Dubas bug Ommatissus lybicus (Hemiptera: Tropiduchidae) is one of the major insects of the date palm (Phoenicx dactylifera) trees, in Oman and the most of Arab Peninsula. The main objective of this experiment was to study monitoring of larvae and adult parasitoid Bocchus hyalinus (Hymenoptera: Dryinidae) and egg parasitoid Pseudoligosita babylonica on Dubas bug O. lybicus De Berg., on date palm in Harmet village in Bahla Wilayat in the Sultanate of Oman. This work was started in autumn generation 2010 and continued until spring 2019. In this village where insecticides were not sprayed earlier, natural enemies have ability to minimize the infestation of Dubas bug in the following generation. In the laboratory studies, the samples of egg, nymph and adult stages of Dubas were inspected by using stereomicroscope to study the life cycle and behavior of the parasitoids and to find a host for mass rearing purposes. Besides, the life cycle of B. hyalinus and P. babylonica were observed, and the development of immature stage of B. hyalinus and P. babylonica were recorded. In the field studies, the seasonal activity and population density of the two natural enemies of the insect in both the spring and autumn generations were monitored in the nature where no chemicals were applied. In case of egg parasitoid P. babylonica, observations on parasitism were taken during the period from May to July of spring generation and from October to December of autumn generation. The results indicated that the percentages of parasitism of both spring and autumn generations from spring 2010 to spring 2015 were respectively as 1.9% & 5.3% in 2010, 11.5% & 13% in 2011, 9.9% & 18.3% in 2012, 7.7% & 14.8% in 2013, 10.8% & 15.6% in 2014. Whereas in spring 2015 was failed to 6.1% and then was increased in autumn by 10.4%. However, in the next seasons which included spring 2017 and 2018 was reduced approximately from 4.4% to 2.7%, respectively. The graphs and charts wear illustrated that Dubas percentage was reduction from 96.3% in spring 2010 to 84.5% in autumn 2014 after 10 generations which scored 12.3% as a reduction rate. Among all 17 generations from spring season in 2010 until spring generation in 2019 the highest parasitism percentage of P. babylonica was 19.7% in autumn 2012. In addition, there was a laboratory work for egg parasitoid P. babylonica which included the releasing of the parasite to new Dubas eggs and then dissecting under the microscope to identify the differentiation of immature stages and in determining its morphology forms.

The seasonal activity of nymph and adult parasitoid B. hyalinus was recorded from spring 2010 to spring 2015. The results indicated that the percentages of parasitism of both spring and autumn generations from spring 2010 to spring 2015 were respectively as 0% & 42.2% in 2010, 2.4% & 6.5% in 2011, 67.5% & 0% in 2012, 50.8% & 0% in 2013, 0% & 0% in 2014 and was 0% in spring 2015, respectively. The biological studies of Bocchus were continued by following the situation of parasitism by counting the infestation of Dubas and by collecting specimens of parasitized individuals and dissecting under the microscope. In addition, many female adults of parasitoid were collected and exposed to a number of Dubas bugs nymphs and adults for about 24 hours in the laboratory. After that Dubas bug adults were dissected to identify the immature stages of B. hyalinus. As a result, we observed the fourth (part inside and other outside) and fifth (inside soil) instars of larva and the pupa stage (inside soil).