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

Abstract

The wide host range and strong dispersal ability of Bactrocera dorsalis make it a persistent challenge for fruit and vegetable production in tropical and subtropical regions. Conventional control methods, including attractant-based trapping and entomopathogenic fungi, each has inherent limitations when used alone. This study developed and evaluated a lure-and-infect strategy integrating attractants with a highly virulent entomopathogenic fungus, Beauveria bassiana, for B. dorsalis management. First, we optimized a solid-state fermentation medium for mass production, identifying a peptone-free formulation that achieved significantly higher biomass (29.65 g), conidial yield (2.44 × 10⁸ conidia/mL), and germination rate (84.51%) compared with the complete medium. Subsequently, compatibility screening revealed that 50% (v/v) fresh orange juice and 10% (v/v) β-caryophyllene exhibited minimal inhibition of fungal growth while maintaining attractant activity. Laboratory bioassays (26 ± 1 °C, 75 ± 5% RH) demonstrated that the lure-and-infect combination with 50% (v/v) orange juice enabled flies to acquire significantly more conidia per fly, resulting in substantial mortality within 15 days and horizontal transmission of infection to non-exposed individuals. Field trials in a rambutan orchard showed that the B. bassiana + 50% (v/v) orange juice treatment reduced mean adult capture to 21.6 flies/trap (control: 48.3), achieved a 38.3% infection rate, and decreased fruit damage by 40.2 percentage points after 75 days. These findings demonstrate that integrating compatible attractants with entomopathogenic fungi can enhance contact between pathogens and highly mobile pests. Future studies should focus on multi-season field evaluations and formulation standardization for biosafety compliance, to further advance this promising IPM approach.