Field assessment of Phytomyza orobanchia Kalt. (Diptera, Agromyzidae) as a natural enemy of the parasitic weed Orobanche crenata Forsk. (Orobanchaceae)

Abstract Background The broomrape, Orobanche crenata Forsk. (Orobanchaceae) is a noxious root parasite weed which seriously damages the productivity of many crops, particularly in the Legumes such as faba bean Vicia faba . The parasitism caused by this weed leads to significant yield losses in infested fields. Results This study investigated the natural occurrence and infestation dynamics of the fly, Phytomyza orobanchia Kalt. in faba bean fields naturally infested by the parasitic weed O. crenata. The study was conducted during three successive faba bean seasons, 2020–2023 during, February, March, and April in two locations; Abies and Nubaria farms. The fly populations were generally low in the three seasons in February, increase to its maximum in late March in the 1st season and in April during the 2nd and 3rd seasons. In Nubaria farm, most larvae and puparia of Ph. orobanchia fly were found within the seed capsules of the O. crenata , with significantly lower proportions in plant base and stem parts. The fly preferred to attack the middle and upper fruits than lower ones. In contrast, at Abies farm, most of Ph. orobanchia flies were significantly found at plant base followed by seed capsules, and the lowest proportion was in the plant stem. Conclusions Infestation with Ph. orobanchia fly is efficient in reducing Orobanche seed yield so it has a great effect in the reduction of Orobanche seed bank. The findings suggested that the fly, Ph. orobanchia could serve as a promising biological control agent for Orobanche spp. in Egypt, especially when combined with cultivation of resistance faba bean cultivars and the application of mass rearing and release program in infested areas.