Development and field evaluation of a lure-and-infect strategy integrating attractants with Beauveria bassiana for controlling Bactrocera dorsalis

The wide host range and strong dispersal ability of Bactrocera dorsalis (Hendel) have made it a persistent challenge for fruit and vegetable production in tropical and subtropical regions worldwide. Conventional control methods, including attractant-based trapping and the application of entomopathogenic fungi, each have inherent limitations when used alone. This study developed and evaluated a lure-and-infect strategy that integrates attractants with the entomopathogenic fungus Beauveria bassiana for the management of B. bassiana . First, we optimized a solid-state fermentation medium for B. bassiana mass production and identified a peptone-free formulation (C5: rice 171 g, corn meal 20 g, yeast extract 2 g, sucrose 5 g, KH ₂ PO ₄ 1 g, and FeSO ₄ ·7H ₂ O 1 g per 200 g substrate) that achieved significantly higher biomass, sporulation, and germination rates compared with other media. Subsequently, compatibility screening revealed that 50% fresh orange juice and 10% β-caryophyllene exhibited minimal inhibitory effects on fungal growth while maintaining attractant activity. Laboratory bioassays demonstrated that the lure-and-infect combinations achieved high mortality within 15 days, with horizontal transmission of conidia to non-exposed individuals. Field trials conducted in a rambutan orchard showed that the B. bassiana  + 50% orange juice treatment reduced adult density by approximately 80%, increased infection rate, and decreased fruit damage by 40.2 percentage points compared with untreated controls after 75 days. These findings demonstrate that integrating compatible attractants with entomopathogenic fungi can enhance contact probability between pathogens and highly mobile pests, providing a promising approach for sustainable B. bassiana management.