urea concentrations, urea concentrations plus ground water melon
seeds, and other ammonia- producing lures, were hung on mango trees. In male lure
experiments, methyl eugenol (ME) products, from different manufacturers were tested
for efficacy in attracting fruit flies. In addition, trap design, lure status (dry or
immersed in water in trap) and ME longevity were tested. Results showed that with
increasing urea concentration, the fruit flies catch was also increasing. However, when
ground watermelon seeds were added to urea, this direct relationship was not valid for
the lowest concentration (7 g urea per 700 mL water) which had greater fruit fly
catches than those of higher urea concentrations, except for the highest concentration
(140 g per 700 mL water). Moreover, the addition of ground watermelon (at 0.2g per
700 ml water) to different urea concentrations significantly increased fruit fly catches
relative to treatments containing urea only. It was also noticed that urea treatments
(different concentrations with and without ground watermelon seeds) were attracting
a high percentage of fruit flies, while other tested lures (especially yeast-based lures)
were either attracting equal percentages of fruit flies and other flies, or attracting a low
percentage of fruit flies. There were significant differences among ME lures from
different manufacturers, with Chemtica ME being the best in terms of having the
highest catch of fruit flies when water was added to traps.
However, Chinese ME was the best when no water was added to traps. SunPet jar trap
(750 mL clear plastic jar having four holes) with no vial inserts in its holes was the
most catching trap design when lures were applied in water inside traps, but MacPhail
trap had the highest catch when lures were applied without water. Methyl eugenol (as
IPS lure) needs to be changed every 4 weeks to ensure maximum efficacy in caching
male fruit flies. Overall, this study indicates that urea is an effective, inexpensive and
environmentally friendly substitute to the use of synthetic insecticides in terms of
lowering the population of female fruit flies, especially when sufficient number of
traps per tree are placed over a large agricultural area (area-wide trapping). In addition,
the study evidently demonstrates that the addition of water to ME traps increases the
catches of male fruit flies. Moreover, ME lures from manufactures such as Chemtica
and Chinese are more effective than the Russell IPM lure while having a cost similar
to or lower than the latter. Therefore, they should be adopted for more common use in
Oman as part of an area-wide IPM program.
