Role of Parasitoids, Entomopathogens and Chemical Compounds in Managing Liriomyza congesta Populations in Faba bean Fields

Faba bean (Vicia faba L.) is an important source of dietary protein in Egypt, consumed as green vegetable, dried and canned seed. This highly nutritious crop is attacked by several insect pests, including the leafminer, Liriomyza congesta (Becker) (Diptera: Agromyzidae), which negatively affects the yield. The present investigation was conducted at the experimental farm of Sakha Agricultural Research Station, Kafr El Sheikh Governorate, Egypt during two growing seasons, 2021/2022 and 2022/2023, to monitor population dynamics of L. congesta and its larval and pupal parasitoids. In addition, the efficiency of an entomopathogen and some compounds against L. congesta larvae were investigated. The population density of L. congesta larvae was the highest in March, moderate in January and February, and lowest in December and April. Three hymenopterous parasitoids were recorded; Diglyphus isaea (Walker) (Eulophidae) which attacked L. congesta larvae with an average of 5.18 and 6.05% parasitism in the two seasons. L. congesta larvae exhibited highest rates of parasitism on January 29th (12.40%) and on March 12th (17.31%) during the first season and on February 26th (17.20%) and March 12th (20.90%) during the second season. The pupal parasitoid, Opius sp. (Braconidae) was observed with an average of 16.76 and 18.41% parasitism, in the two seasons. The highest parasitism level of Opius sp. reached 21.78 and 34.95% on February12th and March 19th, respectively, in the first season and 22.78 and 33.95%, on February 26th and March 12th, respectively, during the second season, whereas the parasitoid Chrysocharis sp. (Eulophidae) was observed at an average of 15.96 and 16.99% in the two seasons, respectively. The conventional insecticide, abamectin reduced the larval population of L. congesta by 89.85% and was superior over the entomopathogenic fungicides BioMeta (Metarhizium anisopliae) and Biossiana (Beauveria bassiana), as they produced 50.68 and 42.91% larval population reduction, respectively. The present research emphasized the effectiveness of parasitoids, entomopathogens and plant–derived materials against L. congesta as an important safe pest control agents, and their use help to reduce conventional chemical insecticide applications. Keywords: Faba bean, Liriomyza congesta, parasitoids, entomopathogens, conventional insectic