Investigation of biological control agents for the invasive plant Parthenium hysterophorus L. (Asteraceae) in Southern Oman

Parthenium hysterophorus L. (Asteraceae) is an invasive alien weed of increasing ecological and agricultural concern in Oman. Surveys in the monsoon-influenced Dhofar region to assess the natural herbivore complex associated with this species resulted in the documentation of fifteen insect taxa representing Coleoptera, Lepidoptera, Diptera, Hemiptera, and Orthoptera feeding on different plant tissues. Thirteen of these species were prioritized for detailed study of their abundance and impact on Parthenium. These included stem and leaf feeders (Nematocerus omanicus Rheinheimer, 2003; Chaetocnema tarsalis Wollaston, 1860; Aphtona cookei LeConte, 1859), a folivorous erebid moth (Hypena Schrank, 1802), flower- and leaf-feeding dipterans (Lethyna Munro, 1957; Liriomyza Mik, 1894; Phytoliriomyza cf. perpusilla (Meigen, 1830); Toxomerus floralis (Fabrícius, 1798) (New World hoverfly)), and several hemipteran sap feeders (Adria parvula (Dallas, 1851); Myzus persicae (Sulzer, 1776); Dictyopharidae Spinola, 1839; Deltocephalinae Dallas, 1870; Taylorilygus pallidulus (Blanchard, 1852), Phaenococcus Cockerell, 1902). Orthopteran assemblages were also observed consuming foliage. Abundance and distribution varied across sites, with Hypena sp, Lethyna sp, and Liriomyza sp causing substantial damage to foliage and flowers, indicating potential utility as biological control agents. In contrast, highly polyphagous taxa such as M.persicae and Phaenococcus sp. appeared less suitable due to their broad host range and associated risks to crops. These findings represent the first comprehensive inventory of herbivores feeding on P. hysterophorus in Oman and highlight candidate species for further evaluation. Targeted studies on taxonomy, life history, host specificity, and ecological interactions are required to determine their suitability for integration into biological control programs against Parthenium.